Aurélie Isebaert

Bio: Aurélie Isebaert is an academic researcher from University of Mons. The author has contributed to research in topics: Mortar & Repointing. The author has an hindex of 2, co-authored 4 publications receiving 42 citations.

Compatibility assessment for repair mortars : an optimized cement-based mix for Tuffeau de Lincent

Abstract: Mortars developed for the reconstitution and ‘plastic repair’ of natural stones have become increasingly popular They are an alternative for the replacement of deteriorated stones, since they are capable of preserving the (memory of) diversity in building materials This article addresses some key elements for the compatibility between repair mortars and stones This research accordingly studies the compatibility of a repointing mortar designed for the Tuffeau de Lincent (Belgium), a friable stone in need for restoration and replacement, which was developed using an auto-formulation tool, based on strength and colour compatibility The selected repointing mortar was further tested in order to assess its use as plastic repair mortar for the Tuffeau de Lincent stone The developed mortar was considered compatible in colour with the stone and had a strength of 14 MPa, which falls within the strength range of the stone (8–18 MPa) However, porosity and pore size distribution measurements indicated that the stone and the mortar were different This study compares the first product of the prototype formulation tool and lays the foundations for a more expanded and larger auto-formulation tool for the repair of natural stone

Targetting colour and modulus of resistance for a repointing mortar through a genetic algorithm

Abstract: Smart constructive system used for centuries in many places around the world, masonry is widely encountered in numerous heritage structures to be rehabilitated. For durability purposes, preservation operations that will be carried out on such structures require achieving a sufficient compatibility between parts that will be conserved and materials that will be brought through the rehabilitation process. Classically, incompatibility problems appear in relationship with the formulation of the mortars that will be used for repointing or repairing works. For setting up the compatibility problem, engineers usually focus on three axes: the mechanical one (Modulus of Resistance and/or Modulus of Elasticity), the physical one (gas and/or liquid transfer capabilities) and the perceptive one (colour and/or texture). In the daily practice, some practitioners typically insist on aesthetical aspects as they intend not to alter the perception of treated buildings. Replicating a satisfying texture is achieved by acting on sand granularities and finishing tools while the colour question usually requires manual trial and error procedures to be followed. Other practitioners privilege mechanical aspects for avoiding progressive damages induced by stress concentrations and target suitable values of MOR and MOE by relying on empirical recipes. Practically gathering both the approaches inside a same project is rare because it reveals difficult. The present paper describes an automatic computer-aided approach relying on evolutionary strategies (elitist genetic algorithm) in order to establish a mortar formulation encountering both aspects. The global framework in which the reflexion may take place, the optimization problem as well as the sharp manner to take each aspect into account are detailed. In its preliminary shape, the proposed tool focuses on the integration of strength and colour aspects but the method is designed to be extensible to complementary characteristics in a near future.

The Vitruvian legacy: Mortars and binders before and after the Roman world

Abstract: A brief history of the nature, use and technology of binders in ancient constructions and buildings is outlined, including the apparent chronological discontinuities related to technological developments. The skilled and clever use of mineral resources is at the base of the technical achievements related to architectural activities, from simple adobe to high-performance modern concrete. It is argued that among pre-industrial binders the Roman pozzolanic mortars were highly optimized materials, skillfully prepared and very durable. Their innovative use in architecture is one of the keys of the successful expansion of the Roman Empire. The role of mineralogy and mineral reactions is emphasized in terms of: (1) the preparation and manufacturing of the binding materials; (2) the hardening process and the development of the physical properties of the binder; and (3) the archaeometric reconstruction of the ancient materials.

Experimental Study on the Shear Behavior of the Bonding Interface Between Sandstone and Cement Mortar Under Freeze–Thaw

Abstract: Shear experiments were conducted on the cement mortar–sandstone bonding interface and the materials themselves to investigate their loss of shear strength and the deterioration mechanism caused by freezing and thawing cycles. The experimental results show that the shear strength of the bonding interface is much lower than that of the original materials themselves under the same normal stress. The shear strength of this interface decreases linearly with increasing number of freeze–thaw cycles, but it linearly increases with increasing normal stress. The cohesion and internal friction angle also decrease as the number of freeze–thaw cycles increases. In addition, obvious freeze–thaw debonding of this interface is observed and it is first caused by the difference in frost-heaving deformation between the cement mortar and the red sandstone, followed by the frost-heaving pressure in the crack formed in the interface. Finally, the shear damage of this interface has been quantified by reconstitution of the interface morphology. As a result, almost all the shear breakage occurs on the red sandstone side, and a concave rough face arises. With the absence of normal stress, the shear abscission area in the red sandstone increases quickly with increasing number of freeze–thaw cycles. However, with increasing normal stress, this shear abscission area decreases, and the layered composite specimens were prone to shear failure straightly along the bonding interface, because the shear dilatancy deformation is constrained. This study provides the shear failure characteristics of cement mortar–rock interfaces under freeze–thaw cycles and contributes to a better understanding of the freeze–thaw debonding mechanism of protective cement mortar layers on rock surfaces.

Freeze-thaw durability of repair mortars and porous limestone: compatibility issues

Abstract: Freeze-thaw cycles can cause considerable damage to porous materials and thus have an adverse effect on the durability of mortars and porous stone. To assess the behavior and frost resistance of two types of porous limestone, three commercially available repair mortars and four mixtures of laboratory-prepared repair mortars were subjected to freeze-thaw cycles according to EN 12371. During the test, samples of stone and mortar were bonded together and the weight loss was continuously monitored. The adhesion bond between the stone and the mortar was also observed during the cycles. Petrographic analysis and thin sections were also made before and after the freeze-thaw test. The pore size distribution (mercury intrusion porosimetry, MIP) of mortars and stones was also measured. The test showed that most of the repair mortars were damage more than porous limestone due to frost action. Two exceptions are two commercial available repair mortars. These mortars were able to keep the adhesion with the stone, and the frost did not modify significantly the cubic shape of the test specimens, only rounding of the edges was observed. All other samples were broken during the frost tests; stone/mortar interface was dismounted. Other typical damage features such as delamination, blistering, powdering, and granular disintegration were also observed leading to the gradual surface loss of the material. Our tests proved that low pozzolanic cement content in mortars decreases the material durability. According to the pore size distribution (MIP), the small pores (around 0.1 μm) control the weathering behavior of tested porous materials.