三七灰土是按体积比算的,那就是说一立方三七灰土含干石灰0.3立方.土0.7方.定额用量：石灰0.51912吨,黏土1.22306吨.但从定额消耗量看,每立方米3：7灰土含石灰0.51912吨,黏土1.22306吨,0.51912/1.22306=0.4244约等于3/7=0.4286.从这个角度看实际应该是重量比!