Prediction model of compressive strength of foamed concrete considering pore size distribution

To more accurately evaluate the relationship between pores and compressive strength of foamed concrete, the effects of density, water-cement ratio, and foaming agent type on porosity, pore size distribution, and compressive strength were studied. It was found that as the density decreased and the water-cement ratio increased, the number of larger-sized pores increased and the pore size distribution became wider and more nonuniform. Further, the pore structure of lower-density foamed concrete was more susceptible to the influence of density and water-cement ratio more likely to produce larger size pores. Particularly, foaming agent type had a significant effect on the pore size distribution. The pore size variation of foamed concrete was primarily attributed to the initial size of fresh foam and the complex merging and escape phenomena occurring in the foam in the slurry, the process of preparation and forming. It was also found that smaller porosity and more concentrated and uniform pore size distribution were more beneficial for strength. Additionally, to quantify the combined effect of porosity and pore size distribution on compressive strength, this paper innovatively proposes the parameters of the "pore synthesis impact factor". Finally, a new empirical model relating the porosity, size distribution, and compressive strength is presented.