This document summarizes different techniques for treating recycled concrete aggregate (RCA) by either eliminating the adhered mortar or improving its quality. The techniques can be categorized as either removing mortar through thermal, mechanical, thermal-mechanical, water cleaning, or chemical means, or improving mortar quality using polymer, carbonate biodeposition, pozzolanic materials, carbonation, or sodium silicate treatments. Common methods for removing mortar include heating RCA to different temperatures, grinding with mechanical forces, a combination of heating and grinding, soaking in acid, or microwave heating to fracture mortar.
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The method of micro-tunnelling comes with many advantages compared to other methods. In addition to the features such as faster and more precise progress compared to the open-cut methods, carbon emissions, noise, pollution, vibration, and environmental nuisance are lesser disruptive.
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The chemical machining processes include those wherein material removal is accomplished by a chemical reaction, sometimes assisted by electrical or thermal energy applications. This group includes chemical milling, photochemical machining, and thermo-chemical machining.
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Separation of mineral matter from indian coal by using solventseSAT Journals
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Coal resources have been estimated at over 861 billion tone globally. India accounts for 236 billion tonne of coal. Coal meets around
30.3 % of global primary energy needs and generates 42% of the world’s electricity. Indian electricity capacity has a rapid growth
from 1350MW in the year 1947 to more than 140,000MW presently. Wide spectrum of coal is required ranging from power generation
to steel production, infrastructure and commercial purposes. Indian coals contain high in ash content ranging from 15% to 55% [1]
but low in sulphur content. Power plants complain of high ash content, inconsistent quality and size. Research and process
development to produce the ash-free coal (Hyper-coal, HPC) has been carrying out since 1999 [5]. To improve the quality of coal by
washing to reduce the environmental impact, enhance coal quality and increase process efficiency. Coal washing and coal
beneficiation processes are the major thrust in terms of developing strong research cells for developing better practices, suiting
requirements of all the coalfields of India. The extraction yield depends strongly on the coal particle size, solvent and extraction
conditions. Experimental investigation for removal of mineral matter from Indian coal by using three different solvents such as
Tetrahydrofuran, 1,4 Dioxane and Diethyl ether. Comparative study on reduction of ash content of Indian coals having different
average particle sizes(0.126mm,0.258mm and 0.403mm) using different solvents reveals that Tetrahydrofuran is the best solvent with
respect to these used solvents. The maximum reduction of ash content is found to be 23.16%. Experimental studies also highlighted
how ash removal of coal by using solvents is increased with the decrease of particle size due to the easy liberation of ash bearing
components from coal particles [16].
Keywords: Ash-free coal, Coal particle size, Coal beneficiation, Tetrahydrofuran, 1, 4 Dioxane, Diethyl ether
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
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By various coating and deposition method tool life increases of hot forging die. There are 5 research paper from trusted and authorised sites. Review of that papers have been shown here.
A presentation done by Undergraduates in Chemical and Process Department in University of Moratuwa on engineering aspects of Sodium Hydroxide Production.
Sustainable construction trough heat processed recycled coarse aggregateAlok Sharma
Heat process recycling of coarse aggregate has made vital possibilities in civil and construction industry, cement can not take stand temperature above 300-degree centigrade, therefore concrete disintegrated easily at high temperature
MICROSTRUCTURAL CHARACTERIZATION AND HOT EROSION BEHAVIOR OF CRC-NICR COATED ...IAEME Publication
Erosion behavior of the High Velocity Oxygen Fuel (HVOF) deposited CrC - NiCr coating on stainless steel was evaluated. Th e solid particle erosion stu dy was conducted using an air jet erosion test rig at a velocity 60m/sec and impingement angle 60 ° , 75 ° and 90 ° , on HVOF spray coated steel at 600 ° C. Microstructure, chemical composition, phases present in the coating on the steel substrate was studied by using Scanning Electron Microscope (SEM) and X - Ray Diffraction method. The Hardness is gradually increasing with increasing content of Cr 3 C 2 particles in all three samples. The erosion mechanism of coatings was also discussed and erosion rate is maximum at impingement angle 75 °
Separation of mineral matter from indian coal by using solventseSAT Journals
Abstract
Coal resources have been estimated at over 861 billion tone globally. India accounts for 236 billion tonne of coal. Coal meets around
30.3 % of global primary energy needs and generates 42% of the world’s electricity. Indian electricity capacity has a rapid growth
