1. In the ACI 306R (Recommended Practice for Cold-Weather Concreting), explain why higher than ambient concrete temperatures are required placement in cold weather.

In order to evaluate the suitability of nonpotable water available at the job site for mixing concrete, six standard mortar cubes were made using that water and six others using potable water. The cubes were tested for compressive strength after 7 days of curing and produced the loads to failure (in kN) shown in Table P6.21. a. Based on these results only, would you accept that water for mixing concrete according to ASTM C94? b. According to ASTM C94, are there other tests to be performed to evaluate the suitability of that water? Discuss briefly. TABLE P6.21 Cubes Made with Cubes Made with Potable Water Nonpotable Water 64.6 73.5 70.4 74.8 63.0 79.7 71.6 69.8 70.6 83.7 64.0 74.4

Hand written solution is not allowed bro.

Design the concrete mix according to the following conditions:  Design environment Tennis court, subjected to freezing Required design strength =21 MPa Slab thickness=300 mm Statistical data indicate a standard deviation of compressive strength of 3.7 MPa is expected (for 50 samples) Only air entrainer is allowed Available materials: Air=7% Air entertainer: Manufacturer specification is 9.0 ML /1% air/100kg cement Slump=50 mm Coarse aggregate: 50 mm nominal maximum size, crushed stone Bulk volume oven-dry specific gravity=2.61, absorption=2.8%, oven-dry rodded density=1870 kg/m3 Moisture content=1% Fine aggregate: Natural sand Bulk oven-dry specific gravity=2.54, absorption=3.4% Moisture content= 4.5% Fineness modulus=2.60 Cement: Type I, relative density=3.1

What is the value of the Whitney stress block parameter, β1β1, for 6000 psi concrete?

Which of the following is NOT a benefit of using SCMs? Increase required concrete curing time Increase long term strength Reduce permeability Increase the resistance to chloride ions

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Compare the compressive strength and the splitting tensile strength.of following concrete.