Testing of Hardened Concrete

Part B Testing of hardened cover 1. Objectives The quarry of the hardened cover strain was to determine the compressive and validatory plastic lastingness. On the other hand, this experiment was withal used to witness the effect of hardening condition on specialness of cover, the influence of pattern regularize on compressive personnel, the effect of compaction on compressive military force and this experiment was as well to examine the effect of increasing wet to cementum symmetry on compressive and in direct flexible attitudes of cover. 2. purpose (Refer AS1012 for full details) 2. 1 Compressive Strength In this test, standard piston chambers and blockings go out be subjected to uniaxial compressive committal and the lode will be use gradually at a standard underline number of 15MPa/min. , up to failure. The maximum utilize load is recorded for the determination of the compressive military efficiency. * When examen a piston chamber, a hard- rub ber cap is necessary to gr asp alike loading. * When testing a auction block the load is applied to cast rally and no capping is needed. * Compressive personnel of cover fc (MPa) = Maximum Load P (N) / Load go-cart bea A (mm2) Load bearing bea for cylinder = ? (r2), where r is the r of the cylinder Load bearing atomic number 18a for stop = d x d, where d is the stoppage size 2. 2 In-direct tensile cogency (AS 101210) In this test, a standard cylinder is subjected to a compressive loading along its duproportionn and the cylinder splits in indirect-tension along the diagonal, payable to the generate tension (Poissons effect). It is indispensable to use bearing strips betwixt the cover and the testing auto platens to head off local crushing. In-direct tensile effectiveness fst (MPa) is calculated using the following expression (MPa) = 2000 x Maximum load P (kN) / ? l (mm) x d (mm) Where d and l are the diameter and length of the cylinder in mm. Testing procedure * Fix the compressometer centrally around the 100mm diameter cylinder. cautiously center the specimen in the testing machine. * Three times gradually load the specimen (15+2 MPa/minutes) to the test load level (40% of the cylinder ability) and unload it. Records need not to be kept during first loading Record the following 1. Applied load when the deformation is such that the specimen is subjected to a longitudinal strain of 50 microstrain 2. Deformation attained at test load. 3.From these results the following are to be determined 4. 1 = applied stress at the strain of 50 microstrain 5. 2 = applied stress corresponds to the test load 6. 3 = strain at test load 3. Test Result 3. 1 Compressive Strength Cylinders (Water vul keepized for 28 days) sample no(prenominal) diameter Height Weight Max. Load cylinder carriage (Mpa) reasonable cylinder fortissimo (Mpa) (mm) (mm) (g) (kN) A1. 1 100. 1 200 4138 569 72. 3 71. 6 A1. 2 100. 1 200 4109 555 70. 5 A1. 3 100. 0 200 4125 566 72. 1 B1. 1 100. 3 202 4050 490 62. 0 60. 5 B1. 2 100. 2 200 4025 463 58. B1. 3 100. 1 200 4018 478 60. 7 C1. 1 100. 4 203 3995 345 43. 6 45. 5 C1. 2 99. 7 204 3981 366 46. 9 C1. 3 100. 4 202 3978 365 46. 1 D1. 1 100. 2 198 3842 286 36. 3 36. 5 D1. 2 100. 3 202 3833 277 35. 1 D1. 3 99. 9 201 3865 299 38. 1 Table1. Compressive Strength Cylinders (Water ripened for 28 days) Observation 3. 2 Compressive Strength Cylinders ( aviation stored for 28 days) warning no Diameter Height Weight Max. Load cylinder fortissimo (Mpa) bonny cylinder faculty (Mpa) (mm) (mm) (g) (kN) A1. 4 100. 2 201 3946 373 47. 3 48. A1. 5 100. 2 200 3947 397 50. 3 A1. 6 99. 7 201 3954 383 49. 1 B1. 4 99. 8 200 3863 319 40. 8 41. 3 B1. 5 100. 3 201 3890 334 42. 3 B1. 6 100. 2 200 3883 323 41. 0 C1. 4 100. 0 202 3800 305 38. 8 38. 4 C1. 5 99. 7 203 3795 296 37. 9 C1. 6 100. 2 202 3783 304 38. 6 D1. 4 99. 8 203 3738 193 24. 7 25. 7 D1. 5 100. 1 202 3726 205 26. 0 D1. 6 99. 7 202 3717 205 2 6. 3 Table2. Compressive Strength Cylinders (Air stored for 28 days) Observation 3. 3 validating Tensile Strength Cylinders (Water aged(a) for 28 days) Specimen No. Diameter Length Weight Max. Load cylinder readiness (Mpa) average cylinder force-out (Mpa) (mm) (mm) (g) (kN) A1. 7 100. 2 201 4151 151 19. 1 20. 1 A1. 8 100. 1 201 4137 169 21. 5 A1. 9 100. 1 203 4166 155 19. 7 B1. 7 100. 2 201 4044 136 17. 2 16. 5 B1. 8 100. 1 201 4022 129 16. 4 B1. 9 99. 8 200 4002 124 15. 9 C1. 7 100. 2 202 3899 one hundred fifteen 14. 6 14. 6 C1. 8 99. 7 200 3912 109 14. 0 C1. 9 99. 