Determination of Mohr–Coulomb failure envelope, mechanical properties and UPV of commercial cement-lime mortar

Abstract

Mortar in masonry structures can be subjected to both uniaxial and triaxial loading. Determining the mechanical properties and/or failure criteria of the commonly used mortar is necessary for the structural performance assessment of new and existing masonry buildings using non-destructive testing and/or finite element modelling methods. In this paper, the stress–strain behaviour of a commercially available cement-lime mortar is investigated under uniaxial and triaxial loading. The axial compressive strength, modulus of elasticity, Mohr–Coulomb failure envelopes of the mortar are determined over a range of conditions. Mortar specimens were prepared with a water to cementitious material ratio (w/cm) of 0.6–0.7 and were tested at curing ages of 3, 7, 14, and 28 days, under confining pressures of 0, 100, 250, 500 and 750 kPa. Ultrasonic pulse velocity (UPV) of the specimens were measured before the destructive testing. The results indicate that the influence of curing age and confining pressure on the axial compressive strength of the mortar can be predicted using proposed linear correlations between (i) The confining pressure and the axial compressive strength and (ii) The UPV and the axial compressive strength. From the test results, the strength parameters of the Mohr–Coulomb failure criterion were also determined. It is observed that cohesion is more sensitive to changes in curing age and w/cm than the friction angle, which varied between 32 and 33 degrees.

3D analytical and numerical upper‐bound homogenization approaches to the in‐plane strength domain of a running‐bond masonry wall

“…Table 5 summarizes the input data and their source. Source Identification on the above-described auxiliary problem Lourenço, 64 Kawa et al, 62 Stefanou et al 34 Identification on Page's 43 data Ghimire et al 46 and Wang et al 63 It can be noticed that the brick cohesion chosen here is a bit higher than the one chosen by Lourenço, 64 Kawa et al 62 or Stefanou et al 34 Indeed, the latter approaches consider infinitely thin joints. Considering such an assumption, the vertical compressive strength of the masonry prism corresponds to the vertical compressive strength of the blocks, and the effect of the thickness of the joints cannot be taken into account.…”

“…One of the advantages of this yield criterion lies in its simplicity, since it involves only two parameters, namely the cohesion and the friction angle. The most reliable way to determine these parameters is to resort to triaxial testing, as it was done by Abdallah et al 45 for Saint-Maximin limestone or by Ghimire et al 46 and Khoo 47 for cement-lime mortar. However, such a laboratory testing apparatus is rarely available to engineers.…”

“…Zhu et al 52 measured friction angles ranging from 25 to 34 • for various limestone. Concerning mortars, Khoo 47 and Ghimire et al 46 measured friction angles from 24 • to 32 • for cement-lime mortar, while Pelà et al 48 measured a friction angle of 26 • on aerial lime mortar.…”

“…The formulation of the support function 𝜋 for Mohr-Coulomb materials, as well as the expression of the relevance condition, can be found in Martin and Makrodimopoulos 39 for instance. Equation (46)…”

“…Although Page's experimental campaign is well detailed, there is unfortunately no information concerning the cohesion or the friction angle of both materials. As regards the mortar, the friction angle of similar mortar has been recently assessed by Ghimire et al 46 and Wang et al 63 as 33 • -34 • . As its compressive strength is given by Page (5.5 MPa), a cohesion value of c m = 1.5 MPa can be deduced.…”