Air Lime Mortars Research Articles

Preliminary Valorization of Climatic Conditions Effects on Curing of Air Lime-Based Mortars for Restorative Applications in the Pasargadae and Persepolis World Heritage Sites

Air lime mortars with addition of two types of sesame cooking oil were synthesized and cured in two different conditions: laboratory and natural climatic conditions of the Pasargadae and Persepolis World Heritage Sites. For the mortars cured in the laboratory, addition of oils in the mortar induced hydrophobic effects, but it adversely affected on permeability values and carbonation rates. However, the air lime mortars cured in the site conditions demonstrated increment in their hydrophobicity and superficial durability without retarding their setting time and adverse effects on their calcium carbonate formation values, due to various climatic parameters existing in natural outdoor conditions.

Study of Materials and Technique of Late Baroque Stucco Decorations: Baldassarre Fontana from Ticino to Czechia

From the 16th to the 18th century, many artists and craftspeople coming from villages in the Italian-speaking part of Switzerland, well known for its stucco tradition, worked actively in Central Europe. Baldassarre Fontana (Chiasso 1661–1733) was one of them; after a period in Rome, he was active in Moravia and Poland. This contribution presents an analytical insight into stucco works in the Ticino canton and Czech lands in order to provide an understanding of how artistic and technical skills were transferred according to local traditions, materials, or other requirements found abroad. By comparing two works that Fontana realized in his homeland and two works that he realized in today’s Czech Republic, the historic techniques used to make stucco are characterized, with an emphasis on technological aspects and materials. The detailed analyses provide information on materials and their production and processing methods in relation to the specific sites. They also reveal certain specific technological approaches which were common in all four cases that were studied. The most significant was the layered system of high-relief pieces, where the ground layer was made of lime–gypsum mortar and the finishing layer was pure air lime mortar. The construction of the finishing layer differed between the Czech and Swiss sites, suggesting some other influential factors.

Improving the carbonation of air lime mortars at ambient conditions via the incorporation of ball-milled quarry waste

The carbonation of air lime mortars modified by the addition of 5% and 15% w/w (in partial replacement to lime) quarry waste, rich in Ca-, Mg- and Fe-silicate minerals, is hereby investigated. Ball milling was initially applied to the waste to reduce its particle size to the nanoscale and increase its reactivity towards CO2. The incorporation of the nano-sized waste at 15% w/w resulted in mortars with denser microstructure and higher compressive strength. This is attributed to the enhanced diffusion of atmospheric CO2 through the mortar pore structure and the improved CO2 uptake of the nano-sized waste additive.

Air lime mortar consolidation by nanolimes and ammonium phosphate: Compatibility, effectiveness and durability

In this study, a systematic comparison is presented between a commercial dispersion of Ca(OH)2 nanoparticles (so-called nanolimes) and aqueous solutions of diammonium hydrogen phosphate (DAP) for consolidation of air lime mortars. The effects were evaluated in terms of compatibility (composition and morphology of the new phases, changes in color, porosity and water absorption), effectiveness (product uptake, dynamic elastic modulus, scotch tape test) and durability (permanence of the consolidating action after accelerated ageing). While both consolidants proved to be compatible, DAP solutions outperformed nanolimes in terms of effectiveness and durability, especially when highly concentrated DAP solutions were used.

Bio-waste influence on air lime mortar performance corrosion – optimization using the surface response method

PurposeThe purpose of this paper is to characterize the properties lightweight green air lime and marble waste mixtures, relating microstructural and chemical properties with physical development of the material, an effort has been made to simulate the structure of the different mortar reinforced by two main layers plants.Design/methodology/approachThis paper presents an experimental design of response surface methodology, a model which predicts the mechanical strength and evaluate the effectiveness of bio-waste as a corrosion inhibitor to resist the steel corrosion in air lime mortars as a function of the proportion of the constituents of a new air lime mortar based on a combination of different percentages of marble waste (MRW), air lime and deferent type, layers of natural fiber reinforcement. Luffa sponge gourd and oakum hemp fiber residues capabilities in civil engineering are evaluated by combining numerical and experimental approaches for repair mortar based on air lime and marble waste. Several electrochemical techniques, mechanical strength tests and visual inspection of steel surface were performed.FindingsThe results revealed good mechanical strength and corrosion protection properties of air lime mortar containing the fiber naturel. These green wastes are considered economically feasible, as well having possessing good performance efficiency in protecting rebar reinforcement. These results were confirmed via polarization curves and electrochemical impedance spectroscopy measurements.Originality/valueThe prepared green air lime mortar provided good corrosion protection to the rebar. The significance of this study is to encourage the usage of solid white marble waste to prepare biomass-based repair mortar with good mechanical and anti-corrosion properties on the long term is still a big challenge.

