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Abstract

ABSTRACT:The coefficient of thermal expansion (CTE) of cementitious paste at various ages was studied. Pastes were prepared with various water to binder and fly ash to binder ratios. The CTE of paste increased with age, and decreased with fly ash content, particularly at an early age. A model for predicting the CTE of paste was proposed as a time, material, and mix proportion dependent function. The model was verified with various experimental results and the verification results were satisfactory.

Evaluation of Thermal Conductivity of Sustainable Concrete Having Supplementary Cementitious Materials (SCMs) and Recycled Aggregate (RCA) Using Needle Probe Test

“…The coefficient of thermal expansion of several concrete ingredients was reported by Choktaweekarn and Tangtermsirikul [27]. For example, the thermal expansion of cement, fly ash, and limestone, are 14.4 × 10 −6 , 6.45 × 10 −6 , and 4.5 × 10 −6 , respectively.…”

“…On the other hand, it was found by Choktaweekarn and Tangtermsirikul [27] that incorporating fly ash at high replacement percentages may reduce the thermal conductivity of the concrete at an early age, especially within the first 7 days, but yet it continues to increase with the increase in age as a result of the abovementioned reaction that later offset the reduction of thermal conductivity related to fly ash material. Therefore, the thermal properties of concrete are time dependent, as the pozzolanic reaction continues for the later age of concrete curing, which is 28 days.…”

“…For example, the thermal expansion of cement, fly ash, and limestone, are 14.4 × 10 −6 , 6.45 × 10 −6 , and 4.5 × 10 −6 , respectively. Although the coefficient of thermal expansion of concrete can be initially estimated by summation of the volumetrically weighted average of the thermal expansion of its ingredients, the effect of the degree of cement hydrations and pozzolanic reactions of SCMs have significant impacts on this measurement [27]. For example, although fly ash has a relatively lower thermal expansion coefficient than other concrete ingredients, the results in the current study showed an increase in the thermal expansion of concrete with a higher replacement level of fly ash.…”

Effect of polypropylene fibre on cementitious mortar early shrinkage cracking using the eccentric-ring test

“…Rapid penetration of harsh chemicals, enhanced carbonation, and faster corrosion of reinforcement in concrete are indicators of decreased durability. Under certain circumstances, shrinkages of cement-based materials cause internal stress during the initial stages of hydration, and may lead to cracking if the strain is not dispersed (Wongtanakitcharoen and Naaman, 2007;Choktaweekarn and Tangtermsirikul, 2009;Kanavaris et al, 2019;Idrees et al, 2022).…”