Investigating the use of the adiabatic calorimetry to characterize concrete road pavement mixes

Abstract

Determining in-situ concrete properties can be a challenge due to limitations on current test methods where laboratory conditions and in-situ conditions are not the same. The heat released from cementitious materials during the exothermic hydration process can be used to characterize important properties of different mix designs for concrete pavements. In this investigation, an adiabatic calorimeter for concrete mixes was used to measure the real time heat of hydration of concrete mixes for road pavements. The adiabatic calorimeter captures the true temperature of concrete specimens with minimal heat exchange between the concrete and surroundings to determine real-time concrete heat properties. This study investigates three different concrete pavement mix designs that incorporate CEM II 32.5 R, CEM II 42.5 N and CEM I 52.5 N cements respectively. The heat of hydration and the correlation with concrete properties such as 28-day flexural strengths, 7-day, and 28-day compressive strengths, initial and final setting times are discussed in this paper. The results indicate a high correlation (0.91<R2

<0.99) between the compressive strength and heat of hydration of the investigated mixes. Low regression values (0.004<R2

<0.023) were found for setting time and flexural strength (R2

=0.0911). The results also suggest high correlation between the heat flux of the concrete mixes and setting times (0.95<R2

<1) and flexural strength (R2 =0.80).