石膏对铝酸钙水泥混凝土力学与耐久性能的影响

Effect of CaSO4 on Mechanical Properties and Durability of Calcium Aluminate Cement Concrete

用二水石膏(CaSO4·2H2O)和α型半水石膏(α-CaSO4·0.5H2O)粉末分别部分取代铝酸钙水泥(CAC)制备了CAC混凝土,研究了其在不同掺量下对CAC混凝土力学与耐久性能的影响。试验研究了CAC混凝土试样的抗压强度、劈裂抗拉强度、氯离子渗透性以及抗硫酸盐的侵蚀性能,探究了CaSO4类型和掺量对各项指标的影响。结果表明,掺入CaSO4会降低CAC混凝土的早期强度,但可显著抑制其后期强度衰减,当CaSO4·2H2O和α-CaSO4·0.5H2O掺量分别为6%和4%时,CAC混凝土的后期强度衰减量最低,Cl-扩散系数最小,且在Na2SO4侵蚀溶液中劣化程度最低。因此,CaSO4·2H2O和α-CaSO4·0.5H2O均可有效改善CAC混凝土的力学性能与耐久性能,两者的最优掺量分别为6%和4%。

The effect of CaSO4 with various contents on mechanical properties and durability of calcium aluminate cement(CAC) concrete was investigated by partially substituting CAC powder with dihydrate(CaSO4·2 H2O) and α-hemihydrate(α-CaSO4·0.5 H2O). The performances of the CAC concrete samples with different mixing proportions were tested, including the compressive strength, splitting tensile strength, chloride ions penetrability, and sulfate corrosion resistance. Also, the influence of the type and amount of CaSO4 on such properties was discussed. The results show that the early strength of CAC concrete can be reduced due to the incorporation of CaSO4, whereas the attenuation of their later strength may be evidently inhibited. When the contents of CaSO4·2 H2O and α-CaSO4·0.5 H2O are 6% and 4%, respectively,the strength attenuation of CAC concrete reaches the minimum, and the minimum chloride ions permeability coefficient is observed. The sulfate corrosion resistance of CAC concrete can be obviously enhanced by incorporating CaSO4. Specifically,when the amounts of CaSO4·2 H2O and α-CaSO4·0.5 H2O are equal to 6% and 4%, respectively, the deterioration degree of CAC concrete exposed to Na2 SO4 solution is the lowest. Therefore, the incorporation of CaSO4·2 H2O and α-CaSO4·0.5 H2O can improve greatly the mechanical properties and durability of CAC concrete, and the optimum contents of the two type of CaSO4 are 6% and 4%, respectively.