Enhancing Acid Resistance of Recycled Aggregate Concrete Using Rice Husk Ash and Hybrid Fibers
摘要
Concrete made with recycled concrete aggregate (RCA) has poor durability behavior compared to its counterpart normal concrete, especially when concreting in a chemically aggressive environment. Hence, this research work aims to improve the acid attack resistance of recycled aggregate concrete by incorporating rice husk ash (RHA) and hybridization of alkali-resistant glass fiber (Ar-GF) and steel fiber (SF). The RCA substitution was kept constant at 75%, while cement was partially substituted with RHA at dosages of 10, 15, and 20%. The hybridization of Ar-GF to SF was included in each of these ages in the respective proportions of 0.5%–0.5%, 0.25%–0.75%, and 0.75%–0.25%. The methodology adopted was by evaluating the compressive strength of the specimens at 28, 56, and 120 days of exposure to 4.0% of sulfuric acid attack to determine any loss in their strength and weight. Afterward, field emission scanning electron microscopy and Fourier transform infrared-ray characterization methods were performed to study the microstructure properties. The results revealed that the specimen made with a mix combination of RHA15% and hybridization of Ar-GF0.5% and SF0.5% (S1–4) exhibited better resistance to sulfuric acid attack than the ordinary concrete (control). Furthermore, the results of the microstructural analysis demonstrated that the S1–4 specimen had less micro- and macropores with more calcium silicate hydrate gel than the control specimen. Therefore, it is concluded that this mixture can be used when concreting in harsh chemical environments.