19 Nonairentrained concrete designed in accordance with the

19. Non-air-entrained concrete, designed in accordance with the Port land Cement Association, is pared and tested, and required for a slab foundation. Two trial batch mixes have been pre the data is summarized in the table below. The aggregates used in the trial batcn wet, with the f having a summarized in the laboratory test data shown below: mixes were ine aggregate having a moisture content of 6.5% and the course aggregate moisture content of 2.5%. Laboratory tests performed on the aggregates are Trial Mix Data Tria Mix. No.Wet Course Wet Fine Added ai batch Weight of ght of Weight of Weight of Volume of e (psi) Added consolidated Aggregate Aggregate Cement (b) Water (Ib) concrete (lb) 130.0 129.0 (lb) 100.0 101.0 50.0 55.0 30.0 30.3 (ft3) 2.27 2.30 4,500 5,000 2 Laboratory Test Data 1) Saturated Surface Dry Moisture Content: Coarse Aggregate = 0.50% Fine Aggregate = 1.5% 2) Saturated Surface Dry Specific Gravity Coarse Aggregate 2.65 Fine Aggregate 2.70 For Trial Mix No. 1, the unit weight (pcf) is most nearly: (A) 132 (B) 137 (C) 140 (D) 145

Solution

Unit weight is Total weight per unit Volume.

Option (B) 137

Total weight = weight of wet course aggregate + weight of wet fine aggregate + weight of added cement + weight of added water

Total Weight = 130.0+ 100.0 + 50.0 +30.0

Total Weight = 310 lb.

Total Volume = 2.27 ft³

unit weight = (310) / 2.27

unit weight = 136.56 ~ 137 lb / ft³