1) Dr. A. Costigan, Dept of Civil Engineering, Trinity College, Dublin 2,

2) A Prof. S. Pavía, Dept of Civil Engineering, Trinity College, Dublin 2,


Water content affects mortar and masonry properties however, it is often determined by the mason assessing mortar workability. This can lead to lack of consistency and variable masonry performance. This paper investigates the compressive, flexural and bond strength and stiffness of brick masonry bound with natural hydraulic limes (NHL2, 3.5 and 5), hydrated lime (calcium lime-CL90s) and cement-lime mortars with two different water contents (those required to produce a 165 and a 170mm initial flow) both delivering an adequate workability. Increasing water content by 0.6-1.3% generated the required 5mm flow increase. It was found that this water increment generally improves the compressive/flexural/bond strength and stiffness of the cement-lime and NHL masonry whereas it adversely affects the properties of CL masonry. The results also indicate that varying water content affects brick masonry stiffness, bond and flexural strength to a greater extent than compressive strength; and that the impact of water content on masonry compressive/flexural/bond strength and stiffness reduces as the hydraulic strength of the mortars increases. Furthermore, varying mortar water content within the range specified in this research generally has a greater effect on the mechanical properties of masonry in the first 28 days of curing than it does at 6 months.


Keywords: compressive and flexural strength, flexural bond strength, elastic modulus, initial flow, water content, workability.