فهرست مطالب حسین چوب کار

One of the useful and efficient ideas in pavement and flooring is use of permeable concrete which is called pervious concrete. Pervious concrete that has many economic and especially environmental impacts can be used for reducing surface runoff during rainfall, delaying the entry of rainwater into the sewage system due to its absorption by the ground, improving the quality of groundwater due to lack of water flow from the ground and contact with possible contamination. In this study, four different mix design were used for three types of aggregating aggregates, which contains 12 general mixing states, including samples of simple concrete and examples of microsilica fume additives. At the end, compressive strength and permeability tests have been carried out on them. The results obtained from the research show that the individual with a higher density or, in other words, a finer grain size, exhibited a compressive strength of 9 Mpa, but had a 15% lower permeability. In general, according to the results of these experiments, the factors affecting the density of pervious concrete can be expressed by the size of the aggregates, the efficiency and the amount of microsilica fume. Because of its superplasticizering, the microsilica fume increases the strength and durability of concrete but reduces porosity of concrete, but its permeability is still acceptable to simple concrete. Finally, the optimum aggregate for compressive strength and optimal permeability, is obtained in third type of aggregating in this study, In which half of the aggregates have been formed of residues on the sieve of 3.8 and the remaining half of the residues on the sieve of 4 and depending on the need for greater resistance or permeability, parameters such as water to cement ratio, sand/cement ratio and microsilica fume addition can be obtained, which has been investigated in this study.

Pervious concrete being a particular type of high porosity concrete, is mainly used for pavement purposes. Pervious concrete is usually free of fine aggregates and the coarse aggregates are only coated by the cement matrix. The use of additives including superplasticizer and the consequent effects on engineering characteristics of pervious concrete is outlined in this study. The pervious concrete should be designed in such a way to resist against deterioration during the freezing and thawing cycles, while keeping the permeability index within reasonable limits. In this study, six sets of pervious concrete samples including three granular aggregates in both water to cement (W/C) and aggregate to cement (G/C) of typical pervious concrete samples containing lubricating additives and antifreeze. It was produced by measuring the efficiency, density, porosity and compressive strength in two main characteristics of this concrete, namely compressive strength and porosity, to the following results. According to the results of the study, the compressive strength of the pervious concrete was increased by about 9 MPa, and the porosity decreased at most by 15%.