Effect of weather conditions on the properties of cement rendering

Abstract EN

The cement mortar used in rendering external walls, in Iraqi hot weather summer, suffers from appearance of many cracks on surface during and after its setting.

So, this research aims to study the effect of different factors that can affect those cracks.

The studied variables include mix proportions of mortar, grading of the used sand, method of curing, and environmental temperature (rendering during winter or summer).

The rendering was laid on two types of walls build from clay bricks or concrete blocks.

Tests were carried out on the mortar mixes of the different variables including flow test and drying shrinkage.

Results indicate that the suitable flow of cement mortar for rendering should be 190±10%, which means the water content should be higher than that required for standard flow of 110±5% by 10%.

Also, found that the amount of cement and water content and fineness of sand have an important role in the appearance of cracks on the cement rendering.

Those cracks can be reduced to large extent by a continuous water spraying twice daily for seven days.