多孔性混凝土砌块抗冻指标试验研究

Experimental investigation on the frost-resistance indexes of cellular concrete blocks

多孔性混凝土砌块标准通常采用抗冻等级、质量损失率和强度损失率来表征材料的抗冻性能,显然超出了材料标准的范畴。通过蒸压加气混凝土砌块和陶粒泡沫混凝土砌块的毛细吸水试验,采用毛细吸水动力学分析了不同孔半径毛细孔吸水规律,得到了影响多孔性混凝土冻融破坏的毛细吸水系数。冻融试验结果表明,多孔性混凝土砌块第二阶段吸水对抗冻性能影响最大,冻融后的质量损失和强度损失与第二阶段毛细吸水系数成正比。提出了多孔性混凝土砌块的抗冻指标,该指标与毛细吸水系数成正比,与抗压强度的平方根成反比。根据我国现行标准对多孔性混凝土砌块抗冻要求和抗冻指标的对比分析,严寒地区的最低强度等级要求偏低,夏热冬冷地区和夏热冬暖地区的最低强度等级要求偏高,为我国应用标准修订提供了参考。

The frost-resistance of cellular concrete blocks is usually characterized by frost-resistance levels,mass loss rate and strength loss rate,which is obviously beyond the scope of material standard.The capillary water absorption coefficient,which affects the freeze-thaw failure of porous concrete,is obtained by the capillary water absorption experiment of the autoclaved aerated concrete block and the ceramsite foam concrete block and analyzing the capillary water absorption law of different cellular pore radius by capillary water absorption kinetics.The results of freeze-thaw experiment show that the water absorption of cellular concrete blocks in the second stage has the greatest influence on the frost-resistance performance,and the mass loss and strength loss after freeze-thaw are direct proportional to the capillary water absorption coefficient in the second stage.The frost-resistance index of cellular concrete block is presented,which is direct proportional to capillary water absorption coefficient and inversely proportional to the square root of compressive strength.According to the comparison and analysis of the frost-resistance requirements and frost-resistance indexes of cellular concrete blocks in Chinese current standards,the minimum strength level requirements in severe cold areas are low,and the minimum strength level requirements in hot-summer and cold-winter areas and hot-summer and warm-winter areas are high,providing references for the revision of Chinese standards.