Concrete Mixtures 22

Hot Weather Concreting


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Increased water demand, slump loss, setting rate, plastic cracking, rapid surface water loss, entrained air problems, and early curing start, are problems encountered when placing concrete in hot weather. Adding water to the concrete mix is not very effective because it decreases strength, durability and watertightness, gives the surface a non uniform appearance, and increases drying shrinkage. Hot weather concrete problems can be resolved by cooling the concrete materials before mixing; protecting the concrete mixers, belts, hoppers and pump lines from sunlight with shade, white paint, or wet burlap covers; moistening the subgrade the evening before concreting without leaving puddles; restricting concrete placement to early morning, evening or night; making sure adequate personel are available to transport and place the concrete quickly; erecting sunshades over the concrete during finishing operations; covering the concrete surface with white polyethylene between finishing operations; hosing water on to the concrete surface and letting it run down inside the loosened forms; spraying fog without leaving puddles between placing and finishing; tining concrete immediately after troweling; spraying evaporation retarders on the concrete right after screeding; spraying fog into the ambient air to raise the relative humidity while waiting for a curing material to be applied to the concrete; reducing the time between placing and curing.




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  Concrete Mixtures Links

1.The Materials In Concrete.
2.Concrete Aggregates - Concrete Slump.
3.Concrete Placement - Vibration - Hydration.
4.Types of Portland Cement - Concrete Moisture & Cracking.
5.Watertight Concrete - Supplementary Cementing Materials.
6.Supplementary Cementing Materials.
7.Chemicals That Damage Concrete.
8.Concrete Aggregate Properties.
9.Angular & Smooth Aggregate Properties.
10.Admixtures.
11.Admixtures Continued.
12.Air Entraining Admixtures.
13.Air Entraining Admixtures Continued.
14.Conditions Affecting Concrete Air Volume.
15.Superplasticizers & Other Admixtures.
16.Ordering & Mixing Concrete.
17.Concrete Mixing - Subgrade Preparation.
18.Subbase Preparation - Concrete Placement.
19.Concrete Consolidation.
20.Concrete Finishing.
21.Concrete Curing.
22.Hot Weather Concreting.
23.Cold Weather Concreting.
24.Concrete Slump Test.

                                                     
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Ronald Hunter
           
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