低气压成型的非引气水泥基材料水化与孔结构

Hydration and Pore Structure of Non⁃air⁃entrained Cement⁃based Materials Prepared Under Low Air Pressure

本工作探究了低气压与标准大气压下搅拌成型的非引气水泥基材料在水化进程与孔结构发育方面的差异。研究分为模拟试验与现场试验两部分。模拟不同的气压环境成型水泥基材料,对水泥净浆进行水化产物、水化程度与孔结构分析,对砂浆进行气孔参数试验;在不同气压的现场成型水泥基材料,对水泥净浆进行密度试验,对砂浆进行密度试验、气孔参数试验与抗压强度试验。结果表明:不同气压下成型的水泥净浆后续水化产物、水化进程与孔结构发育皆基本一致;低气压下砂浆的气泡尺寸与气泡间距系数较常压下分别减小3.1%和8.1%,而抗压强度差异小于0.5%。由此可见,搅拌成型过程中的低气压环境基本不会对水泥基材料的性能带来不良影响。因此,在研究高海拔地区非引气混凝土问题时可在单位驻地制件,不必远赴高原现场。

This work investigates the differences in hydration and pore structure between cement⁃based materials prepared(i.e.,mixed and set)under low and standard air pressures.The study is divided into two parts,namely,a simulation test and a field investigation.In the simulation study,hydration products,hydration degree and pore structures of cement pastes and air⁃void characteristics of mortars prepared under different simulated air pressures were analyzed.In the field study,the densities of cement pastes and densities,strengths and air⁃void characteristics of mortars prepared in regions under different air pressures were tested.The results show that hydration products,hydration process and pore structure of cement pastes prepared under various air pressures are essentially unchanged.Compared to the average radius and spacing factor of air⁃voids in the mortar prepared under standard air pressure,those of air⁃voids in the mortar prepared under low air pressure are respectively 3.1%and 8.1%lower;however,the difference in compressive strength is less than 0.5%.In general,low air pressure during mixing and setting stages do not negatively affect the properties of cement⁃based materials.Therefore,the properties of concrete to be used in construction projects in high⁃elevation locations can reliably be established by testing specimens prepared at low elevations.