嵌锁密实水泥混凝土粗集料级配组成设计方法

Gradation design method of coarse aggregate for interlocking-dense cement concrete

根据水泥混凝土中粗集料的作用,引入了集料填充比参数来表征粗集料的级配组成结构与集料颗粒之间的关系。以粒子干涉理论和颗粒填充理论为基础,参考体积法设计思想,提出了水泥混凝土粗集料嵌锁骨架结构级配组成设计方法,并编制了设计软件。根据试验工程水泥混凝土设计要求,应用设计软件确定了粗集料级配组成和嵌锁密实水泥混凝土设计配合比,并进行了混凝土性能试验验证。试验结果表明:应用设计软件直接确定的嵌锁骨架结构粗集料级配组成,比《公路水泥混凝土路面施工技术规范》(JTG F30—2003)推荐的级配范围下限偏粗,整体骨架结构更好;嵌锁密实水泥混凝土的坍落度为25 mm,满足10～30 mm的工作性设计要求;28 d弯拉强度为7.9 MPa,大于配制弯拉强度7.7 MPa,满足设计强度要求;应用快冻法试验得出的混凝土最大抗冻循环次数为250次,抗冻耐久性指数为49.2%,满足寒冷地区200次抗冻循环的要求。

According to the roles of coarse aggregate in cement concrete,the aggregate filling ratio was put forward to present the relationship between coarse aggregate gradation structure and aggregate particle.Based on particle interference theory and particle filling theory,the design idea of volumetric method was consulted,the gradation design method of coarse aggregate with interlocking skeleton structure for cement concrete was put forward,and the corresponding design software was developed.On the basis of cement concrete design requirements of testing project,the coarse aggregate gradation was calculated,and the design mix proportion of interlocking-dense cement concrete was determined by using software.Furthermore,the concrete performances were tested and verified.Test result indicates that the coarse aggregate gradation with interlocking skeleton structure directly determined by using the software is more coarse than the lower limit of the gradation range recommended by the technical specification for construction of highway cement concrete pavements（JTG F30—2003）,and its whole skeleton structure is better.The slump of interlocking-dense cement concrete is 25 mm and meets the workability requirement 10 to 30 mm.The 28 days flexural strength is 7.9 MPa,which is greater than the preparation strength 7.7 MPa and meets the design strength requirements.The maximum number of frost cycles tested by using quick freezing method is 250,and the froze-resistance index is 49.2%,which meets the frost cycles requirement 200 for cold region.5 tabs,2 figs,19 refs.