钢渣-水泥稳定碎石性能及环境影响试验

Experimental study on properties and environmental impacts of steel slag cement stabilized aggregates

针对钢渣在半刚性基层中的应用,确定钢渣在水泥稳定碎石中的最佳替代量,并对其力学性能、体积稳定性以及环境影响进行评价。采用扫描电镜(SEM)对钢渣表面的微观结构进行检测,X射线荧光法对其化学元素进行测试,火焰原子吸收分光光度计法(FAAS)对其金属成分进行测定;在不同水泥含量(质量分数,3%、4%、5%、6%)的水泥稳定碎石中掺入不同掺量钢渣(体积分数,0%、30%、50%、75%),开展了无侧限抗压强度、无侧限压缩模量、抗折强度、体积稳定性试验,并对不同水泥含量、颗粒粒径和盐度环境下的重金属析出进行了研究。结果表明:钢渣颗粒具有较好的工程力学性能,能一定程度上改善钢渣水泥稳定碎石的强度、刚度和干缩性能;当钢渣掺量为50%时,整体力学性能最佳;通过醋酸处理或加入硅灰可有效防止钢渣的体积膨胀,但硅灰含量不宜超过4.5%;当水泥含量较少、钢渣粒径较小或周围盐度较高时,钢渣中的重金属析出风险更大,建议采用大颗粒钢渣(粒径>4.75 mm)和较高的水泥含量,以降低环境污染风险;在沿海地区,钢渣可能暴露在盐水环境中,应多加关注。通过在生产和应用过程中采取适当的控制措施,钢渣可以作为一种有效的替代骨料,在水泥稳定基层中具有良好的应用前景。

The feasibility of utilizing steel slag in road base was investigated and optimum steel slag content was determined, mechanical properties, volumetric stability as well as environmental influences were evaluated. Microstructure of surface was examined by the scanning electron microscope(SEM), element distribution was characterized by the X-ray fluorescence test and metal constitute was determined by flame atomic absorption spectrophotometer(FAAS). Four levels of steel slag contents(0%, 30%, 50%, 75%, volume fraction, the same as below) were blended into mixtures with different cement contents(3%, 4%, 5%, 6%, mass fraction, the same as blew). Tests of unconfined compressive strength, unconfined compressive modulus, bending strength and volume stability were conducted. Heavy metal precipitation of different cement contents, particle sizes and salinities were also checked. The results show that steel slag has good engineering mechanical properties, and is beneficial for strength, stiffness and dry shrinkage of cement treated aggregates. Overall best performance is obtained at 50% replacement of steel slag. Volume expansion of steel slag can be effectively prevented by means of CH3COOH or silica fume, but the addition of silica fume should be controlled below 4.5%. There is higher risk of heavy metal precipitation when cement content is low, steel slag is small or salinity level is high. Large size steel slag(particle size is greater than 4.75 mm) and higher cement content is recommended to ease environmental burden based on heavy metal precipitation analysis. More concerns should be raised in coastal areas where steel slag may be exposed to salty water surroundings. With proper control in the process of production and application, steel slag is a very promising alternative material to be utilized in cement stabilized base course in road engineering. 7 tabs, 12 figs, 30 refs.