Experimental study of the mechanical properties and microstructure of geopolymer paste containing nano-silica from agricultural waste and crystalline admixtures
Ar Razi Alvee, Rizka Malinda, Alfie Muna Akbar, Resa Dwi Ashar, Cut Rahmawati, Thamer Alomayri, Ali Raza, Faiz Uddin Ahmed Shaikh
Abstract
This study explored the influence of nano-silica and Crystalline Admixture (CAs) on the mechanical properties and microstructure of geopolymer pastes. Nano-silica and CAs was added to the mixture at 3%, 4% and 5% respectively by weight of fly ash. The bulk density, the yield stress of geopolymer paste, compressive strength, and flexural bending tests were carried out to evaluate the effect of nano-silica and CAs effect on the geopolymer paste. Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Transmission Electron Microscope (TEM), and Fourier Transform Infrared Spectroscopy (FTIR) techniques are employed to examine the microstructure of nano-silica and geopolymerization products. The test results demonstrated that adding nano-silica and CAs by 5% increased the bulk density by 5.32%, yield stress by 64.20%, compressive strength by 33.63%, flexural strength and fracture toughness by 232.69% than the control specimens, respectively. The SEM, XRD, and FTIR analysis revealed that the effect of nano-silica and CAs on geopolymer paste occurred mainly in increasing the CSH bond and self-healing products. These findings suggest that rice husk ash can be processed into nano-silica by the sol-gel method and combined with CAs to obtain better mechanical strength.