集料中石盐对混凝土耐久性的影响

Effect of halite mixed in aggregate on durability of concrete

集料中掺杂的石盐会使混凝土表面形成黑斑,通过干湿循环、碱-集料反应、冻融循环、钢筋锈蚀等几个方面的试验,研究了集料中石盐对混凝土耐久性的影响.结果表明,干湿循环过程中NaCl结晶可使混凝土表面砂浆剥落,表面的石盐逐步迁移出混凝土,试件的体积没有明显变化.内部的石盐颗粒溶解与试验条件有关,当石盐溶解使砂浆中Cl-浓度达到一定值时,混凝土的抗冻性下降,碱-集料反应过程中膨胀率增大,同时可能引起钢筋锈蚀.

When the halite mixed in aggregate was dissolved, some black stain appeared on the surface of concrete. The effect of halite which mixed in aggregate on durability of concrete had been studied in the dry-wet cycle, freezing-thawing cycle, including AAR and steel corrosion. The results indicate that the surface mortar is cracked during crystallization of NaCl and the volume of concrete does not change a lot . The dissolved halite increase the Cl^- concentration and impair the durability of concrete. When it is high enough, the concrete freezing resistance declines, the expansion during AAR increases and the steel corrosion arises.