Contributions of fly ash and ground granulated blast-furnace slag to the early hydration heat of composite binder at different curing temperatures

Abstract

Hydration heat evolutions and non-evaporable water contents of binders and reaction degrees of fly ash and ground granulated blast-furnace slag (GGBS) were tested to investigate the contributions of fly ash and GGBS to the early hydration heat of composite binders at 25°C and 50°C. Results show that fly ash makes a very small contribution to the early hydration heat of composite binder at 25°C, but GGBS makes a considerable contribution at 25°C. Elevated temperature enhances the contributions of both fly ash and GGBS to the early hydration heat of composite binder significantly. The promoting effect of elevated temperature on the hydration heat and non-evaporable water content of GGBS binder is greater than that of fly ash binder. The reaction heat per unit mass of GGBS is only 16·7% higher than that of fly ash. The main reason for the difference of hydration heats between GGBS binder and fly ash binder is that GGBS shows much higher hydraulic activity than fly ash.

Hydration heat, strength and microstructure characteristics of UHPC containing blast furnace slag

“…The cumulative heat releases of ref., FS30, and FS60 mixtures were 140, 120 and 90 J/g at 20 • C, whereas they were 152, 134 and 110 J/g at 35 • C at the end of 48 h, respectively. An increase in the curing temperature increased the total heat release in concordance with the conclusions of the previous studies [24,25]. Moreover, GGBS-bearing mixtures were found to be more sensitive to curing temperature when compared with the control mixture in terms of cumulative heat.…”

Hydration of Binary Portland Cement Blends Containing Silica Fume: A Decoupling Method to Estimate Degrees of Hydration and Pozzolanic Reaction

“…Since hydration of cement and pozzolanic reactions of SCMs are exothermic processes, several models based on direct calorimetry measurements have been developed to describe the hydration of blended cementitious materials (De Schutter and Taerwe, 1995;Swaddiwudhipong et al, 2003;Riding et al, 2013). They are useful in predicting the heat of hydration and semiadiabatic temperature rise in mass concrete, and can be used to broadly estimate the overall degree of hydration of blended cementitious materials (Fanghui et al, 2016;Qiang et al, 2016;Zhang et al, 2016). However, the interactions between cement hydration and pozzolanic reaction of SCMs (with portlandite) are not explicitly considered by these models.…”

The Influence of Ground Fly Ash on Cement Hydration and Mechanical Property of Mortar

“…While at later ages, the chemical effect of fly ash works. Fly ash can react with Ca(OH) 2 , which is a product of cement hydration, to form C-S-H gel [11,12]. is is the so-called pozzolanic reaction.…”