Research On Pore Structure And Properties Of Foam Concrete

As a new type of insulation lightweight building material, the foam concrete has been widely used in the practical project. Foam concrete with two dry density level was studied in this paper. The influence of the ratio of the mixture on the pore structure and the effect of pore structure on the macro performance was studied. The corresponding finite element model of foam concrete was established by the experimental results of the foam concrete pore structure as the geometric parameters. The main contents were that:(1) As the equivalent average pore size and porosity and circular value was the main performance indicators. water binder ratio, fly ash, sand binder ratio and foaming agent dilution ratio of two kinds of dry density grade(600kg/m3? 900kg/m3) foam concrete thin view structure influence was studied through orthogonal test. The result showed that, the porosity decreased with water cement ratio and fly ash increased, increased with cement sand ratio increased, and water binder ratio factor influence on the porosity of the maximum. Equivalent of average pore diameter was positively correlated with water binder ratio, fly ash and mortar ratio. The pore roundness was related to the equivalent average pore size, and decreased with the increase of the pore size.(2) Using strength and water absorption ratio as the index of evaluation of foam concrete pore structure, porosity and equivalent average pore size on the macroscopic properties of the foam concrete effect were studied by surface fitting formula. The results showed that water absorption rate and average pore size, porosity were positively correlated, that of 900 grade foam concrete was 14.12~17.23%. Intensity ratio increased with the increase of porosity, the impact of average pore size was relatively small, the fitting formula were 14 0.64371735 8.416 vn ? ?e ?d ?, R2=0.9319.(3) Models of foam concrete were established with different geometric parameters such as porosity and average pore size, the model applied pressure 1.0MPa and compressive strength test of stress load finite element calculation. Calculation results showed that: the larger Von Mises stress was in the center of the model which was 7~27 times larger than load. The errors of stress under two kinds of load were 0~4%; The difference of stress ratio between theoretical calculation and the test was 15.58%~31.24%.(4) FLUENT software was used to calculate the difference between thermal conductivity of 50 K temperature difference and the same model of foam concrete. The result showed that: the temperature of the inner pore were 2~5K higher than the temperature around the base material part in finite element model. The calculated thermal conductivity ratio was less than that of the experimental results, and the error is 13.09%~17.98%. And the thermal conductivity ratio was correlated with the porosity, and increases with the increase of porosity, average pore size on the thermal conductivity ratio also had a lot of influence.