Experimental and numerical investigation on clogging by trapped solid particles in permeable porous concrete

Clogging due to entrapment of solid particles in pores is a recurring process that limits the performance of permeable porous concrete (PPC). In this work, an analysis based on the results of laboratory and numerical modelling is presented. The experimental work involved the preparation and testing of PPC cylindric samples (100 mm diameter and 160 mm in height) to obtain the porosity and permeability parameters, and based on these two, the seepage velocity. These three parameters were used as inputs in the further numerical models, which were accomplished with the commercial software COMSOL Multiphysics v.6.2, based on the finite element method. Two scenarios with six simulations (3 each) were performed using three types of materials as solid particles, as well as two dimensional samples with the dimensions of the experimental samples. From the experimental work we found that the porosity and permeability varied from 26 to 28% and 1.75 to 1.96 mm/s, respectively, and from these parameters the calculated seepage velocity varied from 8.28 to 9.61 mm/s. However, for a comparative analysis, a different value of seepage velocity was used in each modelling scenario: the resulting from the experimental work, this is 8.98 mm/s for scenario 1, while for scenario 2, a value of 2.43 mm/s was used, which corresponds to the minimum recommended for the performance of PPC, according to American Concrete Institute ACI 522 R technical report. In the numerical work, we observed that the reduced seepage velocity of scenario 2 permitted the exit of particles from the model in all cases.