混凝土孔径分布模型及其应用

Model of pore size distribution in concrete and its application

研究了混凝土100 nm以下的孔径分布特征及其与氯离子快速扩散测试中6 h电通量的关系。粉煤灰单掺、矿渣粉单掺及复掺粉煤灰/矿渣粉用于制备混凝土,养护龄期为7、14、28和90 d,采用压汞法获取各龄期样品的孔径分布数据。将粉体颗粒尺寸分布的Rosin Rammler Bennet（RRB）模型用于描述混凝土中100 nm以下的孔径分布,得到特征孔径X和孔径分布均匀性系数n。研究表明,在全部样品中,X的分布范围为30~70 nm,最可几范围为40~50 nm,孔径分布均匀性系数n的分布范围为1.1~2.1,最可几范围为1.3~1.6;在较大水胶比（0.50）时,特征孔径X呈现先增后减的趋势;特征孔径X与氯离子快速扩散测试的6 h电通量存在正相关的趋势,孔径分布均匀性系数n与6 h电通量则存在负相关趋势,综合n与X影响的n/X与6 h电通量存在非线性的负相关趋势且更为明确。

Characteristics of pore size distribution within 100 nm in concrete as well as its relation with 6 h electric flux were investigated.Cement individual and composite replacement by fly ash and ground slag were applied to concrete cured at 7,14,28 and 90 d.Mercury intrusion porosimetry results were obtained from all samples,and Rosin Rammler Bennet（RRB）model of powder particle size distribution was applied to describe the pore size distribution below 100 nm in concrete,thus characteristic pore size X and uniformity coefficient n of pore size distribution were obtained.The results indicated that,for all samples the distribution range of characteristic pore size X was 30~70 nm,and the most probable range was 40~50 nm.The distribution range of uniformity coefficient n of pore size distribution was 1.1~2.1,and the most probable range was 1.3~1.6;when water/binder（W/B）= 0.50 the characteristic pore size X showed the tendency of increase then decrease as curing age prolonged;trend of positive correlation between characteristic pore size X and 6h electric flux from chloride ion rapid diffusion test,and trend of negative correlation between uniformity coefficient n and 6-hour electric flux were observed.In addition,the trend of nonlinearly negative correlation between n/X and 6h electric flux was more obvious.