Durability of historic mortars (2008)

Title: Some considerations about the durability of historic mortars
Author: Fernando Pacheco Torgal, J. P. Castro Gomes and Said Jalali
Conference: HMC08 : Historical Mortars Conference : characterization, diagnosis, conservation, repair and compatibility
Publisher: Laboratório Nacional de Engenharia Civil (LNEC)
Year: 2008
Type of document: Article
Download: http://uminho.pt/... (pdf, 4.9 Mb)

Abstract:

The current manuscript discusses the durability of historical mortars. The majority of the descriptions about those mortars are mainly related to the Roman period and refer the mixture of calcium hydroxide and pozzolans (volcanic ashes and calcined clays) as the right recipe to get strong and durable binders. Those descriptions lack explanations about the reaction mechanisms that could explain the durability of those mortars, not can they explain the presence of analcime zeolites that several researchers found in historical mortars. The present manuscript discusses the durability of historical mortars trough the alkali-activation theory, according to which geopolymeric compounds and calcium silicate hydrates are responsible for the durability of historical mortars.

Lime-based restoration mortars (2009)

Title: The effect of linseed oil on the properties of lime-based restoration mortars
Author: Eva Čechová
University: University of Bologna (Italy)
Year: 2009
Type of document: PhD thesis
Download: http://amsdottorato.cib.unibo.it/... (pdf, 4.9 Mb)


Abstract:

The traditional lime mortar is composed of hydrated lime, sand and water. Besides these constituents it may also contain additives aiming to modify fresh mortar´s properties and/or to improve hardened mortar´s strength and durability. Already in the first civilizations various additives were used to enhance mortar´s quality, among the organic additives, linseed oil was one of the most common. From literature we know that it was used already in Roman period to reduce water permeability of a mortar, but the mechanism and the technology, e.g. effects of different dosages, are not clearly explained. There are only few works studying the effect of oil experimentally. Knowing the function of oil in historical mortars is important for designing a new compatible repair mortar. Moreover, linseed oil addition could increase the sometimes insufficient durability of lime-based mortars used for reparation and it could be a natural alternative to synthetic additives. [...]

Table of contents (compact version):

1. Introduction

2. Theory
2.1 Definition of Mortar
2.2 Mortar Composition
2.3 Types of Mortar
2.4 Deterioration of Mortars
2.5 Natural Polymers as Mortar Admixtures

3. Experimental Part
3.1. Used Materials
3.2 Experimental Methods

4. Results
4.1. Basic Characteristics of Materials Used
4.2. Setting Time Determination
4.3. Composition and Properties of Fresh Mortars
4.4. Properties of Hardened Mortar
4.5. Observation of Oil in Mortar Strucutre
4.6. Studying of chemical Changes of Oil in mortar and Oil Aging

5. Discussion
5.1. The effect of Linseed Oil on the Properties of Fresh Mortars
5.2. The effect of Linseed Oil on the Properties of Hardened Mortars

6. Conclusions
6.1. The Effect of the Addition of Linseed Oil on Mortars Properties and the Mechanisms of its Operation
6.2. Suggestions for further Research