The Role of Glass Additives in the Properties of Lime-Based Grouts

Abstract

Various types of additives have been diachronically used in historic mortars, whereas their use in lime-based grouts, used for the restoration of historic structures, is rather limited. In this study, an effort was made to investigate the performance of glass additives in grouts, consisting of lime and natural pozzolan. The additives concerned glass fibers (3 and 6 mm in length), glass beads and bubbles, added in a proportion 0.3–3% w/w of binders. Five grout compositions were manufactured and their properties at fresh and hardened states were tested. From the evaluation of the results, it was asserted that glass additives influenced the grouts’ performance in a favorable way. Their fresh state and physical properties were maintained or slightly improved, while there was a significant enhancement of the long-term mechanical characteristics of the mixes. Additionally, the adhesion capability of grouts was notably increased, which is a crucial aspect indicating their efficacy.

Development of a Gypsum-Based Grout for the Stabilisation of Gypsum-Based Plasters

“…Quartz sand (from Taiana, Switzerland, 100-250 μm), inert, was also considered. Scotchlite K1®, round, hollow and non-porous, helps to improve injectability in grouts [9,5,27] and aids in obtaining mixtures with low density; the other aggregates tend to have an angular shape, helping packing geometry and therefore cohesion. Pumice 0-140 μm (1 pt/V) coupled with Scotchlite K1® (3 pt/V) was chosen as the best fillers combination (see Tab.…”

The Influence of Water Content on the Fresh and Hardened State Properties of Lime–Pozzolan Grouts

“…Lime-based grouts have been extensively used for the restoration of heritage structures, both concerning the strengthening of historic masonries and the consolidation of architectural surfaces [1][2][3][4][5][6][7][8][9][10]. Their type, constituents and properties are usually defined by the characteristics of each case, as well as the restoration requirements.…”

“…Their type, constituents and properties are usually defined by the characteristics of each case, as well as the restoration requirements. They usually consist of one or more binding agents, whereas additives and admixtures have been applied in order to enhance specific properties [1][2][3][4][5]. Regarding the lime type, hydrated lime [1][2][3]9,[11][12][13] or natural hydraulic lime may be used [4][5][6][7][8], either solely (especially in the latter case), or mixed with natural and artificial pozzolans.…”

“…Regarding the fresh state properties of grouts, fluidity, injectability and volume stability are usually measured, according to relevant standards and specifications that define their performability during application [1][2][3][5][6][7][8][11][12][13]15]. Further testing procedures could be applied, focusing on determining rheological properties, such as plastic viscosity, shear and yield shear stress [5,7,9,13].…”

“…Regarding the hardened state properties of lime-based grouts, they are significantly influenced by their water content, both regarding their physical and mechanical properties. According to former research work and literature [1][2][3][4][5], lime-based grouts, such as limepozzolan ones, present a very slow strength development rate, attributed to their usually high water content, as well as the characteristics of their binding agents. Generally, the water content increase significantly influences their properties, both regarding shrinkage deformations, absorption and strength [1][2][3][4][5][8][9][10].…”