Prinya Chindaprasirt

A Mix Design Procedure for Alkali-Activated High-Calcium Fly Ash Concrete Cured at Ambient Temperature

This research focuses on developing a mix design methodology for alkali-activated high-calcium fly ash concrete (AAHFAC). High-calcium fly ash (FA) from the Mae Moh power plant in northern Thailand was used as a starting material. Sodium hydroxide and sodium silicate were used as alkaline activator solutions (AAS). Many parameters, namely, NaOH concentration, alkaline activator solution-to-fly ash (AAS/FA) ratio, and coarse aggregate size, were investigated. The 28-day compressive strength was tested to validate the mix design proposed. The mix design methodology of the proposed AAHFAC mixes was given step by step, and it was modified from ACI standards. Test results showed that the 28-day compressive strength of 15–35u2009MPa was obtained. After modifying mix design of the AAHFAC mixes by updating the AAS/FA ratio from laboratory experiments, it was found that they met the strength requirement.

Fire-resistant geopolymer bricks synthesized from high-calcium fly ash with outdoor heat exposure

This research proposed an alternative utilization of high-calcium fly ash to produce geopolymer bricks for fire-resistant applications. Outdoor heat exposure (OHE) was applied to cure geopolymer mortar. The temperature was up to 40xa0°C. Geopolymer brick was created with a 30-day compressive strength of 47xa0MPa via OHE curing for 3xa0days. The brick experienced a low weight loss after the firing test, which indicated its fire-resistant property. For the flame test, the maximum temperature on the opposite side of the brick from the flame was lower than 380xa0°C, with no observable cracks, complying with the fire-test requirement. Therefore, high-calcium fly ash geopolymer cured with OHE is suitable for use as a fire-resistant material. In addition, outdoor heat exposure is a promising renewable means to cure geopolymer.