基于CT扫描技术研究引气剂对混凝土孔结构的影响

Study of the Effect of Air Entraining Agents on the Pore Structure of Concrete Based on CT Scanning Techniques

为探究引气剂掺量及冻融循环作用对混凝土孔结构的影响,通过坍落度、含气量、相对动弹性模量,研究引气剂掺量对混凝土工作性能及抗冻性能的影响,并利用工业CT扫描仪,研究其对混凝土孔隙率、孔隙直径、形状因子的影响因素。结果表明,引气剂的掺入可提高混凝土相对动弹性模量、坍落度和含气量。随着引气剂掺量持续增加,孔隙率呈增加趋势,形状因子呈先增加后下降趋势,且相同冻融循环次数下(25)引气剂掺量为0.3%时,无害孔占比达到最高(48%),较h=0,h=0.1%,h=0.2%,h=0.4%掺量引气剂分别增加700.1%,496.4%,381.1%,493.6%。但引气剂掺量为0.4%时会导致混凝土内部多害孔增加,且孔隙率过高,孔隙形状的不规则会进一步导致抗冻性能下降。研究结果可为寒冷地区引气剂的使用提供参考依据。

In order to explore the influence of air entraining agent content and freeze-thaw cycle on concrete pore structure,the influence of air entraining agent content on concrete workability and frost resistance was studied through slump,air content and relative dynamic modulus of elasticity,and the influence factors of concrete porosity,pore diameter and form factor were studied using industrial CT scanner.The results indicate that the addition of air entraining agent can improve the relative dynamic elastic modulus,slump,and air content of concrete.With the continuous increase of the amount of air entraining agent,the porosity shows an increasing trend,and the form factor first increases and then decreases.Under the same number of freeze-thaw cycles,when the amount of(25)air entraining agent is 0.3%,the proportion of harmless pores reaches the highest(48%),which is 700.1%,496.4%,381.1%,493.6%higher than that of h=0,h=0.1%,h=0.2%,and h=0.4%air entraining agent respectively.However,when the amount of air entraining agent is 0.4%,it will lead to an increase in multiple harmful pores inside the concrete and too high porosity.The irregular shape of the pores will further lead to a decrease in frost resistance performance.The research results can provide a reference basis for the use of air entraining agents in cold regions.