Semi-quantification of cementing products using X-ray diffraction technique in stabilized aggregate

Abstract

A laboratory study was undertaken to investigate the performance of limestone aggregate base stabilized with different stabilizing agents, namely, class C fly ash, cement kiln dust and fluidized bed ash. Cylindrical specimens were compacted and cured for 1 hour, 3 days and 28 days prior to tests of unconfined compressive strength (UCS), scanning electron microscopy, energy-dispersive spectrometry and X-ray diffraction. Results showed that the UCS values increased with curing time. It was also found that the different stabilizing agents produced different UCS values. The reference intensity ratio (RIR) method was employed to identify and quantify the mass percent of minerals and cementing compounds in the mixtures. Results revealed the formation of cementing compounds such as ettringite, C-S-H, C-A-H and C-A-S-H, which were responsible for an increase in the UCS values. In this study, the sum of all the cementing compounds (SCC) showed the same beneficiation trend as the UCS trend with curing time. Finally, the UCS values correlated fairly well with SCC. The SEM micrographs showed the intensity of crystal formation and hydration coating, which increased with curing time and percentage of additive.