An Iowa paving project requires a water-to-cement ratio (w/c) of 0.45 in concrete due to exposure (freezing and thawing) condition, 0.50 due to sulfate content in soil and ground water, and 0.40 due to the concrete strength requirement. What should be the controlling w/c of the designed concrete?
A: 0.45
B: 0.50
C: 0.40
D: 0.48
A: 0.45
B: 0.50
C: 0.40
D: 0.48
举一反三
- The cause of cracks in concrete are: stress due to applied （） and stress due to temperature or （） change when concrete is restrained。
- 血细胞比容的正常范围是（） A: 男0.50～0.60，女0.40～0.50 B: 男0.30～0.50，女0.25～0.40 C: 男0.40～0.50，女0.37～0.48 D: 男0.60～0.70，女0.45～0.50
- Modern concrete blends are reinforced with steel fibers and __________ for strength and to prevent cracking.( ) A: water reducing fibers B: water condesation polymers C: water tower D: water reducing polymers
- 水泥浆中水灰比宜为（），掺入适量减小剂时，水灰比可减小到0.35。 A: 0.35～0.40 B: 0.15～0.20 C: 0.40～0.45 D: 0.45～0.50
- Fly ash can partly take the place of （）. A: paving material B: cement C: concrete D: the coal by-product