9 201 3903 great hundred 15. 3 D1. 7 99. 8 198 3861 96 12. 3 12. 3 D1. 8 100. 1 200 3837 93 11. 8 D1. 9 100. 2 198 3859 102 12. 9 Table 3 verifying Tensile Strength Cylinders (Water cured for 28 days) Observation 3. 4 Ultrasonic Pulse Velocity Cubes (Water cured for 28 days) Specimen No. Path Length Elapsed Time pulse rate rate velocity(km/s) average velocity(km/s) cylinder authorisation (Mpa) (mm) (? sec) A1. 10 100. 1 21. 1 4. 7 4. 8 20. 1 A1. 11 100. 2 20. 9 4. 8 A1. 12 100. 1 20. 7 4. 8 B1. 10 100. 0 21. 2 4. 7 4. 7 16. 5 B1. 11 100. 1 21. 4 4. 7 B1. 12 99. 9 21. 3 4. 7 C1. 10 99. 9 21. 5 4. 6 4. 6 14. 6 C1. 11 100. 0 21. 6 4. 6 C1. 12 100. 1 21. 6 4. 6 D1. 10 99. 9 21. 9 4. 4. 5 12. 3 D1. 11 100. 2 22. 0 4. 6 D1. 12 100. 1 22. 1 4. 5 Table 4. Ultrasonic Pulse Velocity Cubes (Water cured for 28 days) 3. 5 Compressive Strength Cubes (Water cured for 28 days) Specimen No. Width Depth Weight Max. Load cylinder strength (Mpa) average cylinder strength (Mpa) (mm) (mm) (g) (kN) A1. 10 100. 1 100. 2 2631 695 88. 3 86. 2 A1. 11 100. 2 100. 0 2625 677 85. 9 A1. 12 100. 1 100. 1 2611 664 84. 4 B1. 10 100. 0 100. 0 2536 555 70. 7 72. 2 B1. 11 100. 1 99. 9 2548 567 72. 0 B1. 12 99. 9 99. 9 2539 580 74. 0 C1. 10 99. 9 100. 2497 431 55. 0 54. 6 C1. 11 100. 0 99. 8 2484 420 53. 5 C1. 12 100. 1 100. 1 2500 436 55. 4 D1. 10 99. 9 100. 0 2461 357 45. 5 44. 2 D1. 11 100. 2 100. 1 2453 345 43. 8 D1. 12 100. 1 100. 0 2462 340 43. 2 Table 5. Compressive Strength Cubes (Water cured for 28 days) Observation 4. Presentation of Test Results Materials commix A Mix B Mix C Mix D Cement subject (kg/m3) 16 16 16 16 Free piss means (kg/m3) 6. 4 7. 2 8 8. 8 Free piss/cement proportionality 0. 4 0. 45 0. 5 0. 55 Hardened unit of measurement weight (kg/m3) 2614. 03 2550. 70 2476. 86 2467. 41 Cylinder strength (MPa) 71. 3056253 60. 4904288 45. 5208526 36. 49120537 Indirect tensile strength (MPa) 20. 10660749 16. 4968345 14. 6184321 12. 34162357 Ultrasonic pulse velocity (km/s) 4. 791360998 4. 69489736 4. 63680017 4. 548533685 Cube strength (MPa) 86. 18075386 72. 236373 54. 6216624 44. 16699149 Plot the following graphical kinds and discuss these descents a) Cylinder compressive strength versus discontinue body of urine-to-cement ratio body of water-cured As seen from the graphical relationship, as the unleash wate r message of cement decreases the compressive strength of the cover specimen will increase.These two properties are inversely proportional to each other. This may be due to the unneeded water diluting the cement paste miscellany which will weaken the hold fast between cement paste and aggregates, and hence decreases the compressive strength of the cover. b) Cylinder compressive strength versus loosen water-to-cement ratio zephyr-stored The ratio between the compressive strength and the unembellished water to cement ratio for the air cured specimens shows a similar soaring to that of the water cured i. e. inversely proportional to each other. However it fecal matter be come upond that the compressive strength is lower than that of the water cured specimens.This is due to the superior wet conditions that the water set option provides. c) Cylinder compressive strength water-cured to cylinder compressive strength air-stored ratio versus cylinder strength water-cured Compar ing the ratio of strengths of water cured concrete and air stored concrete against the strength of well(p) water cured concrete, a difference in strength back be seen. From the graph in a higher place, concrete cured in water pack higher compressive strength than that of air stored concrete. Therefore, if high strength concrete is needed for construction, it would be important to expose concrete to moist conditions during curing. ) Cylinder indirect tensile strength versus free water-to-cement ratio water-cured e) Cylinder indirect tensile strength versus cylinder compressive strength water-cured f) Cylinder indirect tensile strength to cylinder compressive strength ratio versus cylinder compressive strength water-cured g) Cylinder compressive strength versus ultrasonic pulse velocity water-cured h) Cube compressive strength versus free water-to-cement ratio water-cured A large free water to cement ratio base cause segregation of aggregates, which leads to uneven distribution o f aggregate, strength will vary.This supposition can be clearly seen in the graph above. As free water to cement ration increases, compressive strength decreases. i) Cylinder compressive strength versus cube compressive strength water-cured include the theoretical relationship cylinder compressive strength = 0. 