Mechanical Characteristics of Lightweight Mortars on Small-Scale Samples

Occasionally, in laboratory conditions, it can be advantageous to use small-scale specimens, e.g., when the amount of available material is limited or expensive or when there are space limitations. The characteristics of any tested material such as concrete or mortar are affected by the specimens’ size; therefore it is important to consider this effect when estimating the properties of these materials. Despite the extensive studies about the effect of the specimens’ size in concrete, there is a shortage of information about this matter in mortars. This study presented the effects of specimens’ size on the mechanical properties of cement-based lightweight mortars. These included the compressive strength and flexural strength, bulk density, dynamic Young’s modulus, and ultrasonic pulse velocity. For this purpose, statistical analyses were conducted in order to correlate test values from standard samples and small-scale samples and to analyze the feasibility of estimating the mechanical strength from non-destructive tests on small-scale samples. In order to facilitate the production of small-scale specimens, an alternative mixing method was also tested. The results obtained show correlation factors around 0.9, which was found suitable to estimate the mechanical characteristics by using small-scale samples instead of standard specimens. The correlations obtained from the relationships between the results of mechanical strength and non-destructive tests were also evaluated.