Mutual Effect Between Moisture Transfer and Mechanical Response in Infill Masonry Walls of Reinforced Concrete Building Envelope

Abstract

The external envelope of buildings with reinforced concrete structures (RCS buildings) is subjected to environmental actions, particularly related to wind-driven rain (WDR), external humidity variations, and rising dampness, which can cause significant variations in moisture content to their unreinforced masonry (URM) infill walls, mainly associated to water penetration across that envelope. The consequent moisture transfer across the envelope can change the mechanical response of the URM infill walls and lead to their cracking, which could aggravate the referred water penetration, with a subsequent increase in the risk of building envelope degradation. In reverse, the effects of mechanical loads on moisture transfer across that envelope can be also relevant, in terms of change in the moisture content of these URM infill walls. The aim here is to analyze this type of mutual effect between moisture transfer and mechanical response in URM infill walls of RCS buildings. Essential elements about the characteristics of moisture transfer across URM infill walls and of the interface resistance with moisture flows are summarily described, and the essential evaluation of the mechanical behavior of URM infill walls when subjected to moisture variations is carried out. Moisture transport characteristics are discussed, focusing on analyses of the behavior of masonry elements when subjected to moisture variations. An initial assessment of the mechanical behavior of URM infill walls when subjected to different moisture variations is made through a compression test of a brick masonry specimen with variable moisture content. Following that analysis, an evaluation is made of the moisture transfer in URM infills, as well as the influence of the interface between layers in that moisture transfer and, subsequently, an assessment is made of hygromechanical couplings. Finally, elements for prevention about the causes of degradation of URM infill related to humidity and mechanical actions in the RCS building envelope are discussed.