水泥稳定碎石基层温缩性能试验及预估控制

针对水泥稳定碎石基层在温度变化时易产生温缩裂缝,且现有试验方法和评价指标无法对其进行有效控制的问题,采用不同级配和水泥剂量的水泥稳定碎石混合料进行温缩性能试验,得出混合料温缩性能与水泥剂量、级配、温度等因素之间的关系,建立并验证了温缩性能预估模型.试验结果表明,粗集料含量较多、水泥剂量较低时,混合料的温缩应变和温缩系数均较小;但温缩性能随水泥剂量增加而增长的幅度有限.结合有限元温缩应力分析和劈裂强度试验结果,对基层内的应力强度比进行分析,提出了相应的基于温缩的强度控制标准.研究结果将为设计和施工中预估并减少水泥稳定碎石基层温缩裂缝、确定基层合理强度提供参考.

Test and estimate control on temperature shrinkage performance of cement-treated macadam

Aiming at the problems that temperature-shrinkage cracks are easy to occur in cement-treated macadam base when temperature changes and current test methods and evaluate index can not control it efficiently,experiments on shrinkage performance of mixture of various gradation composition and cement content were conducted.Relationship between mixture shrinkage performance and cement content,gradation composition and temperature are educed,and temperature-shrinkage estimate model for cement-treated materials are established and validated.Test results indicate that shrinkage strain and coefficient are lower in mixture with more coarse aggregate and lower cement dosage,however,the increase of temperature-shrinkage performance is limited with augment of cement content.The stress ratio in the base is analyzed through combining the results of calculated shrinkage-stress with splitting strength test,and the strength criterion based on temperature shrinkage is proposed.Research results can provide consultations to estimate and reduce base temperature-shrinkage crack in design and construction,as well as to determine reasonable base strength.