The effects of dosage and production process on the mechanical and physical properties of natural hydraulic lime mortars

Abstract

Natural Hydraulic Lime (NHL) mortars are well-extended in restoration works presently. However, there is still a lack of standardization on their dosage methodology. Thus, seven types of mortar were fabricated and five factors which have an influence on their properties have been studied, in particular the water-binder ratio, the mold material, the aggregate size and type and the different curing conditions. Furthermore, an advanced mechanical characterization has been performed on these mortars, including the measurement of the fracture energy. Finally, some empirical equations for determining the relationships between these mechanical properties were proposed, which could be helpful when simulating the numerical models of historical constructions.

Mechanical Behavior of Natural Hydraulic Lime Mortars

“…It is worth noting that for NHL09C04W, only the flexural and splitting tensile strengths (Figure 3(a) and (c)) were measured as the cylindrical wooden molds were not fabricated. Moreover, the notched beams were damaged when demolding the specimens from the prismatic wooden molds [12]. Table 3, in general, the mechanical properties of NHL mortars are improved for low water/lime ratio when comparing the experimental results among NHL08C04M, NHL09C04M, and NHL11C04M, due to the fact that the open porosity increases with an increase in water/lime ratio which results in a weakening of the mortar structure and its mechanical properties [12].…”

“…More detailed information on how to determine the fracture energy can be found in the Refs. [12,13].…”

“…Moreover, the notched beams were damaged when demolding the specimens from the prismatic wooden molds [12]. Table 3, in general, the mechanical properties of NHL mortars are improved for low water/lime ratio when comparing the experimental results among NHL08C04M, NHL09C04M, and NHL11C04M, due to the fact that the open porosity increases with an increase in water/lime ratio which results in a weakening of the mortar structure and its mechanical properties [12]. Moreover, using wooden molds also benefits the mechanical properties as they absorb the excess of free water.…”

“…For example, 3 MPa, respectively. This is mainly due to the fact that high humid conditions favor the hydration of NHL mortars [9,10,12].…”

“…In general, NHL mortars are well investigated in terms of compressive and flexural strengths [5,[9][10][11]. Recently, Garijo, Zhang, and Ruiz et al [12,13] have measured fracture energy, splitting tensile strength and characteristic length of such materials. At present time, the dynamic mechanical behavior of lime mortars is getting more attention due to the fact that most masonry structures are situated in zones of seismic activity, such as Lisbon (Portugal), L'Aquila (Italy), Lorca (Spain), Kathmandu (Nepal), Nairobi (Kenya), etc.…”