Pervious Concrete Paver Blocks

Abstract

Today most of the urban areas are covered with the impervious pavement. Pavement are generally constructed of Plain Cement Concrete, or either asphalt, or Paver block. This material has undoubtedly very high strength and are capable of carrying heavy loads. But due to usage of such kind of material the major problem which urban area faces is problem of water logging. Due to the use of impervious pavement water is not able to percolate down to water table and so water is logged in cities which creates lot other major problems. Also, another major problem faced by urban areas due to use to such pavement is Urban Heat Island. So Pervious Concrete can be solution to such problem. Pervious concrete is a type of concrete through which water can be percolated and can be allowed to meet ground water. Pervious concrete has a porosity of 15 – 35 % and has a negligible amount of fine aggregate in them. But the limitations of pervious concrete are that it has a very less amount of strength so it can only be use in walkways. The main aim is to improve the strength parameter of pervious concrete with considerable amount of porosity within it. Attempt has been made to improve the strength of pervious concrete by introducing fly ash and also replacing the same amount of coarse aggregate to fine aggregate. So as a result, increasing in strength has found but simultaneously there is increase in density followed with decreased in porosity of sample. Fly ash is substituted in place of cement by 5 % and by 10 % in various mix, simultaneously fine aggregate is substituted in place of coarse aggregate by 5 % and 10 %. So various mixes are prepared based upon study of literature which limits the amount of supplementary materials and fine content within pervious concrete. Cementitious content is kept constant as 400 kg/m3 and aggregate cement ratio varies from 3.68-4.75:1. The variation in aggregate cement ratio is because of maintaining the density of pervious concrete up to 2150-2200 kg/m3. Water to cement ratio is kept constant of 0.32. Aggregate of size 10mm and 20mm are used, and in some trial’s combination of both the types of aggregates are also used. Various mixes are designed by trial and error method, were above mentioned data are kept as key aspects and either fines or cementitious materials are varied. In one of the trial silica fumes is also used as a replacement of cement by 5 % but doesn't have any significant impact on properties of concrete. From these various mixes, the highest compressive strength achieved is 32.63 MPa for (7 Days) and has an average porosity of 9.25 % which is lower than permissible range, but attempt has been made to modify the trial so that porosity can be achieved. The optimum result achieved till is having an average compressive strength of 23 MPa for (7 Days) with the average porosity of 19.68 %. For paver blocks the highest compressive strength in brick type which contains both the type of aggregate 10mm and 20mm is 18.19 MPa and density is 2464.54 kg/m3 and for Uni-Paver type block it is 35.93 MPa and density is 2214.9 kg/m3 at 28 days at porosity of 19.06 %.