Improvement of the depolluting and self-cleaning abilities of air lime mortars with dispersing admixtures

The aim of this study is to develop new air lime mortars with enhanced photocatalytic depolluting and self-cleaning abilities. Nanosilica, as pozzolanic mineral admixture, was used to improve the strength of mortars, whereas nanotitania (TiO2) was added to impart photocatalytic properties. At the same time, five different dispersing admixtures –superplasticizers– were added in bulk to the mortars to enhance the photocatalytic activity by reducing the rate of charge carrier recombination. Four polycarboxylate-based derivatives and a polynaphthalene sulfonate were tested aiming to achieve an efficient charge separation. In order to increase the lasting of the mortars subjected to water movements, sodium oleate was also added as a water repellent agent. Since the photoinduced hydrophilicity, responsible for the self-cleaning effect, might be affected by the water repellent, the compatibility between this admixture and the photocatalytic performance of the nanotitania was also investigated. Results showed that photocatalytic activity was improved due to the action of the superplasticizers as indicated by an average 33% increase of NO degradation, which is significant to the depolluting activity of these mortars. Furthermore, these mortars also showed a greatly reduced release of intermediate toxic compounds, mainly NO2: the selectivity factor (NOx/NO) reached values up to 87%. The self-cleaning ability, studied through dye degradation, of the mortars with SPs was also enhanced around 1.2 times. Three of the polycarboxylate-based superplasticizers enhanced the photosensitization of the dye under visible light irradiation, resulting in faster decolouring kinetics. In connection with the self-cleaning performance, these same SPs preserved the photoinduced hydrophilicity of the lime mortars, reaching good wettability of the surface of the mortars (water contact angles of ca. 10°), even in the presence of the sodium oleate, proving the compatible characteristics of the admixtures and allowing obtaining a new range of actively depolluting lime mortars.

Effect of Air-entraining and Water-repellent Admixtures and of Their Dosage on the Performance of Lime Mortars

ABSTRACT This work explores the short- and long-term effects of admixtures typically used to improve durability on air lime mortars. With that purpose, two air-entraining admixtures (AEA), based on sodium alpha olefin sulfonate (AOS) and sodium dodecyl sulfate (SDS), and a water-repellent admixture (WRA) based on alkylsilicone resin were studied. The AEAs proved not to be detrimental to mechanical strength both in the short- and long-term, when used in an appropriate dosage, and reduced water intake, while improving water vapour permeability, allowing a faster drying. Comparing the AEAs, SDS led to less entrained air and, thus, to higher mechanical strength and lower porosity and pore size than AOS. In turn, the WRA substantially increased mechanical strength in the short- and long-term, despite delaying carbonation, but also increased stiffness. Water intake was reduced, as well as the mortar’s drying kinetics, which can hamper its compatibility with old masonries. With increasing dosage, both types of admixtures increased the air content, but different implications in the short-term mechanical strength of the mortars were observed: WRA led to an increase, whereas the AEAs led to a decrease in this property.

Evaluating the Impact of Organic Addition and Aggregate Gradation on Air Lime Mortar: New Compatible Green Material for Heritage Application

ABSTRACT This research aims to study the influence of organic additive and aggregate grain size in lime mortar hardening for producing compatible, high-performance and eco-friendly materials for conservation and restoration of heritage structures. Mortar mix with lime to sand ratio of 1:3 by mass and water to binder ratio of 0.75 was considered. Ficus Carica (Moraceae), commonly known as Fig fruit, was used as an organic additive in the mortar mix at 2, 4 and 6% in volume. River sand grounded for 5, 10 and 15 minutes, turning in changes in grain-size distrubution, was used in the mortar mix. Investigations on mortars were performed after 90 curing days; physical and mechanical properties were evaluated, along with mineralogical changes due to organic addition; the influence of organic and aggregate grading in carbonation rate was also assessed. Results indicate that the aggregate with retention value 45 ± 3% in grades between 2 mm to 425 micron and 425 micron to 75 micron; and the addition of organic additive at 4% in volume represents the optimum mix able to assure significant enhansement in carbonation rate and mechanical resistance. Polysaccharides in organic played the central role in the mineralogical transformation responsible for the measured enhanced performances.

