in a ready mixed concrete plant, 28-day compressive strength results of 32-cylinder specimens prepared by using the same concrete mix design were determined as follows. Considering the overdesign required according to ASTM C94 standard, which compressive strength class can this concrete can be belonging to? Show your work. Specimen " 1 2 3 5 6 7 8 Compressive Strength (MPa) 25 20 23 22 20 23 23 24 Specimen # 9 10 11 12 13 14 15 16 Compressive Strength (MPa) 25 21 15 20 20 19 25 26 Specimen " 17 18 19 20 21 22 23 24 Compressive Strength (MPa) 21 15 16 22 21 27 23 24 Specimen # 25 26 27 28 29 30 31 32 Compressive Strength (MPa) [3] [3 3 8 8 35 123 23 23 24 27 20 29 24 25

in a ready mixed concrete plant, 28-day compressive strength results of 32-cylinder specimens prepared by using the same concrete mix design were determined as follows. Considering the overdesign required according to ASTM C94 standard, which compressive strength class can this concrete can be belonging to? Show your work. Specimen " 1 2 3 5 6 7 8 Compressive Strength (MPa) 25 20 23 22 20 23 23 24 Specimen # 9 10 11 12 13 14 15 16 Compressive Strength (MPa) 25 21 15 20 20 19 25 26 Specimen " 17 18 19 20 21 22 23 24 Compressive Strength (MPa) 21 15 16 22 21 27 23 24 Specimen # 25 26 27 28 29 30 31 32 Compressive Strength (MPa) [3] [3 3 8 8 35 123 23 23 24 27 20 29 24 25

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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You are working on a concrete mix design that requires each cubic yard of concrete to have 0.45 water-cement ratio, 1165 kg/m³ of dry gravel, 4% air content, and 335 kg/m³ of cement. The available gravel has a specific gravity of Ggravel = 2.7, a moisture content of 1.6%, and absorption of 2.4%. The available sand has a specific gravity of Gsand = 2.5, a moisture content of 4.8%, and absorption of 1.5%. For each cubic meter of concrete needed on the job, calculate the mass of cement, moist gravel, moist sand, and water that should be added to the batch. Summarize and total the mix design when finished (don't include air entrainer in summary).
2. You are an inspector on a job site, inspecting strength tests from a job with a design strength of 4500 psi. A total of 12 tests were performed on concrete from this job; the strength test results (in psi) are shown below. 4520 4840 4190 4960 4720 4890 4620 4290 4390 4680 4550 4620 Is this concrete acceptable?
A) as follows 1- The reason for the decrease in concrete resistance when the temperature rises? 2- Reasons for preferring ready-mixed concrete over other types of concrete? 3- Why is it not preferred to mix concrete for a period of time more than required? 4- Why is bonding between cement and aggregate paste more important in highly resistant concrete? 5- Why is it important to get rid of the isolation phenomenon in soft concrete? B) between by drawing the following situations? 1. The relationship between checking the compaction factor and checking precipitation 2- The relationship between compressive strength and life of concrete containing fly ash in days
Two 150 mm x 300 mm concrete cylinders with randomly oriented steel fiber contents of 0 and 2% by weight, respectively. After curing for 28 days, the specimens were subjected to increments of compressive loads until fail- ure. The load versus deformation results were as shown in Table P7.45. TABLE P7.45 Specimen no. 2 Fiber content (%) 2 Deformation (mm) Load (kN) 0.0305 507 507 0.0610 645 (failure) 681 0.0915 578 0.0915 396 1.525 338 (failure) Assuming that the gauge length is the whole specimen height, determine the following: a. The compressive stresses and strains for each specimen at each load increment. 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 elasticity ii. Ultimate…
Comparing PCC with mild steel, answer the following questions:a. Which one is stronger?b. Which one has a higher modulus or stiffness?c. Which one is more brittle?d. What is the range of compressive strength for a typical PCC?e. What is the compressive strength for a high-strength concrete?f. What would be a reasonable range for PCC modulus?
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.
Correctly 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 curve
a design engineer has specified a concrete strength of 4400 psi. the ready mixed concrete producer has a plant standard deviation of 260 psi. what is the required average strength for the concrete?
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.
The following table represents a concrete mixture that has not been completely proportioned. The values given are the theoretical mixture proportions (oven dry basis). Material properties are also provided. Please answer the question at the end of the information given. Theoretical Mixture Proportions (oven dry basis) Water Cement Air Coarse Aggregate ASTM C 150 Type I Cement: Specific Gravity: 3.15 Coarse Aggregate: Well-graded 3/4 in. NMSA rounded gravel Oven-dry specific gravity: 2.63 Absorption: 1.10% Moisture content of stockpile: 3.10 % Oven-dry bulk density: 101.5 lb/ft³ Fine Aggregate: Natural Sand Oven-dry specific gravity: 2.60 Absorption: 3.20% Moisture content of fine stockpile: 3.50% Fineness Modulus: 2.80 265 lb/yd³ 675 lb/yd³ 6.00 % 1816 lb/yd³ What is the theoretical unit weight (in lbs/yd³) of fine aggregate in this concrete mixture (oven dry basis)? Round to the nearest whole number and do not include units when entering your answer.
A1-What is the bond strength between steel and concrete and how it can be calculated? 2-What is the segregation of fresh concrete? Give its reason and how to control it? V3- What are the advantages of concrete? 3- Discuss the effect of age and curing on the compressive strength of concrete. 5-What are the main purposes of using plasticizer admixtures? 6-What are the main techniques that should be used to reduce heat of hydration in mass