Pervious concretein road construction as a cost effective alternative for flood control :

Abstract

Flooding is a very big problem in the biggest cities and major towns in Kampala Uganda and the whole world at large. This is of the increase in urbanization which involves many people moving to urban areas. In return there is a need to improve on the services like good transport routes to ease in the movements, in so doing the material used (Asphalt) for this cause is not friendly to the water cycle, the water meant to infiltrate into the soil is trapped on the surface as runoff and will result into flooding. There is a need for a more sustainable road design and design and pervious concrete is a perfect solution to this major problem. It is a type of concrete with voids in it of about 25% to 30% voids ratio which allows a large amount of runoff to infiltrate. Pervious concrete is made by mixing coarse aggregates, cement (OPC) water, Admixtures and HDPE for the case of our project. We came up with a pervious concrete road system that was able to allow 3.4litres of water infiltrate per second. With this result we believe pervious concrete is the way to go if we are to reduce the flooding hazard at Queens Way junction Kampala (our case study area for this research) and other parts of the world. We had four objectives and achieved each one of them to be able to complete this project The first objective was to determine the effective pervious concrete coefficient and we used software like EPANET, SWMM, Arc GIS, and google maps to achieve it. We got a pervious concrete coefficient of 0.89 which showed a gradual decrease in runoff to 35.4m3/sec hence flooding controlled. The second objective was to obtain the optimum mix for the optimum mix ratios and to test for the pervious concrete properties. We did this by carrying out tests at Central materials laboratory in kireka and came up with a ratio of 1:0.45:4.05:0.5. This mix ratio enabled us to achieve the given strength and permeability of 32.5Mpa and respectively. We also carried out tests on each of the materials we used to come up with the pervious concrete system. Results of the laboratory test results are shown in the appendix. The third objective was to design, simulate, construct and test the pervious concrete road system and we achieved this using software like Auto CAD and Solid works. We made design calculations for the layers of the road system that is the pervious concrete slab, the beams and the bottom impervious layer, we designed it in Auto CAD and used Solid works to do a simulation, we constructed the road system and tested for infiltration and found that it was efficient. The fourth objective was to carry out the economic analysis and we found out that pervious concrete in road construction is far much cost effective compared to Asphalt and conventional concrete pavements. In conclusion KCBA is located in a place with clayey soils and many impervious surfaces contributing so much to the flooding. But with this project in place we believe this hazard can be greatly reduced. This is seen in the entire report. “When it Rains it drains”.