Materials for Civil and Construction Engineers (4th Edition)
4th Edition
ISBN: 9780134320533
Author: Michael S. Mamlouk, John P. Zaniewski
Publisher: PEARSON
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Chapter 7, Problem 7.22QP
To determine
The effect of water-cement ratio of on the permeability of hardened concrete.
The effect of permeability on the concrete structure.
The approximate percent increase in the coefficient of permeability if the w/c ratio increases from 0.5 to 0.6.
The approximate percent increase in the coefficient of permeability if the w/c ratio increases from 0.5 to 0.7.
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What 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 , what is the approximate percent increase in the coefficient of permeability if the water–cement ratio increases from 0.5 to 0.6? Using the same figure, what is the approximate percent increase in the coefficient of permeability if the water–cement ratio increases from 0.5 to 0.7?
A concrete mix consists of 5 gallons of water for each bag of cement. What is the
expected compressive strength of this mix based on the compressive strength curve
shown here?
Given information:
Weight of US standard cement bag
= 94 lbs
Water weight = 8.34 pounds per
gallon
COMPRESSIVE
STRENGTH
psi
6000
5000
4000
3000
2000
0.3
0.4
6000 psi
5000 psi
4000 psi
3000 psi
NORMAL CONCRETE
0.5
0.6
W/C RATIO
0.7
MPa
42
35
28
21
14
0.8
Concrete is strongest when subjected to:
O A) Tension
O B) Bending
O9 Torsion
O D) Compression
If a peak load of 250 kN was exerted on a 100 mm x 200 mm test cylinder, the
compressive strength of the concrete is:
OA) 28.6 MPa
O B) 35.2 MPa
O9 31.8 MPa
O D) 32.4 MPa
The approximate volume percentages of the principal components of a concrete
mixture are: 6%, 11%, 41%, 26%, 16%. Which of the following lists matches the
correct order of these main components? Start with the one at 6% and end with the
one at 16%.
O Air, Water, Coarse Aggregate, Fine Aggregate, Cement
O Water, Coarse Aggregate, Fine Aggregate, Cement, Air
O Air, Coarse Aggregate, Fine Aggregate, Water, Cement
O Air, Cement, Coarse Aggregate, Fine Aggregate, Water
Under ideal conditions, concrete should be batched and placed within after
mixing, when retarding admixtures are not used.
OA 90 minutes
O B) 1/2 hour
OC 4 hours
O D) 120 minutes
Chapter 7 Solutions
Materials for Civil and Construction Engineers (4th Edition)
Ch. 7 - The design engineer specifies a concrete strength...Ch. 7 - A project specifies a concrete strength of 24.1...Ch. 7 - A project specifies a concrete strength of at...Ch. 7 - What is your recommendation for the maximum size...Ch. 7 - A concrete mix with a 3-in. slump, w/c ratio of...Ch. 7 - Prob. 7.6QPCh. 7 - You are working on a concrete mix design that...Ch. 7 - Design the concrete mix according to the following...Ch. 7 - Design the concrete mix according to the following...Ch. 7 - The design of a concrete mix requires 1173 kg/m3...
Ch. 7 - Prob. 7.11QPCh. 7 - Prob. 7.12QPCh. 7 - Students in the materials lab mixed concrete with...Ch. 7 - Students in the materials lab mixed concrete with...Ch. 7 - Why is it necessary to measure the air content of...Ch. 7 - What do we mean by curing concrete? What will...Ch. 7 - Discuss five different methods of concrete curing.Ch. 7 - Draw a graph showing the typical relation between...Ch. 7 - Why is extra water harmful to fresh concrete, but...Ch. 7 - Discuss the change in volume of concrete at early...Ch. 7 - Discuss the creep response of concrete structures....Ch. 7 - Prob. 7.22QPCh. 7 - On one graph, draw a sketch showing the typical...Ch. 7 - Using Figure 7.34, a. Determine the ultimate...Ch. 7 - Three concrete mixes with the same ingredients,...Ch. 7 - Three concrete mixes with the same ingredients,...Ch. 7 - Three 100 mm 200 mm concrete cylinders with water...Ch. 7 - Students in the materials class prepared three 4 ...Ch. 7 - Three 150 mm 300 mm concrete cylinders with water...Ch. 7 - Three 6 in. 12 in. concrete cylinders with water...Ch. 7 - A normal-weight concrete has an average...Ch. 7 - Discuss the significance of the compressive...Ch. 7 - What is the standard size of PCC specimens to be...Ch. 7 - Prob. 7.34QPCh. 7 - What is the purpose of performing the flexure test...Ch. 7 - What are the advantages of using a third-point...Ch. 7 - Consider a standard flexural strength specimen of...Ch. 7 - To evaluate the effect of a certain admixture on...Ch. 7 - To evaluate the effect of a certain admixture on...Ch. 7 - Prob. 7.40QPCh. 7 - Prob. 7.41QPCh. 7 - A normal-weight concrete has an average...Ch. 7 - Three batches of concrete were prepared using the...Ch. 7 - Three batches of concrete were prepared using the...Ch. 7 - Prob. 7.45QPCh. 7 - Prob. 7.46QPCh. 7 - Discuss two nondestructive tests to be performed...Ch. 7 - Discuss the concept of concrete maturity meters.Ch. 7 - Discuss four alternatives that increase the use...Ch. 7 - What is self-consolidating concrete? How are its...Ch. 7 - Prob. 7.51QPCh. 7 - Two 6 in. 12 in. concrete cylinders with randomly...Ch. 7 - Discuss the concept of high-performance concrete....Ch. 7 - Comparing PCC with mild steel, answer the...Ch. 7 - Prob. 7.55QP
