基于图像法分析孔隙特征对加气充填砼性能的影响

通过对不同孔隙特征的加气充填混凝土试样沿发气方向进行切割和截面图像提取,采用Matlab对试样截面图像进行分析和统计计算,分别对各组试样的孔隙特征进行了表征;测试了试样各养护龄期的比强度、吸水率、体积膨胀率、冻融后的抗压强度损失率和质量损失率,以分析孔隙特征对加气充填混凝土力学性能和抗冻性的影响。结果表明:采用图像法对加气充填混凝土截面照片进行信息采集,通过Matlab的统计计算,可实现对该加气充填混凝土宏观孔和细观孔的信息提取与表征;大于5.00mm的孔隙占比越大,平均孔径差值c越大,反映出联通孔的相对数量越多,则试样的比强度越低,吸水率越大,体积膨胀率越小,抗冻性越差,反之,试样的比强度越高,吸水率越小,体积膨胀率越大,抗冻性越好;以两种细度混合的铝粉膏作为引气剂可以有效降低该加气充填混凝土连通孔的相对数量。

Research on Effect of Pore Characteristics on Performance of Aerated Backfilling Concrete Based on Imaging Method

The samples of aerated backfilling concrete with different pore characteristics were cut along the direction of gas emission and the cross-section images were extracted. The images of samples were analyzed and calculated by Matlab. The pore cha-racteristics of samples were characterized respectively. The specific strength, water absorption, volume expansion rate, compressive strength loss rate and mass loss rate after freezing and thawing of each sample were tested to analyze the effect of pore characteristics on mechanical performance and frost resistance of aerated backfilling concrete. The results show that the information of macroscopic and microscopic pores of aerated backfilling concrete could be collected and characterized after the cross-section images are collected based on image method and calculation of Matlab; the larger the proportion of pores which above 5.00 mm is, the bigger the diffe-rence of average pore size is, the more the number of connected pores is, the lower the specific strength is, the greater the water absorption is, the smaller the volume expansion rate is, the worse the frost resistance is; on the contrary, the higher the specific strength is, the smaller the water absorption is, the greater the volume expansion rate is, the better the frost resistance is; the relative number of connected pores in aerated backfilling concrete could be reduced effectively by mixing with two kinds of aluminum powder with different particle sizes as the aerated materials.