Soran University

Civil Engineering Department

BATCHING, MIXING, PLACING, AND CURING OF CONCRETE

Student: Sarchia KhursheedExperiment NO.: 5Date: 11.05.2016

Supervisor: Arianfar Haji

IntroductionBatching of Concrete

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It is the process of measuring concrete mix ingredients either by volume or by mass and introducing them into the mixture. Traditionally batching is done by volume but most specifications require that batching be done by mass rather than volume.

Mixing of ConcreteThe mixing operation consists of rotation or stirring, the objective being to coat the surface the all aggregate particles with cement paste, and to blind all the ingredients of the concrete into a uniform mass; this uniformity must not be disturbed by the process of discharging from the mixer.

Placing of ConcreteThe operation of placing and compaction are interdependent and are carried out simultaneously. They are most important for the purpose of ensuring the requirements of strength, impermeability and durability of hardened concrete in the actual structure. As for as placing is concerned, the main objective is to deposit the concrete as close as possible to its final position so that segregation is avoided and the concrete can be fully compacted. The aim of good concrete placing can be stated quite simply.

Curing of ConcreteCuring is the process in which the concrete is protected from loss of moisture and kept within a reasonable temperature range. This process results in concrete with increased strength and decreased permeability. Curing is also a key player in mitigating cracks, which can severely affect durability.

ObjectiveTo learn about the processes of concrete (Batching, Mixing, Placing, and Curing).Materials

Cement Water Coarse aggregate

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Fine aggregate

ProcedureBatching:1. Specify a balance to weigh the ingredients.2. Prepare the materials needed for making concrete.3. Weigh required quantity of cement.4. Find water ratio.5. Weigh quantities required of sand and gravel.6. Ingredients are now ready and can be used. Mixing:1. The materials should be mixed, firstly mix fine and coarse aggregates together as well as possible by hands.2- Then the water and cement are differently poured into the mixture.2. The scoop is used to mix all the ingredients as well as possible in order to obtain Fresh Concrete.

Placing:1. After mixing, oil the cubes.2. Pour the mixture into the cubes in three different layers; by the way each layer must be beaten 25 times by the tamping rod.3. By using the tamping rod straighten the head of the mixture in the cubes.4. After that, leave the cubes until they get hardened.5. After hardening, bring them out from the cubes by pressing. Curing:1. Put the cubes into water.2. Leave them for a week under room temperature.

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3. After that, bring them out from the water and test them concerning their compressive strengths.

Data and Calculations• Slumping test for (w/c = 0.55) (1: 2: 4) 2.5 kg of cement5 kg of fine aggregate10 kg of coarse aggregate0.55 * 2.5 = 1.375 kg of waterThe slump type was collapse and compressive gained with given w/c ratio was 23 Mpa. • Slumping test for (w/c = 0.55) (1: 2: 4)2.5 kg of cement, 5 kg of fine aggregate, 10 kg of coarse aggregate, 0.55 * 2.5 = 1.375 kg of waterCollapse slump, compressive strength gained was 24 Mpa. • Slumping for (w/c = 0.47) (1: 1.9: 2.3)4.5 kg of cement8.5 kg of fine aggregate10.5 kg of coarse aggregate0.47 * 4.5 = 2.115 kg of waterSlump type was shear slumping and compressive strength gained with given w/c ratio was 44.99 Mpa.

• Slumping for (w/c = 0.47) (1: 1.9: 2.3) 4.5 kg of cement8.5 kg of fine aggregate10.5 kg of coarse aggregate0.47 * 4.5 = 2.115 kg of water

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Shear slumping and compressive strength gained was 38.43 Mpa.

Discussion and ConclusionIn this report we talk about the different processes of concrete (Batching, mixing, placing, and curing), each of this processes has a great effect on concrete, and must be carried out according to international standards.Then we take some samples of concrete with different mix designs, and doing slump tests for each of this samples, in the conclusion we get different results from this samples of slump test.

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