Materials For Civil And Construction Engineers In Si Units
4th Edition
ISBN: 9781292154404
Author: Michael S Mamlouk
Publisher: PEARSON
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Chapter 6, Problem 6.40QP
A materials engineer is working in a research project to evaluate the effect of one type of admixture on the compressive strength of concrete. He tested eight mortar cubes made with admixture and eight others without admixture after 28 days of curing. The compressive strengths of cubes in psi with and without admixture are shown in Table P6.40.
Using the statistical t-test, is there a significant difference between the means of the compressive strengths of the two cement mortars at a level of significance of 0.10?
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A materials engineer is working in a research project to evaluate the effect of one type of admixture on the compressive strength of concrete. He tested eight mortar cubes made with admixture and eight others without admixture after 28 days of curing. The compressive strengths of cubes in MPa with and without admixture are shown in Table P6.38. Using the statistical t-test, is there a significant difference between the means of the compressive strengths of the two cement mortars at a level of signifi- cance of 0.10?
A materials engineer is working in a research project to evaluate the effect of one type of admixture on the compressive strength of concrete. She tested 10 mortar cubes made without admixture and 10 others with admixture after 28 days of curing. The compressive strengths of cubes without admixture were 25.1, 24.4, 25.8, 25.2, 23.9, 24.7, 24.3, 26.0, 23.8, and 24.6 MPa. The compressive strengths of cubes with admixture were 25.3, 26.8, 26.5, 24.5, 27.2, 24.8, 24.1, 25.9, 25.3, and 25.0 MPa. Using the statistical t-test, does this admixture show an increase in the compressive strength of the cement mortar at a level of significance of 0.05?
A concrete test cylinder is tested in compression after 7 days of moist curing. If the strength is 22.5 MPa, what do you predict for the projected 28-day strength knowing that the sample only gain 80% strength at 7 days?
Chapter 6 Solutions
Materials For Civil And Construction Engineers In Si Units
Ch. 6 - What ingredients are used for the production of...Ch. 6 - What is the role of gypsum in the production of...Ch. 6 - What is a typical value for the fineness of...Ch. 6 - What are the primary chemical reactions during the...Ch. 6 - Define the C-S-H phase of cement paste.Ch. 6 - What are the four main chemical compounds in...Ch. 6 - Prob. 6.7QPCh. 6 - Define a. interlayer hydration space b. capillary...Ch. 6 - Prob. 6.9QPCh. 6 - The following laboratory tests are performed: a....
Ch. 6 - What is a false set of portland cement? State one...Ch. 6 - The watercement ratio is important because it...Ch. 6 - Discuss the effect of watercement ratio on the...Ch. 6 - Draw a graph to show the general relationship...Ch. 6 - Students in the materials class prepared three...Ch. 6 - Students in the materials class prepared three...Ch. 6 - Two batches of cement mortar with properties as...Ch. 6 - What are the five primary types and functions of...Ch. 6 - Why isnt pozzolan used with Type III cement?Ch. 6 - What type of cement would you use in each of the...Ch. 6 - In order to evaluate the suitability of nonpotable...Ch. 6 - Three standard mortar cubes were made using...Ch. 6 - Four standard mortar cubes were made using...Ch. 6 - Discuss the problem of disposal of waste water...Ch. 6 - State five types of admixtures and discuss their...Ch. 6 - Prob. 6.27QPCh. 6 - Under what condition is an air-entraining agent...Ch. 6 - If a water reducer is added to the concrete mix...Ch. 6 - Prob. 6.30QPCh. 6 - A concrete mix includes the following ingredients...Ch. 6 - The results of an experiment to evaluate the...Ch. 6 - The results of a laboratory experiment to evaluate...Ch. 6 - Referring to Table P6.34, Mix No. 1 was designed...Ch. 6 - Two batches of concrete cylinders were made with...Ch. 6 - Two batches of concrete cylinders were made with...Ch. 6 - What is the source of fly ash? Why is fly ash...Ch. 6 - A materials engineer is working in a research...Ch. 6 - A materials engineer is working in a research...
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- Q3: Discuss importance of sieve analysis test conducted on both fine and coarse aggregateQ4: Concrete cylinder placed in universal testing is subject to axial compressive load. Concretecylinder crushed at a load of 85 kilo pounds, calculate compressive strength of concrete. (Concretecylinder has 6 inches diameter and 12 inches height)arrow_forwardThe specified concrete strength for a new building is 5000 psi. Calculate the required average for the concrete (a) if there are no prior test results for concrete with a compressive strength within 1000 psi of made with similar materials, (b) if 20 test results for concrete with made with similar materials produce a sample standard deviation ss of 560 psi, and (c) if 30 tests with made with similar materials produce a sample standard deviation ss of 540 psi.arrow_forwardThe slump of concrete is being measured. During the test, the height of concrete from the base is 6 inches. The height of the slump cone is 12 inches. The top diameter is 4 inches and the base diameter is 8 inches. What is the slump of concrete? Can you please explain how to obtain the answer.arrow_forward
- 8. A center-point loading flexural test was performed on a concrete beam having a size of 100×100×500 mm. The beam is sitting on two supports located at 25 mm from each edge of beam. If the failure load was 17.5 kN, find the flexural strength.9. Considering the two tests of flexure, 3-points and 4-points, which one is more suitable for bending test and why?10. The compression strength test was performed on several samples of concrete molded in four types of molds cubes of 0.100 m×0.100 m ×0.100 m and of 0.150 m×0.150 m × 0.150 m, and cylinders having a cross section of d=100 mm by H=200 mm and d=150 mm by H=300 mm, respectively. If the weight of the samples and the loads at failure are as given in the Table. Both cubes and cylinder samples are cast from the same concrete batch under the same conditions and subjected to the same curing method.arrow_forwardWhat is the effect of water–cement ratio on the permeability of hardened concrete? How does permeability affect the durability of the concrete structure?Using Figure 7.33, what is the approximate percent increase in the coefficientof permeability if the water–cement ratio increases from 0.5 to 0.6? Using thesame figure, what is the approximate percent increase in the coefficient ofpermeability if the water–cement ratio increases from 0.5 to 0.7?arrow_forwardA hardened concrete cylinder is tested in compression. The ultimate compressive load measured in the laboratory is 262.5 kN. If the sample is 101.3 mm in diameter, calculate the compressive strength in MPa. Round answer to 3 significant digitsarrow_forward
- 1.Why is the compression test the one most frequently made for concrete? 2.Discuss why cross-sectional area of compression specimens must be larger than those of tension specimens. 3.Can you think of any instances where materials are intended to fail in compressionarrow_forwardFor fine aggregate: bulk specific gravity=2.60, SSD Bulk Specific Gravity=2.63, apparent Specific gravity= 2.68, percent absorption=1.54% For coarse aggregate= bulk specific gravity= 2.62, SSD specific gravity=2.63, apparent specific gravity= 2.65, percent absorption=1.70% From the data above, what can you conclude about these bulk aggregate, ssd bulk specific gravity, apparent specific gravity, and percent absorption? What is the effect of these value in concrete?arrow_forwardUSE NSCP 2015 as reference: D. Minimum/maximum value of concrete strain(ec), (from nscp2015) E.Values of concrete and steel Modulus of Elasticity (E). F. Two values of minimum steel area (Asmin).arrow_forward
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