STUDY ON USE OF CORAL SAND AS FINE AGGREGATES IN CONCRETE

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1 International Journal of Civil Engineering and Technology (IJCIET) Volume 8, Issue 4, April 2017, pp Article ID: IJCIET_08_04_061 Available online at ISSN Print: and ISSN Online: IAEME Publication Scopus Indexed STUDY ON USE OF CORAL SAND AS FINE AGGREGATES IN CONCRETE C. Pavithra Assistant Professor, Department of Civil Engineering, D. Anil Ratthen Post Graduate, Department of Civil Engineering, A. Arokiaprakash Assistant Professor, Department of Civil Engineering, S. Karthiga Assistant Professor, Department of Civil Engineering, ABSTRACT The crisis of naturally produced aggregates is one of the major problems faced by nations in recent years. This crisis has led to the production of concretes with aggregates from alternate sources. Aggregates from the marine origin can be an alternate source for concrete especially for structures along the coastline and maritime concrete structures. In this research, the mechanical and durability properties of concrete with coral sand as a fine aggregate in partial replacement of river sand (30%, 40% and 50% by sand mass) is studied. The physical, chemical and mineralogical properties of the collected samples were studied. The hardened concrete specimens were subjected to compression and tensile tests after 7, 14 and 28 days of curing. The durability of the concrete specimens to sulphate attack and acid attack were tested. The concrete specimens with conventional fine aggregates replaced with coral sand showed higher values of compressive and tensile strength when compared to that of conventional concrete. The durability of the concrete specimens to acid and sulphate attacks was found to be similar to that of conventional concrete. Key words: Coral sand, Compressive strength, Split Tensile strength. Cite this Article: C. Pavithra, D. Anil Ratthen, A. Arokiaprakash and S. Karthiga, Study on Use of Coral Sand as Fine Aggregates in Concrete. International Journal of Civil Engineering and Technology, 8(4), 2017, pp editor@iaeme.com

2 C. Pavithra, D. Anil Ratthen, A. Arokiaprakash and S. Karthiga 1. INTRODUCTION The excessive usage of naturally occurring river sand for various construction works is one of the major issues faced by several nations of the world including India. River bed mining has been banned by the government which resulted in scarcity and increased costs of river sand. Therefore it is very important to find a suitable alternative for natural river sand. Research on various sand alternatives has been made already. These alternatives are selected on the basis of strength, availability, cost and its durability. Some of the alternatives considered by the researchers are M Sand, offshore sand, dune sand, construction demolition waste, etc. By doing this, excessive river bed mining can be prevented thus preserving natural resources. In this work, coral sand is adopted as an alternative for river sand. Coral sand is of marine origin. These are formed as a result of bio erosion of stony corals and it also includes skeletal shells of molluscs, crustaceans and other marine organisms. Stony corals are limestone structures. These corals form the base foundation of reef systems. Once the living matter inside these coral rocks die they leave a stony calcareous skeleton behind. The bio erosion of these rocks results in the formation of fine sediments of varying sizes. The samples were extracted from the coastline of Hare Island, Tuticorin. The samples were stored in open air and no washing was carried out. The coral sand have a specific gravity of 2.72 and the CaCo 3 content of the coral sand was found to be 94% with a porosity ratio of 0.75 [3]. A figure of 0.075% by weight of sand was arrived at as a safe limit for allowable Cl - ion content in offshore sand for OPC based reinforced concrete and the results showed that the accelerated corrosion performance of grade 20 concrete with the allowable Cl - content (0.075%) in the sand was satisfactory, and the action of even 80 mm of rain was found to reduce the Cl - ion below acceptable levels [4]. Dredged marine sand (DMS) is obtained by marine dredging which when replaced with conventional fine aggregates reduced the accessible pores, the sorptivity and the water penetration depth under pressure [5]. When only crushed sea shells were partially replaced for fine aggregates, the resulting concrete showed better self-compacting properties without affecting the mortar properties [7]. 2. EXPERIMENTAL PROGRAMME This experiment includes the casting, testing and comparison of conventional concrete partially replaced with coral sand as fine aggregates for 30%, 40% and 50% of sand mass with conventional aggregates Materials The details of the various raw materials used for the production of concrete in this study are given below Cement Grade 53 Type I Portland cement was used for concrete mixes throughout the study Fine Aggregates Naturally occurring river sand was used as fine aggregate of size not more than 4.75mm with a specific gravity of The properties were determined by conducting tests as per IS:1386 (Part-I).The results indicate that the sand conforms to zone III as per IS Coral Sand Coral sand was used as a partial replacement for sand for various volume ratios (30%, 40% & 50%). The specific gravity of the coral sand used was 2.5.The microscopic image of the coral sand particle used is show in fig 1 and the chemical composition of the coral sand is given editor@iaeme.com

3 Study on Use of Coral Sand as Fine Aggregates in Concrete below in fig 2.The sieve analysis test results of the coral sand used was determined and tabulated in Table 1. Figure 1 FESEM image of the coral sand particle Figure 2 Chemical composition of coral sand editor@iaeme.com

