STUDIES ON THE EFFECTS OF SEAWATER ON COMPRESSIVE STRENGTH OF CONCRETE CUBE

Transcription

1 International Journal of Civil Engineering and Technology (IJCIET) Volume 9, Issue 12, December 2018, pp , Article ID: IJCIET_09_12_109 Available online at ISSN Print: and ISSN Online: IAEME Publication Scopus Indexed STUDIES ON THE EFFECTS OF SEAWATER ON COMPRESSIVE STRENGTH OF CONCRETE CUBE Sakthivel R Research Scholar, Department of Civil Engineering, Pondicherry Engineering College, Puducherry, India Dr. V. Murugaiyan Professor, Department of Civil Engineering, Pondicherry Engineering College, Puducherry, India ABSTRACT Concrete is commonly used materials in all over the world after that of water. Generally, the normal water is the most considerable ingredients in conventional concrete. This research shows the effects of salt water and normal water for curing on compressive strength of concrete. The cubes are casted with two different set of design mix of M20 and M30 using normal and sea water for curing purpose. The specimens are cured in 7, 14,28,56,84 days of concrete. Finally the results show that the compressive strength of concrete cube with curing of seawater does not give much variation when compared with normal conventional water used in curing of concrete. The compressive strength obtained from normal water curing during 84 th day has maximum value of 34.5N/sq.mm when compared with sea water curing. Key words: Compressive strength, Normal water, Sea water, Normal water Cite this Article: Sakthivel R, Dr. V. Murugaiyan, Studies on the Effects of Seawater on Compressive Strength of Concrete Cube, International Journal of Civil Engineering and Technology (IJCIET) 9(12), 2018, pp INTRODUCTION Concrete is a composite material composed of fine and coarse aggregate blended together with fluid cement. When aggregate is mixed with ordinary Portland cement and water, it forms a fluid and moulded into given shape. The lower water-cement ratio yields a stronger and more durable concrete, otherwise more water gives a free flowing of concrete with a higher slump. Quality of water plays an important role on final product of durability. Hydration is a long term process which involves different reaction when it reacts with sand and gravel and also the components of concrete forming a solid. Water is used to maintain the Saturation in surface of aggregate & concrete and also make a plastic mixture of concrete it s used to place in the desired position. Generally normal water editor@iaeme.com

2 Sakthivel R, Dr. V. Murugaiyan is used for concreting. If it is slightly acidic, water is harmless, but highly acidic or alkaline content of water should be avoided, its leads to loss of strength. Previous review found that seawater reduced the long term strength of concrete, because it contain more chlorides which cause dampness and surface degradation and at last its leads to corrosion. Ocean occupies major part in surfaces of the earth, Coastal and offshore sea structures are exposed to the simultaneous action of a number of physical and chemical action so many number of structure are exposed to sea water either in both way (e.g.: winds can carry drizzles from sea water). The effects of sea water on concrete need an additional attention. Mostly seawater is uniform in chemical composition, by the presence of 3.5 % of soluble salts. The ph of sea water varies from 7.5 to 8.4, the average value in equilibrium with the atmospheric Co2 being 8.2. The ph values became lower than the expected during unexpected condition, it may cause an ordinary Portland cement concrete. In this present work, the design of mix proportion for M20 and M30 grade of concrete were made by as per IS10262 and there are many quality of water is used. We prefer sea water for curing alone, not for mixing of concrete. harmless water were used for casting of concrete cubes The specimen size of 150mm* 150mm were tested in 7, 14, 28, 56 & 84 days of concrete as per Indian standards to find the results of the compressive strength of concrete, ultra-sonic pulse velocity method and rebound hammer test 2. MATERIAL USED 2.1. Cement Ordinary Portland cement of grade of 43 is used in this project work confirming to IS and ultra tech cement is used. The specific gravity of cement is Fine Aggregate River sand is used of size 4.75mm passing sieve used in this project. The properties of fine aggregate are determined as per IS to have a specific gravity of fine aggregate is 2.60 confirming at zone II Coarse Aggregate The natural crushed granite of 20mm aggregate passing on sieve at 60% used and 12mm of retained at 40% is used in this work. The properties of coarse aggregate are determined as per IS to have a specific gravity of coarse aggregate is Water The normal potable water is available in laboratory was used for casting and curing of conventional concrete cube 2.5. Sea Water In this work, the sea water is used for curing of concrete for both M20 and M30 grade. 3. METHODOLOGY The general mix proportions are provided in IS: , for M20 and M30 grade of concrete was arrived as 1: 1.5: 3 and 1: 0.75: 1.5 with water-cement ratio of A total sample of 12 cube specimen of size 150mm x 150mm x 150mm were cast and tested the compressive strength at 7,14,28,56&84 days, Water absorption and Young s modulus were noted at 28 days editor@iaeme.com

