Penetrability of hydraulic grouts

• Published in: Materials and structures Vol. 46; no. 10; pp. 1653 - 1671
• Main Authors: Miltiadou-Fezans, A., Tassios, T. P.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.10.2013; Springer; Springer Nature B.V
• Subjects: Applied sciences; Building construction; Building Materials; Building structure; Buildings. Public works; Civil Engineering; Concretes. Mortars. Grouts; Construction (buildings and works); Cracks; Durability. Pathology. Repairing. Maintenance; Engineering; Exact sciences and technology; Fluid dynamics; Fluid flow; Grout; Grouts; Hydraulics; Machines; Manufacturing; Masonry; Masonry structure; Materials; Materials Science; Original Article; Processes; Repair (reinforcement, strenthening); Solid Mechanics; Strength of materials (elasticity, plasticity, buckling, etc.); Structural analysis. Stresses; Theoretical and Applied Mechanics; Voids; Vulnerability; Penetrability; Penetrability grading criteria; Hydraulic grouts; Injectability; Sand column; Grain size; Strengthening; Construction materials; Penetration test; Calibration; Masonry; Injected grout; Modeling; Properties of materials
• ISSN: 1359-5997; 1871-6873
• DOI: 10.1617/s11527-012-0005-1

Design of hydraulic grouts for strengthening of masonry historical buildings seems to follow rather empirical procedures, with all the related uncertainties, both in terms of economy and efficiency. This paper is part of a broader attempt to establish a rational methodology for the design of such grouts, based on their discrete injectability characteristics, i.e. (i) Penetrability, (ii) Fluidity and (iii) Stability. This paper deals with penetrability and constitutes the first part of this holistic methodology. The second part regarding the fluidity and the third regarding the stability are separately published. Grouting is intended to fill voids, fissures and open joints of the masonry as a system, producing a “dendrite” (a three-dimensional skeleton), directly contributing to the strength of the masonry as a whole. However, to do so, the grout should be able to pass through the “narrowest” possible width of such discontinuities, in order to reach the maximum possible internal volume of masonry and open joints, avoiding most of possible blockages. In the specific case of three-leaf masonries, the most decisive result of the grouting is expected to be the strengthening of the bond along the interfaces between the external layers and the infill; the rather small voids, as well as pre-existing fissures along these interfaces have to be penetrated. In this paper the penetrability of hydraulic grouts is discussed, and relationships between two characteristic diameters of the grains of the solid phase of the grout and the nominal minimum width of fissures and voids of the structure to be injected are proposed. Furthermore the beneficial role of replacing part of the cement or hydraulic lime with ultrafine materials in order to improve penetrability is presented, and related criteria are proposed.