80 x cube compressive strength for each mix) As seen from the trend of the results, the cube strength of concrete for a event mix is always stronger than that of the rounded number. The reason for this result is due to the advantageous geometric properties that a cube precedes over the cylindric shape.The cubic specimen has anchor points at the corners of the cube which provide greater compressive strength. A general rule states that cylinder strength is about 80% of cube strength. Therefore, it can be stipulated that in construction, members with a square cross section would have greater compressive strength than that of a cylindrical member. Members with square cross section would be able to divvy up futher loads than a same sized cylindrical member. According to our results, the data-based data is quite close to our theoretical data.However, experimental result tends to be slightly higher than theoretical data. Indirect tensile test mechanism Avery 200Ton concrete test console Bearing strips Dental plaster Procedure Using the same machine as the compressive test, a compressive load is induced along the cylinders length which caused failure along the diagonal direction by tension. Bearing strips are used between the cylinder and testing machine platens which avoids local crushing. Concrete sample was fit(p) between bearing strips which was placed on the undersell testing machine laterally.A constant load was applied to the sample at a rate of 15Mpa/min until the sample fails. Specimen No. Diameter Length Weight Max. Load cylinder strength (Mpa) average cylinder strength (Mpa) (mm) (mm) (g) (kN) A1. 7 100. 2 201 4151 151 19. 1 20. 1 A1. 8 100. 1 201 4137 169 21. 5 A1. 9 100. 1 203 4166 155 19. 7 B1. 7 100. 2 201 4044 136 17. 2 16. 5 B1. 8 100. 1 201 4022 129 16. 4 B1. 9 99. 8 200 4002 124 15. 9 C1. 7 100. 2 202 3899 115 14. 6 14. 6 C1. 8 99. 200 3912 109 14. 0 C1. 9 99. 9 201 3903 120 15. 3 D1. 7 99. 8 198 3861 96 12. 3 12. 3 D1. 8 100. 1 200 3837 93 11. 8 D1. 9 100. 2 198 3859 102 12. 9 Indirect Tensile strength Cylinders (Water cured for 28 days) Non-destructive testing Specimen No. Path Length Elapsed Time pulse velocity(km/s) average velocity cylinder strength (Mpa) (mm) (? sec) A1. 10 100. 1 21. 1 4. 7 4. 8 71. 6 A1. 11 100. 2 20. 9 4. 8 A1. 12 100. 1 20. 7 4. 8 B1. 10 100. 0 21. 4. 7 4. 7 60. 5 B1. 11 100. 1 21. 4 4. 7 B1. 12 99. 9 21. 3 4. 7 C1. 10 99. 9 21. 5 4. 6 4. 6 45. 5 C1. 11 100. 0 21. 6 4. 6 C1. 12 100. 1 21. 6 4. 6 D1. 10 99. 9 21. 9 4. 6 4. 5 36. 5 D1. 11 100. 2 22. 0 4. 6 D1. 12 100. 1 22. 1 4. 5 Ultrasonic Pulse Velocity Cubes (Water cured for 28 days) Cylinder i ndirect tensile strength versus free water-to-cement ratio water-cured The tensile strength of concrete showed a li just about relationship with the free water to cement ratio.As the free water to cement ration increased, the tensile strength of concrete fall. This shows a similar relationship between free water to cement ratio and the compressive strength of concrete as seen in part A and B. It also follows the general trend that an increase in free water to cement ration will decrease the strength of hardened concrete. Cylinder indirect tensile strength to cylinder compressive strength ratio versus cylinder compressive strength water-cured From this diagram we are able to observe the relationship between cylinder tensile strength vs. ompressive strength. It is k instantlyn that concrete is naturally weak in tension, however and increase in the compressive strength will also increase the tensile strength. This is increase the two properties of concrete is due to the lower water to cement ratio which increases the concentration of cement paste providing aggregates to cement paste bonding. This diagram shows the fraction of tensile strength in comparison to its compressive strength of a particular mix. The magnitude is just about constant for all four mixes, therefore showing a concrete tensile strength is an approximate.Cylinder compressive strength versus ultrasonic pulse velocity water-cured The above graph shows the relationship between compressive strength and ultrasonic pulse velocity. The relationship shows that the higher the cylinder strength, the to a greater extent ultrasonic pulse velocity is produced. This tangency indicates that with higher concrete strength, the denser the concrete specimen. The transmission time of the pulse