Proceedings of 2022 6th International Conference on Green Technology and Sustainable Development (GTSD)

July29-30,2022-NhaTrangCity,Vietnam
PROCEEDINGS OF
TH
20226 INTERNATIONALCONFERENCE
ONGREENTECHNOLOGY
ANDSUSTAINABLEDEVELOPMENT
(GTSD)
VNUHCM PRESS

Proceedings of
2022 6th
International Conference on Green Technology
and Sustainable Development (GTSD)
July 29-30, 2022 - Nha Trang City, Vietnam
VNUHCM PRESS

2022 6th
International Conference on Green Technology and Sustainable Development (GTSD)
i
Table of Contents
Editors Preface.....................................................................................................................................................viii
GTSD2022 Organizing Committee.........................................................................................................................ix
A Novel Mechanism Design following Augmented Objective with Flexible Energy Control.........................1
Xuan Phu Do and Van Chi Le
Evaluating Green Marketing Trending Determinants by a Text Mining Approach......................................5
Phan-Anh-Huy Nguyen
A Simple Synthesis of Antibacterial and Antifungal ZnO Nanorods ...............................................................8
Khanh Son Trinh and Vinh Tien Nguyen
An Assessment of Complementary Energy of HPFRCs under Tension.........................................................15
Duy-Liem Nguyen, Tien-Tho Do, Thi-Ngoc-Han Vuong and H. T. Tai Nguyen
A Study of the Scavenging Process in a Two-stroke Free Piston Linear Engine at Low Velocity Using
CFD and DPM .....................................................................................................................................................21
Nguyen Huynh Thi, Nguyen Van Trang, Huynh Thanh Cong, Dao Huu Huy, Huynh Van Loc, Truong Hoa
Hiep, Ngo Duc Huy and Vo Bao Toan
Investigating the Relationship between Workers’ Needs and Commitments to Garment Enterprise........27
Tu Tran
Optimization of Aggregates in Concrete Brick with Recycled Materials from Stone...................................32
Nguyen Thang Xiem, Ho Minh Chau, Tran Doan Hung and Truong Thanh Chung
A Comparison on the Flexural Capacity and Dynamic Performance of a Reinforced Concrete Beam
and a Steel Beam in a High-rise Building..........................................................................................................36
Tham Hong Duong
Optimization Model for Biomass Supply Chain Planning: A Case Study in Mekong River Delta –
Vietnam ................................................................................................................................................................44
Thi-Be-Oanh Cao, Duc Duy Nguyen, Thanh-Tuan Dang and Chia-Nan Wang
Developing a Digital Competence Performance Assessment Platform for University Students Based on
the DigComp Framework ...................................................................................................................................50
Anh Tho Mai, Thi Kim Oanh Duong and Anh Tuan Ngo
The Performance of Geonet Reinforced Straw Rolls as a Flexible Waterbreaker for Riverbank
Protection .............................................................................................................................................................57
Minh-Duc Nguyen, Le-Nhat-Huy Nguyen and Tran-Phuong-Thao Hua
SSD21, Educational Toolbox for Static, Stability, and Dynamic Analysis of Frame ....................................63
Truong Thanh Chung, Le Nguyen Anh Vu, Le Cong Lap and Nguyen Thang Xiem
Digital Competence of University Students: A Comparative Study at Three Universities in Vietnam.......67
Anh Tho Mai, Quynh Trang Mai and Anh Tuan Ngo

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Load Capacity Evaluation of Simple Reinforced Concrete Girder Bridges with Considering the
Corrosion of Reinforcement and Concrete .......................................................................................................75
Tran The Truyen, Tran Thu Minh, Nguyen Dac Duc, Tran Duc Manh and Nguyen Quoc Cuong
Effect of Biodegradable and Metallic Mordants on Dyeing Cotton Fabric with Spent Coffee Grounds....80
Tuan Anh Nguyen
The Importance of Green Technology for Sustainable Development Education: A Case Study at Lac
Hong University...................................................................................................................................................85
Nga Hong Thi Doan and Truong Van Nguyen
Unique Competitive Advantages of Vietnam’s Garment Industry in the Sustainable Development
Trend ...................................................................................................................................................................89
Quang-Tri Tran, Thanh-Nhan Nguyen, Tho Alang, Tuyet-Anh Truong, Kim-Chi Le and Nguyen Thi Le
Driving Factors of Green Economy for Smart Cities in the Context of Developing Countries ...................95
Tiep Nguyen, Nghia Hoai Nguyen, Leonie Hallo and Bao Van Pham
Impacts of Green Training on Green Competencies of Employees: Empirical Case of Industrial
Manufacturers in Dong Nai Parks...................................................................................................................101
Thanh-Lam Nguyen, Doan Thi Chuyen, Nguyen Thi Phuong Thao and Doan Van Ly
Mathematical Modelling of Combined Infrared and Heat Pump Drying of Squid ....................................107
Pham Van Toan, Phan Nhu Quan, Nguyen Hay and Le Anh Duc
Improving the Tensile and Compressive Strength of Cement-Based Materials by Hybrid Electrospun
Nanofibers ..........................................................................................................................................................114
Tri N. M. Nguyen, Xuan Tung Nguyen, Thanh Toan Dao, Huy Q. Nguyen and Jung J. Kim
Controlling Crystal Morphology via Crystallization Processes, Cases Studied of KDP and Zinc Lactate
.............................................................................................................................................................................118
Tam Le-Minh, Cuong Nguyen Van and Venkata Subbarayudu Sistla
A Green Solution for Kitchen Waste Treatment Using Earthworm, Experimental and Mathematical
Approaches.........................................................................................................................................................122
Tam Le-Minh, Phuong Pham Thi Hong and Nhu Vo Thi Thu
Effect of Reinforcement Corrosion on Crack Development in Concrete Under Load ...............................127
Vo Van Nam and Tran The Truyen
Study on Synthesizing and Size Controlling of Silver Nanoparticles by Using a System of Two
Protectants Trisodium Citrate and Polyvinylpyrrolidone.............................................................................132
Hien Chuc Mai, Quynh Nguyen Thi Nhu, Thuan Hoang Duc, Du Cao Van, Cuong Ngo Van and Dung Duong
Thi Ngoc
Study on Chemical Composition and In-vitro Biological Activities of Salvia officinalis L. in Lamdong,
Vietnam ..............................................................................................................................................................137
Thao Tran Thach, Cuong Ngo Van and Xuan Nguyen Bang
Dynamic Analysis of Plates under Moving Discontinuous Impulsive Load on Viscoelastic Foundation..141
The Tuan Nguyen and Trong Phuoc Nguyen

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Isolation and Quantitative Determination of Geniposide from Gardenia jasminoides Ellis. Using High-
Performance Liquid Chromatography............................................................................................................147
Vo Thi Nga, Truong Thi Khanh Van and Bui Trung Huu
Oxygen-LPG Torch for Thermal Spraying.....................................................................................................152
Ngo Thanh Binh, Le Van Canh and Pham Huy Dong
Predicting Land Use Change in Buon Ma Thuot City, Dak Lak Province by Integrating GIS and
Markov Chain....................................................................................................................................................158
Nguyen Thi Ngoc Quyen, Nguyen Thi Tinh Au, Nguyen Cong Tai Anh and Tran Thi Xuan Phan
Dissimilar Friction Stir Welded Lap-joint of Aluminum Alloy 6061 and 316 Stainless Steel....................165
Huy Huu Ho, Hao Dinh Duong, Nam Hoai Quach, Thuyen Van Phi, and Tra Hung Tran
A Stochastic Half-Car Model for Vibration Analysis with Uncertain Parameters .....................................169
Nguyen Van Thuan
Sources of Payment Risks to Contractors in the Vietnam Construction Industry......................................173
Duong Vuong, Thao Huynh and Phu Tran
Pharmacognostic Assessment of Polyscias Fruticosa Leaves in Vietnam.....................................................180
Dao Phan Thi Anh, Hue Ha Thi, Trang Le Vu Khanh, Thanh Le Duc, Huong Nguyen Thi Thu and Trieu Ly
Hai
Alkali-Activated Slag/Sugarcane Bagasse Ash Pastes Cured in Room-Air Ambient and in Saturated
Lime Water: A Study on the Compressive Strength and Shrinkage............................................................185
Duc-Hien Le and My Ngoc-Tra Lam
Production Efficiency Improvement Using Value Stream Mapping with Simulation: A Case Study in
Vietnam ..............................................................................................................................................................191
Xuan-Quang Bach, Thanh-Tuan Dang and Chia-Nan Wang
Study on the Effect of Mixing Ratio of Biodiesel Fuel Made from Animal Fat on Exhaust Emissions of
the Fishing Vessel’s Diesel Engines..................................................................................................................199
Pham Dinh Trung, Mai Duc Nghia and Ho Duc Tuan
A Study on Mechanical Properties of Ca-Alginate Hydrogels ......................................................................204
Thanh Tan Nguyen, Van Tron Tran, Long Nhut-Phi Nguyen and Nguyen Thi My Le
Mechanical Characteristics of PBT Based Blend ...........................................................................................208
Hoang-Khang Lu, Ngoc Tran-Nhu Nguyen, Huy Huynh-Nhat Do, Van-Huong Hoang, Van-Thuc Nguyen,
Nga Thi-Hong Pham, Van-Tron Tran, Long Nhut-Phi Nguyen and Thanh-Tan Nguyen
An Evaluation of Corporation Social Responsibility Performance for Vietnamese Contractors..............213
Nguyen Van Minh, Ha Duy Khanh, Soo Yong Kim and Chu Viet Cuong
Local Waste Seeds as Organic-Based Coagulant Aids in Water and Wastewater Treatment...................218
Nhung Thi-Tuyet Hoang, Anh Thi-Kim Tran and Luu Hong Quang
The Implementation of 5C’s in Online-Foreign Language Teaching for Vietnamese Students in the 4.0
Era.......................................................................................................................................................................222
Chau Le Thi Bao, Nhu Vo Hoang Nhu and Nhi Ho Yen

