CIVL284 Materials of Construction

Spring 2014-2015

HOMEWORK 2

(Concrete Mix Design)

Due date: 14 June 2015 (by 16:45, Submission Office)

  1. Calculate the field quantities of cement, water, fine and coarse aggregate per trial mix of 1 m3 for the following specifications.Show your results on Table 1.

Target mean compressive strength = 25 MPa at 7 days; Cement strength class 52.5; Slump required = 120 mm; Max. Aggregate size = 20 mm; Coarse aggregate UNCRUSHED (10:25mm, 1:2), fine aggregate UNCRUSHED (60% passes 600 microns); Maximum allowable free – water/cement ratio = 0.60; Minimum allowable cement content = 350 kg/m3; Absorption of fine aggregate = 2.5%; Absorption of coarse aggregate = 1.5%; Total Moisture content of coarse aggregate = 2.0%; Total Moisture content of fine aggregate = 3.0%.

  1. The following requirements are specified for the mix design as follows; Make a trial mix of 0.08 m3 concrete for site conditions. Show your results on Table 1.

Characteristic compressive strength = 40 MPa at 28 days; Defective rate = 10%; Standard Deviation=5 MPa (out of 15 results); Cement strength class 42.5; Slump required = 95 mm; Max. Aggregate size = 40 mm (10:20:40mm; 1:1.5:3) CRUSHED, fine aggregate UNCRUSHED (70% pass 600 microns); Relative density of aggregates = 2.65; Maximum allowable free – water/cement ratio = 0.50; Minimum allowable cement content = 320 kg/m3; Maximum allowable cement content = 450 kg/m3 ; Absorption of fine aggregate = 2%; Absorption of coarse aggregate = 1.1%; Total Moisture content of coarse aggregate = 2.2%; Total Moisture content of fine aggregate = 1.5%

  1. The following requirements are specified for the mix design as follows;

Characteristic compressive strength = 45 MPa at 28 days; Defective rate = 2.5%; standard deviation=4 MPa (out of 30 results); cement strength class 42.5; Slump required = 60-75 mm; Max. Aggregate size = 20 mm CRUSHED (10:20mm, 1:2), fine aggregate UNCRUSHED (60% pass 600 microns); Relative density of aggregates = 2.68; Maximum allowable free – water/cement ratio = 0.50; Minimum allowable cement content = 310 kg/m3 ; Maximum allowable cement content = 450 kg/m3; Absorption of fine aggregate = 1.6%; Absorption of coarse aggregate = 1.5%; Total Moisture content of coarse aggregate = 2.5%; Total Moisture content of fine aggregate = 3.5%

Make a trial mix of 0.07 m3 concrete. Show your results (site conditions) on Table 1.

  1. The following requirements are specified for the mix design as follows;

Characteristic compressive strength = 50 MPa at 28 days; Defective rate = 5%; standard deviation= 7 MPa (out of 6 results); Cement strength class 52.5; Slump required = 35 mm; Max. Aggregate size = 40 mm CRUSHED (10:20:40; 1:1.5:3), fine aggregate CRUSHED (80% pass 600 microns);Maximum allowable free – water/cement ratio = 0.55; Minimum allowable cement content = 250 kg/m3; Absorption of fine aggregate = 2.5%; Absorption of coarse aggregate = 2.0%; Total Moisture content of coarse aggregate = 2.5%; Total Moisture content of fine aggregate = 3.0%

Make a trial mix of 0.09 m3 concrete by considering moisture corrections. Show your results on Table 1.

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