scholarly journals Rheology of Natural Hydraulic Lime Grouts for Conservation of Stone Masonry—Influence of Compositional and Processing Parameters

Fluids ◽  
2019 ◽  
Vol 4 (1) ◽  
pp. 13 ◽  
Author(s):  
Luis Baltazar ◽  
Fernando Henriques ◽  
Maria Cidade
Keyword(s):  
Processing Parameters ◽  
Stone Masonry ◽  
Hydraulic Lime ◽  
Historic Masonry ◽  
Natural Hydraulic Lime ◽  
Extrinsic Parameters ◽  
Scientific Papers ◽  
Significant Research ◽  
Intrinsic And Extrinsic Parameters ◽  
Measuring Instrumentation

This review provides an overview of the recent progress in the field of the rheology of grouts for historic masonry consolidation. During the last two decades, significant research has been devoted on the grouting technique for stone masonry consolidation but most results are scattered by scientific papers, congress communications, and thesis. This paper compiles and briefly demonstrates the effect of several intrinsic and extrinsic parameters, such as admixtures, additions, pressure, temperature, and measuring instrumentation, on the rheological performance of natural hydraulic lime-based grouts.

Design and evaluation of restoration mortars for historic masonry using traditional materials and production techniques

2002 ◽  
Vol 712 ◽  
Author(s):  
Antonia Moropoulou ◽  
Asterios Bakolas ◽  
Petros Moundoulas ◽  
Eleni Aggelakopoulou ◽  
Sofia Anagnostopoulou
Keyword(s):  
Mechanical Strength ◽  
Water Absorption ◽  
Mechanical Tests ◽  
Hydraulic Lime ◽  
Historic Masonry ◽  
Natural Hydraulic Lime ◽  
Total Percentage ◽  
Lime Mortars ◽  
Production Techniques ◽  
Absorption Measurements

ABSTRACTCement based mortars used for historic masonry restoration presented unsatisfactory results, due to their chemical and physico-mechanical incompatibility to original buildings. In the present research, several syntheses of restoration mortars are produced using traditional techniques and materials such as binders (aerial and natural hydraulic lime), pozzolanicadditives (natural and artificial pozzolanas) and aggregates (sand and crushed brick). The technical characteristics of the mortars were determined using mechanical tests (compressive and flexural) and mercury intrusion porosimetry measurements at the time of 1, 3, 9, 15 months of curing. Water absorption measurements were performed at the time of 9 and 15 months curing, in order to evaluate mortars microstructural characteristics, their rate of water absorption and the total percentage of absorbed water. The aerial lime - artificial pozzolana mortar presented the best mechanical and microstructural performance. Hydraulic mortars acquired the maximum of the mechanical strength in 1 month, lime - pozzolana mortars in 3 months while aerial lime mortars continue to gain mechanical strength even in 15 months curing. Furthermore, the use of ceramic aggregates produces lightweight and elastic mortars, compatible to historicones.

Shaking Table Tests on Multi-Leaf Stone Masonry Structures: Analysis of Stiffness Decay

2010 ◽  
Vol 133-134 ◽  
pp. 647-652 ◽  
Author(s):  
Nicola Mazzon ◽  
Cano M. Chavez ◽  
Maria Rosa Valluzzi ◽  
F. Casarin ◽  
Claudio Modena
Keyword(s):  
Dynamic Behaviour ◽  
Shaking Table ◽  
Stone Masonry ◽  
Mode Shapes ◽  
Masonry Structures ◽  
Shaking Table Tests ◽  
Grout Injection ◽  
Hydraulic Lime ◽  
Natural Hydraulic Lime ◽  
Before And After

The influence of the natural hydraulic lime-based grout on the dynamic behaviour of injected multi-leaf stone masonry elements is discussed in the paper. Shaking table experiments on two stone masonry buildings, tested before and after grout injection, have been performed. The paper focuses on the analysis of both the recorded accelerations and related displacements, at the bottom and at each further storey. This leads to evaluate the stiffness of the unstrengthened and injected structures. The input at increasing PGA allowed the stiffness decay to be studied, simulating a gradual damaging of the structures. These results were also interpreted in the light of both computed frequencies and mode shapes. Finally, the comparison among these results, obtained from all the models, allows to deepen the knowledge concerning the effects induced by the lime-based grout injection and on its capability to modify the dynamic behaviour, when intervening on a damaged (repairing) or on an undamaged (strengthening) structure.

