# Rheological and mechanical performance of sustainable LC3 concrete modified with nano-silica and rubber latex

## TL;DR

This paper explores a new eco-friendly concrete by replacing traditional materials with nano-silica and rubber latex, improving its performance and sustainability.

## Contribution

The study introduces a novel LC3 concrete formulation using nano-silica and rubber latex to enhance mechanical and rheological properties.

## Key findings

- LC3 concrete with nano-silica and rubber latex showed up to 84% lower volumetric shrinkage compared to traditional OPC concrete.
- Compressive strength improved by 15.6% at 90 days with the new LC3 concrete formulation.
- Rheological properties like workability and structural built-up rate were enhanced in the engineered LC3 concrete.

## Abstract

Alternative sustainable and environmentally friendly cement-based materials are now possible because of substantial advancements in concrete technology. In building engineering, supplementary cementitious materials (SCMs) have gained popularity and promise as partial binder substitution in recent decades. This study examines the production of a new eco-friendly LC3 concrete (lower cement clinker concentration and CO2 footprint) by substituting nano silica for calcined clay. Surkhi has been used as a calcined clay in the present LC3 concrete and replaced by nano-silica at 2%, 4%, and 6% by weight. A new water replacement material has been introduced as rubber latex, which has helped to reduce the porosity of concrete. Rubber latex has replaced the water at 2% and 5%. Eight new mixes are prepared from which seven mixes are engineered LC3 concrete and one mix belongs to traditional OPC concrete of M40 grade. Several laboratory tests such as rheology, volumetric shrinkage, FTIR, TGA, compressive strength, and split tensile strength are carried out on the above-mentioned mixes of LC3 concrete and compared with the test results of traditional OPC concrete. However engineered LC3 concrete enhanced the workability by showing lower values of static yield stress, structural built-up rate and thixotropic energy as compared to traditional OPC concrete. Introducing rubber latex in LC3 concrete, the workability increases due to the production of similar charges around the cementitious materials which are repulsive. Losing the plasticity of rubber latex the voids of concrete have been filled by solid materials and correspondingly reduce the voids and shrinkage. The volumetric shrinkage was reduced by up to 84%, and compressive strength improved by 15.6% at 90 days compared to OPC concrete. Rheological tests using an eBT2 rheometer and shrinkage tests using laser measurement were performed. The mechanical and microstructural qualities of LC3 concrete have improved due to partial substitution of water with rubber latex and increased the packing density due to the partial substitution of nano-silica for surkhi.