Journal of Research in Engineering and Applied Sciences JREAS, Vol. 1, Issue 04, Oct. 2016 172 STRENGTH PROPERTIES OF PARTIAL REPLACEMENT OF COCONUT SHELLS AS COARSE AGGREGATE IN CONCRETE 1 2 K. Rajasekhar and K. Spandana 1 Assistant Professor, Department of Civil Engineering, Krishna Chaitanya Institute of Technology & Sciences, Markapur, Andhrapradesh, India 2 PG student, Department of Civil Engineering, Krishna Chaitanya Institute of Technology & Sciences, Markapur, Andhrapradesh, India 1 2 {Email: sekhar.raj541@gmail.com, spandana.kande@gmail.com} Abstract Concrete is a group of raw materials similar in appearance and properties to some natural lime stone rock. It is a man-made mixture, the major constituent is natural coarse aggregate such as gravel or crushed rock, fine aggregate such as sand and cement powder all mixed with water. As the time goes on, the cement paste starts it process of hydration and after hardening it gets its required strength to withstand the load. The coconut shells used as replacement for coarse aggregate has never been usual practice in particular areas where light weight concrete is required for non-bearing walls, non-structural floors and in strip footings.Because of the high cost of construction, if we use waste materials as replacement materials in the construction of concrete structures, the cost of construction will be reduce. By the replacement of coconut shells we can get the light weight concrete. As the replacement of coconut shells increases the strength of the concrete will be reduce. The strength properties of concrete were found by the replacement of coconut shells by 0%, 5%, 10%, and 15% at the age of 3days, 7days and 28days. This type of concrete can be treated as eco-friendly concrete. Key Words : Coarse aggregate, Crushed coconut shell, Compressive strength, Split tensile strength, Waste utilization. 1. Introduction Concrete is a composite material which composed of aggregates, cement and water. Concrete is used more than any other manmade material in the world. In addition, concrete is the 2nd most consumed substance in the world-behind water. About 7.23 billion tons of concrete is produced every year. The planet production of concrete is increasing due to high growth of infrastructure development and construction activities in the world Production of concrete demand its constituents like aggregates, cement, water and admixtures. Sources of conventional aggregates occupy the major part of the concrete. The large scale production of concrete in construction activities using conventional coarse aggregate such as granite immoderately reduces the natural stone deposits and affecting the environment hence causing ecology im-balance. Increasing demand of natural aggregates show that crushed stone demand will be 2050 million metric tons in 2020. This huge demand of natural aggregate raises a serious question about preservation of natural aggregate sources for sustainable development. Extraction and processing of aggregates is also a major concern for environment. Therefore consumption of alternative waste material in place of natural aggregate in concrete production not only protects environment but also makes concrete a sustainable and environment friendly construction material. Different waste material like rubber, fly ash, glass, bottom ash, artificial sand etc has been used as alternative for replacing natural aggregates. Apart from the above mention waste material, a few studies shows that agriculture waste coconut shell can also use as coarse aggregate for concrete. 1.1. Coconut Shell Coconuts are referred to as "man's most useful trees", "king of the tropical flora" and "tree of life". Coconuts or its scientific name “cocos-nucifera” are the most important of cultivated palms and the most widely distributed of all palms. Coconut is a tall cylindrical- stalked palm tree, reaching 30 m in height and 60-70 cm in diameter. It is a tropical plant for low altitudes. It needs sunshine and a soil rich in calcium and phosphorus, and is thus generally suitable for cultivation in sandy seashore. The coconut industry in India accounts for over a quarter of the world's total coconut oil output and is set to grow further with the global increase in demand. However, it is also the main contributor to the nation's pollution problem as a solid waste in the form of shells, which involves an annual production of approximately 3.18 million tones. Fig. 1 Coconut Shells