Pozzolanic Reactivity and the Influence of Rice Husk Ash on Early-Age Autogenous Shrinkage of Concrete

Abstract

In this study, the role of a locally available rice husk ash (RHA) in reducing early-age shrinkage of high performance concrete (HPC) after evaluating its pozzolanic reactivity was evaluated. The X-ray diffraction (XRD) and energy dispersive X-ray (EDX) analyses were performed after burning rice husk to 700 and 950 • C. Presence of relatively high deposits of amorphous siliceous phases in RHA at 700 • C indicated its pozzolanic potential. Subsequently, this RHA was ground to desired fineness, followed by sieving through sieve No. 200. Eventually, the fine RHA was used as a substitute of cement in different percentages (10, 15, and 20%) to evaluate its influence in mitigating autogenous shrinkage in concrete. Prismatic concrete beams (100 × 100 × 800 mm) were cast to measure autogenous shrinkage along with cylinders (150 mm dia. x 300 mm height) to test compressive strength of concrete. The results indicated a slight increase in compression strength with addition of 10% RHA, which however, reversed and slightly reduced in concretes containing 15 and 20% RHA. Unlike strength results, the trend of autogenous shrinkage was rather uniform as the rate as well as the amount of early-age autogenous shrinkage continued to decrease with increasing percentage of RHA. Moreover, despite of reduced rate during first 24 h, thereafter, the effect of 20% RHA on further reduction of autogenous shrinkage was insignificant and ended up only slightly lesser than the 15% RHA concrete at 7 days. Finally, the control cement sand mortar and mortar containing 15% RHA were cast to further validate the pozzolanic reactivity of RHA through scanning electron microscopy (SEM), EDX, and thermogravimetric analysis (TGA) tests. An observation of reduced amount of calcium hydroxide (Ca(OH) 2) in RHA mortar samples indicating its excellent pozzolanic potential when used as a partial substitute of cement in HPC.

A Review on the Use of Self-Curing Agents and Its Mechanism in High-Performance Cementitious Materials

“…It can absorb the aqueous phase, enabling water supply for the hydration process in the cementitious material [32,87]. Porous superfine powders possess nanometre-size pores, for instance, cenosphere [43,[88][89][90], rice husk ash (RH) [44,45,91,92], and biochar [93,94]. Generally, the particle size of porous superfine powders ranges between 5 µm and 10 µm, which is much smaller compared to SAP particles and LWA, where the pore size ranges between 4 nm and 10 nm.…”

Investigation on material physical properties for application in seawater-RHA concrete added with coal bottom ash

“…Rice husk ash was collected from Nibong Tebal, Pulau Pinang which has undergone an incineration process with 600°C temperature and passing 75micron of sieve plate as the required replacement to cement [29]. Meanwhile, CBA was collected from Tanjung Bin Power Plant, Johor as the replacement to sand with a passing sieve size of 5 mm.…”

Mapping Research Knowledge on Rice Husk Ash Application in Concrete: A Scientometric Review

“…The application of RHA in concrete has sparked tremendous interest in the usage of sustainable and environmentally friendly SCM [ 64 , 65 , 66 , 67 ]. RHA has amorphous nature, high surface area, and compatibility with OPC-concrete, which results in outstanding pozzolanic capabilities [ 55 , 68 , 69 , 70 ]. Each kilogram of rice milled yields 0.28 kg of rice husk [ 71 ].…”