Effects of Salt Water on Concrete – Civil Engineering Project Topics
This project is carried out to know the effects of saltwater on concrete. Saltwater has a salinity of about 3.5%. in that, about 78% is sodium chloride and 15% is chloride and sulphate of magnesium. The result gotten from the experiment being carried out shows the different results from the mix design, casting, curing and crushing of different dates of each cube. The compressive strength of each cube was also determined e.g. for the compressive strength of mix design 1.2.2:4 for both salt water and fresh water for different days such 7,14,21,28 days are “for freshwater” 26.0N/mm2, 33.1N/mm2, 3.8.4N/mm2, 4/06N/mm2 “for saltwater” for different days such as 7, 14, 21, 28days which results are 25.9N/mm2, 28.3N/mm2, 36.3N/mm2, 38.9N/m. For compressive strength of Design Ratio “1:1:5:3:3” for different days such as “7, 14, 21 and 28 days respectively which are “43.3N/mm2, 47.7N/mm2, 48.4N/mm2, 47.3N/mm2 for fresh water and that of saltwater are as follows, 42.1N/mm2, 44.9N/mm2, 46.3N/mm2, 47.26N/mm2. For mix design ratio “1:3:3:5:8” we have their compressive strength to be 16.3N/mm2, 21.8N/mm2, 25.03N/mm2, 29.6N/mm2 for each respective day for fresh water and that of saltwater to be 16.2N/mm2, 20.3N/mm2, 23.57N/mm2, 27.6N/mm2, which also helps in the plotting of the graph of compressive strength against the curing days, to determine the strength of each cube.
Table of Content
List of figures
Table of content
1.2 Salt Water (Sea Water)
1.3 Objective and Purpose of Study
1.4 Scope and Limitation of Study
1.5 Definition of Terms
2.1 LITERATURE REVIEW
2.3 Quality of Water for Preparing Concrete
2.4 Batching, Proportioning and Mixing of Concrete
2.5 Comparison of Saltwater and Freshwater
2.6 Cement Hydration
2.7 Workability and Shrimp of Fresh Concrete
2.8 Curing of Concrete
3.1 MATERIALS AND METHODS
3.2 Collection of Fresh/Tap Water Sample
3.3 Analysis of the Water Sample
3.4 Grading of Coarse Aggregates
3.5 Batching and Mixing of Samples Materials Required
3.6 Curing of Concrete Cubes
3.7 Determination of the Compressive Strength and Density of the Concrete Cubes
3.8 Mix Design
4.1 DATA PRESENTATION
1.1 WHAT IS CONCRETE?
Concrete is an artificial engineering material made from a mixture of Portland cement, water, fine and coarse aggregates, and a small amount of air. It is the most widely used construction material in the world.
Concrete is the only major building material that can be delivered to the job site in a plastic state. this unique quality makes concrete desirable as a building material because it can be moulded to virtually any form or shape. Concrete provides wide latitude in surface textures and colours and can be used to construct a wide variety of structures, such as highways, and streets, bridges, dams, barge buildings, airport runways, irrigation structures, breakwaters, piers and docks, sidewalks, soles and farm buildings, homes and even barges and ships.
Other desirable qualities of concrete as a building material are its strength, economy, and durability. Depending on the mixture of material used, concrete will support, in compression, 700 or more kg/sq cm (10,000 or more 1b/sq in). The tensile strength of concrete is much lower, but by using properly designed still reinforcing, structural members can be made that are as strong in tension as they are in compression. The durability of concrete is evidenced by the fact that concrete columns built by the Egyptians more than 3000 years ago are still standing.
There are, however, many different types of concrete, the names of some are distinguished by the types, sizes and densities of aggregates e.g. eight weight, normal weight or heavyweight. Concrete is similar in composition to mortar, which is used to bond unit masonry. Mortars, however, are normally made with sand as a whole aggregate.
Whereas, concrete contains much larger aggregates and usually have greater strength. As a result, the concrete has a much wider range of structural applications, including pavements, footings, pipes, unit majoring, walls, dams and tanks. Because ordinary concrete is much weaker in tension than in compression, it is usually prestressed or reinforced with a much stronger material, such as steel, to resort to tension.
There are various methods employed for carting ordering concrete. For very small projects, sacks of prepared mixes may be purchased and mixed on the site with water, usually a dream-type, portable, mechanical mixer.
For large projects, mixed ingredients are weighed separately and deposited in a stationary batch mixer or a continuous mixer. Concrete mixed or agitated in a truck is called ready mixed concrete. In general, concrete is placed and consolidation is formed by hand tamping or pudding around reinforcing steel or by spreading at or near vertical surface. Another technique vibration or mechanical pudding is the most satisfactory one for achieving proper consolidation.
CONSTITUENT OF CONCRETE
The two major components of concretes are cement parts and inert materials. The cement parts consist of Portland cement, water, and some air either in the form of naturally entrapped air voids or minute intentionally entrained air bubbles. The inert materials are usually composed of fire aggregate, which is a material such as sand, and coarse aggregate, which is a material such as gravel, crushed stone, or slag. In general, fire aggregate particular are smaller than 6.4mm (.25mm) in size, and coarse aggregates particles are larger than 6.4mm (.025mm). Depending on the thickness of the structure to be built, the size is used, when Portland cement is mixed with water, the components of the cement react to form a cementing medium. In properly mixed concrete, each particle of sand and coarse aggregates is surrounded and coated by this paste, and all spaces between the particular are filled with it. As the cement part sets and hardens, it binds the aggregates into a solid mass.
