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CONCRETE TECHNOLOGY

by Sdcep 2018
Type: PracticalInstitute: sri balaji college of engineering amd technology jaipur Downloads: 1Views: 57Uploaded: 4 months agoAdd to Favourite

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SBCET/CE/SEM. IV/ CONCRETE TECHONOLOGY LABORATRY (4CE8A) Experiment No.-1 Object: - To determine the fineness of cement by sieving through a 90 micron IS Sieve. Necessity: -To represent/correlate with specific surface area of cement and to check the proper grinding of cement. Apparatus: - (i) IS Sieves no. 9(90 micron) (ii) Weigh balance accuracy up to 1gm. Brief Procedure: (i) (ii) (iii) Take 100 gm. of cement and break down any lumps. Sieve through 90 micron IS Sieve for 15 minutes. Weigh the residue left on sieve. (iv) Remarks:(A) Finesse of cement increases :(i) (ii) (iii) (iv) (v) (B) Rate of hydration. Rate of gain of strength. Rate of evolution of heat. Greater surface area. Increases drying shrinkage of concrete. Different cements are ground to different fineness:The cement must be properly ground to be uniformly fine; otherwise the concretes will be of poor workability causing bleeding. (C) The standard cement should comply with following conditions of fineness as given by IS; 460-1978 and IS; 369-1976. (D) Disadvantage :- (i) Susceptible to air set. Early deterioration. (ii) CONCRETE TECHONOLOGY LABORATRY (4CE8A) Page 1
SBCET/CE/SEM. IV/ CONCRETE TECHONOLOGY LABORATRY (4CE8A) Observation Table:OBSERVATION SHEET Wt. of cement sample W1 =100 gm. S.no. Test values and calculation 1 wt. of cement sample taken on IS Sieve, W1 gm. = 2 Wt. of cement residue after sieving on 90 micron sieve W2 gm. = 3 Fineness of cement % =W2 / W1 X 100 Average % 100 100 Results: - The residue (fineness) of given sample of cement = ………………………% Comments:(i) (ii) (iii) For ordinary Portland cement, the residue by mass on IS test sieve shall not exceed 10 %. For rapid hardening cement, the residue by mass on IS test sieve should not exceed 5 %. The fineness value of given sample of cement is ………………. % which is less than 10 %. Hence it can be used as ordinary Portland cement for concrete work. Questions:(i) (ii) (iii) (iv) (v) (vi) What does the fineness of cement indicate? What is maximum limit of fineness of cement for ordinary Portland cement? Enumerate the methods to determine fineness of cement. What is the field application of fineness test of cement? What are the disadvantages of fineness cement? How is the fineness expressed when using the 90 micron IS Sieve? CONCRETE TECHONOLOGY LABORATRY (4CE8A) Page 2
SBCET/CE/SEM. IV/ CONCRETE TECHONOLOGY LABORATRY (4CE8A) Experiment No.-2 Object: - To determine the flexural strength of Concrete. Necessity: - This test comes into play when a road slab with inadequate sub-grade support is subjected to wheel loads and / or there are volume changes due to temperature / shrinking. Principle: - Flexural strength, also known as modulus of rupture, bend strength, or fracture strength, a mechanical parameter for brittle material, is defined as a material's ability to resist deformation under load. The transverse bending test is most frequently employed, in which a specimen having either a circular or rectangular cross-section is bent until fracture or yielding using a three point flexural test technique. The flexural strength represents the highest stress experienced within the material at its moment of rupture. Apparatus: - Flexural test machine Brief Procedure: - 1. Test specimens shall be prepared by moldings concrete to a beam section, curing and storing in accordance with standard procedure. The section of the beam shall be square of 100 mm or 150 mm. The overall length of the specimen shall be 4d to 5d. The ratio of d to the maximum particle size of aggregate shall be not less than three. 2. Circular rollers manufactured out of steel having cross section with diameter 38 mm will be used for providing support and loading points to the specimens. The length of the rollers shall be at least 10 mm more than the width of the test specimen. A total of four rollers shall be used, three out of which shall be capable of rotating along their own axes. CONCRETE TECHONOLOGY LABORATRY (4CE8A) Page 3
SBCET/CE/SEM. IV/ CONCRETE TECHONOLOGY LABORATRY (4CE8A) The distance between the outer rollers (i.e. span) shall be 3d and the distance between the inner rollers shall be d. The inner rollers shall be equally spaced between the outer rollers, such that the entire system is systematic. 3. The specimen stored in water shall be tested immediately on removal from water; whilst they are still wet. The test specimen shall be placed in the machine correctly centered with the longitudinal axis of the specimen at right angles to the rollers. For moulded specimens, the mould filling direction shall be normal to the direction of loading. 4. The load shall be applied slowly without shock at such a rate as to increase the stress at a rate of .06 + .04 N/mm2 per second. Calculation:The Flexural Strength is given by fb = pl/bd2 a > 20.0cm for 15.0cm specimen or > 13.0cm specimen. fb = 3pa/bd2 a <20.0cm but >17.0 for 15.0cm specimen or <13.3 cm but >11.0cm for 10.0cm specimen. b = width of specimen d = failure point depth l = supported length p =max. Load Reports:The Flexural strength of the concrete is reported to two significant figures. Precaution: ➢ Use hand gloves while, safety shoes at the time of test. ➢ After test switch off the machine. ➢ Keep all the exposed metal parts greased. ➢ Keep the guide rods firmly fixed to the base & top plate. ➢ Equipment should be cleaned thoroughly before testing & after testing. CONCRETE TECHONOLOGY LABORATRY (4CE8A) Page 4

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