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- Objective Questions : Answer the following question briefly. 1. How do you test flexural strength ? 2. How do you conduct the flexural strength of concrete ? Show a sketch. 3. What are the factors affecting flexural tests? 4. What is the importance of flexural strength in concrete? 5. What does the higher flexural modulus mean ? 6. How do you calculate the flexural strength of concrete?. 7. Why is flexure test two point loading.?arrow_forwardCompare and discuss the microstructural characteristics of the materials. MERICA FIGURE A.15 Concrete microstructure using optical microscope. FIGURE A.16 Viewing concrete specimen with an optical microscope.arrow_forwardA concrete mix includes the following ingredients per cubic meter: Cement%3D400 kg Water=184 kg No admixture Table below shows possible alternatives mix ingredients. Indicate in the appropriate boxes in the table what will happen in each case for the workability and the ultimate compressive strength as increase, decrease or approximately the same. What will happen? Cement Water Admixture (kg) (kg) Ultimate compressive Workability strength 400 225 None 449 184 None Water 400 184 Reducer Water 400 128 Reducer 400 184 Super Plasticizer 400 184 Air Entrainer 400 184 Accelerator DFocusarrow_forward
- n=20 1. The relation between concrete strength (E) and maturity (M) is as follows: fe = (5+ +10 log10 M. Calculate the strength when concrete is cured at (20 +)°C for (7+") days. What temperature would be required to reach a strength of 30 MPa at 28 days?arrow_forward2. In a ready-mix concrete plant, cylindrical samples are prepared and tested periodically to detect any mix problem and to ensure that the compressive strength is higher than the lower specification limit. The minimum target value was set at 5,000 psi. The following compressive strength data were collected. Sample No. 1 2 3 4 5 6 7 8 9 10 Compressive strength (psi) 5595 5139 6359 5192 5188 5241 5964 5875 6155 5115 Sample No. 11 12 13 14 15 16 17 18 19 20 Compressive strength (psi) 6695 5449 5278 6697 5195 6021 5320 5657 6595 5235 a. Calculate the mean, standard deviation, and the coefficient of variation of the data b. Using a spreadsheet program, create a control chart for these data showing the target value and the lower specification limit. Is the plant production meeting the specification requirement? If not, comment on possible reasons. Comment on the data scatter.arrow_forwardQ.1 Two groups of concrete produced with exactly the same mixing properties are given in the Table below. Select the group you expect to have higher compressive strength by explaining the reason in your own words and by calculating if necessary. (Similarities in your description will be checked !!!) 1st Concrete 2nd Concrete choise Explanation A Water/Cement=0.45 Water/Cement =0.60 B Dosage: 300 Dosage: 400 C Cured for 28 days in water at 20°C Cured for 28 days in air at 20°C D| 150 mm cube 100 mm cube specimen specimen E 150/300 mm cylinder specimen F Steam cured for 6 hours at 100°C 200/200 mm cube specimen Water cured for 20 hours at 40°Carrow_forward
- List the types of aggregate used in concrete and their desirable characteristics.arrow_forwardThe relation between strength and maturity for a concrete is known to be as follows: in SI units: f -33 + 21 logi, M in US units: f, = -5570 + 3047 log, M Calculate the strength when the concrete is cured at 30 °C (86 °F) for 7 days. What temperature would be required to reach a strength of 30 MPa (4400 psi) at 28 days?arrow_forwardA concrete mix includes the following ingredients per cubic meter: a. Cement = 400 kg b. Water = 176 kg c. No admixture Table P6.30 shows possible changes that can be made to the mix ingredi- ents. Indicate in the appropriate boxes in the table what will happen in each case for the workability and the ultimate compressive strength as increase, decrease, or approximately the same.arrow_forward
- 6.33 The results of a laboratory experiment to evaluate the effects of a plasticizer are shown below. d. Using water reducer, how can we reduce cost without changing workability or strength? (Assume that the cost of the small amount of water reducer added is less than the cost of cement.) Refer to the appropriate case in the table. e. Summarize all possible effects of water reducers on concrete.arrow_forwardCorrectly define which of the stress versus strain graphs represent the comparison of 8 ksi and 4 ksi concrete for the chart below (say left or right). Qualitatively compare the w/c ratio, elastic modulus, and brittleness. 0.000 0.003 0.000 0.003 Sean, e Sane Feure 2 Strss vesus Srain curves Feure 2. Stress vasus rain curvearrow_forward4b. Deformation occurs on freshly lay concrete when it finally set or harden.discuss the various causes for dimensional changes in the hardened concrete.arrow_forward
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