水泥稳定碎石基层成型早期内部温度场解析与温缩裂缝控制

Study on Early Time Interior Temperature Field of Cement Stabilized Macadam Base and Control of Contractive Cracks

通过不同配比集料的比对试验,论证了水稳碎石基层早期温缩开裂的形成原因及其危害性,对水泥含量和水泥品种选择、集料级配等进行了试验分析,并结合试验结果给出了相应的防治措施。结果表明:在水稳混合料设计时,当水泥用量为5%时,混合料最大温缩应变最小;外掺剂掺量在3%时,混合料具有相对较小的最大温缩应变;为降低混合料的温缩应变,应控制细集料的含量,4.75 mm通过量宜在29%~34%之间;水泥稳定碎石混合料在60^-30℃的温缩系数变化规律是相似的,总体是逐渐减小的,在摊铺初期温缩系数最大,在40~5℃期间敏感性最强,至冰点阶段达到最小。应尽可能采用强度高、低水化热、高放热速率的水泥。

By comparison of the experiment of the aggregates with different mixture ratios, the reasons and the hazardous nature of the contractive crack of the cement stabilized macadam base in early time were proved, and the corresponding preventing and controlling measures were given. The selection of content and type of cement and aggregate gradation were experimentally analyzed. The test results of the content type selection and aggregate gradation of cement show that （1） when cement content is 5 %, the maximum temperature shrinkage strain of the mixture is the smallest; （2） when mixed with the additive of 3 %, the maximum temperature shrinkage strain is relatively small; （3） for reducing the temperature shrinkage strain of the mixture, the content of fine aggregate should be controlled to the passage of 4.75 mm at 29% to 34% ; （4） the variation patterns of the temperature shrinkage coefficients of cement stabilized macadam mixture between 60℃ to - 30℃ are similar and gradually decrease in general; （5） in the early paving, the temperature shrinkage coefficient is the largest, its sensitivity is the strongest between 40℃ and 5℃, and it reaches the minimum when temperature reaches the freezing stage. The cement with high intensity, low hydration heat and high heat release rate should be chosen.