Answer Happy

1. Design a concrete mix for specified design strength of concrete of 35 MPa at 28 days. OPC TYPE I is used & slump of 50 mm is necessary. [ 4 Marks Other data as shown below Non air entrained concrete is used FM of fine aggregate is 2.4 Nominal maximum size of aggregate used 19 mm Dry rodded bulk density of coarse aggregates = 1600 Kg/m Specific gravity of cement = 3.15 Specific gravity of FA = 2.65 Specific gravity of CA = 2.7 Table 9-3. Relationship Between Water to Cementing Materials Ratio and Compressive Strength of Concrete Compressive Water cementing materials to by strength at Non-air entrained Airtrained 28 days, MPa concrete concrete 0.38 030 40 0.42 0:34 0.47 0.39 0:54 0.45 0.61 0.52 20 0.00 0.00 15 0.79 070 Strengthenindes wird das with CSA 212C (ASMC) whip maxim dhe 302 Adalid from 2011 and 121 Specified compressive strength, fc. MPa Required average compressive strength, for MPa Less than 21 fc+7.0 21 to 35 rc.8.5 Over 35 1.107 c+5.0 Bulk volume of dry-rodded coarse Nominal maximum aggregate per unit volume of concrete for size of aggregate different fineness moduli of fine mm (in.) aggregate 2.40 2.60 2.80 3.00 9.5 (3/8) 0.5 0.48 0.46 0.44 12.5 (1/2) 0.59 0.57 0.55 0.53 19 (3/4) 0.66 0.64 0.62 0.6 25 (1) 0.71 0.67 0.65 37.5 (11/2) 0.75 0.73 0.69 50 (2) 0.78 0.76 0.74 0.72 75 (3) 0.82 0.8 0.78 0.76 150 (6) 0.87 0.85 0.83 0.81 0.69 = 0.71 1
Water, Kilograms per cubic meter of concrete, for indicated sizes of aggregate Slump, mm 9.5 12.5 19 37.5 50 75 150 mm mm mm 25 mm mm mm mm mm Non-air-entrained concrete 207 199 190 179 168 154 130 113 25 to 50 75 to 100 228 216205 193 181 169 145 124 150 to 175 243 228 216 202 190 178 160 Appropriate amount of entrapped air in non-air-entrained concrete, percent 30 | 25 | 20 | 15 1.0 0.5 0.3 0.2 Air-entrained concrete 25 to 50 181 175 168 160 150 142 122107 75 to 100 202 193 184 175 165 157 133 119 150 to 175 216 205 197 184 174 166 154 . Recommended average total air content, percent, for level of exposure Mild exposure 4.5 40 35 30 25 20 15 10 Moderate exposure 6.0 5.5 5.0 4.5 4.5 4.0 3.5 3.0 Severe exposure 7.5 70 6.0 6.0 5.5 5.0 45 4.0