低场核磁共振低温测孔技术表征硬化水泥浆体孔结构

Characterization of Pore Structure in Hardened Cement Paste by Low Field NMR Cryoporometry

摘要:

采用低场核磁共振低温测孔技术表征了硬化水泥浆体的孔结构，探讨了水灰比、龄期及掺和料对其孔结构的影响.结果表明：随着水灰比的增大，硬化水泥浆体的毛细孔含量增大，凝胶孔占比逐渐降低，加权平均孔径逐渐增大；龄期延长使凝胶孔占比逐渐增大，加权平均孔径逐渐降低；纳米CaCO₃主要增加40 nm左右毛细孔的量，粉煤灰则主要增加60 nm左右毛细孔的量，活性更强的硅灰则有更强的细化孔径的作用.

Abstract:

The pore structure of hardened cement paste was characterized by low field nuclear magnetic resonance （NMR） cryoporometry. The effects of water-cement ratios， ages and admixtures on the pore structure were investigated. The results show that with the increase of water-cement ratio， the capillary pore content of hardened cement paste increases， the proportion of gel pore decreases gradually， and the weighted average pore size increases gradually. With the increase of age， the proportion of gel pore increases gradually and the weighted average pore size decreases gradually. Nano calcium carbonate mainly increases the amount of small capillary pores at about 40 nm， while fly ash mainly increases the amount of large capillary pores at about 60 nm， and silica fume with stronger activity has a stronger role in refining pore size.