This document summarizes research into developing new construction materials using nano-silica and recycled aggregates from construction and demolition waste. Experiments were conducted to examine how nano-silica and recycled aggregates influence the compressive strength, modulus of elasticity, water absorption, density, and void volume of concrete. Replacing cement with three levels of nano-silica (0.75%, 1.5%, and 3%) in both natural aggregate concrete and recycled aggregate concrete was tested. The results showed that nano-silica improved early compressive strength and offset the reduction in strength from using recycled aggregates. Additionally, recycled aggregates led to increased water absorption and voids but reduced density, while nano-silica enhanced density and reduced water absorption and

1. Development of construction materials using nano-silica and
aggregates recycled from construction and demolition waste
Bibhuti Bhusan Mukharjee
Sudhirkumar V Barai
Department of Civil Engineering, Indian Institute of Technology Kharagpur, Kharagpur, India
Bibhuti Bhusan Mukharjee, Department of Civil Engineering, Indian Institute of Technology
Kharagpur, IIT Kharagpur, Kharagpur
721302, India. Email: bibhuti.2222atgmail.com
Abstract
The present work addresses the development of novel construction materials utilising commercial
grade nano-silica and recycled
aggregates retrieved from construction and demolition waste. For this, experimental work has been
carried out to examine the
influence of nano-silica and recycled aggregates on compressive strength, modulus of elasticity,
water absorption, density
and volume of voids of concrete. Fully natural and recycled aggregate concrete mixes are designed
by replacing cement with
three levels (0.75%, 1.5% and 3%) of nano-silica. The results of the present investigation depict that
improvement in early
days compressive strength is achieved with the incorporation of nano-silica in addition to the
restoration of reduction in
compressive strength of recycled aggregate concrete mixes caused owing to the replacement of
natural aggregates by recycled
aggregates. Moreover, the increase in water absorption and volume of voids with a reduction of bulk
density was detected with
the incorporation of recycled aggregates in place of natural aggregates. However, enhancement in
density and reduction in
water absorption and volume of voids of recycled aggregate concrete resulted from the addition of
nano-silica. In addition,
the results of the study reveal that nano-silica has no significant effect on elastic modulus of
concrete.

2. Article Notes
Declaration of conflicting interests The authors declare that there is no conflict of interest.
Funding This research received no specific grant from any funding agency in the public, commercial,
or not-for-profit sectors.