矿渣混凝土硫酸盐腐蚀研究

Damage of Concretes with GGBS Attacked by Sulfate Salt

研究了矿渣混凝土在5%Na2SO4溶液中浸烘循环,其相对动弹性模量、幅值及抗压强度演化规律.试验结果表明:混凝土相对动弹性模量先下降,后上升,再保持稳定,最后下降直至破坏;其幅值在前100次保持稳定,后下降直至破坏.混凝土抗硫酸盐腐蚀能力随矿渣掺量的增加而增加.相比于普通混凝土,随矿渣掺量增加,混凝土抗压强度损失率下降了28%～62%.混凝土在硫酸盐溶液中浸烘循环,其腐蚀产物为钙矾石和石膏.膨胀性腐蚀产物导致了混凝土浆集界面区和浆体区开裂,并最终导致混凝土破坏.

Evaluation of Erd （relatively dynamic modulus of elastically）, ultrasound amplitude and compressive strength verse corrosion time of concretes were conducted. Four sets of concretes, the one was plain concrete, and others were concretes with GGBS in different addition. The corrsion solution was 5.0%Na2SO4 （in mass）. The corrosion system was dryingimmersion cycles. Experiments show that the value of Erd decreases firstly, then increases with corrosion time, after that the value of Erd keeps steady, finally it declines to failure. And the value of ultrasound amplitude is stable before 100 times of corrosion cycles, then decreases to failure. The damage degree of concrete due to sulfate corrosion reduces with increased GGBS replacement level, and the compressive strength loss rate of concretes with GGBS decreases by 28%-62% comparing to plain concrete. Additionally, the gypsum and ettringite are main corrosion products of concrete, which attacked by sulfate solution and drying-immersion cycles. And the expanded corrosion products lead to cracks in paste and in interface of paste and aggregate, finally cause the deterioration of concrete.