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Concrete Technology

concrete technology related to civil engineering

DanishAli
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Concrete Technology

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  1. Civil Engineering DeptU.E.T Peshawar Ist semester Section “B” Group 5 Group Members: Hamza Ali Jadoon Danish Ali Hidat Ullah Bilal YOusaf Hafiz Mohammad Hamza

  2. Course of Week 6 and 8 Mini Project Topics Aggregates Properties Batching Mixing Transporting Handling Placing of the Concrete Control Tests of The Concrete

  3. Aggregates Aggregates are used in concrete along with water and cement in order t provide the strength to Concrete

  4. Classification According to Formation

  5. Classification According to Shape Rounded Aggregates Irregular Aggregates Flaky Aggregates Elongated Aggregates Angular Aggregates

  6. Classification According to the size

  7. Sieve Analysis This test is used for the classification of the aggregates according to the different size

  8. Total weight of Aggregates is 7200gm Sieve Analysis Calculation

  9. Fineness modulus of Aggregates Definition: “Empirical figure obtained by adding the total percentage of the sample of an aggregate retained on each of a specified series of sieves” Fineness modulus of the coarse aggregates is between 6.50 to 8 and of fine aggregates is 2.00 to 4.00

  10. Bulk Density Relative Density or Specific Gravity ”Themassof many particlesof the material divided by the total volumethey occupy. The total volume includes particle volume, inter-particle void volume, and internal pore volume.” Formula Bulk Density = B-A/V where B = Mass of filled vessel A = Mass of empty vessel V = Volume of the vessel Relative density orspecific gravity is the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material . Specific gravity usually means relative density with respect to water Formula: Relative Density = ῥ substance/ῥ reference material

  11. Bulking of sand Bulking of sand means increase in it's volume due to presence of surface moisture . The volume increases with increase in moisture content the volume may increase up to 20 to 40% when moisture content is 5 to 10 %.

  12. Soundness of Aggregates Soundness of aggregatesis the ability of aggregates to resist changeof volume due to change of physical condition. These physical conditions include freezing and thawing , temperature change, alternative change of drying and wetting in normal condition and alternative change of drying and wetting in salt water . The aggregates which are weak, porous and containing undesirable materials undergo large volume change in change of those physical conditions

  13. Batching of the Concrete Batching is the process of measuring concrete mix ingredients by either mass or volume and introducing them into the mixer.

  14. Mixing of the Concrete There are essentially three classifications of mixers the drum mixer, pan mixer, and continuous mixer. Each of these mixers can be further classified as batched or continuous, free-falling or forced movement, and stationary or portable.  "complete blending of the materials which are required for the production of a homogeneous concrete" Drum Mixer Pan Mixer Continuous Mixer

  15. Transporting And handling Of the Concrete Transporting the concrete mix is defined as the transferring of concrete from the mixing plant to the construction site There are many modes of transportation as shown below: Wheelbarrow or motorized buggy Truck mixer Bucket or steel skip Cranes Belt conveyor Concrete pump Helicopters

  16. Transporting of Concrete Wheel Barrow Truck Mixer Helicopter Pumping Belt Conveyer Crane

  17. Placing of the concrete For the placing of concrete vibrator are used. When the concrete is vibrated the internal fraction the internal friction between the aggregate particles is temporarily destroyed and the concrete behaves like a liquid; it settles in the forms under the action of gravity and the large entrapped air voids rise more easily to the surface. Internal friction is reestablished as soon as vibration stops

  18. There are many tests of the concrete some of them are: Air contents Test Pressure method is used in measuring the air contents Explanation: The pressure method is based on Boyle’s law, which relates pressure to volume. Many commercial air meters of this type are calibrated to read air content directly when a predetermined pressure is applied. The applied pressure compresses the air within the concrete sample, including the air in the pores of aggregates. Control tests of Concrete

