矿质集料承载比试验方法研究

Study on Test Method of California Bearing Ratio of Mineral Aggregate

矿质集料为散体材料,在其承载比(CBR)测定过程中常遇到成型方式不当和变异系数过大等问题。参照现行公路工程集料试验规程规定的粗集料堆积密度及空隙率试验方法,分别采用“三装三捣”和“三装一压”法成型石灰岩、花岗岩、辉绿岩集料试件,进行矿质集料承载比试验对比研究,推荐采用“三装一压”的成型法进行矿质集料CBR承载比测试。考虑到“三装一压”离析较小、变异系数较小等优势,石灰岩、花岗岩和辉绿岩采用“三装一压”法成型集料试件时的成型压力宜采用15kN,变异系数允许值取CV≤17%。

Mineral aggregate is a bulk material,in the process of determining its California Bearing Ratio(CBR),the problems of improper molding method and excessive coefficient of variation have been often encountered.In this article,on the basis of test methods for the coarse aggregate bulk density and porosity according to the current highway engineering aggregate test regulations,by adopting the"three-packed,three-pounded"and"three-packed,onepressed"methods to form limestone,granite,and diabase aggregate samples,a comparative study on the bearing ratio test of mineral aggregates has been carried out,it has been recommended to use the"three packs and one pressing"molding method for the CBR bearing ratio test of mineral aggregates.Considering the advantages of small segregation and small coefficient of variation of"three loading and one pressure",the forming pressure of limestone,granite and diabase should be 15kn when using"three loading and one pressure"method to form aggregate specimen,and the allowable value of coefficient of variation is CV≤17%.