Essay Example on The details of mix proportions used in this Research

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The details of mix proportions used in this research are given in Table 1 Ordinary Portland cement type I with high grade 52 5N and silica fume SF were used as cementitious materials The chemical compositions and physical properties of the cementitious materials used are listed in Table 2 For all test specimens a W C of 0 18 was applied Sand with grain size smaller than 0 6 were used Natural crushed basalt graded from 1 18 mm to 10 0 mm max nominal size was used as a coarse aggregate To improve fluidity a high performance water reducing agent Sikament NN super plasticizer SP was added to investigate the effect of steel fiber volume fraction and aspect ratio on the mechanical properties steel fibers with a length of 30 mm and a diameter of 1 0 mm and steel fibers with a length of 50 mm and a diameter of 1 0 mm were considered in three different volume fractions 0 1 2 and 3 with aspect ratios 50 and 30 leading to seven series of test specimens The properties of steel fiber are presented in Table 3 The test specimens were cured at clean tab water for 28 days Compression test The compression test was carried out on cube specimens 100 100 100 mm and cylinders with 100 mm diameter and 200 mm height after 28 days curing 



The preparation of the cylinders for testing was somewhat more involved than that normally used for cylinder testing The largest difference is that the end planeness of the cylinders was ensured through the use of an end grinder Compression tests were completed primarily according to the ASTM C39 standard test method for cylinders and the ASTM C109 standard test method for cubes A slight modification to ASTM C 39 and ASTM C109 was made to make the testing of UHPFRC more practical namely the increase of the load rate applied to the specimen The current standard sets the load rate at 35 7 psi per second which would dictate that a specimen of UHPC could take up to 15 minutes to break This lengthy time period would be unacceptable for the time required to break specimens for production use Modulus of Elasticity and Poisson's Ratio The modulus of elasticity and Poisson's ratio were conducted on 100 mm diameter and 200 mm height cylindrical specimens Specimen ends were prepared as described for compression testing The testing process followed ASTM C 469 except the load rate was increased to 150 psi per second as mentioned for the compression testing In this test electrical strain gauge was located on the face of cylinder specimens in order to measure transverse and vertical displacements The specimens were completely unloaded at approximately the same rate and the gauges zeroed


This process occurred three times for each specimen following the ASTM procedure The initial loading was used to seat the gauges Data from the second and third loading was averaged and reported as the results for the specimen Strain for each 0 50 Mpa stress was recorded and were used to calculate the modulus of elasticity Calculate of elasticity and Poisson s ratio according to ASTM C 469 equations 1 2 E S2 S1 ε 2 0 000050 Equation 1 Where E chord modulus of elasticity S2 stress corresponding to 40 of the ultimate load of the concrete S1 stress corresponding to a longitudinal strain of ε 1at 50 millionths ε 2 longitudinal strain produced by S2 Poisson s ratio to the nearest 0 01 as follows µ ε t2 ε t1 ε 2 0 000050 Equation 2 Where µ Poisson's ratio ε t2 transverse strain at mid height of the specimen produced by stress S2 and ε t1 transverse strain at mid height of the specimen produced by stress S1 Flexure strength Testing was conducted on 100 x 100 x 500 mm prism specimens The specimens were demoulded after 24 hours of casting and were transferred to curing tank wherein they were allowed to cure for 28 days ASTM C 1018 Using a Beam with Third Point Loading was used to determine the flexural strength This test consists of loading a small prism at the third points to create a constant moment region and recording the load and deflection so the data can be analyzed to give the flexural cracking stress flexural strength of the fiber reinforced concrete This configuration loaded the specimens at the third points of the span and created a simple support condition as outlined in ASTM C 78 where the specification for the loading apparatus is given The deflection measuring was secured to the prism at the neutral axis of the prism directly above the support points In each category three beams were tested and their average value is reported

The flexural strength was calculated as follows was conducted on 100 x 100 x 500 mm prism specimens The specimens were demoulded after 24 hours of casting and were transferred to curing tank where in they were allowed to cure for 28 days ASTM C 1018 Using a Beam with Third Point Loading was used to determine the flexural strength This test consists of loading a small prism at the third points to create a constant moment region and recording the load and deflection so the data can be analyzed to give the flexural cracking stress flexural strength of the fiber reinforced concrete This configuration loaded the specimens at the third points of the span and created a simple support condition as outlined in ASTM C 78 where the specification for the loading apparatus is given The deflection measuring was secured to the prism at the neutral axis of the prism directly above the support points In each category three beams were tested and their average value is reported The flexural strength was calculated as follows


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