KIOY, STELLA1; WALKER, PETER2; BALL, RICHARD3; PETER, ULRIKE4; VERHELST, FREDERIK5
1 Student, University of Bath, Architecture and Civil Engineering Department, S.M.Kioy@bath.ac.uk
2 PhD Professor, University of Bath, Architecture and Civil Engineering Department, P.Walker@bath.ac.uk
3 PhD, Lecturer, University of Bath, Architecture and Civil Engineering Department, R.J.Ball@bath.ac.uk
4 PhD, R&D Engineer – Building Construction, Lhoist Recherche et Developpement, Ulrike.Peter@lhoist.com
5 Senior Market Manager – Materials, Lhoist Group Marketing, Frederik.Verhelst@lhoist.com
Movement in masonry walls is caused by unit and mortar moisture movement (shrinkage, expansion), creep, diurnal and seasonal temperature changes, elastic stress related deformations and ground movements. Traditional lime mortars are commonly believed to better accommodate movements than modern cement mortars. Although modern mortars are mostly cement:plasticiser or cement:lime mixes, specifications for movement joints make no differentiation for mortar type. There are currently minimal data quantifying the movement characteristics of cement, cement:plasticiser and cement:lime mortars, or relating masonry movement to its mortar properties and characteristics. This paper summarises some initial findings from an experimental study into the effects of mortar composition on the creep of clay unit brickwork. Tests have been completed on brickwork specimens using increasing quantities of hydrated lime from 0% to 60% (by mass) and the addition of plasticiser in cement mortars. Model masonry walls and cylindrical mortar specimens were tested under constant compressive stress for periods up to 180 days. This research is part of a wider programme aimed at improving understanding of the effects of mortar composition on masonry movement characteristics. This paper presents the results of creep movements in model masonry walls, comparing the effect of a Portland cement mortar with plasticiser, without plasticiser and with hydrated lime.
Keywords: Creep, mortar, plasticiser, lime, movement, experimental