Microstructural Investigation of High-Volume Fly Ash Composites Containing Nano-Calcium Silicate Hydrate Crystals

Zhiyuan Zhou,Ylias Sabri,Shaobo Kang,Junli Liu,Massoud Sofi,Priyan Mendis

doi:10.1061/(asce)mt.1943-5533.0003974

Abstract

AbstractThis paper reports on the effect of addition of nano-calcium silicate hydrate (nano-CSH) seeds on the early-age strength development and microstructural evolution of concrete containing hig...

Highlights

Concrete is widely produced and used as construction material because of its low cost and desirable strength
By increasing the replacement ratio of fly ash to 70%, the compressive strengths of FA70 were slightly reduced to 54.2% and 79.5% of ordinary portland cement (OPC) at 1 and 28 days, respectively
Fly ash can participate in the chemical reaction only after the pH value in the pore solution reaches 13.2, as a result of the accumulation of CaðOHÞ2 generated from OPC hydration (Neville 2011)

Summary

Introduction

Concrete is widely produced and used as construction material because of its low cost and desirable strength. One practical way to promote the sustainability of concrete is to partially replace OPC constituents with supplementary cementitious materials (SCMs), one of which is fly ash (FA). The aim of making traditional concrete more environmentally friendly has led researches to put more emphasis on high-volume fly ash (HVFA) based concrete, in which more than 50% of OPC constituents is substituted by FA (Siddique 2004). The addition of fly ash has positive effects on the sustainability and workability of concrete, the early-stage strength of concrete is normally negatively affected due to the prolonged setting time and extended dormant period (Sofi et al 2012; Zhang and Islam 2012; Kocak and Nas 2014; Soutsos et al 2016). Early-age strength is required for early load transfer and managing timely completion of the projects (Sofi et al 2008)

Objectives

Results

Conclusion