Comparative Study of Superabsorbent Polymers and Pre-soaked Pumice as Internal Curing Agents in Rice Husk Ash Based High-Performance Concrete

Abstract

Utilisation of superabsorbent polymers (SAP) and pre-soaked lightweight aggregates (LWA) as internal curing (IC) agents for the mitigation of autogenous shrinkage and micro-cracking of high strength/highperformance concrete (HSC/HPC) have been well researched and documented in literature. Rice husk ash (RHA) on the other hand has been adjudged to be of good pozzolanic activity and a possible alternative to silica fume (SF) in low water/binder (W/B) concrete production. An experimental comparative study was conducted in the current work to assess the effectiveness of the two known ICagents on rice husk ash (RHA) based HPC. HPC mixtures of fc,cube28=60 MPa minimum target strength produced and internally cured with 0.3% content of SAP by weight of binder (bwob) and varied content of pre-soaked pumice (5 to 10% in steps of 2.5%) by weight of coarse aggregate (bwocg) were cast using 100 mm cubes samples. Thereafter, the samples were cured for 7, 14, 28 and 56 days by water immersion before subjecting them to compressive strength test. The results showed 0.2% bwob SAP HPC (SHPC1) to be the best performed internally cured HPC at the early ages with similar long-term strength values as 5 and 7.5% bwocg saturated pumiced HPC (PHPC1&2). The study thereby recommends SAP content of 0.2% bwob and saturated pumice content up to 7.5% bwocg for use as ICagent in HPC.

Assessment of Water Transport and Chemical Attack of Meta-Illite Calcined Clay Blended Cement in High-Performance Concrete

“…The other mixtures comprise MCC tagged meta-illite calcined clay concrete (MCCC), which partially substitutes CEM II from 5% to 30% at 5% intervals at a permanent W/B of 0.3%, permanent SAP content of 0.3% b wob , and SP content (1.5% b wob ). Extra water of 12.5 g/g of SAP was settled following the SAP absorbency established by the work of Olawuyi [34]. HPC ingredients were thoroughly prepared and mixed uniformly in a 120 litre pan-type concrete mixer.…”

Mechanical and microstructural properties of high-performance concrete made with rice husk ash internally cured with superabsorbent polymers

“…Subsequently, a spherical or irregular-shaped “SAP void” is formed and filled by either calcium hydroxide or ettringite developed near the SAP particles. This interaction of SAP in cementitious material improved compressive strength ( Nduka et al., 2020 ; Olawuyi et al., 2020 ). In addition to the laboratory results of SAP in minimising plastic and autogenous shrinkage in cementitious materials, its practical application in large-scale concrete projects has been seen.…”

“…Nigerian investigators' low compressive strength of concrete and sandcrete blocks may be linked to an open burning system used in calcining the RHA resulting in weak or non-reactive silica ( Fapohunda et al., 2017 ; Olutoge and Adesina, 2019 ). However, the cement replacement with RHA in high-performance concrete and mortar is adjudged to improve concrete performances regarding strength, durability, and pore refinement ( Nduka et al., 2020 ; Olawuyi et al., 2020 ).…”