ABSTRACT— combining the advantages of Light Weight Concrete (LWC) and Self Compacting Concrete (SCC) is a new field of research. Considering its light weight of structure and ease of placement, Light-weight self-compacting concrete (LWSCC) may be the answer to the increasing construction requirements of slender and more heavily reinforced structural elements. Results showed that Pumice stone powder met the requirements for structural applications. Aggregate is a major ingredient for making concrete, occupy almost 70-80% part of concrete. The waste coconut shell may be utilized to replace natural coarse aggregate. In this study, M 20 grade of concrete was produced by replacing natural coarse aggregates at 0%, 5%, 10%, 20%, 30%, by weight with waste coconut shell. In all total thirty six (36) cubes were casted and their compressive strength was evaluated at 7 and 28 days. The compressive strength of concrete was reduced as the percentage replacement increased. Concrete mixtures were tested and compared in terms of compressive strength of the conventional concrete at 28 days. The results showed that Coconut Shell Concrete (CSC) can be used in light weight concrete construction. Utilization of Coconut Shell is cost effective and Eco friendly.
Index Terms– Coarse Aggregate, Concrete, Coconut Shell, Compressive Strength, Light Weight Concrete, Sustainable Development.
Concrete is the world’s most widely used construction material owing to its excellent versatility, availability and economy. Despite all advantages associated with the use of concrete in civil engineering infrastructures, its use is sometimes limited in some structures because of its high self weight compared to other construction materials. Moreover, in recent years the construction sector has experienced a shortage in skilled workers as a result of an aging workforce and the difficulty to attract a new generation of skilled workers. Therefore, over the last few decades there has been a tremendous interest to develop new high performance materials that require less skilled workers to be placed/used. In this regard, the development of new types of high performance concretes, such as self-consolidating concrete (SCC) and lightweight concrete (LWC) responds to some of the urgent needs of the construction sector . The development of SCC has been perceived by many specialists as a giant step towards achieving high performance cement based materials.
The utilization of concrete is increasing at a higher rate due to development infrastructure and construction activities all around 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. Annual production represents one ton for every individual on the planet. Production of concrete is increasing due to high growth of infrastructure development and construction activities in the world. However, there are some negative impacts of more production of concrete like continuous extensive extraction of aggregate from natural resources will lead to its depletion and ecological imbalance. Researchers are in search of replacing coarse aggregate to form the concrete less expensive and to lead sustainable development. This environmental reason has generated a lot of concern in the construction world. The role of sugarcane bags’, wood chips, plastic waste, fabric waste, polyethylene, rice husk ash, rubber tires, vegetable fibers, paper and pulp industry waste, vegetable fibers, paper and pulp industry waste, peanut shell, waste glass, broken bricks are some cases of replacing aggregates in concrete
Concrete is the best material of choice where strength, durability, impermeability, fire resistance & absorption resistance are required. Concrete production demands its constituents like aggregates, cement, water and mixtures. 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 imbalance. Increasing demand of natural aggregates shows that crushed stone demand will be 2050 million metric tons in 2020. This huge demand of natural aggregate raises a serious question about the preservation of natural aggregate sources for sustainable development. Extraction and processing of aggregates are also a major concern for the environment. Hence consumption of alternative waste material in lieu of natural aggregate in concrete production not only protects the environment, but also makes concrete a sustainable and environment friendly construction material. The high demand for concrete in the construction using normal weight aggregates such as gravel and granite drastically reduces the natural stone deposits and this has damaged the environment thereby causing ecological imbalance. Therefore, there is a need to explore and to find out suitable replacement material to substitute the natural stone. In developed nations, the construction industries have identified many artificial and natural lightweight aggregates (LWA) that have replaced conventional aggregates thereby reducing the size of structural members. Coconut shell is categorized as light weight aggregate.
