纳米硅粉水泥土抗腐蚀性能研究

水泥土搅拌法处理近海软土时, 水泥土常处于腐蚀性环境中。系统研究掺入纳米硅粉的水泥土的抗腐蚀性能, 为水泥土抗腐蚀性能改良、近海区软土水泥土搅拌法加固提供依据。选取珠江三角洲典型的淤泥质粘土, 按天然含水量配制试验用土,加入掺入比为0%～4%的纳米硅粉配制水泥土试件, 在腐蚀性硫酸盐溶液和纯水中养护到不同龄期, 对其进行无侧限抗压强度对比试验, 得到了水泥土强度与纳米硅粉含量及腐蚀性养护环境关系的变化规律。主要结论是: 两种养护环境下, 纳米硅粉提高水泥土强度的长期效果比短期效果显著, 龄期90 d内纳米硅粉掺入比为2%的水泥土强度最大; 但龄期180 d时水泥土强度随纳米硅粉掺量的增加而增加; 硫酸盐腐蚀环境能加速纳米硅粉和水泥水化产物的二次水化反应, 大幅提高水泥土的强度, 纳米硅粉能显著提高水泥土的抗腐蚀性能; 龄期180 d时, 养护在硫酸盐溶液中纳米硅粉掺入比为2%～4%的水泥土, 强度比掺入比为0%的水泥土强度高(2～3)倍, 也比相同配比养护在纯水中水泥土强度高15%～20%。

Study on Corrosion Resistance of Soil-cement Mixed with Nanometer Silica Powder

Soil-cement usually is in corrosive circumstance when soft soil in the inshore area is improved with soil-cement mixing method. The systematic investigation into the effect of nanometer silica powder(NSP) on the corrosion resistance of soil-cement can provide useful data for the design and construction of soil-cement mixed with soft soil in the inshore area. The mucky soil was drilled from a place in the Delta of the Pearl River. The NSP of different blend ratio, added to the soil samples with natural water content, made soil-cement samples. The soil-cement samples were then cured in the corrosive circumstance of sulfate aqueous solution and in the water for different ages, followed by the measurement of the unconfined compression strength(UCS). Therefore, the variation laws of the strength of soil-cement with the blend ratio of NSP and with the corrosive curing circumstances were obtained, thus coming to the conclusions that the NSP more obviously increases the UCS of soil-cement at the age of long time than of short time, that the sulfate corrosive circumstance in which the secondary hydration reaction between the NSP and the hydration product of cement is accelerated can increase the UCS of soil-cement mixed with NSP by a big margin, that the UCS of soil-cement with 0.02 to 0.04 in the blend ratio of NSP, cured in the circumstance of sulfate solution is higher 2 to 3 times than that with no NSP, cured in the same circumstance at the age of 180 days.