Working on major construction project that requires considerable amounts of concrete to be used, you are asked to design a concrete mix following the BRE methodology. The concrete mix specifications are: o Characteristic compressive strength of 50 N/mm 2 at 7 days. o Failure rate of 1% o Previous control data yielded a standard deviation of 5 N/mm 2 o CEM-I 52.5 o Air-entraining is not required o Required slump 50 mm o Maximum cement content is 550 kg/m 3 o Coarse aggregate: Uncrushed maximum size 10mm o Fine aggregate: Uncrushed with 45% passing 600 μm sieve o Relative density of aggregates: 2.7 o Assume both types of aggregate as SSD. Proceed with the concrete mix design methodology and comment on any implications during this process.

How does the addition of air-entraining materials to Portland cement improve the concrete?

Estimate the transverse tensile strength of the concrete in Problem 12.6.

Given four different types of aggregates to be used to produce a blended aggregate for use in the manufacture of asphaltic concrete, determine the bulk specific gravity of the aggregate mix.

According to Figure 5-20, is ii possible to completely separate one of the four materials from the other three? Explain your answer.

What is the main value in pre-stressing pre-cast concrete columns?

A tensile test was performed on a metal specimen having a circular cross section with a diameter 0. 510 inch. For each increment of load applied, the strain was directly determined by means of a strain gage attached to the specimen. The results are, shown in Table: 1.5.1. a. Prepare a table of stress and strain. b. Plot these data to obtain a stress-strain curve. Do not connect the data points; draw a best-fit straight line through them. c. Determine the modulus of elasticity as the slope of the best-fit line.

Why is nothing added to the concrete quantities for wastage at the time of the takeoff?

Note For Problems 9.6-1 through 9.6-5, use the lower-bound moment of inertia for deflection of the composite section. Compute this as illustrated in Example 9.7. 9.6-1 Compute the following deflections for the beam in Problem 9.2-1. a. Maximum deflection before the concrete has cured. b. Maximum total deflection after composite behavior has been attained.

Three groups of students from the Geotechnical Engineering class collected soil-aggregate samples for laboratory testing from a recycled aggregate processing plant in Palm Beach County, Florida. Three samples, denoted by Soil A, Soil B, and Soil C, were collected from three locations of the aggregate stockpile, and sieve analyses were conducted (see Figure 2.35). (a) (b) Figure 2.35 (a) Soil-aggregate stockpile; (b) sieve analysis (Courtesy of Khaled Sobhan, Florida Atlantic University, Boca Raton, Florida) a. Determine the coefficient of uniformity and the coefficient of gradation for Soils A, B, and C. b. Which one is coarser: Soil A or Soil C? Justify your answer. c. Although the soils are obtained from the same stockpile, why are the curves so different? (Hint: Comment on particle segregation and representative field sampling.) d. Determine the percentages of gravel, sand and fines according to Unified Soil Classification System.