Development of Pervious Concrete For Pavement Applications

Abstract

Indian economy is developing at a rapid pace and to maintain equilibrium between nature and growth, it needs to conserve all its natural resources. Complete progress can be achieved by any society if it judiciously uses all resources including water which is the most important one. Also sustainable development is the need of the day. Modern-day infrastructure design principles promote use of impervious materials like concrete and bitumen for construction of parking, curb and gutter systems to rapidly collect and transport rain runoff. Conventional Portland cement concrete and asphalt is used for pavement construction in India, US, UK and other countries around the world. The impervious nature of these construction materials is responsible for the increased water runoff. Under these conditions, storm water reaches the receiving water bodies rapidly, in greater volume and carries more pollutants than natural conditions, all causing an imbalance in the ecosystem. One such material that can be used to produce porous surfaces is pervious concrete, which can play a vital role for solving many environmental issues including depletion of ground water. Pervious concrete pavement on parking lots, sidewalks, and driveways provides solution to this problem. In pervious concrete, carefully controlled amounts of water and cementitious materials are used to create a paste that forms a thick coating around the aggregate particles. The hypothesis for the present investigation on pervious concrete is divided into following compartments. 1. Development of mixture proportioning of pervious concrete 2. Construction of pervious concrete pavement and its monitoring The first phase of this investigation is to develop mixture design of pervious concrete for pervious concrete pavement. Target properties of pervious concrete are assumed for the development of mixture design such as compressive strength, void ratio, permeability and density. The main properties studied include compressive strength, density, and permeability and void ratio. For the measurement of permeability of pervious concrete, a test set up is developed. The falling head test method was used to evaluate permeability coefficient for pervious concrete. Pervious concrete is produced using two sizes of natural coarse aggregates. The first group is 4.75-10 mm i.e. size A (passing from 10 mm and retaining on 4.75 mm IS sieve) and second group is 10-20 mm i.e. size B (passing from 20 mm and retaining on 10 mm IS sieve). The cement content is varied from 250 kg/m3 to 450 kg/m3 at an interval of 50 kg/m3 for the experimental investigation, The aggregate/cement ratio is kept constant as 4. Three w/c ratio are attempted i.e. 0.3, 0.35 and 0.4, respectively. It has been observed that for 4.75-10 mm size aggregates, the compressive strength is more as compared to 10-20 mm size aggregates. For the further improvement in the pervious concrete properties, mixture design optimization is carried out for its practical application on the field. To achieve desired workability for pervious concrete, investigations have been carried out on using different dosages of chemical admixture. It was found that 0.9% super plasticizer dosage is sufficient for pervious concrete. The paste flow test is performed for different mixes of pervious concrete. Mini slump cone is used for the measurement of the paste flow diameter of the cement paste. For the enhancement of compressive strength of pervious concrete, VSI aggregates are used as a replacement to natural coarse aggregates. VSI aggregates is having lesser values of flakiness and elongation index. VSI aggregates having rounded edges are provided to improve proper bond between aggregates and cement paste. Pervious concrete with VSI aggregates has observed increase in the compressive strength around 25 to 30%. The second phase of the present investigation is to construct the pervious concrete pavement. Pervious concrete mixture design is selected based on laboratory investigations carried out in Phase 1. The construction of pervious concrete pavement is conducted at the campus of Nirma University, Ahmedabad, Gujarat. The site selected is located near the petrol pump and besides the main parking of the University campus. The size of pervious concrete pavement is 3 m ×10 m. The step-by-step procedure construction of the pervious concrete pavement was discussed in detail. In the laboratory, a miniature scale model of pervious concrete pavement was developed to understand the construction process and drainage system of the pervious concrete pavement. Miniature scale model is developed using polyvinyl chloride sheets. The dimension of the miniature model is 1 m × 0.40 m × 0.35 m. Maintenance plan and inspection checklist is prepared to monitor the pervious concrete pavement. The basic information for the maintenance plan and inspection checklist are collected from the literature survey and NRMCA guidelines. Maintenance plan consists of the maintenance activities and the frequency at which these activities are to be performed on the pavement. Inspection checklist consists of the maintenance activities as per the maintenance plan. The maintenance activities performed on pervious concrete pavement includes measurements of infiltration rate, loss of coarse aggregates, collection of water, surface cleaning, cleaning of outlets, removal of vegetation, etc. Core are extracted from the pervious concrete pavement. The comparison between laboratory study and field study has been carried out for pervious concrete after a period of 8 months of construction. It is observed that test results of compressive strength, void ratio and density of pervious concrete were found in close agreement with laboratory results. The pervious concrete pavement structure is found to be highly permeable and no cracks are observed even after the time duration of 1.5 years of construction. From the results, design charts are developed for the pervious concrete mixture proportioning. This design charts will be useful for the development of preliminary mixture design of pervious concrete. Step by step construction procedure is developed for pervious concrete pavement. Successful drainage performance of pervious concrete pavement shows the ability to construct such pavement in water logged areas of Gujarat.