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Antibacterial Activity of Aqueous Extracts from Marine Sponges Found in Vietnam’s Sea.....................229
Huynh Nguyen Duy Bao and Nguyen Khac Bat
Digital Competence of University Students: Developing Information and Data Literacy for IT
Students at Ho Chi Minh City University of Technology and Education ....................................................233
Anh Tho Mai and Quynh Trang Mai
A Simple Design Method for Piled Raft Foundations ....................................................................................239
Tong Nguyen, Nhat Nguyen Le Anh and Dat Nguyen Thanh
Evaluating Performance of Petroleum Industry Using Data Envelopment Analysis: A Case Study in
Vietnam ..............................................................................................................................................................247
Kristofer Neal C. Imperial, Chia-Nan Wang, Thanh-Tuan Dang and Nguyen Ngoc Hiep
Fire Resistance Properties and Geopolymer Coating ....................................................................................254
Van Su Le, Van Vu Nguyen, Artem Sharko, Doan Hung Tran, Petr Louda, Piotr Los, Thang Xiem Nguyen,
Stanislaw Mitura and Katarzyna Buczkowska
Effects of Intake Air Temperature on Power and Emission Characteristics of the HCCI Engine Fueled
with the Blends of 15% Ethanol and 85% Petrol Fuels.................................................................................259
Minh Xuan Le and Thanh Tuan Nguyen
Linear Viscoelastic Characterization of an SMA Mixture Using Dynamic Indirect Tensile Test.............263
H. T. Tai Nguyen, Hong Ha Mai and Van Hien Nguyen
Effect of the Limestone Powder Content on the Properties of Alkali–Activated Slag Mortar ..................268
Tai Tran Thanh, Chung Pham Duy, Tu Nguyen Thanh and Hyug-Moon Kwon
The Educational Philosophy of Existentialism with the Development of Personalized Learning for
Learners in Massive Open Online Courses (MOOCs) – The Case of Ho Chi Minh City University of
Technology and Education ...............................................................................................................................273
Thi Thao Tran, Tran Phuong Thao Hua and Thi Chu Tran
Transportation Infrastructure Strategy for Sustainable Development: A Case Study of Vietnam
Mekong Delta.....................................................................................................................................................281
Le Thu Huyen
Study on Behaviour of Short Pile Groups in Soft Ground with Sand Leveling on a Small Scale Model
Using Schneebeli Analogue Soil........................................................................................................................286
Sy Hung Nguyen and Thi Phuong Huyen Tran
Research and Preparation of Thinking Strategies for Quality of Textile and Garment Products
Manufactured in Vietnam.................................................................................................................................292
Nguyen Phuoc Son, Nguyen Ngoc Chau and Nguyen Thi Tuyet Trinh
Building Students’ Self-Reliant on Problem-Based Learning by Embedding Mind of Engineering
Design Concept at HCMC University of Technology and Education...........................................................296
Xuan Tien Vo
Modeling and Comprehensive Assessment of Construction Risks: A Perspective of PPP
Transportation Projects....................................................................................................................................300
Ha Duy Khanh, Soo-Yong Kim and Nguyen Van Khoa

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Fabrication of Graphene Oxide from the Graphite Rod of a Disposed Battery..........................................305
Huy-Binh Do, Hoang-Trung Huynh, Thien-Trang Nguyen, Van-Cuong Pham, Tien-Luat Nguyen, Anh-Vu
Phan-Gia and Maria Merlyne De Souza
Design and Optimization of a Compliant Mechanism for Vibration-Assisted Drilling..............................309
Hai-Thanh Nguyen, Van-Khien Nguyen, Phan-Khanh-Tam Nguyen, Huy-Tuan Pham, Quang-Khoa Dang
and Pham Son Minh
Eco-friendly Adsorbent Formulated from Rubber Shell Biochar to Remove Chromium (Cr(VI)) from
Aqueous Solutions .............................................................................................................................................313
Linh My Nguyen
A Study on the Effect of the Shape of the Center Rib on Thermal Resistance on the Dual-Layer Micro-
channel Heat Sink..............................................................................................................................................317
Hung-Son Dang and Thi-Anh-Tuyet Nguyen
Experimental Study of the Effect of Heat Input on Tensile Strength and Microstructure of the Weld
using the Orbital TIG Welding Process ..........................................................................................................321
Thien Tran Ngoc, Ngoc-Huy Dinh, An-Duong Tra, Kha-Duy Doan, Binh-Minh Ngo and Anh-Duc Pham Duc
A Study of Customer Satisfaction in Online Food Delivery Service Quality During the Covid-19
Pandemic: Baemin’s Case Study......................................................................................................................326
Hong-Xuyen Thi Ho, Ngoc-Tra Tran Thi and Ngoc-Anh Ha Thi
Controllable Green Synthesis and Morphological Properties of Gold Nanostar ........................................332
P. Quoc-Duy Huynh, Van-Dung Le, Chi-Hien Dang, Radek Fajgar, The-Ha Stuchlikova, Jiri Stuchlik and
Thanh-Danh Nguyen
Isolation, Selection and Identification of the Probiotic Properties of Lactobacillus spp. from Shrimp
Ponds in Nhon Trach, Dong Nai.......................................................................................................................336
Doan Thi Tuyet Le, Le Thi Thu Huong, Phan Pham, Pham Minh Thinh, Vo Thi Lan Chi, Nguyen Phuoc
Trung, Huynh Minh Hieu and Do Minh Anh
Production of Cheese from Reconstituted Milk and Soy Milk with the Addition of Microbial
Transglutaminase ..............................................................................................................................................340
Pham Thi Hoan and Trinh Khanh Son
Studying the Effect of Biodiesel Blend Ratios Derived from Rubber Seed Oil on the Technical
Characteristics of Diesel Engines without Modifying the Structure by Simulation and Experiment .......349
Nguyen Manh Cuong and Huynh Phuoc Son
Work from Home during the Covid-19 Pandemic: A Qualitative Research with Women Taking Care
of Young Children.............................................................................................................................................355
Hien Phan Thi Thanh, Thuy Nguyen Thi Thanh and Tram Nguyen Thi Mai
Study on Determining the Freezing Mode of Frozen Fillet Bigeye Tuna (Thunnus obesus) ......................361
Dzung Tan Nguyen, Linh Khanh Thuy Do, Chuyen Van Hoang and Tuan Thanh Chau
Numerical Investigation of the Optimum Operating Condition in Magnetically Confined Plasma with
Sheared Slab Ion-Temperature-Gradient Model ...........................................................................................367
Thanh Tinh Tran

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Using Brake and Engine Torque to Control Traction on Either Side of the Drive Wheel .........................371
Tan Tai Phan and Van Nhu Tran
Fatigue Life of Accelerated Corroded Steel Plate ..........................................................................................377
Dao Duy Kien, Nguyen Thanh Hung, Nguyen Thi Thu Hao, Nguyen Van Hung and Haidang Phan
A Study on Ultrasonic Shear Horizontal Waves in Composite Structures ..................................................381
Duy Kien Dao, Hoang Ngoc Quy, Truong Giang Nguyen, Ductho Le, Hoai Nguyen and Haidang Phan
Designing and Modeling Pipe Welding Machine............................................................................................385
Tuong Phuoc Tho, Phan Phuc Khang, Tran Thanh Nhon and Pham Phi Long
Investigation of the Mechanical Properties of Lightweight Geopolymer Concrete Using Keramzite as
Coarse Aggregate...............................................................................................................................................390
Kiet Tran Tuan, Duc Nguyen Phan, Tuan Le Anh, Khoa Nguyen Tan and An Huynh Thao
Researching and Improving the Registration and Treatment Process in Health Care Facility with Lean
Principles and Ergonomics Standards.............................................................................................................394
Minh-Tai Le
Application of Lean and Six Sigma Tools to Improve Productivity and Product Quality at Dien Quang
Company, Vietnam............................................................................................................................................401
Minh Tai Le, Hoang Khang Lu and Nhat Huy Do Huynh
Hydrogen Plasma Annealed Gallium and Aluminum co-doped Zinc Oxide Films Applied in Low-
emissivity Glass..................................................................................................................................................408
Shang-Chou Chang, Yun-Che Tsai, Huang-Tian Chan, Jian-Liang Lai, Jian-Syun Wu and Wei-Min Wang
Study on Pectinase Production by Bacillus subtilis in Molasses and Its Application for Coffee
Fermentation......................................................................................................................................................412
Ngan K. Le, Duy Q. Nguyen, Nhi Y. Dinh and Phu H. Le
Environmental Sustainability: Exploring Managers’ Attitudes and Behaviours at High-End
Accommodation Businesses in Vietnam ..........................................................................................................417
Thanh-Nhan Nguyen, Quang-Tri Tran and Tho Alang
Research on Optimal Algorithms Using Experimental Planning to Improve Shoe Production Line
Productivity........................................................................................................................................................425
Minh Tai Le, Thi Cam Duyen Doan and Huynh Thao Vy Nguyen
Application of Multivariable Linear Regression Algorithm to Support Inventory Management.............431
Trung Tin Ngo, Minh Tai Le, Nguyen Kim Thoa Vo and Thanh Nam Luong
Ethanol in Gasoline Fuel Blends: Experimental Investigation Effects on Exhaust Emission of the
Homogeneous Charge Compression Ignition Engine.....................................................................................437
Minh Xuan Le and Thanh Tuan Nguyen
The Impact of the Industrial Revolution 4.0 on Logistics Businesses: A Case in Mekong Delta...............441
Ngo Hong Ngoc and Huang Ying Yin

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Enhancement in Dielectric Constant of Poly Vinyl Alcohol by Loading of Strontium Titanate for
Supercapacitor Applications ............................................................................................................................447
Anju Yadav, Dinesh Kumar Yadav, Khushbu Meena, Kiran Devat, Narendra Jakhar, Rajesh Sahu, S. K. Jain
and Balram Tripathi
Free Vibration Analysis of Smart FG Porous Plates Reinforced by Graphene Platelets Using
Isogeometric Approach.....................................................................................................................................451
Lieu B. Nguyen and Duc-Thien Pham
Free Vibration of MSGT Porous Metal Foam Microplates Using a Moving Kriging Meshfree
Approach............................................................................................................................................................459
P. T. Hung
Impacts of Adverse Weather on Mode Choice Behavior: A case study in Hanoi City, Vietnam...............469
Binh Nguyen Mai, Thi Anh Hong Nguyen, Akimasa Fujiwara and Canh Do
Travel Behavior on Ground Access Mode Choices by Introducing a New City Air Terminal: A Case
Study of Vientiane Airport, Laos.....................................................................................................................474
Komack Keochampa, Canh Do, Akimasa Fujiwara and Thi Anh Hong Nguyen
A Study of The Tensile Strength for The Mixing Ratio of Eva in Pa6/Eva Blends.....................................482
Minh-Nhat Nguyen, Quy-Long Nguyen, Ngoc-Thien Tran, Vinh-Tien Nguyen and Minh The-Uyen Tran
Cytotoxicity of Isoxazole/Pyrazole Curcuminoids against Human Oral Epidermal Carcinoma-KB Cell
Line .....................................................................................................................................................................486
Hoang Minh Hao, Ho Dung Manh and Vo Thi Nga
Modeling of Flow Mixed with Polymers in Open Channel Flow: Application on the Blumenau River in
Brazil...................................................................................................................................................................491
Walid Bouchenafa, Airton Hoenicke, Bruna Luiza Cunico, Huyen Xuan Dang-Vu and Trong Dang-Vu

