Effect of Addition of Steel Fibers on The Properties Of Pervious Concrete

Abstract

In recent years, several areas of the country are facing the problem of reduced ground water table which is directly affecting the production of crops. This is a very serious situation for the country as the production of crops is reduced and the cost is increased. Also, due to inadequate drainage facilities, the storm water runoff is not drained properly in the event of a flood. This results in flash flooding, destruction of fertile land and the functioning of roadways and pathways gets blocked. Since it is not very cost effective to provide an expensive storm water management solution in rural areas so there is a need to develop a sustainable design to reduce the strain on our environment and for the well-being of the society. Pervious concrete is a relatively new concept in the field of pavements and is a mixture of coarse aggregate, water and cement. Due to the presence of a large number of voids, it has a high permeability and thus allows water to pass through it at a high rate. It has widespread pavement applications in Europe where it is being used in parking lots, walkways, sideways and low volume traffic roads. In a developing nation like India, it can be a very useful tool to reduce frequent floods and manage storm water runoff. Due to its open graded structure, pervious concrete suffers from the drawback of low flexural strength. In this research work, attempts have been made to enhance the flexural strength of pervious concrete without significantly affecting its permeability. The present study is divided into three phases. The first phase involves development of a suitable mix design which has good mechanical properties. In the second phase steel fibers are added to the normal mix design in different percentages, i.e., 1%, 1.5% and 2% by volume of concrete to check for its effect on mechanical properties and permeability. Two types of steel fibers are used in this study, i.e., Hooked End (4-D) and Crimped steel fibers with an aspect ratio of 67 and 50 respectively. The third phase involves the design of a pervious pavement to check for its adequacy in field applications. An attempt has been made to check the increase in durability of steel fiber reinforced pervious concrete with water absorption. The pervious concrete is checked for its compressive strength, flexural strength, durability, water absorption and permeability at different percentages of steel fibers. The compressive strength and flexural strength tests are conducted as per the relevant Indian Standards whereas the permeability test is done by using Falling Head Method which is a common test for obtaining iv permeability of soil samples in laboratory. The crimped fiber modified concrete exhibited a maximum increase in compressive strength of 4.19% and maximum increase in flexural strength of 11.19% at a dosage of 2% fiber by volume of concrete without any major change in permeability. For the addition of hooked end (4-D) fiber, the maximum increase of 19.03% in flexural strength and 5.11% in compressive strength is observed on addition of 1.5% fiber without any significant effect on the permeability. Compressive and flexural strength decreased on addition of 2% hooked end fiber. The test results also show that durability increases with decrease in water absorption for all fiber types and fiber proportions or percentages. It can be concluded from the final results that hooked end (4-D) fibers impart best flexural strength to the pervious concrete. The outcome indicates that pervious concrete with hooked end fibers can be used for the design of low-volume traffic roads. Thus, more efficient land use can be made and water can be directly transmitted to the underground surface and thus recharging the ground water table.