No abstract

This research investigated high calcium fly ash geopolymer stabilized recycled concrete aggregate (RCA-FAG) as pavement base material. The effect of recycled concrete aggregate (RCA):high calcium fly ash (FA) ratios, sodium silicate (Na2SiO3):sodium hydroxide (NaOH) ratio, and curing time on the unconfined compressive strength (UCS) and scanning electron microscope (SEM) properties of RCA-FAG samples were evaluated. The maximum dry unit weight of the RCA-FAG sample was 20.73 kN/m3 at RCA:FA ratio of 80:20 and Na2SiO3:NaOH ratio of 60:40. The 7-d UCS of RCA-FAG samples increased as the FA content and Na2SiO3:NaOH ratio increased. The 7-d UCS of the RCA-FAG sample was better than that of the RCA with no FA because FA particles filled in RCA particles, resulting in a dense matrix. The 7-d UCS of RCA-FAG samples passed the 7-d UCS requirement for the low-traffic road. All ingredients met the 7-d UCS requirement for the high-traffic road except the sample with RCA:FA of 100:0 and Na2SiO3:NaOH of 50:50 and 60:40. The 7-d SEM images indicated that spherical FA and RCA particles are bonded together, resulting in the dense matrix for all Na2SiO3:NaOH ratios. The proposed equation for predicting the UCS of RCA-FAG offered a good coefficient of correlation, which is useful in designing pavement base material from RCA-FAG material.

Lightweight materials are the most popular building wall construction materials because of their fast installation, high insulation, and low cost. However, these materials use cement as a binder. Cement production releases carbon dioxide emissions resulting in environmental issues. The research investigated the use of fly ash geopolymer and polyvinyl alcohol (PVA) to enhance the mechanical and thermal properties of cellular lightweight mortar. The effects of PVA concentrations, foam content (Fc), and curing time on properties of the cellular lightweight fly ash geopolymer (CLFAG) mortar reinforced with PVA specimens were evaluated. The results revealed that the PVA concentrations and Fc had an effect on the unit weights of the CLFAG reinforced with PVA specimens. The lowest unit weight of the specimens was 10.10 kN/m 3 at a PVA concentration of 20% and Fc of 2%. According to the Thailand industrial standard for C12 and C14 CLC block types, all mixed ingredients met the unit weight and compressive strength requirements. The correlation between unit weight and thermal conductivity of CLFAG reinforced with PVA specimens was represented by a linear function, which was a useful equation for estimating the thermal conductivity of specimens.