Under normal conditions, concrete grows stronger as it grows older. The chemical reactions between cement and water that cause the parts to harden and bind the aggregates together require time. The reactions take place very rapidly at first and then slowly over a long period of time.
1.2 SALTWATER (SEA WATER)
Seawater has a salinity of about 3.5%. in that, about 78% is sodium chloride and 15% is chloride and sulphate of magnesium. Seawater also contains small quantities of sodium and potassium salts. This can react with reactive aggregates in the same manner as alkalizes in cement. Therefore, seawater should not be used even for Pcc if aggregates are known to be potentially alkalise reactive. It is reported that the use of seawater for mixing concrete does not appreciate reduce the strength of concrete although it may lead to corrosion of reinforcement in certain cases. Research workers are unanimous in their opinion, that seawater can be used in un-reinforced concrete or mass concrete seawater slightly accelerates the early strength of concrete. But it reduces the 28day strength of concrete by about 10 to 15percent.
However, this loss of strength could be made up by redesigning the mix. Water containing large quantities of chlorides in seawater may cause efflorescence and persistent dampness. When the appearance of concrete is important, seawater may be avoided.
Granite, limestone, sandstone, or basaltic rock are crushed for use principally as concrete aggregate or road stone.
ADVANTAGES OF CONCRETE
Under normal conditions, concrete grows stronger as it grows older. It is the most widely used material (construction) in the world because it is the only major building material that can be delivered to the job site in a plastic state.
Concrete can be moulded into different forms or shapes due to its unique quality. Other qualities of concrete as a building material are its strength, durability, and economy, depending on the mixture of material used.
Concrete provides wide latitude in surface texture and colours and can be used to construct a wide variety of structures, such as highways and street bridges, dams, large buildings, airport runways, irrigation structures, breakwaters, piers and docks, sidewalks, silos and farm buildings, home and even barges and ships.
DISADVANTAGES OF CONCRETE
• Ordinary concrete is much weaker in tension than in compression.
• Concrete is a bottle material and presses very low tensile strength, limiting ductility and little resistance to cracking
• Internal micro-cracks as inherent present in the concrete and its poor tensile strength propagates such micro-cracks and eventually leading to bottle failure of concrete.
• Concrete containing micro silica is vulnerable to plastic shrinkage, cracking and therefore, sheet or mat curing should be considered.
1.3 OBJECTIVES AND PURPOSE OF STUDY
The purpose of the study is to know the adverse negative effect the water (salt) may have on concrete.
Water is an important ingredient of concrete as it actively participates in the chemical reaction with cement. Since it helps to form the strength-giving cement gal, the quantity and quality of water is required to be looked into very carefully. Seawater has a salinity of about 3.5percent, in that, about 78% is sodium chloride and 15% is chloride and sulphate of magnesium. It is said that the use of saltwater (sea) for mixing concrete does not appreciably reduce the strength of concrete through it may lead to corrosion of reinforcement in certain cases. The experiment aims to prove whether or not if seawater can reduce the strength of concrete.
1.4 SCOPE AND LIMITATION OF STUDY
A popular yard-stick to the suitability of water for mixing concrete is that, if water is fit for drinking, it is fit for making concrete. This does not appear to be a true statement for all conditions. Some water containing imparities may be suitable for another purpose, but not for the mixture of concrete.
Some specification requires that if the water is not obtained from a source that has proven satisfactory, the strength of concrete or mortar made with questionable water should be compared with similar concrete or mortar made with pure water. Seawater has a salinity of about 3.5percent, in that, about 78% is sodium chloride and 15% is chloride and sulphate of magnesium. It is reported that the use of seawater for mixing concrete does not appreciably reduce the strength of concrete although it may lead to corrosion of reinforcement in certain cases.
The purpose of the experiment is to prove the doubt of people whether or not if saltwater affects concrete.
1.5 DEFINITION OF TERMS
ACCELERATION:- There are substances that speeds up the rate of a reaction, for photography, an accelerator speeds the action of a developer. For structural engineering, an accelerator speeds the setting of concrete. In the manufacture of plastics, an accelerator is used to speed up the curing of epoxy and other reason-type plastics.
GRAVEL:- Gravel, loose material consisting of rock or mineral fragments. Gravel fragments are larger than sand particles and smaller than boulders specifically, gravel particles are larger than 2mm (0.08m) in diameter and smaller than 256mm (10m) in diameter. Gravel is a constituent of concrete, which is used in construction.
Gravel is produced by the weathering and erosion of rocks, strong river currents or glaciers often transport gravel greats distances before it is disposited. Rock fragments in gravel that have been transported by water are worm and rounded, while the carried by ice usually have sharp angular edges. The rock fragments in gravel transported by rivers also vary in sizeless than those transported by glaciers. Gravels are also found on beaches where there are strong wave actives that are very round and smooth.
SAND:- Sand loose incoherent mass of mineral materials in a finely granular condition, usually consisting of quartz (silica) with a small proportion of mica, feldspar, magnetite, and other resistant minerals. It is the product of the chemical and mechanical disintegration of rocks under the influence of weathering and abrasion. When freshly formed, the particles are usually angular and sharply pointed, becoming smaller and more rounded by attrition by the wind or by water.
QUARRY AND QUARRYING: Quarry and quarrying, open excavation from which any useful stone is extracted for building and engineering purposes and the operations required to obtain rock in useful form from a quarry. The two principal branches of the industry are the so-called dimension-stone and crushed-stone quarrying. In the firms, blocks of stones such as marble, are extracted in different shapes and sizes for different purposes. In the crushed-stone industry.
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