不同养生方式下水泥混凝土路面早期开裂风险分析

Risk Analysis of Early Cracking for Cement Concrete Pavement under Different Curing Methods

针对水泥混凝土路面的早期养生问题,选择液体养生剂覆盖养生和PE薄膜、麻布保水养生等6种方式对混凝土面层进行养生;基于HIPERPAV软件,分别测算铺筑72h内不同养生方式下面层弯拉强度和最大应力的发展规律。结果表明：面层铺筑后的第13h,应力强度比达到第一次峰值。此时,水泥水化是结构应力急剧增加的关键因素。之后,应力强度比的发展趋势与气温变化曲线基本吻合,水化热不再起主导作用。铺筑后的第13~24h是早期裂缝的风险高发期,该时段是混凝土水化热高速积聚期,若环境温度也处于高位,则路面随时面临最大应力超出弯拉强度而产生开裂的风险。为降低该风险,应避免采用覆盖后不补水的养生措施,在水源充足的条件下,宜采用覆盖物及时保水并上覆PE薄膜的养生方式。

Based on HIPERPAV software, six curing methods are brought to cure the cement concrete surface, such as liquid curing agent, PE film and burlap, then the developing regularity of tensile strength and maximum stress for these six curing methods are tested and calculated within 72 hours after paving. The results show that stress-strength ratio of cement concrete surface reached maximum after 13 hours from paving. In this case, cement hydration is a key factor for significant increase of stress. Then stress/ strength ratio change curve is basically coinciding with ambient temperature change because cement hydration doesn＇t play the leading role. From the 13rd to 24th hour after paving is a high risk period because of early cracking for surface. In this period, hydration heat increases sharply, if ambient temperature is also high, pavement would face the risk of cracking because maximum stress exceeds the flexural-tensile strength at any time. To reduce the risk of early cracking, curing method without supplement water after covering should be avoided. Meanwhile, supplement water to coat cover timely and coving PE film at same time is the priority curing method if water is sufficient.