QUESTION 1 (30%). Concrete is required for a reinforced concretebuilding. The 28-day target mean (cube) compressive strength shouldbe 40 N/mm2. Use the BRE method to determine the concrete mixproportions for 0.05 m3 concrete (BRE tables and figures areattached below for each stage). (30%) The properties of materialsand site conditions are as follows: - Cement strength class: 42.5 -Slump required: 50 mm - Coarse aggregate: crushed 20 mm (use 1:2proportions for 10 mm and 20 mm combination); Fine aggregate:uncrushed (40% passes 600 micron sieve) - Minimum allowable cementcontent: 300 kg/m3; Maximum allowable cement content: 450 kg/m3 -Maximum allowable free w/c ratio: 0.55 - Relative density ofaggregates (SSD): 2.65 - Free Moisture content for CoarseAggregate: +1.0% - Free moisture content for Fine Aggregate:+1.0%
1.1 characterisitic compressive strength (MPa) and age (days):Proportion defective (%)