Admixtures potential role on the improvement of the freeze-thaw resistance of lime mortars

The work explores the use of admixtures as a way to improve the freeze-thaw resistance of lime mortars. To that end, different types of admixtures (water-reducers, viscosity-modifiers, air-entrainers and water-repellents) were added to air lime mortars and several properties on the hardened state were determined before, during and after subjecting the specimens to freeze-thaw cycles. Results showed that the water-reducer (superplasticizer) based on polynaphthalene sulfonate and the water-repellent based on silicone resin were the admixtures that more significantly improved the resistance to freeze-thaw, followed by the air-entrainers based on sodium dodecyl sulfate and sodium alfa-olefin sulfonate. Tensile strength and water absorption capacity were the factors that most influenced the resistance of the mortars to freeze-thaw. Ultrasonic pulse velocity and drilling resistance proved to be very useful methods for detecting alterations in the mechanical properties of the specimens due to freeze-thaw cycles.

Effect of innovative bioproducts on air lime mortars

In this work, air lime mortars were bioformulated with two innovative bioproducts, one resulting from iron supplemented Escherichia coli cultures and a second one exploiting microbial mixed cultures grown with crude glycerol as substrate. The bioproducts were lyophilized and, for the mortar formulation, suspended in water and used as mixing liquid. Workability of mortars was evaluated by the flow table consistency and 90-days-old samples were tested for different properties, such as thermal conductivity, bulk density, porosimetry, water absorption, drying, surface hardness and compressive strength. With water content to ensure workability, bioformulated mortars presented higher thermal insulation and reduced water absorption when compared with a non-bioformulated control mortar. However, the presence of bioproducts decreased the compressive strength of the air lime mortar. Contact with water, simulating weathering, diminished that decrease.The strategy utilized in the present work meet some of the goals of a circular economy approach maximizing natural resources by the use of wastes to produce the bioproducts and increasing lime mortars durability.

Comparative analysis of the behaviour of integral water-repellents on lime mortars

The paper compares the behaviour of three types of integral water-repellents (WRs) on air lime mortars. These were based on sodium oleate, silane and silicone resin. Results demonstrated that sodium oleate was the most effective in reducing water absorption without compromising water vapour permeability, but decreased mechanical strength. Conversely, silicone resin had the lowest impact on porosity and water absorption, but it was the only WR that increased mechanical strength, even at early ages. These trends were intensified with increasing WR dosage. Silane had a performance between that of the other two substances. Based on the results, silicone resin has the highest potential to be used in lime mortars for restoration purposes.

Natural hydraulic lime mortars - The effect of ceramic residues on physical and mechanical behaviour

In the past, it was common the use of ceramic residues as a pozzolan and/or aggregate in air lime mortars and concrete. Nowadays, incorporating ceramic residues in mortars is one of the ways to increase sustainability of the construction sector and introduce some benefits in the properties of those mortars.Ceramic residues were collected from several ceramic industries, namely from bricks, roof tiles and pots production, milled in laboratory and incorporated in natural hydraulic lime (NHL) mortars. Two distinct groups of mortars were prepared, with two different proportions, and samples were produced. A group with a volumetric proportion of one part of NHL and three parts of aggregate (1:3) and three different percentages of replacement of the aggregate by each of the residues (0, 20 and 40% in volume) and a second group with a volumetric proportion of one part of NHL and four parts of aggregate (1:4) and percentages of replacement of 0 and 30% were prepared. Their behaviour was analysed by determining its properties after 28 days of curing.The incorporation of ceramic residues in the NHL mortars led to an increase in open porosity, capillarity water absorption and water vapour permeability but also an increase in dynamic elasticity modulus and mechanical strengths. This increase was more significant for higher replacement percentages. The behaviour of these mortars seems appropriate for new construction renders and plasters but caution must be taken concerning moisture migration, namely when used in rehabilitation.