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Preface
This proceedings contains the scientific contributions included in the program of the 6th
International
Conference on Green Technology and Sustainable Development (GTSD2022), which was organized on July
29-30, 2022 in Nha Trang University, Khanh Hoa Province, Vietnam. The GTSD International Conference
series is a prestigious bi-annual event created to provide an international scientific research forum in
technologies and applications in the field of Green technology and Sustainable development in the Industrial
revolution 4.0. The areas of GTSD include but are not limited to energy engineering, environmental
engineering, education, digital transformation, new materials and solutions for sustainable development,
advances in computational intelligence and their applications to the real world and so on.
The conference is structurally organized in order to promote the active participation of all attendees and
presenters, via plenary presentation sessions, keynote addresses, interactive workshops and panel
discussions, to find out how to further contribute to and solve various problems in life and manufacture. The
aim was to further increase the body of knowledge in this specific area by providing a forum to exchange
ideas and discuss results.
The program committee members of GTSD2022 come from various countries, and the 269 selected papers
(out of more than 450 submitted papers) are from 27 countries and from 5 continents. This certainly attests to
the widespread and international importance of the theme of the conference. Each paper was carefully
reviewed on the basis of originality, novelty and rigorousness.
We would like to take this opportunity to express our deep appreciation to all authors, participants, keynote
speakers, program committee members, session chairs, organizing committee members, steering committee
members, as well as the organizers for their great efforts and contributions to making the GTSD2022
successful, surging the global care about green technology research for sustainable development.
On behalf of GTSD2022 Organizing Committee
Assoc.Prof. Hoang An Quoc
General Co-Chair of GTSD2022
and
Dr. Nguyen Vu Lan
Publication Chair of GTSD2022

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GTSD2022 Organizing Committee
General Chairs
A/Prof. Le Hieu Giang, HCMUTE, Vietnam
A/Prof. Trang Si Trung, NTU, Vietnam
Prof. Nguyen Ngoc Thanh, WUST, Poland
Prof. Wen-June Wang, NCU, Taiwan
Prof. Yo-Ping Huang, NPU, Taiwan
Honorary Chairs
A/Prof. Thai Ba Can, HCMUTE, Vietnam
A/Prof. Do Van Dung, HCMUTE, Vietnam
A/Prof. Ngo Van Thuyen, HCMUTE, Vietnam
Dr. Khong Trung Thang, NTU, Vietnam
General Co-Chairs
Dr. Quach Hoai Nam, NTU, Vietnam
A/Prof. Hoang An Quoc, HCMUTE, Vietnam
Prof. Huann-Ming Chou, KSU, Taiwan
Prof. Chang-Ren Chen, KSU, Taiwan
A/Prof. Nguyen Vu Quynh, LHU, Vietnam
A/Prof. Nguyen Thanh Lam, LHU, Vietnam
Program Chairs
A/Prof. Nguyen Truong Thinh, HCMUTE, Vietnam
A/Prof. Do Thanh Trung, HCMUTE, Vietnam
A/Prof. Nguyen Minh Tam, HCMUTE, Vietnam
Dr. Huynh Phuoc Son, HCMUTE, Vietnam
Dr. Tran Thi My Hanh, NTU, Vietnam
Dr. Pham Thi Thu Thuy, NTU, Vietnam
Program and Steering Committee
Prof. Nguyen Trung Kien, HUTECH, Vietnam
Prof. Surya Narayan Panda, Chitkara Uni., India
Prof. Arun Patil, SGU, India
Prof. Sid Nair, VIT, Australia
Prof. Pracha Yeunyongkul, RMUTL, Thailand
A/Prof. Atul Sharma, RGIPT, India
A/Prof. Truong N. Luan Vu, HCMUTE, Vietnam
A/Prof. Le Chi Kien, HCMUTE, Vietnam
A/Prof. Bui Van Hong, HCMUTE, Vietnam
A/Prof. Nguyen Tan Dung, HCMUTE, Vietnam
A/Prof. Chau Dinh Thanh, HCMUTE, Vietnam
A/Prof. Vo Viet Cuong, HCMUTE, Vietnam
A/Prof. Truong Dinh Nhon, HCMUTE, Vietnam
A/Prof. Duong Thi Kim Oanh, HCMUTE, Vietnam
A/Prof. Trinh Khanh Son, HCMUTE, Vietnam
A/Prof. Ngo Dang Nghia, NTU, Vietnam
Dr. Irma Kunnari, HAMK, Finland
Dr. Lisa Donaldson, DCU, Ireland
Dr. Lai Jiang, KULEUVEN, Belgium
Dr. Manoj Kumar Dash, IIITM Gwalior, India
Dr. Le Minh Nhut, HCMUTE, Vietnam
Dr. Nguyen Xuan Vien, HCMUTE, Vietnam
Dr. Diep Phuong Chi, HCMUTE, Vietnam
Dr. Huynh Van Vu, NTU, Vietnam
Dr. Mai Thi Tuyet Nga, NTU, Vietnam
Dr. Tran Quang Huy, NTU, Vietnam
Dr. Jari Jussila, HAMK, Finland
Dr. Phan Gia Anh Vu, HCMUTE, Vietnam
Dr. Tran Vu Tu, HCMUTE, Vietnam
Dr. Dang Quang Vang, HCMUTE, Vietnam
Dr. Nguyen Khac Hieu, HCMUTE, Vietnam
Dr. Vu Van Phong, HCMUTE, Vietnam
Publication Chairs
Dr. Nguyen Vu Lan, HCMUTE, Vietnam
Media and Publicity Chairs
Chau Ngoc Thin, HCMUTE, Vietnam
Nguyen Van Nguyen, HCMUTE, Vietnam
Local Arrangement Chairs
Tran Nhat Tan, NTU, Vietnam
Vu Thi Thanh Thao, HCMUTE, Vietnam
Do Thi Ngoc Dung, HCMUTE, Vietnam
Phung Phuong Thu Thuy, HCMUTE, Vietnam
Nguyen Thi Minh Ngoc, HCMUTE, Vietnam
Nguyen Thi Hoa, HCMUTE, Vietnam

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Copyright © authors. This work is licensed under a Creative Commons
Attribution-NonCommercial-NoDerivatives 4.0 International License.
A Novel Mechanism Design following Augmented
Objective with Flexible Energy Control
Xuan Phu Do
Mechatronics and Sensor Systems Technology
Vietnamese German University
Binh Duong, Vietnam
phu.dx@vgu.edu.vn
Van Chi Le
Mechatronics and Sensor Systems Technology
Vietnamese German University
Binh Duong, Vietnam
levanchi1991@gmail.com
Abstract: This study presents a newly proposed theory for
design of augmented structure, especially in exoskeleton
design. A general model is proposed with basic elements of a
featured actuator related to mechanism. The calculation
theory is based on dynamical analysis with new modifications
to obtain general equations for design. The new theory is
different from the conventional theory, which always
assumed that the analyzed structure was zero in a static state.
The augmented theory has broken out the barrier of the
classical model with a new added element related to the
accumulated energy in the structure, especially in the
mechanical spring. After formulating, antagonistic variable
stiffness mechanism is chosen to evaluate the proposed
analysis. The simulation results show that the proposed
theory can meet the requirement in the design of new
augmented mechanism.
Keywords: augmented mechanism, exoskeleton design,
general augmented mechanism, upper exoskeleton, lower
exoskeleton
I. INTRODUCTION
Design of exoskeleton with low power consumption and
high efficacy is always the ultimate objective. The main
design is to develop special calculation and modified
mechanisms based on the conventional structure such as beam
deflection. Normally, the trials in design are always the safe
choice to guarantee the performance of the proposed structure
when manufacturing. However, this also leads to unexpected
results that the efficiency of the structure is lower than the
desired values. This study presents a new view of design
mechanism based on the dynamical parameters to overcome
the disadvantage. Generally, a view of the existing
publications related to the content of this study is carried out.
A design of a low-power stiffness mechanism was presented
in [1]. The ideal variable stiffness mechanism with its
potential energy was analyzed based on many assumptions
related to the consumption value. To use the internal energy
to control the exoskeleton mechanism’s movement was
presented in [2]. The internal energy [2] was from the muscle
states of a human, and this value belonged to the physical
health of every person. The disadvantage of the internal
energy is its unstable value and can be attacked by the working
environment. As mentioned above, the theory of beam
deflection is main analysis in any research of design
mechanism. The review of this analysis was presented in [3].
An extension of the research [2] was studied in [4]. The
infinity energy in the calculation of the exoskeleton was
presented in [4]. The analyzed theories [1,2,4] are different
from the conventional analysis [5]. The result [5] was the
background to interpolate the efficient area of the stiffness
mechanism. The metabolic cost was studied in [6]. This issue
is one of the problems when controlling the mechanism and
directly affects the structure’s functions [6]. New modification
of the structure [1] was presented in [7]. This modification [7]
concentrated on improving the mechanical function of the
spring at the knee exoskeleton. In addition, the movement of
the centroid point in the robotic mechanism was studied in [8].
When designing the structure, the centroid point is also a part
of soft compliance calculation. The stiffness of the above
mechanisms is different from the application of smart material
as shown in [9-13] with the same objective in control the
movement.
From the above summarization, stiffness control is still a
state-of-art issue when controlling and designing the structure.
However, the conventional theory does not fully view the
affection of the initial energy in the designed model. Hence it
needs support from the controllers to fulfil the desired
requirements. This is also the main objective of this research
which is shown in the next sections.
II. CONVENTIONAL AND PROPOSED THEORY
Figure 1. Suddenly energy at the first time of vibration control
There exists a phenomenon as shown in Fig. 1 in any
system at the first state. The energy at this state is always
larger than other positions and also affects the control system.
To analyze the phenomenon, two specific models are chosen
in this study. The conventional model of the design
mechanism is shown in Fig. 2. In this figure, three main
mechanism elements are listed: motor, transmission, and
dynamic functions. The output of the mechanism includes
force, stiffness. In some particular cases, the output force can
be replaced by the output torque belonging to the objective
control. This model is also similar to the featured model of an
exoskeleton. The potential energy of the structure is defined
as follows [1]:

2022 6th
2
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V p x f l dl

   (1)
Where, fi is the ith force of the structure with its
equilibrium l0 and the length li at ith position. It is noted that
Eq.(1) is the general model for any mechanism. The value p
is angular position, and the value x is the translational
position of the system.
Figure 2. The first model of Antagonistic Variable Stiffness
Mechanism (AVSM)
Energy (1) includes the internal and external energies.
Normally, the internal energies are always assumed zero
value for all calculations. This assumption is used in the
conventional model to neglect the complicated analysis, and
the obtained results are acceptable. From definition (1), the
official dynamic parameters related to the movement are
determined as follows [1]:
   
