Chapter 2 Concrete Table 2.7 Water requirements of concrete mixes (75 mm slump) for average-quality sand Nominal size of

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Chapter 2 Concrete Table 2 7 Water Requirements Of Concrete Mixes 75 Mm Slump For Average Quality Sand Nominal Size Of 1 (88.96 KiB) Viewed 41 times

Chapter 2 Concrete Table 2.7 Water requirements of concrete mixes (75 mm slump) for average-quality sand Nominal size of stone (mm) 9.5 Water requirement of concrete (l/m?) 235 13.2 225 19.0 210 26.5 200 37.5 190 For example, if you are using a 19 mm stone, the water required in the mix would be about 210 l for every cubic metre. This volume of water is based on a 75 mm slump. If the slump requirement is under or abov this value then step 3 is required. Step 3: Modify the water requirement to suit the required slump nonumes that the slump of the mix is 75 mm. If a slu mi 27.
where St CBD K = mass of stone in one cubic metre of concrete (kg/m?) = a factor that depends on the nominal size of the stone and = dry compacted bulk density (CBD) of stone (kg/m3) the workability of the concrete (see table 2.8) = fineness modulus of sand FM Table 2.8 Values for K for determining stone content K Approx. slump Compaction range (mm) Nominal maximum size of stone (mm) 9.5 13.2 19.0 26.5 75-150 Hand compaction 0.75 0.84 (0.94 1.00 25-100 0-25 0.80 Moderate vibration Heavy vibration 1.00 0.90 1.05 1.06 1.00 1.05 1.10 Continuing the above example, if you are using 19 mm stone, a sand with a fineness modulus of 2.3, a slump of 100 mm and it is required that the concrete be hand compacted, a K value of 0.94 will be obtained from table 2.8. Given a CBD of 1 580 kalu
the horizon the vertical column. For 30 MPa will need a wc of 0.56, if made cements. Strengths of mixes made with specific cements should be (The table is based on the average performance of South African verified.) Table 2.6 Suggested wc for trial mixes for various characteristic strengths and cements W:C* СЕМ strength class 52.5 СЕМ strength class 42.5 СЕМ strength class 32.5 50% CEM I 42.5 50% GGBS 70% СЕМІ 42.5 30% FA Characteristic strength of concrete at 28 days, MPa 0.60 0.64 0.82 0.72 20 0.77 0.55 0.59 0.66 0.61 (0.56 25 0.67 30 0.62 0.72 0.50 0.54 35 0.53 0.57 0.67 0.47 0.51 40 0.50 0.52 0.62 0.44 0.48 * Crefers to total cementitious material, e.g. CEM I 42.5 plus FA. The amount of water to the amount of cement plays an important role in its strength characteristics The
Question - Concrete Mix Design - (25 marks = 100%) a) Design a concrete mix for the reinforced concrete elements of a Housing project using the given information below. Make use of the following tables 2.6, 2.7, 2.22, and 2.8. b) Determine the mass (kg) of cement, sand and stone required to cast 5 reinforced concrete beams of dimensions 230mm x 350mm x 5000mm as well as a reinforced concrete slab of dimensions 5000mm x 5000mm x 200mm. Consider a 5% waste factor. GIVEN INFORMATION a) Characteristic strength: 30 MPa c) Hand compacted. d) Slump: 100 mm e) Stone: f) Size 19mm, RDst=2.72, CBD= 1225kg / m2 g) Sand: h) Type: beach sand, RD sand=2.65, CBD= 950 kg / m² i) Cement: j) Type: CEM strength class 32.5, RD=3.15