钢渣-杂填土基层材料的性能研究

将钢渣、矿渣微粉与废弃混凝土碎料混拌制备钢渣-杂填土基层,并对其性能开展研究。体积安定性试验表明,矿渣微粉具有明显抑胀作用,掺入50%(质量分数,下同)钢渣、50%杂填土以及外掺钢渣质量30%矿渣微粉的试件的10 d高温水浴膨胀率仅为1.32%,而未掺矿渣微粉的试件3~5 d膨胀率均超过2%限值。7 d无侧限抗压强度和28 d劈裂强度正交试验表明:7 d无侧限抗压强度、28 d劈裂强度影响因素大小顺序为钢渣、水泥掺量、混凝土碎料占比、土壤固化剂;各组试件中7 d无侧限抗压强度、28 d劈裂强度最大值分别为12.41 MPa、2.24 MPa;钢渣-杂填土基层最佳配比为50%钢渣、50%杂填土(m(混凝土碎料)∶m(素土)=6∶4),外掺钢渣质量40%的矿渣微粉、5%水泥、0.018%固化剂,此时试件具有良好的水稳定性。强度影响因素试验表明,矿渣微粉对试件强度的增幅影响最大。X射线衍射及扫描电子显微镜分析表明,在矿渣微粉和土壤固化剂的作用下,钢渣中f-CaO被有效消解,团聚体与混凝土碎料、钢渣颗粒的密实包裹阻止了内部水分的挥发和外部自由水的侵入,既保证了钢渣-杂填土基层的强度,又有效抑制了膨胀。

Properties of Steel Slag-Miscellaneous Fill Base Material

The steel slag-miscellaneous fill base was prepared by mixing steel slag, slag micropowder and waste concrete debris, and its performance was studied. The volume stability test shows that the slag micropowder has obvious anti-expansion effect. The 10 d high temperature water bath expansion rate of the specimen mixed with 50% (mass fraction, the same below) steel slag, 50% miscellaneous fill and 30% slag micropowder is only 1.32%, while the 3~5 d expansion rate of the specimen without slag micropowder exceeds the 2% limit. The orthogonal test of 7 d unconfined compressive strength and 28 d splitting strength shows that the order of influencing factors of 7 d unconfined compressive strength and 28 d splitting strength is steel slag, cement content, concrete debris proportion and soil stabilizer. The maximum values of 7 d unconfined compressive strength and 28 d splitting strength in each group are 12.41 MPa and 2.24 MPa, respectively. The optimum ratio of steel slag-miscellaneous fill base is 50% steel slag, 50% miscellaneous fill (m(concrete debris)∶m(plain soil)=6∶4), adding 40% slag powder, 5% cement and 0.018% stabilizer. At this time, the specimen has good water stability. The test of strength influencing factors show that slag micropowder has the greatest influence on the increase of specimen strength. X-ray diffraction and scanning electron microscope analysis show that f-CaO in steel slag is effectively digested under the action of slag micropowder and soil stabilizer. The dense package of aggregates, concrete particles and steel slag particles prevents the volatilization of internal water and the invasion of external free water, which not only ensures the strength of steel slag-miscellaneous fill base, but also effectively inhibits the expansion.