2
2
, , , ,
IN OUT OUT
V V V
f p x f p x k
x x p
  
   
  
(2)
Where, fIN is the input force, fOUT is the output force, and
kOUT is the output stiffness. In Fig. (1), the transmission
element is normally the mechanical spring-like model. In
some exceptional cases, the element is the beam and the
activated actuators. The condition for an ideal elastic element
is proposed as follows:
 
 
0
,
1
( ,K) ( , ) , 0
i
l p K
N
IDEAL
IDEAL i
i l
V
V p V p K f l dl
K


  

 
(3)
Where, K is a symbolized translational position. In the
proposed equation (3), the condition energy for an ideal
mechanism is different from the classical definition. This is
from the characteristic of the manufactured elements always
remains an initial power inside its model. The energy can be
seen as lower power, but it is complete affection to combine
the external energy. This combination brings an unexpected
phenomenon in dynamic response at the first time to apply a
controller. The power motor can be defined as follows:
 
   
    
2
3 0 1 2 0 1 2 3
2
1 2 0 3 0
, , , IN
IN IN
IN IN
p x x x f UI
w P w x w x P w x w x f w f
= w x w x P f w P f

     
   
(4)
Where, the values of 1 2 3
, ,
w w w are found based on the
experiment data corresponding to acceleration, velocity, and
initial power of the system; 0
P is the initial power of the
motor (W). Eq.(4) is designed based on the assumption in
Eq.(3). Eq. (4) also satisfies the phenomenon in the first time
of vibration control as shown in Fig. 1. This phenomenon
always exists in any system, especially in suspension. The
variation of the energy also leads to the changing stiffness of
the system as follows:
 
 
,
0, , 0
OUT
IN
k K x
f K x
x

 

(5)
Eq.(5) also satisfies the assumption as shown in (3) and
(4). The stiffness and its energy are not always obtained zero
value or equilibrium as seen in the conventional theories.
Hence the criterion for the design of variable stiffness
mechanism with low power can be determined as follows:
 
, n
IN IN
d f k f
 (6)
Where, n is the order of the mechanism belonging to the
potential energy of the actuator and the desired objective. The
value n can be defined as a fraction or an integer. Normally,
the integer value of n is a favorite choice, which will bring a
flexible calculation for design progress.
III. APPLICATION TO ANTAGONISTIC
VARIABLE STIFFNESS MECHANISMS AND
DISCUSSIONS
A. First modification of AVSM
The potential energy of the first model of AVSM as
shown in Fig. 2 is given by:
   
3 3
1
( , )
3
V p x k x pR x pR
 
   
 
 
(7)
The potential energy (7) is rewritten as dimensionless
function as follows:
 
2 2
1
( , ) 3
3
V p x x p x
  (8)
Where, ,
x
x p p
R
  . Using Eq.(2), the output stiffness
and the input force of AVSM are found as follows:
    2 2
2 , ,
OUT IN
k x x f p x p x
   (9)
The input force (9) can be written as:
 
 2
2 2
,
4
OUT
IN IN
k x
f p x p fun
   (10)
Using Eq.(10), the criterion for design AVSM is
determined as:
  2
,
IN OUT IN
d f k fun
 (11)
The result (11) shows that the energy mechanism for
control is a square exponential function with the input control
and the stiffness output. The exponential value also reflects
the relation in the connection that the energy for every spring
cannot dependently. In addition, the source energy must be
large and obtain double value for control the system.
This research is funded by Vietnam National Foundation for Science and
Technology Development (NAFOSTED) under grant number 107.02-
2020.13. Corresponding author: Dr. Xuan Phu Do

2022 6th
3
B. Second modification of AVSM
Figure 3. The second model of AVSM
The second mode of AVSM is shown in Fig. 3. The
potential energy of the first model of AVSM as shown in Fig.
3 is given by:
 2
1 2 1 2
1
( , ,x ) , ,x
2
V p x k l p x
  (12)
Where, k is the input stiffness of the structure, p is the
angular position, l
 is the deflection of the spring length, x1
and x2 are the position of the first and the second springs. The
input force and the output stiffness are determined as follows:
 
 
 
 
2
1 2
1 2
2
1 2
1 2 2
, ,
,
, ,
, ,
OUT
l p x x
k x x k
p
l p x x
k l p x x
p
 

 
 
 

 
 
 

(13)
   
 
1 2
1 2 1 2
, ,
, , , ,
IN
l p x x
f p x x k l p x x
p

 

(14)
It is remarked that the input stiffness is defined as
 
2
1 2
2
k R x x

  , where  is a constant related to the
proportionality of the force-deflection springs. The input
force (14) can be written as follows:
 
1 2
, ,
IN IN
f p x x fun
 (15)
Using Eq.(10), the criterion for design AVSM is
determined as:
 
,
IN OUT IN
d f k fun
 (16)
The result (16) shows that the mechanism’s energy for
control is first order function with the input control and the
stiffness output. This also points out that the movement is
independent when controlling.
IV. SIMULATION AND DISCUSSIONS
Simulation results of the first and the second AVSMs are
shown in Fig. (4) and Fig. (5). In the first model as shown in
Fig. (4), the criterion for design follows the second-order
function of the input force and the output force. This relation
is reflected clearly in Fig. 4(a). It is shown that the increased
value of the output stiffness from 0 to 2 N/m corresponds to
the input force of approximately 100 N. In this point, the
potential energy is nearly zero value. However, the output
stiffness changes from 2 to 4 N/m with the potential energy 5
W as shown in Fig. 4(b). It is remarked that the relation
between the input force and the potential energy is not linear
as shown in Fig. 4(c). In Fig. 4(c), it is shown that the
potential energy is not zero value if there exists internal
energy of the structure as shown in Eq.(4).
The result of second AVSM is shown in Fig. 5(a,b,c). The
relation of the input force and the output stiffness is linear-
like as shown in Fig. 5(a). This response is from the
connection of the first and the second mechanical springs as
shown in Fig. 3. The affection of the connection is also shown
in Fig. 5(b). It is remarked that the values of the output
stiffness are the actual value of the mechanical spring, which
is different from Fig. 4 as the difference value when
controlling. The result in Fig. 5(c) also points out that the
potential energy will increase if there is internal energy in the
structure.
(a)
(b)
(c)
Figure 4. Result of the first AVSM: (a) input force versus output
stiffness, (b) potential energy versus output stiffness, (c) potential
energy versus input force

2022 6th
4
(a)
(b)
(c)
Figure 5. Result of the second AVSM: (a) input force versus
output stiffness, (b) potential energy versus output stiffness, (c)
potential energy versus input force
V. CONCLUSION
In this study, a new view of the stiffness mechanism is
presented. This proposed theory is designed from the mutation
energy at the first time to control the system. This theory also
modifies the traditional mechanism theory that the energy is
always approximate zero value. The proposed theory also
presents equations related to the stiffness, input energy, and
output energy. These equations point out that the energy
cannot assume the zero value related to the design of the
mechanism. Two AVSM models are used to apply the
proposed theory. The simulation and its results show that the
proposed theory can be developed to design the augmented
mechanism for supporting the movement of the upper limb
and lower limb. The theory also gives a new view of design
mechanisms when the energy and the stiffness of the system
cannot be predicted.
REFERENCES
[1] Vincent Chalvet, David J.Braun, “Criterion for the design of
low-power variable stiffness mechanisms”, IEEE Transactions
on Robotics, vol. 33, no. 4, pp. 1002-1010, 2017.
[2] Amanda Sutrisno, David J.Braun, “How to run 50% faster
without external energy”, Science Advances, vol. 6, no. 13,
eaay1950, 2020.
[3] Ke Wu, Gang Zheng, “A comprehensive static modeling
methodology via beam theory for compliant mechanisms”,
Mechanism and Machine Theory, vol. 169, pp. 104598, 2022.
[4] Amanda Sutrisno, David J.Braun, “Enhancing mobility with
quasi-passive variable stiffness exoskeletons”, IEEE
Transactions on Neural Systems and Rehabilitation
Engineering,vol. 27, no. 3, pp. 487-496, 2019.
[5] C.E.English, D.Russell, “Mechanics and stiffness limitations
of a variable stiffness actuator for use in prosthetic limbs”,
Mechanism and Machine Theory, vol. 34, pp. 7-25, 1999.
[6] Daniel F.N.Gordon, Christopher McGreavy, Andreas Christou,
Sethu Vijayakumar, “Human-in-the-loop optimization of
exoskeleton assistance via online simulation of metabolic
cost”, IEEE Transactions on Robotics, pp. 1-20, DOI:
10.1109/TRO.2021.3133137
[7] Sung Y.Kim, David J.Braun, “ Novel variable stiffness spring
mechanism modulating stiffness independent of the energy
stored by the spring”, 2021 IEEE/RSJ International Conference
on Intelligent Robots and Systems (IROS), pp. 1-6, DOI:
10.1109/IROS51168.2021.9636339, 2021
[8] Qiang Huang, Chencheng Dong, Zhangguo Yu, Xuechao
Chen, Qingqing Li, Huanzhong Chen, Huaxin Liu, “Resistant
compliance control for biped robot inspired by humanlike
behavior”, IEEE/ASME Transactions on Mechatronics, pp. 1-
11, DOI: 10.1109/TMECH.2021.3139332, 2022
[9] Do Xuan Phu, Kruti Shah, Seung Bok Choi, “A new
magnetorheological mount featured by changeable damping
gaps using a moved-plate valve structure”, Smart Materials and
Structures, vol. 23, pp. 125022, 2014
[10] D. X. Phu, S. B. Choi, Y. S. Lee, M. S. Han, “Design of a new
engine mount for vertical and horizontal vibration control using
magnetorheological fluid”, vol. 23, pp. 117001, 2014
[11] Do Xuan Phu, Seung Bok Choi, “Vibration control of a ship
engine system using high-loaded magnetorheological mounts
associated with a new direct fuzzy sliding mode controller”,
vol. 24, pp. 025009, 2014
[12] Xuan Phu Do, Huy Ta Duc, Le Tran Huy Thang, Seung Bok
Choi, Dalseong Yoon, “Design of a new inside multi-coil
clutch for knee-exoskeleton structure based on Helmholtz
phenomenon and magneto-rheological fluid”, Proceedings
Volume 10598, Sensors and Smart Structures Technologies for
Civil, Mechanical, and Aerospace Systems 2018, 105983M,
2018
[13] Xuan Phu Do, Long Mai Bui Quoc, Seung Bok Choi, Nguyen
Quoc Hung, Ae Ri Cha, “Design of a new exoskeleton based
on the combination of two magnetorheological damper”,
Proceedings Volume 10598, Sensors and Smart Structures
Technologies for Civil, Mechanical, and Aerospace Systems
2018, 105983M, 2018

