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/high-performance 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 IC-agents 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 IC-agent in HPC.