Mortar Consumption Characteristics of ‘Brickwork’ and a Framework for Managing Brick and Mortar Walls in Chaotic Environments

Abstract

This study investigated how bricks and mortar could be used in a chaotic environment where brick and joints sizes could be varied to achieve better outcomes (such as cost minimisation) through an understanding of mortar consumption characteristics of brickwork. This was made possible by integrating three innovative concepts, viz. ‘type’ of wall, ‘cost polarity’, and ‘bricks to mortar’ ratio. New formulae for computing mortar volumes had to be developed as the simple formula of subtracting the volume of bricks from the volume of wall that did not produce accurate mortar volumes. Having validated these formulae, mortar volumes in different joints were computed. Accordingly, it was found that the bed-joint accounted for the largest portion of mortar in single brick thick walls in English bond, irrespective of the size of brick used. With more than two thirds of the total volume of mortar in the bed joint (even with a smaller bed joint of 10mm), it plays a significant role in changing the volume of mortar in brickwork. As the volume of mortar in the study walls was as high as 73% when compared with (less than) 25% for walls with standard brick and joint sizes, the very notion of what ‘brick-work’ was challenged. This led to the identification of three ‘types’ of walls, namely, ‘mortar-wall’ (with volume of mortar over 50%), ‘brick-mortarwall’ (with volumes of mortar between 25-50%), and ‘brick-wall’ (with a volume less than 25%) with corresponding ‘bricks to mortar’ ratios of less than 1, 1 to 3, and greater than 3. This classification was used for specifying a ‘type’ of wall. It was found that ‘brick to mortar’ ratio was quite sensitive to variations in small values of the bed joint when large bricks were used though this was not the case with smaller bricks and larger bed joints. This suggests the importance of controlling workmanship if the ratio is to be maintained at small values of bed joint. A strategy-map for selecting a desirable 'bricks to mortar ratio’ was provided based on ‘type’ of wall, brick and joint sizes, and degree of control required for ensuring workmanship. In order to make strategic decisions on costs, the concept of ‘cost polarity’ (cost of density of bricks to mortar) was used. Accordingly, a cost-efficient ‘type’ of wall could be selected based on whether cost polarity was less than 1 or greater, using a strategy-map for such decision making. Further savings in costs could be achieved by using the strategy-map for ‘brick to mortar’ ratios whilst giving consideration to the build ability of the bed joint, and sizes of other joints including joint fullness. The framework thus proposed provides a fresh perspective on how walls built with bricks and mortar could be managed (particularly in Sri Lanka) with potential for enormous cost savings using a chaotic environment to bring a new order.