2022 6th
5
Evaluating Green Marketing Trending
Determinants by a Text Mining Approach
Phan-Anh-Huy Nguyen
Faculty of Economics
HCMC University of Technology and Education
Ho Chi Minh City, Vietnam
huynpa@hcmute.edu.vn
Abstract: Green Marketing can also refer to the
production and marketing of goods based on environmentally
friendly products made from renewable materials. This
approach attracted many companies in recent years.
Identifying the trending factors influencing green marketing
is a complicated task. This paper proposed a novel
approach based on text mining techniques to figure out the
new determinants in green marketing activities. The results
of this paper can be applied to enterprises in their selecting
business strategy development to boost their business
performance.
Keywords: text mining, green marketing, marketing
strategy, data mining
I. INTRODUCTION
Green marketing is an important topic in recent years
since more entrepreneurs focus on the environmental impacts
on society. Furthermore, it is getting more concerns from
many organizations in the era of industrial revolution 4.0. In
current years, there are several studies investigating green
marketing issues in business [1 - 8]. However, most of the
previous papers have not found the main themes which are
affected by green marketing. Figuring out the trending
determinants is critically important to solve those problems.
Therefore, this paper implemented a text mining approach in
order to help the organizations to have better conversations in
the new situation.
The contributions of this study are as follows:
1) A new text mining approach is adopted to analyze the new
dataset.
2) Four main themes with some related factors have been
discovered.
3) The implications are proposed to support the business to
solve the green marketing issues.
The remaining sections of the study are organized as follows:
in section 2, the reviews of related works are presented.
Section 3 proposed the methodology. Section 4 shows the
experimental results and implications.
II. LITERATURE REVIEW
Green marketing has been defined and analyzed in many
studies in recent years. In [1], Peattie and Ken reported the
concepts of green marketing and its main features. Dalton et
al. drilled down about management techniques when
applying green marketing [2]. In [3], Jain, Akansha, et al.
used MCDM to select a suitable green marketing strategy
under fuzzy environment. Suki et al. investigated the impacts
of corporate social responsibility on the links between green
marketing concerns and consumer purchase intentions [4].
Chung, Kuo Cheng reported the green marketing orientation
to achieve sustainable development in hospitality
management [5]. Mujahid, M., et al. analyzed the link
between green marketing and performance in small
businesses [6]. In [7], Mohd Noor et al. tried to understand
the consumers and green product purchase decision in
Malaysia using a structural equation modeling-partial least
square (sem-pls) approach. In [8], Amaliana, Luthfatul, et al.
analyzed the consistency of bootstrap resampling in structural
model with PLS-PM approach with the technology
acceptance model to evaluate in green marketing
management strategy. In [9], Said, Syahnur, et al. applied
green marketing practice in purchasing decision home care
product. The results of the study showed that the attribute of
environmentally friendly product design with the green label
is a variable that dominates the selections of consumers when
purchasing the products. Furthermore, preference attribute
weight is having the smallest influence on making the
purchasing decisions. To the best of our knowledge, there is
a lack of paper applying text mining to figure out the trends
in green marking in recent years. Hence, this paper proposed
a new approach to handle this issue by evaluating the green
marketing determinants.
III. METHODOLOGY
A. Dataset description
In this study, we use a dataset which is collected from
4000 related articles from newspapers recently. The
following keywords are used for the query to get access to the
data: business, experience, data, analysis, technology, skills,
work, management.
B. Text mining method
We use text mining software to visualize word cloud with
co-occurrences of term extracted from the main text dataset.
In this paper, we use topic modeling by co-word analysis. The
frequency of keywords is utilized to create the co-occurrences
matrix and the clusters of related topics. Then, the network
visualization is also conducted to show the relationships
between topics. The algorithm is:
Step 1: Similarity Matrix construction
From the co-occurrence matrix by normalizing the latter
matrix, the similarity matrix is constructed on differences in
the total number of occurrences.

2022 6th
6
Step 2: Mapping technique:
The aim of mapping technique is to minimize a weighted
sum of distances between all pairs of items by the squared
Euclidean.
Step 3: Translation, Rotation, and Reflection.
The objective of three transformation techniques is to
transform the solution obtained for the optimization problem.
Hence, it can create consistent results.
IV. EXPERIMENTAL RESULTS
The text mining results with discovered topics and
implications are described in this section.
Figure 1. The word-cloud
From the resulting data in the word-cloud, it can be seen
that the keyword Green has been updated with a lot of tools,
maybe 5023 from green issues is seen as an issue that many
people care about and talk about. The whole issue is updated
as “Marketing” with 2194 occurrences for marker work in
today's society is very important, especially the Green
Marketing trend. Around the keywords when it comes to this
issue are: product, environment, consumer, company,
enterprise, energy, market and new.
The keywords related to Green Marketing show that
consumers are interested in the company's environmentally
friendly products, affect the market, how is the energy
problem. The keywords related to the issue show that
consumers are now interested in environmentally friendly
green products and new products or new energy sources to
help protect the environment, and companies should grasp
this green trend to influence the company's marketing to help
the company understand the market and develop better.
The results obtained after performing data set analysis on
Green marketing appeared 4 main color clusters. In each
cluster, there will be a particular factor that is larger than the
others because it appears more and has a strong association
with other clusters.
Figure 2. Results for cluster 1 (red)
The factor “climate change” appears 134 times, although
it is not the factor with the highest frequency, it is an
important factor that shows the relationship with other factors
in the same cluster 1 such as person, government, planet,
effort. This shows that climate change is an issue that the
whole world needs to pay attention to. Climate change will
lead to many serious consequences for our planet, so people
and governments are both working to limit and prevent
climate change by saving resources, based on research and
development technology to create new alternative energy.
Figure 3. Results for cluster 2 (green)
The “market” element appears with the highest frequency
620 times among the elements in cluster2. It is not surprising
that the element “market” appears a lot in the analysis results
because the market is the place where marketing strategies
are implemented. In addition, in this cluster 2, we see the
appearance of these factors such as strategy, research, firm
(company), country, ... The appearance of these factors shows
that if companies want to understand the market or dominate
the market, it is essential to do research to analyze and come
up with appropriate strategies for each market in different
countries and different families. In a market where consumers
are increasingly concerned about the environment,
companies need to make changes in product strategies to
meet consumer needs.
Figure 4. Results for cluster 3 (blue)
Product is the element that appears the most with 1837
times and has many close links with factors inside and outside
the cluster to create a strong linked system. The reason that

2022 6th
7
products are mentioned so many times in the topic of green
marketing is because plastic waste is currently a factor that
has a serious impact on the environment. However, most of
the plastic waste discharged into the environment today
comes from product packaging, so in order to implement
green marketing campaigns, the first thing that needs to be
mentioned must be the change. Product packaging becomes
more environmentally friendly.
Through the links between product elements (product)
and factors inside and outside the cluster such as consumers,
technology, brands, strategies, etc., we see that brands should
start making changes to their products by applying new
technologies to research alternative materials in order to
change the product packaging to be more environmentally
friendly by capturing the green living trend that consumers
are aiming. Certainly, this change will also consume time and
money of businesses, but if businesses have specific and
properly executed strategies, they will bring good results such
as gaining advantages in the market as well as building value
for the brand in the hearts of consumers.
Figure 5. Results for cluster 4 (Yellow)
In this cluster, we focus on analyzing the green product
factor. Like the analysis mentioned above, green product is a
trend in the current market. However, creating green and
environmentally friendly products will cost many times
higher than conventional products. Therefore, at present,
green and environmentally friendly products are still very
expensive compared to other common products. That also
creates a huge impact on sales of green products. Hence,
businesses need to have more strategies, learn to apply
technologies, and cooperate with suppliers to minimize the
cost of producing green products. From there, it is possible to
optimize the price to compete in revenue with other
conventional products.
V. CONCLUSION
In this study, a novel text mining approach has been
implemented to find the green marketing trends. There are
four main clusters which are the themes that have been
discovered. From that, we have also analyzed the meanings
of each topic with some related determinants. Then some
business implications have been reported from the results.
The limitation of this research is the number of text
documents in the dataset is not quite huge. For future work,
we could get more data to solve some bias problems. We
could also apply sentiment techniques for implementing
those tasks.
ACKNOWLEDGEMENTS
This research is supported by Ho Chi Minh City
University of Technology and Education, Vietnam.
REFERENCES
[1] Peattie, Ken. Green marketing. The marketing book.
Routledge, pp. 595-619, 2016.
[2] Dalton, Marie, Dawn G. Hoyle, and Marie W. Watts. Green
marketing management. South-Western College, 2010.
[3] Jain, Akansha, et al. Selection of a green marketing strategy
using MCDM under fuzzy environment. Soft Computing for
Problem Solving. Springer, Singapore, pp. 499-512, 2020.
[4] Suki, Norazah Mohd, Norbayah Mohd Suki, and Nur
Shahirah Azman. Impacts of corporate social responsibility
on the links between green marketing awareness and
consumer purchase intentions. Procedia Economics and
Finance, vol. 37, pp. 262-268, 2016.
[5] Chung, Kuo Cheng. Green marketing orientation: Achieving
sustainable development in green hotel
management. Journal of Hospitality Marketing
Management, vol. 29.6, pp. 722-738, 2020.
[6] Mujahid, M., et al. Linking green marketing with
performance: Environmental marketing model for small
business. IOP Conference Series: Earth and Environmental
Science. vol. 737. No. 1. IOP Publishing, 2021.
[7] Mohd Noor, Mohd Nazri, et al. Understanding consumers
and green product purchase decision in Malaysia: a structural
equation modeling-partial least square (sem-pls)
approach. Asian Social Science , vol. 12.9, pp. 51-64, 2016.
[8] Amaliana, Luthfatul, et al. The consistency of bootstrap
resampling in structural model with PLS-PM approach:
technology acceptance model in green marketing
management strategy. IOP Conference Series: Earth and
Environmental Science. Vol. 239. No. 1. IOP Publishing,
2019.
[9] Said, Syahnur, et al. Green Marketing Practice In Purchasing
Decision Home Care Product. International Journal of
Scientific Technology Research, vol. 9.06, pp. 893-896,
2020.
[10] A. Ottman, Green Marketing: Opportunity for Innovation,
Chicago, IL:NTC Business Books, 1997.
[11] M. Charter, Greener Marketing: A Responsible Approach to
Business, Sheffield, UK:Greenleaf Publishing, 1992.
[12] M. Polonsky, An Introduction to Green
Marketing. Electronic Green Journal, vol. 1, pp. 1-10, 1994.