  19. Several methods are used for determining the amount of moisture in aggregate samples. The total moisture content for fine or coarse aggregate can be tested in accordance with ASTM C 566 . In this method a measured sample of damp aggregate is dried either in a ventilated conventional oven, microwave oven, or over an electric or gas hotplate. From the mass before and after drying, the total moisture content can be calculated as follows: P = 100(M – D)/D where P = moisture content of sample, percent M = mass of original sample D = mass of dried sample The surface (free) moisture can be calculated if the percentage of absorbed moisture in the aggregate is known. The surface moisture content is equal to the total moisture content minus the absorbed moisture Moisture content of the Aggregates

  20. Temperature measurement Because of the important influence concrete temperature has on the properties of freshly mixed and hardened concrete, many specifications place limits on the temperature of fresh concrete. Glass or armored thermometers are available . The thermometer should be accurate to plus or minus 0.5°C (±1°F) and should remain in a representative sample of concrete for a minimum of 2 minutes or until the reading stabilizes. A minimum of 75 mm (3 in.) of concrete should surround the sensing portion of the thermometer. Electronic temperature meters with precise digital readouts are also available. The temperature measurement (ASTM C 1064) should be completed within 5 minutes after obtaining the sample

  21. Consistency test (slump Test) The slump test is the most generally accepted method used to measure the consistency of concrete . The test equipment consists ofa slump cone (a metal conical mold 300 mm [12 in.] high, with a 200-mm [8-in.] diameter base and 100-mm [4-in.] diameter top) and a steel rod 16 mm (5⁄8 in.) in diameter and 600 mm (24 in.) long with a hemispheric ally shaped tip. The dampened slump cone, placed upright on a flat, nonabsorbent rigid surface, should be filled in three layers of approximately equal volume. Therefore, the cone should be filled to a depth of about 70 mm (21⁄2 in.) for the first layer, a depth of about 160 mm (6 in.) for the second layer, and overfilled for the third layer. Each layer is rodded 25 times. Following rodding, the last layer is struck off and the cone is slowly raised vertically 300 mm (12 in.)in 5 ± 2 seconds. As the concrete subsides or settles to a new height, the empty slump cone is then inverted and gently placed next to the settled concrete. The slump is the vertical distance the concrete settles, measured to the nearest 5 mm (1⁄4 in.); a ruler is used to measure from the top of the slump cone (mold) to the displaced original center of the subsided concrete

  22. Slump Test Contt… Our Slump test Result Was 4.5” A higher slump value is indicative of a more fluidconcrete. The entire test through removal of the cone should be completed in 21⁄2 minutes, as concrete loses slump with time. If a falling away or shearing off occurs from a portion of the concrete, another test should be run on a different portion of the sample.

  23. Non Destructive Compressive Strength Nondestructive tests (NDT) can be used to evaluate the relative strength and other properties of hardened concreteThe most widely used are the rebound hammer, penetration, pullout, and dynamic or vibration tests. Other techniques for testing the strength and other properties of hardened concrete include X-rays, gamma radiography, neutron moisture gages, magnetic cover meters, electricity, microwave absorption, and acoustic emissions plunger after it has struck a smooth concrete surface. Therebound number reading gives an indication of the compressive strength and stiffness of the concrete. Two different concrete mixtures having the same strength but different stiffness's will yield different readings. In view of this, an understanding of the factors influencing the accuracy of the test is required. The results of a Schmidt rebound hammer test (ASTM C 805) are affected by surface smoothness, size, shape, and rigidity of the specimen; age and moisture condition of the concrete; type of coarse aggregate; and degree of carbonation of the concrete surface.

  24. Destructive Compressive Strength In this test the strength of the concrete is measured with the help of the U.T.M machine Procedure: In this test Cubes of Concrete having same size are made having the same material used in them in same proportion then these cubes are placed for curing for some days and after the specific time period strength of each cube should be measured with the help of U.T.M Machine. The strength of the one cube should be measured after 3 days and 2nd one after 7 days and the 3rd one after 14 days and 4th one after 28 days of making the cubes

  25. The compressive strength of the concrete after 3 days is 405.54psi and after 7 days is 873.489psi Destructive Compressive Strength Contt… We had prepared 4 cubes for finding the compressive strength of concrete after different time intervals and we had checked the strength of one cube after 3 days and 2nd after 7 days and the other are remaining for measuring their strength

  26. THANKS TO ALL

  27. Any Question???

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