干湿循环下钢渣微粉水泥改良膨胀土强度特性试验研究

膨胀土作为一种非饱和黏性土,因其吸水膨胀失水收缩的特性而成为一种具有危害性的地质土体,尤其在干湿气候交替变化的环境中,更会因其湿胀干缩产生变形导致工程事故的发生。通过使用钢渣粉作为新型固化剂,与水泥组合改良膨胀土,研究改良膨胀土在干湿循环条件下的强度特性变化规律。通过室内试验研究了纯膨胀土(Es)、水泥改良膨胀土(Es-C)、钢渣粉-水泥改良膨胀土(Es-SSP-C)和钢渣粉-水泥-NaOH改良膨胀土(Es-SSP-C-N)在不同养护龄期以及不同干湿循环次数作用下其无侧限抗压强度变化规律。试验结果表明:3种改良土体的强度都随养护龄期的增加而增大,并且在干湿循环作用下四种土体都有不同程度的强度损失,但在强度上总是呈现出Es-SSP-C-NEs-CEs-SSP-CEs的规律,意味着在改良效果上Es-SSP-C-N更优于另外两种方案。

Experimental Study on Strength Characteristics of Expansive Soil Modified with Steel Slag Micropowder and Cement under Dry-wet Cycles

Expansive soil, as an unsaturated cohesive soil, is a harmful geological soil due to its nature of bulging in wetness and shrinking in dryness. Especially in the environment of alternating wet and dry climate, it would cause engineering accidents because of its nature. To solve this problem, expansive soils were modified with steel slag powder and cement to improve the performance, and the mechanical variation was analyzed under dry-wet cycles. In laboratory, four differently formulated expansive soils were tested, i.e., pure expansive soil (Es), cement modified (Es-C), steel slag powder-cement modified (Es-SSP-C), and steel slag powder-cement-NaOH modified (Es-SSP-C-N). Their variations in unconfined compressive strength were determined under different curing ages and dry-wet cycles. Results show that the strength of the three modified soils increased with the increase of curing age, and the four soils have different degrees of strength loss under dry-wet cycles, but the strength was always in an order of Es-SSP-C-N > Es-C > Es-SSP-C > Es, which means that Es-SSP-C-N was the best among them all.