change of location through the specimen is much shorter in denser materials. Discussion of all test results make of free water capacitance on the properties of insolent concrete (workability and unit weight of concre te).Free water refers to the add together of water that is available for the concrete hydration process after the absorption of the aggregates has been taken into account. If the aggregate is saturated and wet, this will increase the tote up of water available for the hydration process, increasing the free water content of the concrete mix. The workability and unit weight of fresh concrete are affected by the free water content as the variables turn the way concrete is utilized and transported and a construction site.The most ordinary way of measuring the workability of concrete set is by measuring the amount of slump in accordance with Australian Standards. A linear relationship between fresh concrete and free water content can be seen from the results of testing fresh concrete. When the free water-content increases, the slump of the concrete batch increases respectively. Lubricating effects can be seen between cement and aggregate particles and thus the much water present in the concrete mix, the easier for particles to slip and slide over each other and therefore increasing the workability.In ground of unit weight, it will decrease with the increase in water content. Cement mainly consists of water, cement and aggregates with respective specific gravities of approximately 1. 00, 3. 15 and 2. 65. With water having the to the lowest degree weight per unit volume, it can be assumed that with an increase in water content in a concrete mixture, the lower unit weight of concrete will be in the mixture when the mixture is combined as there are lower amount of aggregates and cement which are the heavier elements in a concrete mixture.Lower unit weigh of concrete indicates that lighter concrete mixture for the same volume, and this is beneficial property of fresh concrete as it allows easier pumping around the construction site, however, higher water content can affect the strength of hardened concrete so counterbalance of cost versus benefit must be consi dered. exercises of free water content on the hardened concrete properties (compressive strength, tensile strength and modulus of elasticity) As shown in the graphs, the compressive strength of concrete generally increases as the free water to cementitious materials ratio is decreased.However as also seen in the graphs the compressive strength of cylindrical shape specimens tends to increase as free water to cementitious materials ratio is decreased at a decreasing rate whilst cube wrought specimens tends to increase in compressive strength as free water to cementitious materials ratios decreased at an increasing rate. However for cube shaped specimens its compressive strength is relatively higher than that of cylindrical shaped specimens as seen in the graphs.Cylinder strength requires a larger reduction in free water to cementitious materials ratio in order to achieve the same strength as cube strength. A similar bearing can be seen between water cured cylinder specimens and ai r cured cylinder specimens. Air cured requires a set ahead reduction in free water to cementitious materials ratio to achieve the same strength as water cured. For tensile strength, as the free water to cementitious materials ratio is decreased at a decreasing rate, the strength of the concrete increases.However tensile strength tends to increase less than compressive strength as the free water to cementitious materials ratio is increased. As seen in the graphs also, the modulus of elasticity for concrete tends to increase as the free water to cement is decreased at an increasing rate. Effects of curing condition on the compressive strength of concrete Curing of concrete is known as the process which encourages cement hydration where an adequate supply of moisture is required to picture that the rate of hydration of cement is adequate enough to achieve the desired strength for the concrete.Curing allows for continuous hydration of cement where the more days that the concrete is cu red the more gain in strength at a decreasing rate there is for the concrete. However this gain in strength will be halted when cement hydration stops, due to the internal relative humidness of the concrete dropping below 80%. Curing of concrete is for the most part influenced by temperature and humidity, where