Simulation on the effect of water absorption on the strength of masonry wall
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Date
2006-06-01
Authors
Chow Shiao Teng
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Abstract
Unit water absorption is an important characteristic in the construction of
masonry structure as it plays a significant role in strength and durability performance.
The moisture transfer mechanism between mortar joint and brick unit would lead to a
reduction in the water content of fresh mortar, thereby causing shrinkage and moisture
expansion in mortar and brick unit, respectively. In addition, poor and porous mortar
joint would be produced. This would affect the masonry’s strength, durability,
serviceability and cause frost damage in seasonal regions. This research was carried out
to develop a new model for predicting the compressive strength of masonry wall
considering the unit water absorption, unit strength and mortar strength as well as to
simulate the effect of water absorption on the strength of masonry wall and to compare
the developed model with other established models. Experimental investigation was
conducted on 60 specimens (individual bricks and brickwork prisms made up of
calcium silicate, clay and cement sand bricks) in obtaining the brick’s compressive
strength, mortar strength, unit water absorption and initial rate of absorption. Based on
the test results, empirical modelling of the masonry wall compressive strength with
regression analysis was carried out using statistical software, MINITAB R14. A series
of multiple regression analyses revealed that brick’s compressive strength and initial
rate of absorption were the most significant predictor variables in the research. The
results of simulation indicated that unit water absorption contributes to the strength
reduction in masonry wall by 0.43 %. Comparison between all models showed that EC
6 and BS 5628 respectively underestimate the wall’s compressive strength by 31.69 %
and 80.10 %, while Mann’s model overestimated the masonry strength by 14.41 % as
compared to the developed model.