Influence of superplasticizer, temperature, resting time and injection pressure on hydraulic lime grout injectability. Correlation analysis between fresh grout parameters and grout injectability

The grout injection technique is commonly used for the consolidation of old stone masonries. In particular, the multi-leaf masonries which generally exhibit low compactness in the inner core and very few links between the internal and external leaves. Grouts are concentrated suspensions that can be seen as mixtures of binder with water, and special admixtures. To ensure an adequate flow of the grout and a correct filling of the internal voids inside the masonry, it is essential to assure good fresh grout properties. Thus, the evaluation of the performance of the grout injectability is firstly started by checking the intrinsic properties of the grout (namely rheological parameters) and then by controlling the injectability, through injection tests in porous media that simulate old masonries. The main goal of this paper is to provide indications and valuable data about the combined effect of superplasticizer dosage, environmental temperature, resting times (i.e. the time after the grout mixing had ended) and injection pressure on grout injectability, aiming at a successful injection process. The lack of information about the influence of the referred parameters on the injectability of hydraulic lime grouts enhances the importance of a detailed research on the subject.