矿渣基胶凝材料稳定碎石路用性能研究

Study on Road Performance of Stabilized Macadam with Slag-based Cementitious Material

为探索矿渣基胶凝(SBC)材料应用于高等级公路基层工程建设的可行性,开展了击实试验、无侧限抗压强度试验、间接抗拉强度试验、弯拉强度试验和干缩、温缩试验。研究了SBC稳定碎石材料的力学性能和体积稳定性,并与PO42.5硅酸盐水泥(OPC)稳定碎石进行了对比。结果表明:随着胶凝材料掺量的增加,稳定碎石材料的无侧限抗压强度均出现不同程度的增长,在相同胶凝材料掺量下,SBC稳定碎石材料的7 d无侧限抗压强度与OPC稳定碎石材料相当,4%掺量的SBC稳定碎石材料的7 d无侧限抗压强度满足行业规范中基层强度要求;延迟时间试验结果显示SBC稳定碎石材料的最大延迟时间超过15 h,应用在半刚性基层可实现3层连铺工艺,提高施工效率;SBC稳定碎石材料的间接抗拉强度和弯拉强度均优于OPC稳定碎石材料,较OPC稳定碎石材料间接抗拉强度提高8%~12%,抗弯拉强度提高4%~7%;SBC稳定碎石材料的干缩性能优于OPC稳定碎石材料,30 d的干缩应变值比OPC稳定碎石材料降低了16%,温缩试验结果显示SBC稳定碎石与OPC稳定碎石的温缩性能相差较小;基于X射线衍射分析和二次电子成像技术,SBC的水化产物主要为针棒状的钙矾石晶体和C-S-H凝胶,钙矾石晶体对改善水稳碎石的间接抗拉强度、抗弯拉性能和抵抗开裂变形能力提高作用显著。

In order to explore the feasibility of the application of slag-based cementitious(SBC)material in the construction of high-grade highway base,the compaction test,unconfined compressive strength test,indirect tensile strength test,flexural tensile strength test,dry shrinkage and temperature shrinkage test are carried out.The mechanical properties and volume stability of stabilized macadam with SBC material are studied and compared with that of stabilized macadam with PO42.5 Portland cement(OPC).The result shows that(1)the unconfined compressive strength of stabilized macadam increases with the increase of the content of cementitious material,the 7 d unconfined compressive strength of SBC stabilized macadam material is equal to that of OPC stabilized macadam material,and the 7 d unconfined compressive strength of 4%SBC stabilized macadam material meets the requirement of basic level strength in industry regulations;(2)the results of delay time test show that the maximum delay time of SBC stabilized macadam is more than 15 h,and it can be used in semi-rigid base to realize 3-layer continuous paving process and improve construction efficiency;(3)the indirect tensile strength and flexural tensile strength of SBC stabilized macadam are better than those of OPC stabilized macadam,the indirect tensile strength and flexural tensile strength of SBC stabilized macadam increase by 8%-12%and 4%-7%respectively,the drying shrinkage of SBC is better than that of OPC,the 30 d drying shrinkage strain of SBC is 16%lower than that of OPC,and the temperature shrinkage test results show that there is little difference between SBC and OPC stabilized macadam;(4)based on X-ray diffraction analysis and secondary electron imaging,the hydration products of SBC are mainly needle-like ettringite crystals and C-S-H gels,ettringite crystals can significantly improve the indirect tensile strength,flexural tensile properties and the resistance to cracking and deformation of waterstable macadam.