2022 6th
8
A Simple Synthesis of Antibacterial and Antifungal
ZnO Nanorods
Khanh Son Trinh
Faculty of Chemical and Food Technology
Ho Chi Minh City University of Technology and
Education
sontk@hcmute.edu.vn
Vinh Tien Nguyen
Faculty of Chemical and Food Technology
Ho Chi Minh City University of Technology and
Education
tiennv@hcmute.edu.vn
Abstract: ZnO nanorods were prepared by precipitation
method with Zn(CH3COO)2 as the precursor, NaOH as the
precipitating agent and soluble starch as the capping agent.
X-ray diffraction analysis showed that the ZnO nanoparticles
(NPs) were structured in the wurtzite lattice with an average
crystallite size of 11.38 nm. Field-emission scanning electron
microscopy coupled with energy-dispersive spectroscopy
showed that the material was mostly nanorods with an
average size of 28 nm. UV-vis absorption spectra showed that
ZnO-NPs strongly absorb UV radiations. The ZnO NRs
demonstrate typical dose-dependent antimicrobial activities
and inhibited Escherichia coli, Staphylococcus aureus, and
Salmonella sp. 99.7, 99.96, and 100% respectively at 184
ppm ZnO-NPs. At 553 ppm concentration, ZnO-NPs
demonstrated 100% inhibition for the three bacterial strains.
Gram-positivity and Gram-negativity seemed to be
unimportant for the resistance of bacteria toward ZnO NRs.
ZnO NRs at 14740 ppm showed a weak 98.2% growth
inhibition against the fungi Colletotrichum gloeosporioides.
FESEM and EDS analyses showed that the cells of bacteria
were distorted and damaged when being in contact with ZnO
NRs in dispersion. The fungal cells in these conditions turned
into spores and were also damaged. The synthesized ZnO
NRs can find a wide range of applications as an antibacterial
and antifungal component in inks, paints, coatings,
cosmetics, and pharmaceutics.
Keywords: ZnO nanoparticles, antibacterial, antifungal,
UV absorption, Staphylococcus aureus, Salmonella
I. INTRODUCTION
In recent years, the synthesis and antimicrobial activities
of ZnO nanomaterials are gaining much attention due to their
low cost, chemical stability, biocompatibility and
biodegradability. Recent research on ZnO nanomaterials
focused on green methods of their syntheses using natural
sources of reagents. For example, plant extracts were used to
synthesize ZnO nanoparticles and their antibacterial activity
was tested on E.Coli, Streptococcus sp, Enterococcus sp, and
Klebsiella sp [1]. Another study used the powder of leaves of
S. multiflorus to prepare ZnO nanomaterials and tested their
antifungal activity on Aspergillus niger and Aspergillus flavus
[2]. ZnO nanomaterials were also synthesized using
diethylene glycol and triethylene glycol and incorporated into
an antimicrobial film against Staphylococcus aureus and
Proteus vulgaris [3].
Most of the methods using natural sources such as plant
extracts are relatively complicated due to involving the extract
preparation and hence increasing the production costs. In this
study, we used a simple chemical method to prepare the ZnO
nanoparticles (NPs) using inexpensive and commercially
available reagents including zinc acetate as the precursor,
sodium hydroxide as the precipitating agent, and soluble
starch as the capping agent to control the size of NPs. The
produced ZnO NPs were then tested for antibacterial and
antifungal activity against different species.
II. EXPERIMENTAL METHODS
A. Synthesis and characterization of ZnO NPs
ZnO NPs were synthesized based on a reported method
[4]. Soluble starch (1.5 g) was completely dissolved in 250 mL
of distilled water by stirring at 90o
C for 10 min. After cooling
the solution to room temperature, 5.4875 g of
Zn(CH3COO)2.2H2O (0.025 mol) was added and stirred until
complete dissolution. After that, 250 mL of 0.2 M NaOH
solution was added dropwise under continuous stirring. The
solution was then left stirred for 2 h to complete the reaction.
The reaction mixture was then filtered and the solid was
washed with 3x 500 mL of distilled water and dried at 80o
C.
The dried solid was then ground into a powder.
UV-vis spectra were recorded using a UH5300 (Hitachi,
Japan) spectrophotometer.
X-ray diffraction spectra were recorded using a D8
Advance platform (Bruker, Germany) with  = 0.15406 nm at
25o
C.
The size of crystallites was calculated using the Scherrer
equation [5]
𝐷 =
𝐾
𝑐𝑜𝑠(𝜃)
Where  was the Full Width at Half-Maximum
(FWHM,rad), 2 was the diffraction angle (rad),  = 0.15406
nm was the wavelength of the X-ray, K = 0.9 was a constant,
and D (nm) was the crystallites size.
Field Emission Scanning Electron Microscopy (FESEM)
was conducted using an S–4800 (Hitachi, Japan) electron
microscope. Energy Dispersive Spectra (EDS) were recorded
using a 7593-H spectrometer (Horiba, Japan). Before FESEM
and EDS measurements, the ZnO sample was sputtered with
a thin layer of Pt to enhance the electrical conductivity of ZnO.
B. Antimicrobial tests of ZnO NPs
Antibacterial activity of ZnO NPs was evaluated based on
a reported method with some modifications [6]. The E.coli
bacteria were first activated in a Nutrient Broth medium at

2022 6th
9
37o
C for 24 h. The ZnO NPs were dispersed in a nutrient agar
medium with different concentrations from 0 to 737 ppm. The
nutrient agar medium was poured into Petri dishes and when
the agar solidified, 100 l of the bacteria suspension was
spread on the surface of the agar. The Petri dishes were then
incubated at 37o
C for 24 h. After that, the density of survived
bacteria was determined by counting the number of bacterial
colonies. The antibacterial activity was calculated using the
formula
%inhibition=
𝐴1−𝐴2
𝐴1
× 100,
where A1 was the bacterial density in the Petri dish without
ZnO NPs (CFU/mL), and A2 was the bacterial density in the
Petri dish with ZnO NPs (CFU/mL).
One-way Analysis of Variance (ANOVA) was conducted
to test the statistically significant difference between the
means with a confidence level of 95%.
Antifungal activity of the ZnO NPs was evaluated using a
reported method [7]. A PDA medium was autoclaved at 121o
C
for 15 min and then ZnO NPs were added with different
concentrations from 0 to 14740 ppm. The medium was poured
into Petri dishes and left for solidification. The spores of the
fungi were then put in the centre of each Petri dish. The size
of the fungal colony was measured every day. The percent
inactivation was calculated using the following formula [8]:
o s
o
inhibition
S S
% 100
S

 
Where So was the area of the fungal colony (cm2
) in the
control Petri dish without ZnO NPs (cm2
) and Ss was the area
of the fungal colony (cm2
) in the Petri dish with ZnO NPs
(cm2
).
To evaluate the effect of the presence of ZnO NPs on the
bacterial cells, the microorganisms were first activated (in
Nutrient Broth medium for bacteria and in Potato Dextrose
Broth medium for fungi) at 37o
C for 24 h. After that, 30 mL
of the bacteria suspension was added to 30 mL of a sterilised
Nutrient Broth medium containing ZnO NPs of 184 ppm for
bacteria and 3685 ppm for fungi. After 24 h of stirring, the
bacterial cells were centrifuged at 2000 rcf for 30 min, put on
a silicon wafer and left for drying under ambient conditions.
The morphology of the cells was observed using the FESEM
and EDS equipment which was used for ZnO NPs described
above [9].
III. RESULTS AND DISCUSSION
In this reaction, zinc ions were first precipitated into
Zn(OH)2 and then dissolved in the presence of excessive
hydroxide ions:
Zn2+
+ 2OH-
→ Zn(OH)2
Zn(OH)2 + 2OH-
→ Zn(OH)4
2-
+ 2H+
The complex was unstable and gradually turned into ZnO
NPs according to the reaction [10]:
Zn(OH)4
2-
→ ZnO +H2O + 2OH-
The presence of excessive OH- ions turned soluble starch
into a negatively charged form and hence stabilized the ZnO
NPs by interacting with the positively charged Zn ions in the
ZnO crystallites [11].
A. Characterization of ZnO NPs
XRD spectrum of the synthesized material (Figure 1)
shows characteristic peaks with corresponding planes of ZnO:
31.8424o
(100), 34.3866o
(002), 36.2351o
(101), 47.4113o
(102), 56.605o
(110), 62.9608o
(103), and 68.0339o
(112),
which were also reported in another study [12]. These peaks
indicated the wurtzite structure of ZnO based on the standard
JCPDS number 36–1451.
Figure 1. XRD spectum of ZnO NPs
The peaks at 2θ of 33.5334o
and 59.5205o
belong to
Zn(OH)2, according to JCPDS number 38–0356 [13]. This
result indicated that the temperature of 80o
C was not high
enough to fully convert Zn(OH)2 to ZnO.
The crystallites sizes of ZnO NPs were calculated using
the Debye – Scherrer equation for different XRD peaks. The
average of these sizes was 11.38 nm, which is close to the size
of the ZnO NPs determined from the SEM images.
Figure 2. FESEM micrograph of ZnO NPs at 50 000 magnification (A) and frequency distribution of particle sizes from
the FESEM micrographs (B)
(
100
)
(002)
(
101
)
(102)
(
110
)
(103)
(
112
)
0
200
400
600
800
1000
20 30 40 50 60 70
Intensity
(a.u)
2 theta (o)
A B

