An Experimental Investigation on Effect of Fly Ash on Egg Shell Concrete

Egg shell which is made of calcium is thrown away as a waste. When the calcium carbonate is heated a binding material called Calcium Oxide (Lime) is obtained. As lime is the major compound of Portland cement, eggshell powder can be used as partial replacement of fine aggregate. Fly Ash is one of the residues generated in the combustion of coal. Fly ash includes substantial amounts if Silicon dioxide (SiO2) and Calcium Oxide (CaO). 75 million tons of fly ash which are rich in Silica is disposed to landfill as a waste annually in India. This project aims at examining the feasibility of eggshell powder as a partial replacement of fine aggregate and also to observe the affect of fly ash on the proposed concrete. In the present study, concrete cubes of grade M30 and M40 were prepared in the laboratory by replacing the fine aggregate with fly ash and egg shell powder at combined proportions of 0%, 7%, 14%, 21%, 28%, 35% & 42% by weight. Tests are conducted at 7 days and 28 days on concrete cubes, cylinders and flexural beams to study compressive strength, split tensile strength and flexural strength/ finally the results are compared with the normal conventional concrete and the effect of fly ash on it is studied KEYWORD: Concrete, Eggshell Powder, Fly Ash, Fine Aggregate, Compressive Strength, Split Tensile Strength and Flexural Strength


Introduction
Concrete is a mixture of cement, sand, coarse aggregate and water. Its success lies in its versatility as can be designed to withstand harshest environments while taking on the most inspirational forms. Engineers and scientists are further trying to increase its limits with the help of innovative chemical admixtures and various supplementary cementitious materials SCMs.
Early SCMs consisted of natural, readily available materials like volcanic ash or diatomaceous earth. The engineering marvels like Roman aqueducts, the Coliseum are examples of this technique used by Greeks and Romans. Nowadays, most concrete mixture contains SCMs which are mainly byproducts or waste materials from other industrial processes.

II. MATERIALS
A. Cement: Cement is a material, generally in powder form, that can be made into a paste usually by the addition of water and, when molded or poured, will set into a solid mass. Numerous organic compounds used for adhering, or fastening materials, are called cements, but these are classified as adhesives, and the term cement alone means a construction material. The most widely used of the construction cements is Portland cement. It is a bluish-gray powder obtained by finely grinding the clinker made by strongly heating an intimate mixture of calcareous and argillaceous minerals. The chief raw material is a mixture of highcalcium limestone, known as cement rock, and clay or shale. Blast-furnace slag may also be used in some cements and the cement is called Portland slag cement (PSC). The color of the cement is due chiefly to iron oxide. In the absence of impurities, the color would be white, but neither the color nor the specific gravity is a test of quality.

C. Egg Shell Powder
The eggshells (ES) were collected from domestic sources. The ES was washed manually and then left to dry at ambient conditions. In order to satisfy the physical requirement for fineness, ES was ground fine enough to pass through a 75 µm sieve. This is accomplished by crushing and grinding the eggshells manually and then sieving the ground ESP to the desired particle size.

D. Fine Aggregate
Fine aggregate / sand is an accumulati mineral matter derived from the disintegration of rocks. It is distinguished from gravel only by the size of the grains or particles, but is distinct from clays which contain organic materials. Sands that have been sorted out and separated from the organic material by the action of currents of water or by winds across arid lands are generally quite uniform in size of grains. Usually commercial sand is obtained from river beds or from sand dunes originally formed by the action of winds. Much of the earth's surface is sandy, and these sands are usually quartz and other siliceous materials. Fine aggregate / sand is an accumulation of grains of mineral matter derived from the disintegration of rocks. It is distinguished from gravel only by the size of the grains or particles, but is distinct from clays which contain organic materials. Sands that have been from the organic material by the action of currents of water or by winds across arid generally quite uniform in size of grains. Usually commercial sand is obtained from river beds or from sand dunes originally formed by the action of of the earth's surface is sandy, and these sands are usually quartz and other siliceous materials.
The most useful commercially are silica sands, often above 98% pure. Beach sands usually have smooth, spherical to ovaloid particles from the abrasive action of waves and tides and are free of organic matter. The white beach sands are largely silica but may also be of zircon, monazite, garnet, and other minerals, and are used for extracting various elements.
Natural river sand confirming to Zone 2 grading as per IS: 383 -1987 was used. The sand was thoroughly flushed with water to reduce the level of impurities and organic matter and later sun dried. The natural broken stone (coarse aggregate) used for the study was of 20mm size maximum.