3 Studies on the Effects of Seawater on Compressive Strength of Concrete Cube 4. RESULT AND DISCUSSION 4.1. Compressive strength The compressive strength of concrete was determined as per IS: , three numbers of cube specimens are cast for curing using conventional concrete and three numbers of specimens for curing on sea water which was tested in compression testing machine. This concrete cube specimens containing OPC, fine and coarse aggregate are tested for compressive strength of concrete at 7, 14, 28, 56 & 84 days. In general, the curing weight of concrete is reduced when it is compared with normal water curing. Generally weight is taken before it is put into curing tank and after 24 hours taken out and dried for few minutes to take the weight of concrete specimens and hence finally it s compared whether it is increased or decreased in normal and sea water curing. Figure 1 In general, the compressive strength of concrete is decreased in sea water curing when its compare to normal water curing, reduction in strength of about 12% by volume. This reduction in sea water is due to porous in concrete which allows salts to penetrate into it and finally leads to loss of strength in concrete Table 1 Compressive strength of concrete with normal water and sea water No of days Compressive strength Normal water Sea water M20 M30 M20 M editor@iaeme.com

4 Sakthivel R, Dr. V. Murugaiyan compressive strength of normal water and sea water no of days Figure 2 Compressive strength of concrete with normal water and sea water 4.2. Ultra-sonic pulse velocity An ultrasonic pulse velocity is an in-situ, non-destructive test to check the quality of concrete and its natural behaviour. Ultrasonic pulse velocity method, involves the measurement of the time travel of electrically generated pulses through the concrete. The pulses are applied to the concrete; three different waves are generated called longitudinal waves. Three different kinds of wave are generated. One is longitudinal or compression waves which travel twice as fast on other two types. Second one is shear or transverse waves are not so fast. Finally the surface waves are the slowest one. The normal techniques of UPV method are transferring the voltage in the form of ultrasonic pulse and back it s transmitting and receiving from the transducer respectively. The transducer is placed into both side of concrete surface which allows the pulses into the concrete and its travel inside of concrete it s received by the transducer at the opposite side. the distance between the two transducer and the velocity of the pulse are known. The velocity criteria of concrete under the grading, if the pulsed velocity is greater than 4.5 its excellent, if its 3.5 to 4.5 are good in condition, if 3.0 to 3.5 it s a medium,finally below 3.0 it s doubtful concrete to used. Figure 3 ultra-sonic pulse velocity 4.3. Rebound hammer test Schmidt s rebound hammer is one of the non-destructive testing methods for concrete to measure the surface hardness. It consists of a spring hammer that side on a plunger within the tubular. When the plunger is pressed against the surface of concrete the mass hit from the editor@iaeme.com

5 Studies on the Effects of Seawater on Compressive Strength of Concrete Cube plunger it reacts to the force against the spring, that impact against the concrete and spring controlled the action of mass, taking the rider with it guide scale. The rider on top of the tubular just above mass rebound to allow the reading to be taken. The distance travelled along the concrete is called rebound number. This test can be done both horizontally and vertically manner Water absorption Water absorption of concrete cubes with normal water curing and sea water curing at 7, 14, 28, 56 & 84 days was shown in Fig.4. The results shows water absorption is increased when it s compared to sea water. 5. CONCLUSIONS Based on the test results, it is concluded that: Figure 4 Water absorption The compressive strength of concrete is decreased at both M20 and M30 grade of concrete used in sea water curing, compared to curing on normal water. Compressive strength for M-20 grade concrete for sea water curing is decreased by 13.52N/Sq.mm with normal water curing during 28 th day and 8.07 N/Sq.mm during 84 th day. Compressive strength for M-30 grade concrete for sea water curing is decreased by 2.73/Sq.mm with normal water curing during 28 th day and 6.9 N/Sq.mm during 84 th day. The ultra-sonic pulse velocity results show that normal water curing of concrete have better quality when compared to sea water curing. The hardness of concrete is increased in both normal water and sea water curing of concrete. The water absorption is increased in normal water curing when it s compared to the sea water curing. REFERENCES [1] Falah M. Wegianoct 10(2010) effects of sea waterfor Mixing and curing on structural concrete [2] P. Krishna raj, v. Lakshmi, s.bhanupravallika (April [3] 2014) Concrete using sea Water International journal of [4] Advanced scientific and technical Research editor@iaeme.com

6 Sakthivel R, Dr. V. Murugaiyan [5] Akinsolaolufemi Emmanuel, (2012) investigation of salinity Effect on compressive strength of reinforced concrete, journal in Sustainable development, Canadian centre of science and education [6] S.K. kaushik, S. islam (1995) suitability of sea water for mixing structural concrete exposed to a marine environment. International journal engg research. [7] Sagargawande, yogeshdeshmukh, (2017) comparative study of effect of salt water and fresh water on concrete. International research journal of engineering and technology. [8] Preeti Tiwari, rajivchandak, R.K. yadeav.(2014) effects of salt water On compressive strength of concrete, international journal of Engineering research& applications [9] E,M. Mbadujea, A.U. ellinwa, effect of salt water in the producton of concrete. June-2011 journal of Nigerian technology [10] Concrete for marine works using opc&sea water, feb-2014 International journal of civil engineering [11] MandarM.joshi study of different parameters of saline water from budana district for its use in concrete editor@iaeme.com