Concreting in hot weather poses some special problems. Among these are strength reduction and cracking of flat surfaces due to rapid drying. Concrete may stiffen before it can be consolidated because of rapid setting of the cement and excessive absorption and evaporation of mixing water. However, this can be avoided with a few precautions. First, plan ahead. Be prepared with necessary equipment and material well in advance of hot weather by having tarpaulins or polyethylene sheets and lumber ready for sunshades and windbreaks. Second, use cool materials. Use concrete which has been chilled during preparation. Stockpiles of coarse aggregate should be sprinkled with water to cool the aggregate by evaporation. Mixing water should be chilled in very hot weather by refrigeration or by using ice as part of mixing water. The ice should be melted by the time concrete leaves the mixer. Third, prevent absorption by sprinkling the subgrade and wood forms just before placing the concrete. Fourth, protect against evaporation by erecting windbreaks to prevent strong, hot winds from drying exposed concrete flatwork surfaces while they are being finished. Fifth, don't delay in placing the concrete. Strike it off and darby it at once. When ready for final finishing, uncover only a small section immediately ahead of the finishers. Cover again at once after final finish and keep the cover wet. Sixth, cure immediately. Start curing as soon as surfaces are hard enough to resist marring and keep the concrete surface constantly wet to avoid alternate wetting and drying during the curing period.