氯盐结晶作用下掺合料对海工HPC性能的影响

Effect of admixture on the properties of marine HPC under crystallization of chloride sal

通过6 mol/L的NaCl溶液半浸泡和干湿循环实验,对海洋环境氯盐结晶作用进行模拟,研究了氯盐结晶作用下矿物掺合料对海工HPC(高性能混凝土)性能的影响。结果表明:混凝土在氯盐结晶作用下,相对动弹模量和抗压强度后期均呈现下降趋势,其中干湿循环的盐结晶破坏作用最为严重;由于盐溶液毛细上升原因,混凝土在泛霜结晶区也产生明显的氯离子渗透。在28 d等抗压强度下,掺矿物掺合料明显有助于提高混凝土抗盐结晶破坏和抗氯离子渗透性能,其中干湿循环90次后的混凝土,氯离子渗透深度仅约为空白混凝土的2/5。通过微观分析发现,盐结晶破坏主要与混凝土中存在的大孔和毛细孔有关。

The effect of mineral admixture on the performance of marine HPC(high-performance concrete)was studied by using 6 mol/L NaCl solution for semi-immersion and wet and dry cycle experiments.The results show that the relative dynamic modulus and compressive strength of concrete decrease in the later stage under the action of chloride salt crystallization and the salt crystallization failure under dry and wet cycles is the most serious.Due to the capillary rise of the salt solution,the concrete also produces obvious chloride infiltration in the frost crystallization area.At the compressive strength of 28 days,mineral admixture can obviously improve the resistance of concrete to salt crystallization damage and chloride ion penetration.After 90 dry-wet cycles,the chloride ion penetration depth of concrete is only about 2/5 that of blank concrete.Through microscopic analyses,it is found that salt crystallization failure is mainly related to the existence of large pores and capillary pores in concrete.