Experimental Assessment of Geopolymer Grouts for Stone Masonry Strengthening

2019 ◽  
Vol 817 ◽  
pp. 507-513
Author(s):  
Luis G. Baltazar ◽  
Fernando M.A. Henriques ◽  
Diana Temporão ◽  
Maria Teresa Cidade
Keyword(s):  
Fly Ash ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Stone Masonry ◽  
Rheological Parameters ◽  
Hydraulic Lime ◽  
Natural Hydraulic Lime ◽  
Improved Performance ◽  
Strengthening Technique ◽  
Research Initiatives

Grout injection is a useful repair and strengthening technique to intervene in old masonry buildings. Until now, a very limited amount of work has been reported on the potential of geopolymers for consolidation of old stone masonry walls. In the last decades there has been several research initiatives focus on the development of materials involving a higher volume of supplementary cementitious materials that substitute the traditional binders. Geopolymers that were developed as a part of these efforts, can not only reduce the dependence on traditional binders, but also potentially present materials with less environmental impacts and improved performance. This study investigates the fresh and hardened properties of grouts composed of natural hydraulic lime (NHL) and geopolymer. The experiments were conducted using a geopolymer made of fly ash, sodium hydroxide and water. The effects of the replacement of NHL by the fly ash-based geopolymer (at the dosages of 0, 20, 50, 80 and 100%) on the rheological parameters, stability, water absorption, compressive strength and durability were investigated. The results showed that the geopolymer-based grout has several advantages regarding the mechanical strength, durability and fresh stability, but the improvement of their rheological performances proved to be a challenging task. Overall, the findings of this study will be useful in assessing the design of grouts incorporating alternative binders and consequently contribute to the improvement of the grouting technique.

Grouts with Improved Durability for Masonry Consolidation: An Experimental Study with Non-Standard Specimens

2017 ◽  
Vol 747 ◽  
pp. 480-487 ◽  
Author(s):  
Luis G. Baltazar ◽  
Fernando M.A. Henriques ◽  
Maria Teresa Cidade
Keyword(s):  
Inner Core ◽  
Linseed Oil ◽  
Stone Masonry ◽  
Mechanical Resistance ◽  
Masonry Walls ◽  
Water Penetration ◽  
Hydraulic Lime ◽  
Natural Hydraulic Lime ◽  
Standard Specimens ◽  
Potential Use

Multi-leaf stone masonry walls are among the most vulnerable elements of historic constructions. Grout injection is a common and efficient technique to consolidate such masonries. It consists of introducing a grout into the masonry inner core in order to upgrading the cohesion of the wall by ensuring the transversal bond between the external leaves and improving its monolithic behaviour. Notwithstanding, the recrystallization of salts due to changes in moisture content causes several damages in these masonries, even after the consolidation intervention. This paper aims to assess the potential use of linseed oil in natural hydraulic lime-based grouts to mitigate the water penetration and therefore the damages from salts crystallization. Linseed oil was used in former times as an additive for mortars in order to grant hydrophobicity. In this study several properties of the grouts were evaluated: rheology, mechanical strength, water absorption, adhesion and durability assessed by testing the resistance to sodium chloride. Moreover, this paper also analyses the correlation between non-standard specimens (with reduced size) and standard specimens (40x40x160 mm3). The experimental results revealed that the grouts durability and water transport are significantly improved with added linseed oil. It was also possible to observe a small reduction in mechanical resistance with the presence of linseed oil; however, acceptable strength values to promote an appropriate consolidation were ensured. Furthermore, the reduced size specimens revealed to be a viable alternative to the standard ones.

scholarly journals Preliminary Investigation of the Mechanical and Physical Properties of Natural Hydraulic Lime Grouts with Nano-Silica

CivilEng ◽  
2021 ◽  
Vol 2 (2) ◽  
pp. 421-439
Author(s):  
Luis G. Baltazar ◽  
João Cardoso
Keyword(s):  
Mechanical Strength ◽  
Yield Stress ◽  
Preliminary Investigation ◽  
Joint Effect ◽  
Plastic Viscosity ◽  
Stone Masonry ◽  
Nano Silica ◽  
Hydraulic Lime ◽  
Natural Hydraulic Lime ◽  
Hardened State

