钢渣骨料混凝土体积安定性及其抑制效果评价

Influence of Steel Slag Aggregate on Volume Stability of Concrete and Its Inhibitory Effect

采用图像分析软件ImageJ分析了钢渣骨料在实际工程用钢渣骨料混凝土(SSAC)中的含量及分布,采用沸煮法研究SSAC的体积安定性,并探明其劣化机理,同时评价了不同表面防护涂层对SSAC膨胀破坏的抑制效果.结果表明:实际工程用SSAC中的钢渣骨料平均含量约为15%,粗、细钢渣骨料体积比接近11∶2;沸煮法可作为工程用SSAC体积安定性的有效评价方法;钢渣骨料中的游离氧化钙(f‑CaO)、游离氧化镁(f‑MgO)和FeO在空气和水分环境中易发生水化及氧化反应,水化产物和氧化产物的体积膨胀是导致SSAC安定性不良的根本原因;硅烷偶联剂(SCA)单层防护、硅烷偶联剂-聚合物防水砂浆(SCA‑P)和硅烷偶联剂-环氧树脂砂浆(SCA‑E)双层防护对SSAC膨胀破坏的抑制效果优于聚合物防水砂浆(PWM)及环氧树脂砂浆(EM)单层防护;表面防护涂层虽可在一定程度上延长SSAC的初裂时间,但未完全抑制其膨胀反应,无法从根本上改善SSAC的体积安定性.

The content and distribution of steel slag aggregate in steel slag aggregate concrete(SSAC)were analyzed by image analysis software ImageJ,and the volume stability of SSAC applied in a practical project during boiling method were evaluated.The deterioration mechanism of SSAC was discussed,and the inhibitory effect of various surface coatings as protection was evaluated.The results show that the average content of steel slag aggregate in SSAC is about 15%,and the volume ratio of coarse and fine aggregates is close to 11∶2;boiling method can be used as an effective way to evaluate the volume stability of SSAC.The hydration reaction of free calcium oxide(f‑CaO),free calcium oxide(f‑MgO)and oxidation reaction of FeO in steel slag aggregate is easy to occur in the presence of air and water,and the volume expansion caused by the above products is the essential cause of the volume instability of SSAC.The inhibition effect of silane coupling agent(SCA)single layer coating,silane coupling agent‑polymer waterproof mortar(SCA‑P)or silane coupling agent‑epoxy mortar(SCA‑E)double layer coatings on SSAC expansion failure is better than that of polymer waterproof mortar(PWM)and epoxy mortar(EM)single layer coatings.To some extent,surface protective coatings can prolong the initial cracking time of SSAC,but it cannot completely inhibit the expansion reaction of steel slag aggregate,thus it cannot fundamentally improve its volume stability.