Properties of Different Mortars and their Effect on the Flexural Strength of Low Density Block Walls

Mortar for masonry is important because it provides the linkage between masonry units so enabling the composite to behave as a single material.  The type of mortar used determines the flexural and compressive strength of the masonry so in this paper, a range of mortars are examined and their effects on the flexural strength of low density block walls determined.  These include traditional designation (iii) (1 cement : 1 lime : 6 sand), designation (iv) (1 cement : 1 lime : 9 sand) mortars as defined in BS 5628, and two thin layer mortars. The conventional mortars were formed using both 42.5N or 32.5N PC to BS EN 197 in order to ascertain the difference these two cements have on the properties of mortar. The thin layer mortars show remarkably high compressive strength. The characteristic flexural strength of low density aircrete wallettes incorporating both these conventional and thin layer mortars was verified. The wallettes were tested in accordance with British and European standards. The flexural strength of aircrete wallettes was derived from the strength of small specimens tested to destruction under four-point loading. The strengths of the wallettes are high with impressive repeatability with the maximum strength being reached for thin layer wallettes within 7 days curing time. In general the strengths of both conventional mortar and thin layer mortar wallettes compare favourably to values reported in the standards.