The coconut shell when dried, contains cellulose, lignin, partisans and ash in varying percentage. Withal, in Asia the construction industry is yet to utilize the advantage of light weight concrete in the construction of high rise structures. Coconut Shell (CS) is not commonly practiced in the construction industry, but are often dumped as agricultural wastes. Until now, Industrial byproducts and domestic wastes have been utilized in concrete, but the utilization of agricultural waste in concrete is in its early childhood phase. Coconut shell is an agricultural waste. The concrete with ground coconut shell was found to be durable in terms of its resistance in water, acidic, alkaline and salty. Coconut shell being a hard and not easily degrade material if crushed to size of sand can be a potential material to substitute sand. At present, coconut shell has also been burnt to produce charcoal and activated carbon for food and carbonated drinks and filtering mineral water use. However, the coconut shell is still under utilized in some places. The purpose of this research is to disseminate awareness of using coconut shell as partial replacement of coarse aggregate in concrete and determining its compressive strength. Olanipekun (2006)  carried out the comparative cost analysis and strength characteristics of concrete produced using crushed, granular coconut and palm kernel shell as substitutes for conventional coarse aggregate. The main objective is to encourage the use of waste products as construction materials in low-cost housing. Crushed granular coconut and palm kernel was used as substitute for conventional coarse aggregate in the following ratios: 0%, 25%, 50%, 75% and 100% for preparing of mix ratios 1:1:2 and 1:2:4. Total 320 cubes were casted, tested and their physical and mechanical properties were determined. The result showed that the compressive strength of the concrete decrease as the percentage of the coconut shell increases in the two mix ratios, Coconut shell exhibited a higher compressive strength than palm kernel shell in the test. Moreover, there is a cost reduction of 30% and 42% for concrete produced from coconut shell and palm kernel shell respectively.
Siti Aminah Bt Tukiman and Sabarudin Bin Mohd (2009)  replaced the coarse aggregate by coconut shell and grained palm kernel in their study. Percentage of replacement by coconut shell were 0%, 25%, 50%, 75% and 100% respectively. Conclusion is that the combination of these materials has potential of being used as lightweight aggregate in concrete and also has reduce the material cost in construction.
Olutoge (2010)  studied the saw dust and palm kernel shells (PKS). Fine aggregates are replaced by saw dust and coarse aggregates by palm kernel shells in reinforced concrete slabs casting. Conventional aggregates were replaced by saw dust and PKS in same ratios of 0%, 25%, 50%, 75% and 100%. Compressive and flexural strengths were noted at difference time intervals. It was seen that at 25% sawdust and PKS can produce lightweight reinforced concrete slabs that can be used where low stress is required at reduced cost. 7.43% reduction can be achieved.
- P. Ries (2011) observed that Lightweight aggregate plays important role in today’s move towards sustainable concrete. Lightweight aggregates contributes to sustainable development by lowering transportation requirements, optimizing structural efficiency that results in a reduction in the amount of overall building material being used, conserving energy, reducing labour demand and increasing the life of structural concrete.
Abubakar and Muhammed Saleh Abubakar (2011)  compared the physical and mechanical properties of coconut shell and crushed granite rock also a total of 72 concrete cubes of size 150x150x150mm with different mix ratios of 1:2:4, 1:1.5 :3 and 1:3:6 were casted and tested for evaluating different properties. Aggregate crushing value (ACV) for coarse aggregate was 21.84 and 4.71 for coconut shell. Elongation and flakiness index were 58.54 and 15.69 respectively for gravels, while for coconut shell, it was 50.56 and 99.19 respectively. Compressive strength of concrete cubes in N/mm2of coconut shell at 7,14,21 and 28 days with mix ratios of 1:2:4, 1:1.5:3, and 1:3:6 are (8.6, 8.9 ,6.4,), (9.6, 11.2, 8.7), (13.6, 13.1, 10.7) and (15.1, 16.5, 11) respectively, likewise (19.1, 18.5, 9.6), (22.5, 23.0, 10.4), (26.7, 24.9, 12.9) and (28.1, 30.0, 15) respectively for gravel. Since the concrete strength of coconut shell with mix ratio 1:1.5:3, attained 16.5 N/mm2compressive strength at 28 days it can be used in plain concrete works, cost reduction of 48% will be achieved.
Maninder Kaur & Manpreet Kaur (2012) published a review paper in which it is concluded that use of coconut shells in cement concrete can help in waste reduction and pollution reduction. It is also expected to serve the purpose of encouraging housing developers in investing these materials in house construction. It is also concluded that the Coconut Shells are more suitable as low strength giving lightweight aggregate when used to replace common coarse aggregate in concrete production.
Vishwas P. Kulkarni et al (2013)  studied that Aggregates provide volume at low cost, comprising 66 percent to 78 percent of the concrete. M20 Concrete is produced by 0%, 10%, 20%, 30% replacement of coarse aggregate by coconut shell. There is no need to treat the coconut shell before use as an aggregate except for water absorption. No bond failure was observed, confirming that there was adequate bonding between the coconut shell aggregate concrete and the steel bars.
Daniel Yaw Osei (2013)  in this experimental study coarse aggregate is partially replaced by coconut shell. Percentages of replacement by coconut shell were – 0%, 20%, 30%, 40%, 50%, 100%. He concluded that CS can be used to produce lightweight concrete and 18.5% replacement of crushed granite with coconut shells can be used to produce structural concrete.
