掺合料对混凝土胶空比及其抗压强度的影响

为研究混凝土抗压强度变化,以掺入不同掺合料为变量来研究混凝土胶空比和抗压强度的变化。通过试验得出:复合胶凝体系的抗压强度在胶空比相同时,还受相应孔隙率的限制。高磷粉掺量体系C-2PP在相同胶空比条件下,其抗压强度有低于C-PP甚至低于C体系的趋势。这是因为高掺量导致的相对高孔隙率,而且孔隙率则又可归因于磷粉反应程度的严重下降;相对于水泥水化形成的C-S-H凝胶,矿粉火山灰反应生成C-S-H凝胶吸附了更多原本可被水化利用的自由水,因此减少了可测得的非蒸发水量,进而降低了水泥的水化程度,从而扰动了该体系胶空比与孔隙率的关系;随着磷粉掺量的增加,其磷粉反应程度的显著降低,将导致该体系孔隙率的升高和胶空比的降低。

Effect of different admixtures on cement-air ratio and compressive strength of concrete

In order to study the change of compressive strength of concrete,the change of cement-air ratio and compressive strength of concrete is studied by adding different admixtures as variables.The experimental results show that the compressive strength of the composite cementitious system is also limited by the corresponding porosity when the ratio of gel to void is the same.The compressive strength of C-2 PP with high fly ash content tends to be lower than that of C-PP or even lower than that of C system under the same binder-to-air ratio.This is due to the relatively high porosity caused by high volume and porosity,which can be attributed to a serious drop in the degree of fly ash reaction.Compared with the C-S-H gel formed by hydration of cement,the silica gel pozzolanic reaction produces more free water which can be hydrated by C-S-H gel,thus reducing the measurable amount of non evaporated water,thereby reducing the hydration degree of the cement.The relationship between the void ratio and the porosity of the system is disturbed.With the increase of fly ash content,the reaction degree of fly ash decreases significantly,which will lead to the increase of the void ratio and the decrease of the void ratio of the system.