非离子纤维素醚改性水泥浆的孔结构

Pore Structure of Cement Pastes Modified by Non-ionic Cellulose Ethers

通过表观密度测试及宏观、微观孔结构观察,研究不同分子结构非离子纤维素醚对水泥浆孔结构的影响.结果表明,非离子纤维素醚会导致水泥浆孔隙率增加;非离子纤维素醚改性水泥浆黏度相近时,羟乙基纤维素醚(HEC)改性水泥浆的孔隙率比羟丙基甲基纤维素醚(HPMC)和甲基纤维素醚(MC)改性水泥浆小;基团含量相似的HPMC纤维素醚,黏度/相对分子质量越低,其改性水泥浆孔隙率越小.非离子纤维素醚掺入水泥浆后,降低了液相表面张力,使得水泥浆容易形成气泡;非离子纤维素醚分子定向吸附在气泡气-液界面,同时还增加了水泥浆液相黏度,使得水泥浆稳定气泡的能力增强.

The effect of non-ionic cellulose ethers（NCE） with different molecular structure on pore struc- ture of cement pastes was investigated by apparent density test, visual observation, optical mieroseope and SEM. The results indicate that the addition of NCE results in higher porosity in cement pastes. The poros- ity in cement pastes modified by hydroxyethyl cellulose ethers（HEC） is lower than that in cement pastes modified by hydroxypropyl methyl cellulose ethers（HPMC） and methyl cellulose ethers（MC） when their viscosity is close to each other. If HPMC with close substituent group content（by mass） is added, the low- er the viscosity/relative molecular mass of HPMC, the lower the porosity of the cement pastes. The addi- tion of NCE reduces the surface tension of liquid in cement pastes and leads to form bubble more easily. The ability of cement pastes to stabilize bubbles is enhanced by the addition of NCE because NCE mole- cules are adsorbed on the gas-liquid interfaee of bubbles orientationally and the viscosity of cement paste is inereased.