2022 6th
10
Figure 2A shows that there were several shapes of ZnO
NPs, including nanorod, nanowire, and nanotube, with the
majority being nanorods. The nanorod shape of ZnO NPs in
this study was due to the usage of precursor zinc acetate. It
was shown that the acetate precursor of zinc produced mainly
nanorods, while the chloride and sulfate precursors produced
nanoprims [14]. Besides, in this study we used dilute 0.1 M
solution of zinc ions, thus facilitating the formation of
nanorods instead of nanoplates [15].
Figure 2B shows that the sizes of nanorods ranged from 10
to 57 nm with an average of 27.7 nm. This result demonstrated
that the soluble starch effectively protected the NPs from
aggregation and growing in diameter [16].
The Energy dispersive spectrum (Figure 3) shows that zinc
and oxygen were the main elements in the synthesized
material. The presence of carbon and the higher atomic
percentage of oxygen compared to zinc were possibly due to
the presence of soluble starch absorbed on the surface of ZnO
NPs. Because the size of ZnO NPs was small, the surface
interaction between the capping soluble starch and the ZnP
was strong, therefore it was difficult to completely remove the
soluble starch by washing with water. The presence of Al was
due to the aluminum holder of the ZnO sample and the
presence of Pt was due to the platinum sputtering process
before SEM and EDS measurements.
Element % mass % atom
C 21.38 39.72
O 31.39 43.79
Al 0.43 0.36
Zn 46.57 16.10
Pt 0.23 0.03
Total 100 100
Figure 3. EDS spectrum (left) and element composition (right) of the synthesized ZnO NPs
UV-vis spectrum of the ZnO NPs dispersion in water
(Figure 4) shows a broad absorption peak near 366 nm. This
result is similar to that of another study that reported an
absorption band of ZnO NPs from 355 to 380 nm [17]. The
strong absorption of UV radiations by ZnO NPs can have
several applications such as in sunscreens or anti-aging
coatings.
B. Antibacterial activity
Table 1 shows that a concentration of 185 ppm of ZnO
NPs inhibited at least 99.0% of the growth of the three
bacteria. ZnO NPs exhibited a dose-dependent antibacterial
activity, which was also reported in other studies [18, 19]. The
high antibacterial effect was due to ZnO NPs because an
equivalent amount of Zn(CH3COO)2 exhibited significantly
lower antibacterial activity [19].
Figure 4. UV-vis spectrum of the dispersion of synthesized ZnO
NPs in water
Table 1 shows that the antibacterial effect of ZnO NPs
against Gram-negative E.coli was lower than against Gram-
positive S.aureus, similar to other reports [20-22]. In Gram-
positive bacteria, the cell is protected by a thick peptidoglycan
membrane composed of teichoic acid, lipoteichoic acid, and
surface proteins, while in Gram-negative bacteria, the cell is
protected by a membrane composed of lipopolysaccharide,
porins and a thin peptidoglycan layer [23]. Although E.coli
and Salmonella are both Gram-negative, E.coli is more
resistant while Salmonella is less resistant than S.aureus to
ZnO NPs. This result indicated that the Gram type of bacteria
might not be a significant factor in their resistance toward ZnO
NP.
Table 1. Percent inhibition against bacteria by ZnO NPs at
different concentrations
Bacteria %inhibition
184
ppm
369
ppm
553
ppm
737
ppm
E.coli 99.07a
99.97b
100c
100c
S.aureus 99.96b
100c
100c
100c
Salmonella 100c
100c
100c
100c
Numbers with different superscript letters are significantly different
(p0.05).
366
0,2
0,25
0,3
0,35
0,4
0,45
0,5
0,55
0,6
200 250 300 350 400 450 500
Absorbance
Wavelength (nm)

2022 6th
11
Figure 5. Area growth of C. gloeosporioides treated with ZnO NPs with different concentrations for 7 days
C. Antifungal activity
Figure 5 shows that the fungi C. gloeosporioides
continuously grew even in the presence of ZnO NPs.
However, the presence of ZnO NPs significantly inhibited the
fungal growth in all 7 days of the experiment. Increasing the
ZnO NPs concentration resulted in higher growth inhibition.
After 7 days, with ZnO concentrations from 3685 to 14740
ppm, the percent inhibition ranged from 82.8% to 98.2%,
which is similar to the results of 93% inhibition against C.
gloeosporioides [24] and 84.5% inhibition against
Erythricium salmonicolor [8].
The high antifungal activity of ZnO NPs was due to the
small size of the synthesized material [25]. The mechanism of
antifungal activity was found to be the formation of reactive
oxygen species with high oxidative activity, hence lead to the
alteration of membrane permeability and subsequent cell
death [26, 27].
We used FE-SEM and EDS methods to observe the
microbial cells without and with the presence of ZnO NPs in
the nutrient agar in the previous antimicrobial tests.
D. Morphology and elemental analysis of microbial cells
after ZnO NPs treatments
Comparing sub-figures (A) and (B) in Figures 6, 7, and 8
shows that the bacterial cells were shrinkled and distorted after
the treatment with ZnO NPs. On the cells in sub-figures (B)
there were white dots that contained 3-10% zinc atoms based
on the EDS analysis (data table not shown), which are similar
to other studies [28-31].
It was found that the dispersion of ZnO NPs in the nutrient
medium produced reactive oxygen species (ROS) such as
hydroxide, superoxide, and hydrogen peroxide [29]. These
ROS with high reactivity would then react with components
of bacterial cell walls including proteins, lipids, and DNA,
hence leading to cell death. Hydrogen peroxide penetrates the
cell wall into the cell, while superoxide ions attack the cell [32,
33]. Another antibacterial mechanism of ZnO NPs was the
direct attachment of the NPs on the cell wall and subsequent
interaction with the membrane components such as proteins
and enzymes, which also lead to the dysfunction of the cells
and their death [34].
Figure 6. E.coli cells before (A) and after (B) treating with 184 ppm of ZnO
0,00
5,00
10,00
15,00
20,00
25,00
30,00
35,00
1 2 3 4 5 6 7
Day
Area
of
growth
(cm2)
Control 0 ppm 3685 ppm 7370 ppm 11055 ppm 14740 ppm
A
A
B
B

2022 6th
12
Figure 7. S.aureus cells before (A) and after (B) treating with 184 ppm of ZnO NPs
Figure 8. Salmonella cells before (A) and after (B) treating with 184 ppm of ZnO NPs
Before treating C.gloeosporioides with ZnO NPs, one can
easily find the fungal cell in the FESEM micrograph (Figure
9A). However, after treating the fungi with ZnO NPs for 24 h,
we found only their spores (Figure 9B), with the presence of
approximately 6.5% zinc atoms on the surface.
Figure 9. A cell of C. gloeosporioides before ZnO NPs treatment (A) and a fungal spore after treating the cells with ZnO NPs (B)
The antifungal mechanism of ZnO NPs is different from
their antibacterial mechanism and is attributed to the attack of
Zn2+
ions on N-acetylglucosamine or β-1,3-D-glucan synthase
(FKs1p) [8]. N-acetylglucosamine plays a vital role in the
synthesis of chitin, and β-1,3-D-glucan synthase takes part in
the synthesis of β-1,3-D-glucan [35]. Both chitin and β-1,3-D-
glucan are important components in the structure of fungal cell
walls [8].
A
E
A
N
B
N
B
B
A
I
B
B

2022 6th
13
IV. CONCLUSION
In this study, we synthesized ZnO NPs in the shape of
nanorods with sizes mostly lower than 60 nm due to the
capping role of soluble starch. The ZnO NPs demonstrate a
dose-dependent antibacterial activity toward different bacteria
and fungi. Gram-positivity and Gram-negativity seemed to be
unimportant for the resistance of bacteria toward ZnO NPs.
FESEM and EDS analyses showed that the cells of bacteria
were distorted and damaged when being in contact with ZnO
NPs in dispersion. The fungal cells in these conditions turned
into spores and were significantly inhibited. With the low cost
of zinc acetate precursor and the ease in the synthesis of ZnO
NPs, the material can find a wide range of applications as an
antibacterial and antifungal component in inks, paints,
coatings, cosmetics, and pharmaceutics.
ACKNOWLEDGEMENT
The authors acknowledge Ho Chi Minh City University of
Technology and Education for the facility and equipment
required for this study. We thank Mr Nguyen Duc Manh
(student ID 15116030) and Mr Nguyen Quoc Tuan Anh
(student ID 15116002) for their helpful technical support.
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2022 6th
15
An Assessment of Complementary Energy of
HPFRCs under Tension
Duy-Liem Nguyen
Faculty of Civil
Engineering
Ho Chi Minh City
University of Technology
and Education
Ho Chi Minh City,
Vietnam
liemnd@hcmute.edu.vn
Tien-Tho Do
Faculty of Civil
Engineering
Ho Chi Minh City
and Education
Ho Chi Minh City,
Vietnam
thodt@hcmute.edu.vn
Thi-Ngoc-Han Vuong
Faculty of Civil
Engineering
Ho Chi Minh City
and Education
Ho Chi Minh City,
Vietnam
hanvtn@hcmute.edu.vn
H. T. Tai Nguyen
Faculty of Civil
Engineering
Ho Chi Minh City
and Education
Ho Chi Minh City,
Vietnam
tainht@hcmute.edu.vn
Abstract: This paper deals with the complementary
energy of HPFRCs under tension through an experimental
study. The HPFRCs were prepared from an identity matrix
but with different fiber types or volume contents. The fiber
used in this research is long twisted with a length of 30 mm
and a diameter of 0.3 mm. There were four levels of fiber
volume content as follows: 0.5 vol.%, 1.0 vol.%, 1.5 vol.%
and 2.0 vol.% to investigate the effect of fiber volume content
on the energy parameters of HPFRCs. The complementary
energies of the HPFRCs were evaluated and correlated to a
number of microcracks as the dosage of the fiber was
changed.
Keywords: HPFRC, Complementary energy, First-
cracking, Post-cracking, Energy absorption capacity
I. INTRODUCTION
High-performance fiber-reinforced concretes (HPFRCs)
have been classified as one of the sustainable construction
materials, which can enhance structure resistance and avoid
ruinous disasters [1-3]. The term “high-performance” of
HPFRCs refers to strain-hardening behavior accompanied by
multiple micro-cracks. This property can be identified with an
increase of stress after the first crack due to the crack-bridging
mechanism of reinforcing fibers, and consequently leads to
high strain capacity and large energy absorption capacity of
HPFRCs. HPFRCs only produce strain-hardening behavior
with suitable fiber type/content mixed in the plain concrete [1-
5]. The interfacial bond between the fiber and HPFRC matrix
is strongly dependent on fiber type/content, which will govern
the mechanical properties of HPFRCs
On the other hand, a strain hardening HPFRC with lower
crack spacing, is characterized as a more ductile material. This
is because the fracture strain beyond the first crack is mainly
due to microcracks, which were generated during strain-
hardening [1-3]. Complementary energy is defined as the area
above the stress versus strain response curve of a material. The
ratio of complementary energy to the crack tip toughness of
the mortar concrete will represent the capability of producing
many microcracks, as illustrated in Fig. 1 [6-10]. It is clear that
complementary energy is a key engineering property of
HPFRCs that should be evaluated. Based on the test data of
the previous studies of the first author [11,12], this paper
focuses on the effect of fiber content on the complementary
energy of HPFRCs, which has been not assessed yet. Better
understanding mechanical properties of HPFRCs, including
their complementary energy, is highly expected to widen the
application of HPFRCs.
spc
Tensile
stress
Tensile strain
Crack tip
toughness
(CT)
scc
Hardening energy
(Ghd)
epc
ecc
Multiple
microcracks
Crack
Localization
Complementary
energy (CE)
Elastic energy (Gel)
Figure 1. Illustration of complementary energy of HPFRCs
under tension
II. EQUATIONS TO OBTAIN ENERGY
PARAMETERS OF HPFRCS
Based on the definitions of four energy parameters
described in Fig. 1, the equations for obtaining them were built
to evaluate in the discussion part.
- The elastic energy (named el
G ) is the zone under the
stress versus strain relationship curve within the elastic stage
and calculated using Eq. (1). It characterizes the energy
absorption capacity per unit volume during extending a tensile
specimen from 0 to cc
e .
- The hardening energy (named hd
G ) is the zone below the
stress versus strain relationship curve with the strain range
from 0 to pc
e . The hd
G indicates the energy absorption
capacity per unit volume during extending a tensile specimen
from 0 to pc
e , it can be derived using Eq. (2).
- The crack tip toughness (named CT ) is the zone above
the stress versus strain relationship curve in the elastic stage
and given using Eq. (3). It is noted that this expression is
equivalent to the result obtained by Li et al. [13]. The CT
reveals the energy per unit volume can not be absorbed during
extending a tensile specimen from 0 to cc
e .

