天然浮石粉水泥土力学性质的试验研究

Experiment Study of Mechanical Properties of Natual Pumice Powder Cement-Soil

利用内蒙古丰富的天然浮石矿产资源，将天然浮石粉作为外掺剂应用于水泥土改性研究，可有效地改善水泥土的力学性质，明显增强水泥土的耐久性。通过室内试验，以水泥掺量15％为基准，分别掺入2％、4％、6％、8％、10％等不同掺量的天然浮石粉，养护龄期分别为7d、28d、60d、90d。试验结果表明：天然浮石粉水泥土无侧限抗压强度随着天然浮石粉掺量的增加而增大。当掺量达到8％时，强度达到了峰值，之后随浮石粉掺量的增加，强度不再增长；天然浮石粉水泥土强度随着龄期的增长而增大，90d强度是28d强度的1．52～1．6倍，后期强度增长很大；在不利的冻融循环条件下，天然浮石粉水泥土强度增长规律与冻前基本相同，水泥土强度虽然劣化，但比不掺浮石粉的情况均有很大程度的改善；浮石粉水泥土的渗透系数（对数）随着养护龄期的增长而减小，抗渗能力逐渐增强，特别是在最初的28d以内，其渗透系数降低较快。

The natural pumice powder is used as additives to change the cement - soil properties in order to utilize the abundant natural pumice resources in Inner Mongolia. The mechanical properties of cement - soil can be effectively improved, the durability of cement - soil is significantly enhanced. With the mixing amount of cement 15% as a benchmark, the pumice powder mixing amount is 2%, 4%, 6%, 8%, 10% respectively in the lab. The conservation age is 7 d, 28 d, 60 d, 90 d respectively. The experiments results show that the unconfined compressive strength of cement - soil increases with the mixing amount of the natural pumice powder, it reaches the peak value when the mixing amount is 8%, and there is no increasing after the value with the increasing of the mixing amount of the pumice powder. The strength of the natural pumice powder cement- soil is increasing with the conservation age, which the strength on 90 days is 1.52 to 1.6 times of the strength of on 28 days, the strength increases greatly in the late period. In the conditions of freeze-thaw cycle, the strength increasing trend of the natural pumice powder cement - soil is basically the same as before with the freeze, which the strength of the cement - soil is degraded, but the degree of strength improvement is significantly increased comparing with the soil without pumice powder mixing. The permeability coefficient of the pumice powder cementsoil is decreasing with the conservation age, the impermeability capacity is gradually increased, and particularly the permeability coefficient is decreased rapidly in the first 28 days.