Combination of Polymeric Superplasticizers, Water Repellents and Pozzolanic Agents to Improve Air Lime-Based Grouts for Historic Masonry Repair.

Jesús Fidel González-Sánchez,Burcu Taşcı,José María Fernández,José Ignacio Alvarez,Íñigo Navarro-Blasco

doi:10.3390/polym12040887

Jesús Fidel González-Sánchez, Burcu Taşcı + Show 3 more

Open Access

https://doi.org/10.3390/polym12040887

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Journal: Polymers	Publication Date: Apr 11, 2020
Citations: 15	License type: CC BY 4.0

Affiliation: Izmir Kâtip Çelebi University, University of Navarra

Abstract

This paper presents the experimental procedure to develop air lime-based injection grouts, including polymeric superplasticizers, a water repellent agent and pozzolanic agents as additives. Our research focuses on the development of grouts to improve various characteristics simultaneously by combining different additions and admixtures. Aiming to improve the injectability of the grouts, in this study, different polymeric superplasticizers were added, namely polycarboxylated-ether derivative (PCE), polynaphthalene sulfonate (PNS) and condensate of melamine-formaldehyde sulfonate (SMFC). As a water-repellent agent, sodium oleate was used to reduce the water absorption. The enhancement of the strength and setting time was intended by using microsilica and metakaolin as pozzolanic mineral additions. Compatibility between the different admixtures and action mechanism of the different polymers were studied by means of zeta potential and adsorption isotherms measurements. Diverse grout mixtures were produced and investigated by assessing their injectability, fluidity, stability, compressive strength, hydrophobicity and durability. This research led to several suitable mixtures produced by using more than one component, to enhance efficiency and to provide better performance of grouts. According to the results, the grout composed of air lime, metakaolin, sodium oleate and PCE was found to be the most effective composition, improving the mechanical strength, injectability and hydrophobicity.

Highlights

One of the most widely used methods addressed to repair different masonry defects and cavities in the preservation of the Built Heritage is the injection of grouts [1,2,3]
Quaternary lime, polymer-based superplasticizers, a water-repellent agentagent and and pozzolanic additives studied as grouts be used as repair materials for Built pozzolanic additives were were studied as grouts to be to used as repair materials for Built
The action mechanism of this polymeric superplasticizer was confirmed to be mainly steric, whereas sulfonated melamine formaldehyde condensates (SMFC) and polynaphthalene sulfonate (PNS) acted through an electrostatic repulsion mechanism

Summary

Introduction

One of the most widely used methods addressed to repair different masonry defects and cavities in the preservation of the Built Heritage is the injection of grouts [1,2,3]. The grout must be chemically compatible with the ancient masonry, in order to prevent the historic structure from damages caused, for example, by high contents in soluble salts. Mechanical compatibility is another requirement; for instance, repair materials with too-high stiffness are not compatible with the old masonry [8,9]. Taking into account these aspects, natural hydraulic lime (NHL) and hydraulic lime (as obtained by air lime with pozzolana) have been the most widely used binders for repair grouts of the Architectural

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Conclusion