Water defined by the following analysis is to be softened by excess lime treatment in a two- stage system: HCO; = 150 mg/L as CaCOs so = 120 mg/L Cl=71 mg/L CO2 = 4.5 mg/L Ca+ = 64 mg/L Mg = 37 mg/L Na* = 29 mg/L The plant is to treats a flowrate of 20,000 m/day. The practical limits of removal can be assumed to be 30 mg/L of CaCO3 and 10 mg/L of Mg(OH)2 expressed as CACO3. Assume excess lime of 35 mg/L CaO. Find the following:

Given the specifications for an asphaltic concrete mixture and the results of a sieve analysis, determine the proportion of different aggregates to obtain the required gradation. Coarse aggregates: 60% Fine aggregates: 35% Filler: 5%

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.

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.