Hernández-Bautista E, Sandoval-Torres S, de J Cano-Barrita P F, Bentz D P
Instituto Politécnico Nacional/CIIDIR Unidad Oaxaca, Hornos 1003, Oaxaca, México. C.P. 71230.
National Institute of Standards and Technology, Gaithersburg, MD, USA.
Constr Build Mater. 2017 Oct;151:186-195. doi: 10.1016/j.conbuildmat.2017.05.151. Epub 2017 Jun 22.
During steam curing of concrete, temperature and moisture gradients are developed, which are difficult to measure experimentally and can adversely affect the durability of concrete. In this research, a model of cement hydration coupled to moisture and heat transport was used to simulate the process of steam curing of mortars with water-to-cement () ratios by mass of 0.30 and 0.45, considering natural convection boundary conditions in mortar and concrete specimens of AASHTO Type VI beams. The primary variables of the model were moisture content, temperature, and degree of hydration. Moisture content profiles of mortar specimens (40 mm in diameter and 50 mm in height) were measured by magnetic resonance imaging. The degree of hydration was obtained by mass-based measurements of loss on ignition to 1000 °C. The results indicate that the model correctly simulates the moisture distribution and degree of hydration in mortar specimens. Application of the model to the steam curing of an AASHTO Type VI beam indicates temperature differences (between the surface and the center) higher than 20 °C during the cooling stage, and internal temperatures higher than 70 °C that may compromise the durability of the concrete.
在混凝土蒸汽养护过程中，会产生温度和湿度梯度，这些梯度难以通过实验测量，并且可能对混凝土的耐久性产生不利影响。在本研究中，采用了一个将水泥水化与水分和热传输相耦合的模型，来模拟水灰比（质量比）分别为0.30和0.45的砂浆的蒸汽养护过程，同时考虑了AASHTO VI型梁的砂浆和混凝土试件中的自然对流边界条件。该模型的主要变量为含水量、温度和水化程度。通过磁共振成像测量了砂浆试件（直径40毫米，高度50毫米）的含水量分布。通过对1000℃灼烧失量的质量法测量获得水化程度。结果表明，该模型能够正确模拟砂浆试件中的水分分布和水化程度。将该模型应用于AASHTO VI型梁的蒸汽养护表明，在冷却阶段表面与中心之间的温差高于20℃，内部温度高于70℃，这可能会损害混凝土的耐久性。
