钢渣体积膨胀特性研究与胀裂模拟

Volume Expansion Characteristics and Crack Simulation of Steel Slag

中国钢渣排放量大,综合利用率较低,堆放占地且污染环境,急需开展源头减量、资源化利用和无害化处置,而钢渣体积安定性不良且变异大是制约其大规模利用的首要原因。通过基于钢渣中f-CaO含量、分布、反应活性及与水反应难易程度提出钢渣集料体积膨胀演化模型,并利用钢渣粉、钢渣骨料的浸水膨胀试验开展体积膨胀模型参数的检验、拟合与验证。采用90℃热水浴浸泡试验和X射线衍射仪分析钢渣体积膨胀率、颗粒胀裂率与钢渣中f-CaO含量之间的关系,最后运用ABAQUS有限元模拟中的温度-位移模型和材料脆性断裂模型研究f-CaO的体积膨胀对钢渣骨料胀裂的影响。结果表明:钢渣体积膨胀与f-CaO的含量及分布、钢渣颗粒粒径的大小、浸水温度等因素有关,钢渣体积膨胀模型能很好地预测其体积膨胀的发展规律,模型参数可以通过浸水膨胀试验拟合确定,且采用二阶体积膨胀模型对钢渣粉、钢渣集料的浸水膨胀率预测较为准确。钢渣骨料的体积膨胀率与胀裂率均与f-CaO的含量密切相关,90℃浸水胀裂率宜控制不大于10%。ABAQUS温度-位移模型和材料脆性断裂模型能够近似模拟不同位置及富集程度的f-CaO体积膨胀对钢渣脆性裂纹的产生与扩展,模拟结果表明,位于近表面的f-CaO比内部f-CaO更容易造成局部胀裂。

Steel slag has a large discharge and low comprehensive utilization ratio in China. Its storage occupies lands and pollutes the environment. Therefore, it is urgent to carry out source reduction, resource utilization and harmless disposal. The poor volume stability and large variation of steel slag are the primary reasons that restricts its large-scale utilization. Based on free CaO content, distribution, reaction activity and water reaction difficulty in steel slag, an expansion evolution model for steel slag was proposed, and the fitting and verification of model parameter was carried out based on testing on steel slag powder and aggregate. The water immersion test was used to analyze the relationship between the volume expansion of the steel slag and the particle cracking. Finally, the effect of volume expansion of free CaO on the particle cracking was studied by finite element simulation using temperature-displacement model and material brittle fracture model. Test results show that the volume expansion of steel slag is related to the content and distribution of free CaO, the size of steel slag particles, and the temperature of water immersion. The volume expansion model of steel slag can well predict the development of volume expansion, and the model parameters can be determined by water immersion testing. The volume expansion rate and crack rate of steel slag aggregate are closely related to the content of free CaO. The cracking rate should not be greater than 10% when immersed in water at 90 ℃. The ABAQUS temperature-displacement model can approximately simulate the crack generation and propagation of steel slag due to free CaO volume expansion. Free CaO that located near the slag surface is more likely to cause local cracking than that inside slag.