F. Water
Water fit for drinking is generally considered fit for making concrete. Water should be free from acids, oils, alkalies, vegetables or other organic Impurities. Soft waters also produce weaker concrete. Water has two functions in a concrete mix. Firstly, it reacts chemically with the cement to form a cement paste in which the inert aggregates are held in suspension until the cement paste has hardened. Secondly, it serves as a vehicle or lubricant in the mixture of fine aggregates and cement.

III. METHODOLOGY
In order to study the mechanical properties of fly ash and egg shell powder concrete. Six mix proportions were made. The percentage replacements of aggregates by fly ash and egg shell powder were 0%, 7%, 14%, 21%, 28% 35% and 42%. This was done to determine the proportion that would give the most favorable result. The 0% replacement was to serve as control for other sample which is finally used for the comparison. The mix proportions studied for the fly ash and egg shell powder concrete are totally 5 proportions. Water is weighed exactly and added to the dry mix and entire mix is thoroughly mixed till uniformity is arrived at. The fresh concrete is tested using compaction factor apparatus for workability immediately after thoroughly mixing.

WORKABILITY:
In an indirect by determining the degree of compaction achieved by a standard amount of work done compaction factor measures the workability by allowing the concrete to fall through a standard height. In the upper hopper up to the brim the sample of concrete to be tested is placed. So that the concrete falls in the lower hopper the trap door is opened. Concrete is allowed to fall into the cylinder the trap door of the lower hopper is opened and. It is likely that the concrete may not fall on opening trap door in the case of a dry mix. In such case a slight pocking by the rod may be required to set the concrete in motion. The excess concrete remaining top level of cylinder is then cut off with the help of plain blades supplied with apparatus. The surface of cylinder is wiped clean and weighed to the nearest 10gms. This weight is known as "weight of partially compacted concrete". The cylinder is emptied and then refilled with the concrete from the sample in layers of each about 5cm depth. The layers are heavily rammed or preferably vibrated so as to obtain full compaction. The top surface of fully compacted concrete is then carefully struck off and the cylinder is weighed to the nearest 10gms. The weight is known of fully compacted concrete.
Compaction Factor = Weight of partially compacted concrete/weight of fully compacted concrete. The compaction factor is calculated for various percentages of silica fume concretes and various ordinary concretes keeping the water -cement ratio constant. A compaction factor value of 0.82-0.9 has been maintained throughout the experimentation.

CASTING OF SPECIMENS
For casting the cubes, standard C.I Metal cubes of size 150 mm x 150 mm have been used. The moulds have been cleaned of dust particles and applied with mineral oil on all sides, before concrete is poured into the mould. Thoroughly mixed concrete is filled into the mould.

CURING OF SPECIMENS
After casting the molded specimens are stored in the laboratory free from vibrations, in moist air and at room temperature for 24 hrs. After this period, the specimen are removed from the moulds and immediately submerged in the clean fresh water of curing tank. The curing water is renewed after every 5 days. The specimens are cured for 7 and 28 days in the present work.

TESTING OF CUBE SPECIMENS
After 7 days & 28 days the specimens are removed and the following tests were tested and the results compared with conventional concrete.

COMPRESSIVE STRENGTH OF CONCRETE
The cubes are tested for compressive strength for 7 days and 28 days with the maximum nominal size of the aggregate as 20mm and the average test results are noted.

FLEXURAL STRENGTH OF CONCRETE
The ability of a beam or slab to resist failure in bending is flexural strength. The flexural strength of concrete is 12 to 20 percent of compressive strength. The concrete prisms are tested for flexural strength for 7 days and 28 days.

SPLIT TENSILE STRENGTH
The concrete cylinders are tested for split tensile strength for 7 days and 28 days. The split tensile strength is determined by dividing the maximum applied load by appropriate geometrical factors.