Natural hydraulic lime-based grouts are often used in the structural consolidation of old stone masonry walls, mainly to re-establish the monolithic behaviour of masonry constructions. To ensure an adequate grouting operation, it is essential to have good fresh and hardened grout properties. The motivation of the present study was to examine the fresh and hardened properties of natural hydraulic lime grouts with nano-silica (NS) and silica fume (SF). The contribution of these materials and the dosage of a high range water reducer admixture (HRWR) were investigated on the rheological properties, water capillarity, open porosity and mechanical strength of injection grouts. The effects on rheology were analysed through plastic viscosity and yield stress. The results indicated that, even for reduced NS content, an increase in plastic viscosity and yield stress occurred, which required a higher HRWR content in order to not compromise the grout’s rheological performance. The results also showed that, when NS and SF were combined, a beneficial joint effect occurred, resulting in a substantial and positive change on the mechanical strength and microstructure of the hardened injection grouts. Taguchi’s method was used to optimize the grout’s formulation and to fulfil the required performance concerning the fresh and hardened state.

scholarly journals Bond Properties of NHL-Based Mortars with Viscosity-Modifying Water-Retentive Admixtures

Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 685
Author(s):  
Tomáš Žižlavský ◽  
Patrik Bayer ◽  
Martin Vyšvařil
Keyword(s):  
Water Content ◽  
Adhesive Strength ◽  
Water Retention ◽  
Minor Role ◽  
Clay Brick ◽  
Hydraulic Lime ◽  
Natural Hydraulic Lime ◽  
Binder Ratio ◽  
Paste Viscosity ◽  
A Minor

This article studies the influence of biopolymeric viscosity-modifying admixtures with water-retentive function on the physico-mechanical properties of natural hydraulic lime-based mortars and their adherence to the traditional fired-clay brick substrate. The use of admixtures increases the water/binder ratio, which in turn leads to a decrease in the strength of the mortars. The viscosity-modifying function improves the adhesive strength between mortar and pre-wetter brick by increasing the binder paste viscosity, while the water-retentive function along with increased water content may lead to a decrease in adhesive strength. On the contrary, water retention and increased water content are beneficial on a dry surface, while paste viscosity plays only a minor role. When subjected to temperature-varying cycles, the mortars are more prone to in-mortar failure during the pull-off test. The air-entraining function of some admixtures improves the frost resistance of the mortars; however, it would negatively affect the adhesive strength by incorporating pores into the contact zone between the mortar and brick substrate. This study showed that the use of some of the studied admixtures may improve the adhesion of mortar to the brick substrate.

Influence of Sample Thickness and Capping on Characterization of Bedding Mortars from Historic Masonries by Double Punch Test (DPT)

2014 ◽  
Vol 624 ◽  
pp. 322-329 ◽  
Author(s):  
Enrico Sassoni ◽  
Elisa Franzoni ◽  
Claudio Mazzotti
Keyword(s):  
Compressive Strength ◽  
Poor Quality ◽  
Sample Thickness ◽  
Mortar Sample ◽  
Hydraulic Lime ◽  
Punch Test ◽  
Natural Hydraulic Lime ◽  
Wide Range ◽  
Surface Capping

For determination of compressive strength of bedding mortar used in historic masonries, a promising moderately-destructive technique is double punch test (DPT). DPT consists of loading prismatic samples of mortar (about 4×4×1 cm3) by means of two circular steel platens (typically 2 cm diameter) and then calculating mortar compressive strength as the ratio of the failure load to the cross section of the circular platens. In this study, the influence of mortar sample thickness and mortar sample capping on the reliability of results obtained by DPT was systematically investigated. The influence of sample thickness was assessed by comparing DPT results obtained for samples with 5, 10, 15 and 20 mm thickness with compressive strength determined by testing reference 4 cm-side cubes. Different mortars were considered (cement, lime-cement, natural hydraulic lime), in order to investigate a wide range of mortar mechanical characteristics. The influence of surface capping was evaluated on a lime-cement mortar by comparing compressive strength determined on reference cubes with strength obtained by DPT on proper samples, without capping and after capping with rubber, gypsum and cement. The results of the study indicate that sample thickness substantially influences mortar compressive strength determined by DPT, which may vary by up to three times depending on sample thickness. A good estimation of the actual mortar compressive strength was obtained when samples with thickness similar to the loading platens diameter were tested, which suggests that choosing the size of the loading platens for DPT based on the thickness of mortar joints under investigation may be an effective way for obtaining reliable estimations. As for the influence of surface capping, in those cases where no mortar sample regularization is possible, because of the poor quality of the mortar, the results of the study indicate that sample capping actually seems necessary in order to avoid significant underestimations of mortar compressive strength. Considering the higher practicality offered by gypsum with respect to rapid-setting cement for surface capping, the use of gypsum seems preferable.

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