铁尾矿砂-浮石砂复掺轻质混凝土配合比优化研究

Proportion optimization of iron tailings-pumice lightweight aggregate concrete

以封孔浮石为粗骨料、铁尾矿砂和浮石砂复掺作为细骨料,制备了LC30级轻骨料混凝土,重点研究了砂率和细骨料中浮石砂替代铁尾矿砂的比率这两个因素对混凝土力学性能的影响规律,利用SPSS软件拟合了抗压强度、劈裂抗拉强度和表观密度回归方程,并利用拟合方程进行了配合比优化。结果表明:对铁尾矿-浮石砂复掺细骨料轻质混凝土的抗压强度和劈裂抗拉强度影响较大的因素是砂率,而对混凝土密度影响较大的因素则是浮石砂替代率。当砂率在41%~43%之间,浮石砂替代率在17%~18%之间时,可以得到抗压强度≥33 MPa,劈裂抗拉强度≥2.4 MPa,干表观密度≤1900 kg/m3的铁尾矿砂-浮石砂复掺轻骨料混凝土,并通过验证试验试件的断面结构说明此时骨料分布均匀,浆体与骨料界面结合良好。

LC30 grade lightweight aggregate concrete was prepared by using sealing pumice as coarse aggregate,iron tailing sand and pumice sand as fine aggregate.The influence of sand ratio and ratio of pumice sand replacing iron tailings sand in fine aggregate on the mechanical properties of concrete was studied.Regression equations of compressive strength,splitting tensile strength and apparent density were fitted by software SPSS,and the ratio was optimized by using the fitting equation.The results show that the sand ratio is the main factor affecting the compressive strength and splitting tensile strength of the lightweight concrete with iron tailings and pumice sand as fine aggregate,while the pumice sand replacement rate is the major factor affecting the concrete density.When the sand ratio is between 41%and 43%and the replacement rate of pumice sand is between 17%and 18%,iron tailings-pumice lightweight aggregate concrete with compressive strength≥33 MPa,splitting tensile strength≥2.4 MPa and dry apparent density≤1900 kg/m3 can be obtained.The cross-section structure of the test sample shows that the aggregate distribution is uniform and the interface between the paste and the aggregate is good.