Influence of the aggregate quality on the physical properties of natural feebly-hydraulic lime mortars

Abstract

This paper examines the influence of the shape, average size and calcite content of the aggregate on strength, porosity, water absorption, density and capillary suction of natural feeblyhydraulic lime (NHL 2) mortars. Four types of aggregate were analysed in order to determine calcite content, particle shape and average particle size. Four different mortar mixes were then designed and produced using each of the aggregate types and NHL 2 as a binder. The mixing and curing as well as the aggregate:binder proportions were kept constant in order to attribute variation of mortar properties to the quality of the aggregate. The results suggest that an increase in the aggregate's calcite content lowers the flexural and compressive strength of the mortar. This study also determined that sharp aggregate as well as aggregate with a small average particle size tends to increase the mechanical strength and bulk density of a mortar simultaneously reducing porosity, water absorption and capillary suction. Furthermore, this paper concludes that aggregates containing particles of a wide size range will also increase the mechanical strength and bulk density of the hardened mortar diminishing porosity, water absorption and capillary suction.Résumé Cet article e´tudie l'influence de la forme, de la taille moyenne, de la proportion en calcite des granulats sur la re´sistance, la porosite´, l'absorption d'eau globale, l'absorption d'eau par capillarite´et la densite´de mortiers de chaux naturelle faiblement hydraulique (NHL 2). Quatre types de granulats ont e´te´analyse´s en vue de de´terminer leur teneur en calcite ainsi que la forme et la taille moyenne de leurs particules. Quatre mortiers diffe´rents ont e´teé nsuite conçus et gaˆche´s en utilisant chaque type de granulats et la chaux NHL 2 comme liant. Le temps de malaxage, les conditions de se´chage et la proportion granulats:liant sont reste´s identiques au cours des diffe´rents essais de façon a`attribuer a`la seule qualite´des granulats les diffe´rences de proprie´te´s du mortier observe´es. Les re´sultats sugge`rent qu'une augmentation de la teneur en calcite des granulats diminue la re´sistance en compression et en flexion du mortier. Cette e´tude e´tablit aussi que des granulats anguleux, comme des granulats avec une taille moyenne de particule faible, ont tendance aà ugmenter la re´sistance me´canique et la masse volumique apparente d'un mortier re´duisant simultane´ment sa porosite´, son absorption d'eau globale et son absorption d'eau par capillarite´. De plus, cet article conclut que des granulats contenant des particules a`granulome´trie e´tale´e auront aussi tendance a`augmenter la re´sistance me´canique et la masse volumique apparente du mortier durci diminuant sa porosite´, son absorption d'eau globale et son absorption d'eau par capillarite´.

Physical properties of magnesian lime mortars

“…The compressive strengths recorded are comparable to those reported by previous authors [7,12,21]. In addition, the values obtained compare well to those of equivalent 1:3, NHL2 mortars previously studied [22,23]. This suggests that Mg-lime develops strength similarly to feeblyhydraulic lime, reaching comparable ultimate values as regards resistance to compression.…”

“…8 and [22,23]), however, the strength development may be slightly slower than that of NHL2. According to the results obtained, the 100% Mg-lime mortar is 1.75 times stronger in flexion than the CL mortar, and, roughly, the greater the amount of Mg-lime in the mix, the greater the flexural strength.…”

Porosity and compatibility of repair mortars and Hungarian porous limestones

“…As it has been reported (Lanas et al 2006;Pavia and Toomey 2008) there is a close relation between the pore structure, the mechanical properties and the water absorption of mortars. By adding aggregate these properties can be modified.…”

Influence of aggregate and supplementary cementitious materials on the properties of hydrated lime (CL90s) mortars

“…However, Holmes and Windgate (3) disagree, claiming that limestone aggregate produces weaker lime mortars. Pavía and Toomey (4) found that natural hydraulic lime mortars (NHL2) with limestone aggregate were slightly weaker than those with sandstone and quartz aggregate. Some of these discrepancies are due to the use of different 'parent' limestones to produce the aggregate and different lime binders.…”