What are the precautions during hot weather concreting,in the two cases mix production and construction?

• Ambient temp shall not be exceeded set by the relevant countries. In KSA 40 degree and in Canada 27 degree centigrade
• Concrete temp in KSA shall not be exceeded by 32 degree 
• Night pour is preferable
• Cool down coarse and fine aggregate by shading and sprinkling
• Use of chill water and ice if does not disturb water content (W/C ratio)
• Better if concrete batch plant set up at site OR Time between Batch time and pouring time shall need to be kept minimize
• Use of water reducing agent
• Retarded admixture but with caution because it may reduce concrete compressive strength.
• Better to make workable concrete  Slightly higher slump but shall not be crossed 150mm limit with superplasticizer ( Normal Concrete)
• quickly placed the fresh concrete OR avoid delay in pouring etc.

as per to work per procedure follow the specific Safety plan & Risk Assessment. use specific P.P.E. as required to the work scope.