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利用珊瑚砂取代天然河砂进行了混凝土的配合比设计,系统研究了水胶比、砂率和胶凝材料用量三个因素对珊瑚砂混凝土性能的影响,并通过XRD、SEM和TG-DSC等测试手段对珊瑚砂混凝土和河砂混凝土的微观结构进行了对比分析。试验结果表明,珊瑚砂混凝土的抗压强度随着水胶比的增大而减小,随着砂率的增大先减小后增大,随着胶凝材料用量的增加先增大后减小,在胶材用量为420 kg/m~3时,抗压强度达到最大值;珊瑚砂混凝土和河砂混凝土的28 d水化产物基本相同,都含有氢氧化钙Ca(OH)_2,钙矾石AFt,碳酸钙CaCO_3和C-S-H凝胶。珊瑚骨料内部多孔的微观结构使得珊瑚骨料-水泥浆体的界面黏结力较普通骨料-水泥浆体的界面黏结力大,大大改善了界面结构性能。
The co-sand was used to replace natural river sand to design the concrete mix ratio. The effects of water-binder ratio, sand ratio and cementitious material dosage on the properties of coral sand concrete were systematically studied. The effects of co-sand on the properties of coral sand concrete were studied by XRD, SEM and TG- The microscopic structures of coral sand and river sand concrete were compared by testing methods. The test results show that the compressive strength of coral sand concrete decreases with the increase of water-binder ratio, decreases first and then increases with the increase of sand rate, increases first and then decreases with the increase of cementitious material dosage The compressive strength of coral sand concrete and river sand concrete were the same at 28 d with the dosage of 420 kg / m ~ 3. The hydration products of the coral sand concrete and river sand concrete all contained the same hydration products for the first time, all of them contained calcium hydroxide Ca (OH) 2, calcium Vanadium AFt, Calcium Carbonate CaCO3 and CSH gels. The porous microstructure in the coral aggregates makes the cohesive strength of the coral aggregate-cement paste larger than that of the common aggregates-cement paste, which greatly improves the interfacial structural properties.