2. In order to evaluate the suitability of non-potable water available at the job site for mixing concrete, six standard mortar cubes were made using that the water and six others using potable water. The cubes were tested for compressive strength after 7 days of curing and produced the following loads of failure (in pounds), Cubes Made with Cubes Made with Potable Water Nonpotable Water 16,200 14,530 15,820 17,800 16,530 16,820 14,160 16,100 15,870 14,380 17,920 15,690 18,820 16,720

2. In order to evaluate the suitability of non-potable water available at the job site for mixing concrete, six standard mortar cubes were made using that the water and six others using potable water. The cubes were tested for compressive strength after 7 days of curing and produced the following loads of failure (in pounds), Cubes Made with Cubes Made with Potable Water Nonpotable Water 16,200 14,530 15,820 17,800 16,530 16,820 14,160 16,100 15,870 14,380 17,920 15,690 18,820 16,720

Structural Analysis

6th Edition

ISBN:9781337630931

Author:KASSIMALI, Aslam.

Publisher:KASSIMALI, Aslam.

Chapter2: Loads On Structures

Section: Chapter Questions

Problem 1P

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Q1 What moisture condition should the coarse and fine aggregate be in when mixing the concrete? A Unknown B Saturated C Oven Dry D Air Dried E SSD Q2 What restriction is placed on the size of a sample of a concrete batch? A 30 L B 15 L C 20 L D 10 L E 5 L
Explain why we need to use the smooth surface of the cubes for compressive strength testing. What would be the strength reading if you have used cylinders instead? 6. Discuss the correlation of UPV in terms of compressive strength anf concrete quality? 7. Discuss possible errors leading to unsatisfactory results. What are the modifications that might help to resolve these errors? 8. In your own words, explain your observations on how w/c, admixtures and puzzolans influenced the strength of concrete
Three batches of concrete were prepared using the same materials and ingre- dients, except that they have water-cement ratios of 0.50, 0.55, and 0.60, respectively. The following tests were performed on specimens made of the three batches: - Compressive strength test on 100 mm × 200 mm cylinders - Center point floxure test on 100 mm × 100 mm × 300 mm bcams - Split tension test on 150 mm X 300 mm cylinders Three replicates were tested for each test. Table P7.38 shows the average fail- ure loads for the three replicates of each case. It is required to do the following: a. Complete Table P7.38 b. Using an Excel sheet, plot the relationships between water-cement ratio and compressive strength, modulus of rupture, and tensile strength on the same graph. Label all axes and curves. c. Comment on the effect of water-cement ratio on the compressive strength, modulus of rupture, and tensile strength. TABLE P7.38 w/c Ratio Compressive Strength Test Flexure Test Split Tension Test Compres- sive…
Three 150 mm * 300 mm concrete cylinders with water to cement ratios of0.4, 0.6, and 0.8, respectively. After curing for 28 days, the specimens weresubjected to increments of compressive loads until failure. The load versusdeformation results were as shown in Table P7.26. Assuming that the gauge length is the whole specimen height, it is required todo the following:a. The compressive stresses and strains for each specimen at each loadincrement.b. Plot stresses versus strains for all specimens on one graph.c. The ultimate strength for each specimen.d. The modulus of elasticity as the secant modulus at 40% of the ultimatestress for each specimen.e. The strain at failure for each specimen.f. The toughness for each specimen.g. Comment on the effect of increasing the water–cement ratio on thefollowing:i. Ultimate strengthii. Modulus of elasticityiii. Ductilityiv. Toughness. Curves may be approximated with a series of straight lines.
Three batches of concrete were prepared using the same materials and ingre-dients, except that they have water–cement ratios of 0.50, 0.55, and 0.60,respectively. The following tests were performed on specimens made of thethree batches:■ Compressive strength test on 4′′ * 8′′ cylinders■ Center-point flexure test on 4′′ * 4′′ * 12′′ beams■ Split tension test on 6′′ * 12′′ cylindersThree replicates were tested for each test. Table shows the average failure loads for the three replicates of each case.It is required to do the following:a. Complete Tableb. Using an Excel sheet, plot the relationships between water–cement ratio and compressive strength, modulus of rupture, and tensile strength on the same graph. Label all axes and curves.c. Comment on the effect of water–cement ratio on the compressive strength, modulus of rupture, and tensile strength.
Please give me both a and b answers a. If a concrete with 28 day compressive strength of 4500 psi is being poured, then it how much strength would you expect after 7 days(assuming good curing conditions)? Explain how you obtain the 7 day strength? b. Briefly explain the effect of water to cement ratio on concrete strength?
2. What is the standard size of PCC specimens to be tested for compressive strength? If a smaller size is used, which size is expected to provide higher compressive strengths? Why? Which size provides strengths close to that of an actual concrete structure? 3. What is the purpose of performing the flexure test on concrete? How are the results of this test related to the compressive strength test results? 4. What are the advantages of using a third-point loading flexure test over a center-point loading flexure test? Draw a shear force diagram and a bending moment diagram for each case to support your answer.
Two batches of concrete cylinders were made with and without a calcium chloride (CaCl2) accelerator admixture. Six cylinders were made of each batch and submerged in water for different times before testing for compressive strength and the results are shown in Table P6.34. It is required to do the following: a. Using an Excel sheet, plot the relationship between curing time and compressive strength of the two mixes on the same graph. Label all axes and curves. b. Comment on the effect of the accelerator on the compressive strength of PCC at early and late ages. TABLE P6.34 Cylinder no. 1 2 3 4 5 6 Water submergence (days) Compressive strength of plain concrete (MPa) Compressive strength of concrete with accelerator (MPa) 1 3 7 14 21 28 0.8 7.8 15.8 21.1 24.5 26.8 6.2 14.8 20.1 24.0 25.9 26.8
Three standard mortar cubes were made using questionable water available at the job site, and three others were made using potable water. The cubes were tested for compressive strength after 7 days of curing and produced the failure loads in kN shown in the following table: Questionable Water Potable Water 56.19 63.17 53.13 65.01 52.56 60.06 The Vicat test was conducted on the cement paste made with the questionable water and showed that the set time is 1 hour more than the set time of paste made with potable water. Based on these results, would you accept that water for mixing concrete according to ASTM standards? Explain why.
Students in the materials class prepared three mortar mixes with water to cement ratios. Three 6cm mortar cubes were prepared for each mix. The cubes were cured for 7 days and then tested for compressive strength in Pa. The test results were as shown. Water cement Ratios are 0.40, 0.50 and 0.60 for mix 1, 2 and 3 respectively. Determine the following:a. The compressive strength of each cube. (in Pa)b. The average compressive strength for each mix ( in Pa)
Two 150 mm * 300 mm concrete cylinders with randomly oriented steelfiber contents of 0 and 2% by weight, respectively. After curing for 28 days,the specimens were subjected to increments of compressive loads until failure. The load versus deformation results were as shown in Table P7.45. Assuming that the gauge length is the whole specimen height, determine the following:a. The compressive stresses and strains for each specimen at each loadincrement.b. Plot stresses versus strains for the two specimens on one graph.c. The initial modulus of elasticity for each specimen.d. The ultimate strength for each specimen.e. The strain at failure for each specimen.f. Toughness. Curves may be approximated with a series of straight lines.g. Comment on the effect of adding fiber on the following:i. Modulus of elasticityii. Ultimate strengthiii. Ductilityiv. Toughness