Influence of structural form on hydration-heat-induced temperature rise of precast concrete lining..

[摘要] Concrete is a composite material composed ofcement, water, aggregate, and admixtures.1 Duringthe concrete casting process, the exothermicchemical reaction between cement and water (hydrationof cement) releases a large amount of heat.2,3 The largeamount of hydration heat generated in a short time leads toa rapid rise in the concrete temperature at its early age. Thehigh temperatures (greater than 70°C [158°F]) can give riseto delayed ettringite formation, which could cause the concrete to expand and crack and, in turn, reduce its strengthand durability.4–6 Furthermore, in the interior of concrete,heat is trapped because of the poor thermal conductivityof concrete, whereas on the surface of concrete, heat isreleased into the atmosphere.3,7 The trapped heat causesthe temperature of the interior to be relatively higher thanthe surface temperature. The temperature gradient fromthe core to the surface leads to an internal restraint, whichresults in compressive stresses in the interior and tensilestresses in the surface.8,9 Consequently, thermal crackscould occur as the restraint-induced tensile stress in concrete exceeds its tensile strength.

[学科分类] 建筑学