?Experimental study and prediction of tensile strength for steel fiber reinforced concrete.? International Journal Of Civil And Structural Engineering (ISSN 0976 ? 4399) Volume 1, No 4. ?Steel Fiber Reinforced Concrete: A Review.? ?State-of-the-Art Report on Fiber Reinforced Concrete.? American Concrete Institute, Farmington Hills, Michigan. Also, the cracking/failure pattern of SFRC specimens showed improved ductility over that of plain concrete. The result showed that both compressive and flexural strength of steel fiber reinforced concrete increased with the inclusion of steel fiber, the maximum being found that at 1.5% & 2% steel fiber content for compressive & flexural strength respectively and for aspect ratio of 70. of plain concrete specimens were also cast from the same concrete mix to compare the strength characteristics of plain and fiber reinforced concrete and to predict the effect of fiber inclusion. 100 mm x 100 mm x 500 mm concrete beam specimens were cast from M25 concrete with varying fiber volume fraction (1.0, 1.5, 2.0 & 2.5%) and two different aspect ratios (50 & 70). This paper presents an experimental program to investigate the compressive & flexural strength characteristics of concrete with or without steel fibers. The maximum load at which the specimen breaks is taken as a compressive load.In Steel Fiber Reinforced Concrete (SFRC), steel fiber is added to concrete due to its ability to restrict the growth of cracks and thus changing the brittle mode of composite to a strong cement matrix with superior crack resistance.Now slowly apply the load at the rate of 140kg/cm 2 per minute till the cube collapse.The load will be applied to the specimen axially.Carefully align the specimen with the spherically seated plate. The cubes should be placed correctly on the machine plate (check the circle marks on the machine).Now place the concrete cubes into the testing machine.The Cube weight should not be less than 8.1 Kgs.The specimen should be in dry condition before conducting the testing.The specimen should be removed from the water 30 minutes prior to the testing.Every 7 days the water should be renewed. The specimen should be kept for 7 or 28 days. Keep the specimen submerged under fresh water at 27 ° Celsius.After 24 hours remove the specimen from the mould.After some time the mould should be covered with red gunny bag and put undisturbed for 24 hours at a temperature of 27 ° Celsius ± 2.Finish the top of the concrete by trowel & tapped well till the cement slurry comes to the top of the cubes.Fill the concrete to the mould with the help of vibrator for thorough compaction.Add design quantity of water to the dry proportion ( water-cement ratio) and mix well to obtain uniform texture. Thoroughly mix the dry ingredients to obtain the uniform mixture.The Ingredients should be sufficient enough to cast test cubes Measure the dry proportion of ingredients (Cement, Sand & Coarse Aggregate) as per the design requirements.To find compressive strength value of concrete cubes. Specified characteristic compressive strength (N/mm2) at 28 daysĬompressive Strength of Concrete Lab Test Objective Minimum compressive strength N/mm2 at 7 days If the concrete fails at 14 days, then we will reject that batching.Ĭompressive Strength Table of Concrete at 7 & 28 Days Grade of Concrete So at sites, we do normally test concrete at this interval. Once it attains certain strength at 7 days, then we know (according to the table) only 9% of strength going to increase. So we can’t predict the strength until the concrete comes to that stable state. Concrete Strength Overtime Days after CastingĪs you can see the concrete gains its strength rapidly til 7 th & 14 th Days. Concrete is a macro content with Sand, Cement, & Coarse aggregate as its micro-ingredient (Mix Ratio) and gains its 100% strength over time at the hardened state.
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