2022 6th
16
- The complementary energy (named CE ) is the area
above the stress versus strain relationship curve with the strain
range from 0 to pc
e [13,14]. The CE represents the energy
per unit volume can not be absorbed during extending a tensile
specimen from 0 to pc
e , it can be derived using Eq. (4).
0
( )
cc
el
G d
e e
e
s e e


 
  
 
 

(1)
0
( )
pc
hd
G d
e e
e
s e e


 
  
 
 

(2)
0
( )
cc
cc cc el cc cc
CT G d
e e
e
s e s e s e e


 
    
 
 

(3)
0
( )
pc
pc pc hd pc pc
CE G d
e e
e
s e s e s e e


 
    
 
 

(4)
It is noted that the hd
G and el
G are the true energies
absorbed by a tensile specimen under loading whereas the CE
and CT are the virtual energies only.
III. EXPERIMENTAL TEST
A. Materials and preparation of specimens
0 1 2 3
cm
30 ; 0.3
f f
L mm d mm
 
Figure 2. Photo of the twisted fiber type in this research
Table 1. Composition and compressive strength of Mortar Matrix
Materials Weight ratio
Cement (Type III) 0.8
Silica fume 0.07
Silica sand 1
Fly ash 0.2
Superplasticizer 0.04
Water 0.26
Compressive strength (MPa) 89
Table 2. properties of six fiber types
Fiber type
(Notation)
Tensile
strength
(MPa)
Length (mm)/
Diameter (mm)
Density
(g/cm3
)
Long twisted
(T30/0.3)
2428 30/0.3 7.9
The HPFRCs used an identical mortar matrix, whose
composition is provided in Table 1 according to weight ratio.
The partial materials are sand, fly ash, cement and silica fume,
water and superplasticizer. The amount of superplasticizer
was 0.07 by weight ratio of the cementitious materials. It is
noted that the sand in the mixture plays an engineering role as
coarse filler material whereas the fly ash and silica fume play
a role as fine filler materials to densify the concrete mixture.
The compressive strength of the mortar matrix using a
cylindrical specimen with a size of 100×200 mm was 89 MPa
at 18-day age. Table 2 provides the properties of long twisted
fiber (T30/0.3) used in this research. Photos of the fiber were
presented in Fig. 2
All constituent materials of HPFRC were blended using a
20-L laboratory mixer (Hobart type). Sand, fly ash, cement
and silica fume were dry-mixed for about 10 min. at first.
After dry-mixing, water and then superplasticizer were added
to the mixture and wet-mixed for about 10 min. Because the
plain mortar showed appropriate flow capability and, the steel
fibers were gradually added to the mortar mixture by hand and
further blended for 5 min. After demolding, all specimens
were cured in water at the temperature of 25o
C for 14 days.
The detail of mixing work can be referred to in previous
studies [11,12].
B. Experimental setup
50
125
162.5
200
162.5
25
Gauge
length
of
100
mm
12.5
Wire
mesh
a) Tensile specimen
Gauge
length
100
LVDT 2
LVDT 1
Hinge mechanism
Hinge mechanism
b) Experiment setup for direct tensile test
Figure 3. Tensile specimen detail and experimental setup

2022 6th
17
Dog-bone-shaped specimens were used in the direct
tensile test. The working section over the gauge length of 100
mm is rectangular with a dimension of 50 × 25 mm2
. To
prevent failure beyond the gauge length, both specimen ends
were reinforced by employing steel wire meshes, as described
in Fig. 3a. All the prepared specimens were tested through a
universal testing machine (UTM) with displacement-
controlled loading. The standard displacement rate of 1.0
mm/min. was applied to the movable crosshead of the UTM.
The data collecting rate during loading was 1 Hz. The
specimen elongation under tension was measured by two
linear variable differential transformers (LVDTs), as shown in
Fig. 3b. Besides, the hinge mechanism was designed at both
specimens. Response curves of tensile stress versus strain of
the HPFRCs were built and their complementary energies
were derived and evaluated.
IV. TEST RESULT AND DISCUSSION
A. Tensile responses of HPFRCs with different fiber
contents
Fig. 4 presents the direct tensile responses of the HPFRCs
using the same fiber type T30/0.3 but fiber content varying
from 0.5 to 2.0 vol.%. As can be seen in Fig. 5, all these
HPFRCs also exhibit strain-hardening behaviors, although the
fiber contents were significantly different.
CE
Ghd
a) 0.5 vol.% T30/0.3
CE
Ghd
b) 1.0 vol.% T30/0.3
CE
Ghd
c) 1.5 vol.% T30/0.3
CE
Ghd
d) 2.0 vol.% T30/0.3
Figure 4. Tensile responses of HPFRCs with different fiber contents
Table 3. Tensile parameters with different fiber contents
Fiber
content
(vol.%)
cc
e
(%)
cc
s
(MPa)
pc
e
(%)
pc
s
(MPa)
0.5
0.013
(0.003)
2.54
(0.46)
0.28
(0.077)
4.86
(0.69)
1.0
0.016
(0.003)
2.56
(0.47)
0.52
(0.092)
7.48
(0.78)
1.5
0.020
(0.002)
3.41
(0.03)
0.49
(0.035)
9.99
(1.22)
2.0
0.025
(0.005)
3.41
(0.27)
0.55
(0.013)
12.53
(0.36)
Note: The standard deviations are delivered within parentheses
Table 3 shows the tensile parameters of the HPFRCs using
T30/0.3 type with different fiber contents, varying from 0.5
vol.% to 2.0 vol%. The tensile parameters in Table 4 were
averaged from three tested specimens for each series, the
values in the brackets were standard deviations. As presented
in Table 4, all the tensile parameters increased with the
increase in fiber content. The content of 2.0 vol.% generated
the best performance in terms of cc
s , cc
e , pc
s and pc
e .
B. Energy parameters of HPFRCs
Table 4 gives the results of four energy parameters of
HPFRCs, including CE , CT , hd
G and el
G of HPFRCs.
These results were averaged from three specimens tested for
each series. Fig. 5 graphically displays the comparisons of the

2022 6th
18
energy parameters of HPFRCs using different fiber contents.
As can be seen in Fig. 5, all the four energy parameters of
HPFRCs generally increased as fiber volume content
increased. As the fiber volume content was changed from 0.5
to 2.0 vol.%, the range values of the energy parameters were
observed as follows: from 0.381 to 1.609 kJ/m2
for the CE ,
from 0.014 to 0.027 kJ/m2
for the CT , from 0.981 to 5.419
kJ/m2
for the hd
G , and from 0.019 to 0.051 kJ/m2
for the el
G .
Regardless of fiber content, the CT was observed to be lower
than the el
G at the first crack. At the post crack, the CE was
significantly lower than the hd
G . This means the material
capability of HPFRCs was utilized significantly. The ratio
/
el
G CT was 1.3-2.8 while the ratio /
hd
G CE was 2.6-5.7, as
provided in Table 4.
a) Complementary energy (CE )
b) Crack tip toughness (CT )
c) Hardening energy ( hd
G )
d) Elastic energy ( el
G )
Figure 5. Comparison of energy parameters of HPFRCs
Table 4. Energy parameters of HPFRCs
Fiber
content
(vol.%)
CE
(kJ/m2
)
hd
G
(kJ/m2
)
CT
(kJ/m2
)
el
G
(kJ/m2
)
hd
G
CE
el
G
CT
0.5 0.381 0.981 0.014 0.019 2.6 1.3
1.0 0.579 3.324 0.014 0.027 5.7 1.9
1.5 0.862 4.086 0.018 0.049 4.7 2.8
2.0 1.609 5.419 0.027 0.051 3.4 1.8
Note: Definition of energy parameters can be referred to Fig.1
C. Correlation between complementary energy and number
of microcracks in hardening stage of HPFRCs
As illustrated in Fig. 1, multiple microcracks ( cr
N ) are
generated during the hardening stage. According to Naaman
[14], the average crack spacing ( av
L
 ) of a strain hardening
composite can be predicted using Eq. (5). Eq. (5) relates to a
number of fibers within cross-section ( f
N ), which is possibly
estimated using Eq. (6). Finally, cr
N within the gauge length
of a tensile specimen can be obtained using Eq. (7).
Mathematically, Eq. (7) describes a linear relationship
between cr
N and fiber volume content ( f
V ).
( )
m m
av
f f eq
A
L
N d
s

 
  (5)
2
f
f g
f
V
N A
a

 (6)
2
4 g eq
cr f
av m m f
LA
L
N V
L A d


 s
 
 (7)
where, f
d , 2
/ 4
f f
a d

 are the fiber diameter and area of
fiber section, respectively; eq

is the equivalent bond
strength obtained from a single pullout test; m
A and m
s are
area and tensile strength of matrix, respectively; 2
 is factor
reflecting the orientation of fibers, the 2
 value is 1 for case
of 1D, 2  for case of 2D, and 0.5 for the case of 1, 2 and 3D
fiber orientation; g
A is the cross-section area of tensile
specimens; L is the gauge length of tensile specimen;  is
the crack spacing factor, its value ranging from 1 to 2. It is
highlighted that the author investigated the number of cracks
using experiment only and did not calculate the number of
cracks through theoretical equations proposed by Naaman.
Since the ratio of the complementary energy to the crack
tip toughness ( /
CE CT ) of a composite represents capability
of producing multiple microcracks ( cr
N ), in this section, the
ratio /
CE CT was correlated to cr
N of HPFRCs, which were.
Generally, as the ratio /
CE CT is higher than 1, the multiple
microcracks possibly occur in the composite. Kanda and Li
[15] stated that the conditions for surely producing multiple
microcracks are ratio /
CE CT 2.7 and ratio /
pc cc
s s 1.3.

Proceedings of 2022 6th International Conference on Green Technology and Sustainable Development (GTSD)

Proceedings of 2022 6th International Conference on Green Technology and Sustainable Development (GTSD)

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