混凝土配合比的设计方法较多,常用的有绝对体积法和假定容重法。前者较繁,但适用范围广,理论较完整,有实用价值;后者简便易行,但要有充分的经验数据,要测定大量的混凝土湿容重。由于地方材料(砂、石等)材质不一, 比重各异,比如北京地区的石子比重一般在2.7以上,而上海一般在 There are many design methods for concrete mix ratio, and the absolute volume method and the assumed bulk density method are commonly used. The former is more complicated, but it has a wide range of applications, a more complete theory, and practical value; the latter is simple and easy, but it must have sufficient empirical data to determine a large amount of wet concrete weight. As the local materials (sand, stone, etc.) are of different materials, the specific gravity varies. For instance, the proportion of stone in Beijing is generally above 2.7, while Shanghai is generally