Compressive strength of Millet Husk Ash as alternative to Silica fume in internally cured High Performance Concrete.

Abstract

Challenges of deterioration and premature failure of concrete structures made with normal concrete (NC) has led to the development of high-performance concrete (HPC) which is low water binder concrete and very dense concrete. However, lack adequate internal water for proper curing in HPC are noted to result in autogenous shrinkage and micro-cracking for which existing literature showed are often addressed by incorporating internal curing (IC) agents such as superabsorbent polymers (SAP) and pre-saturated lightweight aggregate (LWA). Also of note is that HPC production requires additional supplementary cementitious materials (SCM) especially Silica fume – a material not readily available in Sub-Saharan Africa like Nigeria. This study thereby is a report of attempt at utilizing Millet husk ash (MHA) as SCM in HPC as an alternative to Silica fume. The HPC specimen was internally cured with presoaked pumice as LWA and SAP respectively with the view to establish the effectiveness of Nigeria supplementary cementitious material (MHA) and IC-agent (presoaked pumice) for production of HPC. This article presents results on 28th day compressive of C55/67 HPC mixtures for 100 mm concrete cubes having 7.5% silica fume content in comparison with MHA based HPC of varied (2.5%, 5%, 7.5%, 10% and 15%) MHA contents. The SAP and Presoaked pumice contents were maintained as 0.2% by weight of binder (bwob) and 5% by weight of coarse aggregate (bwoca) and the cubes were subjected to curing in water by immersion for 28 days before testing.HPC mix with 2.5%MHA internally cured with 5% pre-soaked pumice and 0.2% SAP content gave the best performance having 28th day compressive strength of 53.58N/mm2 and 55.62N/mm2 respectively.