This work presents procedures, results and main conclusions derived from an experimental study aimed at determining the effects of environmental temperature on the workability and microstructural properties of mortars and cement pastes. In this study, three climatic conditions were used: reference, hot weather and cold weather, as related to temperature and relative humidity. The influence of environmental temperature in some physical properties of fine aggregates was defined and its final effects over the mortar’s workability were analyzed. Also, the influence of environmental temperature over the properties of fresh cement pastes considering the admixture dose and over the microstructural properties of cement pastes using NMR and SEM, were studied. The results show that mortar workability is a function of the properties of aggregates that in turn are influenced by temperature. The microstructural studies indicate that extreme environmental conditions have effects on microstructural development of cement pastes, especially at early ages. Based on the above-mentioned results a methodological procedure was proposed in order to optimize the cement dosage in concrete, obtaining satisfactory results regarding cement savings in summer periods, with their associated economical and environmental benefits.

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