Development of High Early Strength Cement Composites with Pozzolans and Accelerators

Abstract

The present research focuses on the development of High Early Strength Cement Composites (HESCC) using pozzolans and accelerators. Pozzolans, including Ground Granulated Blast Furnace Slag, Fly Ash, Silica Fume, Metakaolin and Rice Husk Ash, are incorporated into the Ordinary Portland cement (OPC) mix. Additionally, chemical accelerators, Calcium Nitrate and Triethanolamine are introduced to accelerate the setting and early strength development. This study also explores HESCC with pozzolana blended cement and accelerators. The examination encompasses two variants of pozzolana blended cement, namely Portland Slag Cement and Portland Pozzolana Cement. In the preliminary stage the research involves setting time and compressive strength tests to identify the optimized HESCC mixes. From these results, selected mixes are further evaluated for mechanical properties and durability performance in the form of concrete mixes. Based on experimental findings, high early strength concrete with pozzolans blended/admixed mixes such as OPC concrete with a 15% replacement of Metakaolin, incorporating 1% calcium nitrate and 0.05% Triethanolamine (C-MK) and Portland slag concrete with 1% of calcium nitrate and 0.05% of Triethanolamine (C-PSC) shows the best mechanical and durability performance compared to conventional concrete (C-OPC). C-MK exhibits notable early-age compressive strengths, reaching 56.93% and 90.69% of the 28-day strength within 1 and 3 days. Moreover, C-MK demonstrates enhanced flexural and split tensile strengths compared to C-OPC and C-PSC, along with improved resistance to chloride ion penetration and lower water permeability values at various ages up to 270 days. newline