from 1350MW in the year 1947 to more than 140,000MW presently. Wide spectrum of coal is required ranging from power generation
to steel production, infrastructure and commercial purposes. Indian coals contain high in ash content ranging from 15% to 55% [1]
but low in sulphur content. Power plants complain of high ash content, inconsistent quality and size. Research and process
development to produce the ash-free coal (Hyper-coal, HPC) has been carrying out since 1999 [5]. To improve the quality of coal by
washing to reduce the environmental impact, enhance coal quality and increase process efficiency. Coal washing and coal
beneficiation processes are the major thrust in terms of developing strong research cells for developing better practices, suiting
requirements of all the coalfields of India. The extraction yield depends strongly on the coal particle size, solvent and extraction
conditions. Experimental investigation for removal of mineral matter from Indian coal by using three different solvents such as
Tetrahydrofuran, 1,4 Dioxane and Diethyl ether. Comparative study on reduction of ash content of Indian coals having different
average particle sizes(0.126mm,0.258mm and 0.403mm) using different solvents reveals that Tetrahydrofuran is the best solvent with
respect to these used solvents. The maximum reduction of ash content is found to be 23.16%. Experimental studies also highlighted
how ash removal of coal by using solvents is increased with the decrease of particle size due to the easy liberation of ash bearing
components from coal particles [16].
Keywords: Ash-free coal, Coal particle size, Coal beneficiation, Tetrahydrofuran, 1, 4 Dioxane, Diethyl ether
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Literature review of increasing tool life of hot forging die by reducing wear Bhavesh Panchal
By various coating and deposition method tool life increases of hot forging die. There are 5 research paper from trusted and authorised sites. Review of that papers have been shown here.
A presentation done by Undergraduates in Chemical and Process Department in University of Moratuwa on engineering aspects of Sodium Hydroxide Production.
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Based on our results, Tetra Engineering installed covering plates to reduce the bypass flow. This improved the boiler's performance and increased electricity production.
It is always satisfying when we can help solve complex challenges like this. Do your systems also need a check-up or optimization? Give us a call!
Work done in cooperation with James Malloy and David Moelling from Tetra Engineering.
More examples of our work https://www.r-r-consult.dk/en/cases-en/
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Presentation1.pptx
1. • Name: Muslim Hussaini Adam
• Department: Civil Engineering and Mechanics
• ID: 5102220322
• Topic:Quality Improvement Techniques for Recycled Concrete Aggregate:
• A review
• Wafaa Mohamed Shaban1
• , Jian Yang2*, Haolin Su3
• , Kim Hung Mo4
• , Lijuan Li5
• and Jianhe Xie6 Received 26 December 2018, accepted 10 April 2019 doi:10.3151/jact.17.4.151
2. Outline
introduction
2. Treatment techniques of RCA
3. Eliminating the adhered mortar
3.1 Thermal treatment technique
(1) Traditional heating
(2) Microwave heating
3.2 Mechanical treatment technique
3.3 Thermal-mechanical technique
3.4 Water cleaning technique
3.5 Chemical treatment technique (acid soaking)
3.6 Chemical-mechanical technique
4. Quality-improving the adhered mortar
4.1 Polymer treatment technique
4.2 Calcium carbonate biodeposition
4.3 Incorporating pozzolanic materials
4.4 Carbonation technique
4.5 Sodium silicate solution
5.Summary and conclusions
3. 1. Introduction
The construction sector has seen tremendous expansion recently. This sector is considered the largest carbon dioxide
emitter and energy consumer, accounting for up to 45% of the total global CO2 and about 40% of the global energy
consumption (Peng 2016). In China, about 73% of total energy consumption of building comes from manufacturing the
raw materials (Zhang and Wang 2016). As one of the most used construction materials, concrete not only contributes to
the carbon emission and energy consumption, it also excessively uses the nature materi_x0002_als such as sand,
stone or gravels. In concrete, both coarse and fine aggregates account for 60 to 75% of the total volume. World demand
for concrete aggregates will rise 5.2% annually to 51.7 billion metric tons in 2019 and China remains the largest national
consumer of aggre_x0002_gates, representing nearly half of global demands (Freedonia 2016). Therefore, aggregates
have a signifi_x0002_cant effect on environment and on the sustainability feature of structures. On the other hand, the
construction
and demolition (C&D) waste generated by the construc_x0002_tion sector is one of the most voluminous waste streams
worldwidely. According to Construction and Demolition Recycling Association (CDRA), more than 583 million tons of
C&D wastes were generated in 2015 (Turley 2018). If not recycled, most of them will be sent to landfills, which also
creates significant impact on envi_x0002_ronment. Such dilemma leads to the perfect necessity to recycle C&D
concrete waste.
