Strength–porosity relationships in lime–pozzolan mortars

Lime–pozzolan mortars are the hydraulic mortars widely used in the past for the construction of monumental structures and nowadays for their repair. These mortars are of higher porosity and lower strength in comparison with cement-based mortars but they have exhibited noticeable durability. For the design of lime–pozzolan mortars it is important to know the fundamental strength–porosity relationship as well as the parameters influencing the porosity since it is the driving factor for the functional behaviour of the mortar and its resistance to aging. In this research, an adequate number of mortar series were prepared and tested to find the effect of water/binder (w/b) ratio, the aggregate volume content, the evolution of porosity with time and formulate the strength–porosity relationship based on Power’s basic mathematical expression. According to results it seems that the water/binder ratio is the most important parameter influencing the porosity. Strength–porosity relationship can be predicted with an acceptable deviation. Porosity of lime–pozzolan mortars decreases with time and it is strongly influenced by the curing conditions.