4 C. Pavithra, D. Anil Ratthen, A. Arokiaprakash and S. Karthiga Sieve size (mm) Mass of sand retained on each sieve (g) Table 1 Sieve analysis of coral sand Percent of mass retained on each sieve Cumulative percent retained (%) Cumulative percent finer (100-N) Pan Uniformity coefficient (C u ) = 7.1 Curvature coefficient (C c ) = 1.55 A well graded soil has a co efficient of curvature (C c ) between 1 and 3, provided uniformity co efficient (C u ) > Coarse Aggregates Coarse aggregate of sizes varying from 12mm to a maximum of 20mm was used and with a specific gravity of 2.77 at saturated surface condition. The properties of coarse aggregates were determined by conducting tests as per IS: 1386(Part-III) Mix Proportions The mix design was carried out as per the method featured in IS:10262 [1]. The grade of concrete chosen was M25 and its target strength is 31.6(N/mm 2 ) after 28 days. The mix details are presented in Table 2. The detailed mix proportions and their respective quantities are represented in Table 3. Grade of concrete Table 2 Concrete mix details M25 Target strength 31.6 N/mm 2 Mix ratio 1 : 1.54 : 2.53 Water cement ratio 0.45 Table 3 Mix Proportions Ingredients Mix1 Mix2 Mix3 Mix4 Cement (kg/m 3 ) Fine aggregate (kg/m 3 ) Coral sand (kg/m 3 ) Coarse aggregate (kg/m 3 ) Water, (Lts/m 3 ) editor@iaeme.com

5 3. TEST RESULTS Study on Use of Coral Sand as Fine Aggregates in Concrete 3.1. Test for Compression Cube specimens of size 15 cm x15 cm x15 cm were used for measuring the compressive strength of the concrete. Universal testing machine was used to calculate the maximum load. The cube specimens were tested after 7, 14 and 28 days of curing. The load is applied gradually till the specimen fails. The compressive strength results of various mix proportions are tabulated in Table 4. The graph featuring the variations in compressive strength of different mixes is shown in fig 3. Table 4 Compressive strength of concrete specimens M25 Mix Specification Compressive strength (N/mm 2 ) (coral sand) 7 th day 14 th day 28 th day M1 0% M2 30% M3 40% M4 50% Compressive strength(n/mm 2 )= % 30% 40% 50% 7th day 14th day 28th day Replacement Figure 3 Compressive strength variations of concrete M Test for Split Tensile Strength Cylindrical specimens of diameter 15 cm and height 30 cm were used to measure the split tensile strength of the concrete. Universal testing machine was used to calculate the maximum load. The cylinders were tested after 7, 14and 28 days of curing. The load is applied gradually till the specimen fails. The tensile strength results of various mix proportions are tabulated in Table 5. The graph featuring the variations in split tensile strength of various mixes is shown in fig editor@iaeme.com

6 C. Pavithra, D. Anil Ratthen, A. Arokiaprakash and S. Karthiga Mix Table 5 Split Tensile strength of concrete specimens M25 Specification (coral sand) Tensile strength (N/mm 2 ) 7 th day 14 th day 28 th day M1 0% M2 30% M3 40% M4 50% Compressive stremgth (N/mm2) % 30% 40% 50% 7th day 14th day 28th day Replacement Figure 4 split tensile strength variations of concrete M Test for Durability Chemical attack on concrete often leads to deterioration and results in the failure of the structure. Hence it is necessary to test the durability of the concrete against chemical reactions. Six cubes were casted for each specification of concrete. The casted cubes were cured in clean water for seven days. After curing, the cubes were dried for 24 hours. The dry weights of the cubes were noted down. Then the cubes were cured in the respective chemical for 60 days. The concentration of the acid solution was maintained at 5% at its respective ph level. The weight of the cubes after 60 days of curing in chemical was noted down. The weight loss of the cubes was determined. The weight loss of the concrete cubes due to acid attack is shown in Table 6. Specification (coral sand) 0% (Conventional concrete) Table 6 Weight loss due to acid attack Chemical Avg. weight of specimens (kg) Weight of specimens after 60 days (kg) Loss in weight Conc. H 2 So 4 30% % % 40% % 50% % The weight loss of the concrete cubes due to sulphate attack is shown below in Table editor@iaeme.com

7 Specification (coral sand) 0% (Conventional concrete) Study on Use of Coral Sand as Fine Aggregates in Concrete Table 7 Weight loss due to sulphate attack Chemical Avg. weight of specimens (kg) Weight of Loss in weight specimens after (%) 60 days (kg) Na 2 So 4 30% % % 40% % 50% % 4. CONCLUSION From the results the following observations were made Concrete specimens with 30% of the fine aggregates replaced with coral sand showed an increased compressive strength of nearly 13% on its 28 th day. The split tensile strength of the concrete replaced with coral sand showed similar results as that of conventional concrete. The concrete specimens were found to be durable when subjected to acid and sulphate attacks, which makes it suitable for construction. REFERENCES [1] Indian Standard, I. S. " (2009)." Recommended Guidelines for Concrete Mix Design. [2] BIS, IS456. "Indian Standard Plain and Reinforced Concrete-Code of Practice (fourth revision) " Bureau of Indian Standards, New Delhi (2000). [3] Chengjie, Z., L. U. Peidong, and W. Yanhong. (2013), "Experiment study on physical properties and motional characteristics of coral sand. ",Proceedings of the 7th International Conference on Asian and Pacific Coasts (APAC 2013) Bali, Indonesia, pp [4] Dias, W. P. S., G. A. P. S. N. Seneviratne, and S. M. A. Nanayakkara. (2008) "Offshore sand for reinforced concrete." Construction and Building Materials22.7, pp [5] Limeira, J., et al. (2011) "Mechanical and durability properties of cocrete made with dredged marine sand." Construction and Building Materials 25.11, pp [6] Olivia, Monita, Annisa Arifandita Mifshella, and Lita Darmayanti. (2015) "Mechanical properties of seashell concrete." Procedia Engineering, pp. 125: [7] Safi, Brahim, et al. (2015) "The use of seashells as a fine aggregate (by sand substitution) in self-compacting mortar (SCM)." Construction and Building Materials 78, pp [8] Howdy shell, Paul A. (1974) The Use of Coral as an Aggregate for Portland Cement Concrete Structures. No. CERL-TR-M-88. Construction engineering research lab (army) champaign IL editor@iaeme.com