引气含量对大掺量粉煤灰混凝土耐久性的影响

Effects of Air Content on the Durability of High Volume Fly-ash Concrete

针对大掺量粉煤灰混凝土早期抗渗性、抗碳化性、抗冻性相对不足等问题,通过在大掺量粉煤灰混凝土中掺入引气剂,可以显著改善这些性能。通过试验研究,结果表明:对于中低等级大掺量粉煤灰混凝土,引气后28 d的氯离子扩散系数显著减小,可以达到很低的标准。掺加引气剂后,混凝土含气量在5%以下时,大掺量粉煤灰混凝土的28 d碳化深度显著减小,都在10 mm以下。引气后,大掺量粉煤灰混凝土冻融后相对动弹性模量提高20%—40%。在一定范围内,大掺量粉煤灰混凝土的抗渗性、抗碳化性、抗冻性随着含气量的提高而增大。

The resistances to permeation, carbonation and freezing of high volume fly-ash concrete are not good enough in early time. By mixing air-entraining agent into concrete, these performances can be improved remarkably. The experiment resuits show that the moduli of chloride diffusion of air entrained high volume fly-ash concrete are evidently lower than that of ordinary high fly-ash volume concrete at 28 d age. It can reach the very low standard. The carbonation depth of air entrained high volume fly-ash concrete decreases gradually when the air content is under 5 %. The depth is almost smaller than 10 mm. Dynamic elastic modulus of air-entrained concrete are improved 20 %-40 %. The resistances to permeation, carbonation and freezing of high volume fly-ash concrete are increased as the air content is increased in the certain range.