In: Civil Engineering
QUESTION 1 (30%). Concrete is required for a reinforced concrete building. The 28-day target mean (cube) compressive strength should be 40 N/mm2. Use the BRE method to determine the concrete mix proportions for 0.05 m3 concrete (BRE tables and figures are attached below for each stage). (30%) The properties of materials and site conditions are as follows: - Cement strength class: 42.5 - Slump required: 50 mm - Coarse aggregate: crushed 20 mm (use 1:2 proportions for 10 mm and 20 mm combination); Fine aggregate: uncrushed (40% passes 600 micron sieve) - Minimum allowable cement content: 300 kg/m3; Maximum allowable cement content: 450 kg/m3 - Maximum allowable free w/c ratio: 0.55 - Relative density of aggregates (SSD): 2.65 - Free Moisture content for Coarse Aggregate: +1.0% - Free moisture content for Fine Aggregate: +1.0%
1.1 characterisitic compressive strength (MPa) and age (days): Proportion defective (%)
Complete mix design using BRE method for given specifications is shown below.
Mix quantities for 1m3 and trial mix is tabulated at the end.