Abstract:

For soft clayey soil in Shanghai, the relationship among the strength of stabilized soils, cement contents, initial pH value and curing time is investigated experimentally. The strength obtaining mechanism of cement mixed clayey soil of Shanghai with curing time, cement contents and initial pH value is presented at first. Then, the strength obtaining mechanism of some typical Japanese clay compared with Shanghai clay is discussed. Limited laboratory test studies show that the strength obtaining of Shanghai clay is abruptly increased with the cement content larger than 17%-20% or the pH value is larger than a critical value(pHc) immediately after mixing. For Shanghai clayey soils, the critical value pHc is 11.7. If the cement content is higher, it will take a long time for the strength of cement mixed Shanghai clayey soils to reach a steady value. This phenomenon is much different from that of cement mixed Japanese clay, of which strength is gradually obtained with the cement content.

Key words: Shanghai clayey soil, initial pH value, curing time, strength