concrete cured in air after some(prenominal) days of water or moist curing will neer reach the strength of concrete that is continuously cured in water.Overall the more days that the concrete is water the more gain in strength there will be for the concrete. Therefore it is very important to the right way cure concrete in order to achieve optimum strength. Effect of specimen shape on compressive strength The compressive strength of concrete is also influenced by the shape of the testing specimen. In general, the compressive strength for cube shape concrete is relatively higher than the compressive strength of cylindrical shape concrete.This is largely due to the fact tha t in cube shaped concrete, the stress is further away from the uniaxial cracking whilst for cylindrical shaped concrete the stress is near the uniaxial cracking. Discuss your reflection on the importance of the laboratory session afterward having participated in the laboratory testing of fresh concrete and hardened concrete, we now have an in depth fellowship of the behavior of concrete in civil engineering structures, as well we know the various methods and conceptualisation of producing concrete to achieve a particular goal in terms of strength and durability.The importance of our laboratory class is that it lets us see the working side of concrete properties where practical properties of concrete may sometimes not match the theoretical methods of concrete. This is quite common. The laboratory classes lets us learn how to lay down and produce concrete in order to achieve a particular goal in terms of strength and durability, as well we are able to see how real life situations and surroundingss can affect the behavior of concrete particularly during curing.This would most likely be an important knowledge to us when we go to work in the real world. The laboratory has also helped gain an in depth knowledge of how to produce the most workable, long-lasting and most economical concrete. Conclusion As highlighted in the report, the factors which influence the accomplishment of concrete include free water to cement ratio, curing, specimen shape. The amount of free water in concrete is critical given that concrete strength decreases as free water to cement ratio is increased.Curing purlieu is also an important factor influencing the performance of concrete where an appropriate environment is required to give an adequate supply of moisture is required to ensure that the rate of hydration of cement is adequate enough to achieve the desired strength for the concrete. However in general concrete cured in air after several days of water or moist curing will neve r reach the strength of concrete that is continuously cured in water. Overall the more days that the concrete is water the more gain in strength there will be for the concrete.The shape of the specimen is also an important factor influencing the performance of the concrete. As sight in the report, cubic strength of concrete is generally higher than that of cylindrical strength. The workability of fresh concrete is also largely influenced by the free water to cement ratio, where the workability of concrete increases as the free water to cement increases elongation Standards Australia International Ltd (2010), AS1012. 3. 1-1998Methods of testing concrete determination of properties related to the consistency of concrete slump test, SAI GLOBAL, accessed 24th April 2012 http//www. aiglobal. com. ezproxy. lib. uts. edu. au/online/autologin. asp Standards Australia International Ltd (2010), AS1012. 5 1999 Methods of testing concrete Determination of mass per unit volume of freshly m ultiform concrete, SAI GLOBAL, accessed 24th April 2012 http//www. saiglobal. com. ezproxy. lib. uts. edu. au/online/autologin. asp Standards Australia International Ltd (2010), AS1012. 10 2000 Methods of testing concrete Determination of tensile strength of concrete cylinders, SAI GLOBAL, accessed 24th April 2012 http//www. aiglobal. com. ezproxy. lib. uts. edu. au/online/autologin. asp Standards Australia International Ltd (2010), AS1012. 9 1999 Methods of testing concrete Determination of the compressive strength of concrete specimens, SAI GLOBAL, accessed 24th April 2012 http//www. saiglobal. com. ezproxy. lib. uts. edu. au/online/autologin. asp Vessalas, K. (2010), 48352 Construction Materials Lecture Notes, University of Technology, Sydney http//www. icar. utexas. edu/publications/ one hundred five/105 1. pdf viewed on 24/4/2012