大掺量石灰石粉泡沫轻质土的制备及其性能研究

Preparation and properties of foamed lightweight soil with large content of limestone powder

利用石灰石粉替代部分水泥制备的泡沫轻质土可用作路基的填充材料,达到减小地基的沉降量和附加应力的目的。研究表明:在普通泡沫轻质土体系中,随着石灰石粉掺量增加,泡沫轻质土的流值和强度均逐渐降低,配制设计强度为1.0 MPa的泡沫轻质土,石灰石粉掺量不宜超过20%;而在高性能泡沫轻质土体系中,采用水固比为0.4,减水剂掺量0.2%,且减水剂与泡沫剂具有良好的相容性,石灰石粉的掺量可以达到40%。泡沫轻质土中掺入石灰石粉有利于泡沫的分散,不易形成大孔,大于0.5 mm大孔少,多数孔径在0.2 mm以下,孔径大小不均;孔形呈球状,连通孔少,多为单独的孔。大掺量石灰石粉泡沫轻质土样品的水化产物中C-S-H、CH、AFt和单碳水化铝酸钙C_(3)A·CaCO_(3)·11H_(2)O特征峰明显,石灰石粉具有早期加速水泥水化的作用。

The foamed lightweight soil prepared by replacing part of the cement with limestone powder can be used as the filling material of the subgrade to reduce the sedimentation and additional stress of the foundation.The results showed that in the ordinary foamed lightweight soil system,with the increase of limestone powder mixing,the flow value and strength of the foamed lightweight soil were gradually reduced,and the preparation design strength of 1.0 MPa foamed lightweight soil should not exceed 20%;In the high-performance foamed lightweight soil system,the water-solid ratio was 0.4,the amount of water reducer is 0.2%,and the water reducer and foam agent had good compatibility,and the amount of limestone powder could reach 40%.The incorporation of limestone powder in foamed lightweight soil is conducive to the dispersion of foam,and it was not easy to form large pores,more than 0.5 mm large pores are few,most of the pore size is below 0.2 mm,and the pore size was uneven.The pore shape was spherical,and the connecting hole was less,mostly a separate hole.Among the hydration products of the limestone powder foamed lightweight soil samples,the characteristic peaks of C-S-H,CH,AFt and single carbide calcium aluminate C_(3)A·CaCO_(3)·11H_(2)O are obvious.Limestone powder has the effect of accelerating cement hydration in the early days.