4. RCA: recycled concrete aggregate; RMA: recycled masonry aggregate; MRA: mixed concrete and masonry
recycled aggregate;
MRA - Class H: high-quality recycled aggregate; MRA - Class M: medium-quality recycled aggregate; MRA -
Class L:low-quality recycled aggregate; BA: blending aggregate.
5. 2. Treatment techniques of RCA
Due to the widely varying effects of adhered mortar on the quality of RCA,
there are several approaches and techniques that have been considered
to improve the characteristics of RCA. These approaches and techniques
can be primarily classified into two categories (Purushothaman et al.
2015). The first category mainly includes eliminating the adhered mortar
from the RCA surface using different methods while the second category
includes modifying and improving the properties of RCA by improving the
quality of the adhered mortar.
Several treatment techniques of RCA are reviewed in detail in the
following sections and their categorizing relationship are summarized in
Fig. 1
6. 3. Eliminating the adhered mortar
A large amount of weak adhered mortar is considered as the major
factor compromising the quality of RCA The attached weak mortar
results in poor qualities for RCA, such as low density, high water
absorption and porosity. The weak adhered mortar can be removed
from the RCA surface by using either one or a combination of
thermal, mechanical and chemical treatments. These treatment
methods are described in detail in the following sections.
7. 3.1 Thermal treatment technique
Thermal treatment is considered as a favorable treatment method
for eliminating the attached weak adhered mortar, mainly due to its
operational simplicity and cost effectiveness. The thermaltechnique
that was explored in the past mainly consists of two methods.
namely; traditional heating and microwave heating.
8. (1) Traditional heating
In this technique, RCA particles are heated at various temperatures for about
2hours. The thermal stresses generated through differing thermal expansion of
the original aggregate and the attached mortar are used to loosen the attached
weak mortar from the surface so that the mortar can then be removed.
It is accepted that soaking the RCA before heating can further increase the
efficiency of mortar separation because of the higher internal pore vapor
pressure developed in the adhered mortar or the mortar-aggregate interface
zone, leading to a higher mortar removal rate when RCA is exposed to
temperatures above 100℃
9.
10. (2) Microwave heating
The microwave heating technique benefits from the differences in the electromagnetic
properties between the original aggregate and the adhered mortar (Like et al. 2016). Microwave
heating results in fracturing and separates the adhered mortar without harming the original
aggregate, and consequently reduces the content of adhered mortar in the RCA.
The process comprises two stages.
11. 3.2 Mechanical treatment technique
Mechanical treatment is a common treatment method for producing
high quality RCA by separating adhered mortar from the NA. In this
method, mechanical forces are used to pulverize and remove the
adhered mortar. There are two techniques that have beensuggested
in this method: an eccentric-shaft rotor method and mechanical
grinding, as shown in Fig. 3. In the eccentric-shaft rotor method.
RCA lumps are passed between an outer cylin_x0002_der and an
inner cylinder that rotates eccentrically at a high speed. The
adhered mortar can be removed from RCA by this action . In the
mechanical grinding method (ball-milling), a drum is divided into
small sections.
12. Fig. 2 Various types of RCA particles: (a) RCA particle surrounded by adhered mortar; (b) three RCA
particles held to_x0002_gether and surrounded by adhered mortar, (c) only mortar (Akbarnezhad et al.
2011).
14. 3.3 Thermal-mechanical technique
This technique is a combination of two treatment proc_x0002_esses. The first process involves a
traditional heating technique at temperatures ranging from 300℃ to 500℃ to dry out the adhered
mortar and to weaken it as a result of the generated thermal stresses. The second process includes
mechanical grinding to totally eliminate the adhered mortar from the RCA particles.
15. 3.5 Chemical treatment technique (acid soaking)
3.5 Chemical treatment technique (acid soaking) More
recently, the technique of pre-soaking in acid has been
developed as an effective treatment method for eliminating
adhered mortar and enhancing the quality of RCA.