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. TABLE P6.32 Without Water Reducer With Water Reducer 735 368 2 4,100 Case 1 Case 2 Cement content, lb/yd³ Water content,* lb/yd³ Slump, inches 28-Day compressive strength, psi *Assume that the water content is above the saturated surface-dry (SSD) condition of the aggregate. 735 368 4 4,105 Case 3 735 294 2 5,055 662 331 2 4,104

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. TABLE P6.32 Without Water Reducer With Water Reducer 735 368 2 4,100 Case 1 Case 2 Cement content, lb/yd³ Water content,* lb/yd³ Slump, inches 28-Day compressive strength, psi *Assume that the water content is above the saturated surface-dry (SSD) condition of the aggregate. 735 368 4 4,105 Case 3 735 294 2 5,055 662 331 2 4,104

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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6.31 The results of a laboratory experiment to evaluate the effects of a plasticizer are shown below. a. Calculate the water/cement in each of the three cases. b. Using water reducer, how can we increase the compressive strength of con- crete without changing workability? Refer to the appropriate case in the table. 244 Chapter 6 Portland Cement, Mixing Water, and Admixtures With Water Reducer Without Water Reducer Case 1 Case 2 Case 3 Cement Content, kg/m 850 850 850 765 Water Content, kg/m Slump, mm Compressive Strength, MPa 465 465 370 419 50 100 50 50 37.8 38.0 46 37.9 c. Using water reducer, how can we improve workability without channging the compressive strength? Refer to the appropriate case in the table. 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. Summarize all possible effects of water…
A 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 DFocus
a) Calculate the temperature of aggregates to produce fresh concrete having the sametemperature with the ambient temperature. Following data in Table 1 could be used:
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.
3. A concrete mix includes the following ingredients per cubic foot: (14 pts.) = 25 lbs. = 11 lbs. Cement Water No Admixture Table shows possible changes that can be made to the 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 WIlII Happen? Ultimate Compressive Strength Cement (Ib) Water (Ib) Admixture Workablity None 25 28 15 11 None Water reducer Water reducer Superplasticizer Air entrainer Accelerator 25 11 25 8. 25 11 25 11 25 11
Problem 2: If f = 3 ksi what is the modulus of elasticity Ec and the maximum tensile stress fr that the concrete can carry before cracking (use ACI recommended equations). Assume a unit weight of the plain concrete is: a. Wc = 90- b. w lb lb 118- ft39 ft3) C. W = 160- Problem 3: Wight 3-6 Rugblom 4: Wight ? 7 lb ft3
2. 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.
Introduction on concrete cube test.
4b. Deformation occurs on freshly lay concrete when it finally set or harden.discuss the various causes for dimensional changes in the hardened concrete.
The results of a laboratory experiment to evaluate the effects of a plasticizer are shown.a. Calculate the water/cement in each of the three cases. b. Choose an appropriate case that - by using water reducer, how can we increase the compressive strength of concrete without changing workability? (Refer to the appropriate case in the table) c. Choose an appropriate case that - by using a water reducer, how can we improve workability without changingthe compressive strength? (Refer to the appropriate case in the table)d. Choose an appropriate case that - by using water reducer, how can we reduce cost without changing workability or strength? (Refer to the appropriate case in the table)
Q3: B: Design the concrete mix according to the following conditions: Design Environment Building frame Required design strength = 27.6 MPa Minimum dimension = 150 mm Minimum space between rebar = 40 mm Minimum cover over rebar = 40 mm Statistical data indicate a standard deviation of compressive strength of 2.1 MPa is expected (more than 30 samples). Only air entrainer is allowed. Available Materials Air entrainer: Manufacture specification 6.3 ml/1% air/100 kg cement. Coarse aggregate: 19 mm nominal maximum size, river gravel (rounded) Bulk oven-dry specific gravity = 2.55, absorption = 3.6, Oven-dry rodded density = 1761 kg/m3 %3D Moisture content = 2.5, Fine aggregate: Natural sand Bulk oven-dry specific gravity 2.659, absorption=0.5, Moisture content = 2, Fineness modulus = 2.47
6.32 The results of an experiment to evaluate the effects of a water reducer are shown in Table P6.32. a. Calculate the water-cement ratio in each of the three cases. b. Using water reducer, how can we increase the compressive strength of concrete without changing workability? Refer to the appropriate case in the table. Chapter 6 Portland Cement, Mixing Water, and Admixtures c. Using water reducer, how can we improve workability without changing the compressive strength? Refer to the appropriate case in the table. 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. TABLE P6.32 Without Water Reducer With Water Reducer 735 368 2 4,100 Case 1 Case 2 Cement content, lb/yd³ Water content,* lb/yd³ Slump, inches 28-Day compressive strength, psi *Assume…