The Influence of Lowered Air Temperature During Setting of Construction Mortars on their Technical Parameters

A season of a year, and resulting high or low air temperatures can harmfully affect technical parameters of mortars. The threat results from difficulty in setting and hardening. In Polish conditions there are often temperature fluctuations within the range close to 0 °C, mostly during early spring and autumn. Work realization in these periods obliges a contractor to monitor both environment temperature as well as humidity, and to observe technical standards and specifications referring construction products and systems. Non-fulfillment of declared recommendations, especially during mortar setting and curing can result in worsening its technical features and unfavorably affect its microstructure.In this article there is introduced the influence of low air temperature during masonry mortars setting on their selected technical parameters. The results obtained were compared with reference samples made according to present binding standards. Three types of mortars were selected for tests: CEM I - Portland cement based mortar, Portland cement based mortar CEM I with plasticizer, and cement-lime mortar. Beams formed of these mortars were divided into two groups setting in:-temperature of 20 ±2 °C and 65% relative humidity according to standard's recommendations,-in changing temperature conditions from -5 °C to +10 °C, relative humidity of 55%reflecting natural environment conditions of early spring. After 28 days the samples were examined in laboratory tests (compressive and flexural strength, soaking, humidity, and contraction tests) and microstructure analysis with mercury porosimetry method. The results obtained let us state that lowered air temperature during the mortar setting process negatively affects their technological parameters.