Revisiting the Effect of Slag in Reducing Heat of Hydration in Concrete in Comparison to Other Supplementary Cementitious Materials

Abstract

Blast furnace slag (SL) is an amorphous calcium aluminosilicate material that exhibits both pozzolanic and latent hydraulic activities. It has been successfully used to reduce the heat of hydration in mass concrete. However, SL currently available in the market generally experiences pre-treatment to increase its reactivity to be closer to that of portland cement. Therefore, using such pre-treated SL may not be applicable for reducing the heat of hydration in mass concrete. In this work, the adiabatic and semi-adiabatic temperature rise of concretes with 20% and 40% SL (mass replacement of cement) containing calcium sulfate were investigated. Isothermal calorimetry and thermal analysis (TGA) were used to study the hydration kinetics of cement paste at 23 and 50 °C. Results were compared with those with control cement and 20% replacements of silica fume, fly ash, and metakaolin. Results obtained from adiabatic calorimetry and isothermal calorimetry testing showed that the concrete with SL had somewhat higher maximum temperature rise and heat release compared to other materials, regardless of SL replacement levels. However, there was a delay in time to reach maximum temperature with increasing SL replacement level. At 50 °C, a significant acceleration was observed for SL, which is more likely related to the pozzolanic reaction than the hydraulic reaction. Semi-adiabatic calorimetry did not show a greater temperature rise for the SL compared to other materials; the differences in results between semi-adiabatic and adiabatic calorimetry are important and should be noted. Based on these results, it is concluded that the use of blast furnace slag should be carefully considered if used for mass concrete applications.

Utilization of Waste Polysilicon Sludge in Concrete

“…Fresh properties i.e., air content and slump of the concrete mixes were examined. Paste specimens were made using a W/B ratio of 0.40 and investigated for heat flow using a semi-adiabatic calorimeter [30,31]. For Fourier transform infrared spectroscopy(FTIR) and XRD analyses, paste specimens were made using a W/B ratio of 0.4 and cured for 3, 7, and 28 days.…”

Effects of Light-Burnt Dolomite Incorporation on the Setting, Strength, and Drying Shrinkage of One-Part Alkali-Activated Slag Cement

“…For each test, three replicates were measured; the average value is presented. The heat evolution was investigated using a semi-adiabatic calorimeter according to a previous study [37]. For XRD and TGA analysis, powder specimens were obtained from the AAS mixtures after 7 days of hydration using an X-ray diffractometer (RINT D/max 2500, 40 kV, 30 Ma, scanning speed 2°/min, wavelength 1.54 Å) and a thermogravimetric analyzer (TGA7 PERKINELMER, TA instruments, PerkinElmer, Waltham, MA, USA).…”

Effect of Saturated Tea Waste and Perlite Particles on Early Age Hydration of High-Strength Cement Mortars

“…Before putting the mortar into bottles, bottles were wrapped in an insulating sheet. Early heat release rate or temperature rise was measured for up to 40 h by a semi-adiabatic method [9]. ASTM C191 [27] is a standard test method for measuring setting times of pastes, but in this study, we used this method to measure that for mortars.…”

“…The basic purpose of ICAs in HSMs and HSCs is to release stored water during the hydration process to delay rapid hydration and minimize leading interior temperatures [5,6,7,8]. Other than commonly-used ICAs, Moon et al [9] added slag with other supplementary cementitious materials (SCMs) to concrete to reduce the early heat release rates. Xu et al [10] studied the effects of ground granulated blast-furnace slag (GGBS) and fly ash (FA) on the early hydration and mechanical strength of concrete.…”