Parag S. Kambli & Sandhya R. Mathapati. (2014)  prepared three different Mix Designs for M20, M35, M50 grades of concrete. Percentage replacement by coconut shell varied as 0%, 10%, 20%, 30%, 40% respectively. It is concluded in this study that for M20 grade concrete cubes with 30% replacement of CS aggregates had given strength of 23 MPa at 28 days. Concrete cubes with 30% replacement of CS aggregates had given strength of 42 MPa at 28 days for M35. For M50 grade concrete cubes with 30% replacement of CS aggregates had given strength of 51 MPa at 28 days.
Dewanshu Ahlawat & L.G.Kalurkar (2014) explored the possibility of producing M20 grade of concrete by replacing conventional aggregate of granite by coconut shell. Forty five cubes were casted. Percentage of replacement of conventional coarse aggregate by coconut shell were 2.5%, 5%, 7.5%, 10%. Compressive strength were 19.71, 19.53, 19.08, 18.91 N/mm2 respectively at 28 days. Workability and compressive strength had been evaluated at 7, 14 and 28 days. The compressive strength of concrete reduced as the percentage replacement increased. By these results it can be concluded that coconut shell concrete can be used in reinforced concrete.
- MATERIALS AND MIXES
- Ordinary Portland Cement
The cement used for the entire experiment is Ordinary Portland cement of 53 grade conforming to IS 12269. The cement was tested for fineness and specific gravity. Specific gravity of the cement obtained as per the test was 3.15. The cement used is fresh and without any lumps. It is the basic ingredient of concrete, mortar and plaster.
- Fine Aggregates
They are aggregate most of which passes 4.75mm IS Sieve. M Sand is used as the fine aggregate. Sieve analysis is carried out and as per sieve analysis it comes under Zone-II. The limits for each zone as per IS: 383 – 1970.
- Coarse Aggregates
Aggregate most of which is retained on 4.75mm IS Sieve and containing only so much finer material as is permitted for the various types described in this standard. As per IS: 10262 – 1982 clause 3.6 explaining the combination of different coarse aggregate fractions two different sizes, 20mm and 12.5mm size coarse aggregates were used which results in an overall grading conforming to Table 2 of IS: 383 – 1970.
- Chemical Admixture (Super Plasticizer)
Super plasticizer (normal) 4% by the weight of cement is used in the concrete for improving the workability condition of the concrete.
- Pumice stone powder
Pumice is a natural material of volcanic origin produced by the release of gases during the solidification of lava, and it has been used as the aggregate in the production of lightweight concrete in many countries around the world. So far, the use of pumice was dependent on the availability and limited to the countries where it is locally available or easily imported. The use of pumice as aggregate or mineral additive in the production of self-compacting concrete may be a good approach for the production of lightweight, easy workable, economic and environmentalist concrete.
- Coconut shell
coconut shell as partial replacement for coarse aggregate. The concrete with ground coconut shell was found to be durable in terms of its resistance in water, acidic, alkaline and salty. Density of coconut shell is in the range of 550 – 650 kg/m3 and these are within the specified limits for lightweight aggregate.
Mix proportion for M20 grade of concrete is 1:1.5:3 (cement, fine aggregates, coarse aggregates). Chemical Admixture (Super plasticizer) 4% by the weight of cement. Optimum strength is obtained at 15% replacement of fine aggregate by pumice stone powder. Since we are using coconut shell as a coarse aggregate. So we will mix coconut shell with the coarse aggregate in fix percentage such as 0%, 5%, 10%, 20%, 25% and 30%.
The compressive were conducted on the concrete specimens with pumice stone powder and coconut shell as a coarse aggregate. So we will mix coconut shell with the coarse aggregate in fix percentage such as 0%, 5%, 10%, 20%, 25% and 30%.
Table: – Compressive strength of concrete with coarse aggregate partially replaced be coconut shell
|% of replace of coarse aggregate by coconut shell||Mean Compressive strength|
|7 days N/mm2||28 days N/mm2|
- Optimum strength is obtained at 15% replacement of coarse aggregate by coconut shell.
- When SP was added beyond 4% there was increase in compressive strength at all ages but the increase was marginal.
- The specific gravity under SSD condition of CS and crushed granite was found to be 1.05 and 2.82 respectively.
- The fresh concrete density and 28-day hardened concrete density using coconut shell were found to be in the range between 1975 -2110 kg/m3 and 1880 – 1930 kg/m3 respectively.
- The 28-day compressive strength of the concrete using coconut shell aggregate was found to be 23.25 N/mm2 under full water curing and it satisfies the requirement for structural lightweight concrete. It should, however, further investigations are required before it can be used as a building material.
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