Effects of potassium ferrocyanide used for desalination on lime composite performances in different curing regimes

Negative effects of salt weathering on porous building materials will increase because of the global climate breakdown. The addition of crystallization modifiers as desalination technique has attracted considerable scholarly attention. This study builds on this body of knowledge by investigating the effects of potassium ferrocyanide addition on air-lime mortar under different environmental conditions. Three experimental setups were selected with different curing regimes: i) molding, ii) between sandstones and iii) between salt-laden sandstones. TGA-DSC, ion chromatography, MIP and SEM were conducted to evaluate the effects of ferrocyanide on the whole salt content, lime carbonation and mortar microstructure. Its efficiency/durability under salt exposure and wet conditions were also tested. The decay after salt crystallization cycles was evaluated by comparing air permeability, open porosity, water vapor permeability, capillary porosity, ultrasonic pulse velocity, surface hardness and roughness of samples before and after these cycles. Results showed that adding ferrocyanide improved the mortar performance in all curing regimes and its efficiency continued after capillary water uptake and salt attack.

THE INFLUENCE OF DOSAGE AND PRODUCTION PROCESS ON THE PHYSICAL AND MECHANICAL PROPERTIES OF AIR LIME MORTARS

Abstract. This paper studies the influence of five different factors affecting the dosage and production process of seven types of air lime mortars on their physical and mechanical properties. Such factors comprise the water/lime ratio, the aggregate type and size, the material of the mold and the curing conditions. Moreover, some physical and mechanical properties, not usually measured on air lime mortars, are obtained, such as open porosity, splitting tensile strength, fracture energy and elastic modulus measured through prisms. The results show that under the three different water/lime ratios tested, the material experiences a structural weakening. Ambient curing conditions were more favorable for air lime mortars than high humid ones. Moreover, it is observed that fabrication with wooden molds provided higher mechanical properties as they absorbed the free water, although this effect was probably local. Air lime mortar with an aggregate size of 2 mm had lower consistency in a fresh state as finer sands were more water demanding and the mechanical properties of this mortar were slightly lower than those of mortar with aggregate sizes of 0/4 mm. Furthermore, using limestone aggregates improved the continuity between the lime and the matrix. This fact resulted in higher mechanical properties of the mortars with limestone aggregates in comparison to those with river sand when maintaining the same water/lime ratios. This study can suppose a further step in the improvement of the dosage methodology of air lime mortars.

LIKE-FOR-LIKE AND COMPATIBLE MORTARS FOR THE REPAIR OF TRADITIONAL BUILDINGS

Abstract. The subject of this paper is traditional mortar preparation and materials, particularly earth-lime and air or feebly hydraulic hot mixed lime mortars with particular emphasis upon British practice and experience, whilst stressing their international ubiquity historically. It will demonstrate their appropriate functional performance and attest to the need to use similar mortars, similarly composed and prepared, in the repair and conservation of traditionally constructed buildings. It will question how commonly modern Natural Hydraulic Limes may be considered to be like-for-like or of compatible strength and functional performance. The paper will draw upon extensive research into historic texts, as well as primary archive research into historic building accounts and the latest research into the properties of lime rich air lime mortars and NHL mortars.

Suitability of different surfactants as air-entraining admixtures for lime mortars

The paper examines the suitability of three different surfactants as air-entraining admixtures (AEAs) for air lime mortars. The substances tested were based on sodium dodecyl sulfate (SDS), sodium alfa olefin sulfonate (AOS) and cocamidopropyl betaine (CAPB). Results showed that CAPB had the highest air-entraining action of the three, due to its amphoteric nature and, thus, the greatest impact on mechanical strength and porosity, making the mortars more susceptible to degradation by freezing and thawing. Conversely, SDS and AOS caused only moderate changes in lime mortars, but improved their resistance to freeze-thaw cycles. The differences in the performance of the tested surfactants suggest that their use should be carefully assessed as they can have a harmful effect on the already weak and porous air lime mortars, reducing their durability instead of improving it.

Effects of mussel shell aggregates on hygric behaviour of air lime mortar at different ages

Mussel shells, composed of calcium carbonate (>95%) and organic matter, are suitable alternatives to conventional sand in mortar. In addition, the use of lime instead of cement as a binder has also been considered for sustainable construction materials as well as in restorative applications.This study aims to contribute to the knowledge of air lime mortar through the analysis of the water transport properties of air lime mortar produced with mussel shell aggregates at different ages. Four mortar groups were obtained from the reference mortar by replacing limestone sand with mussel shell sand at substitution rates of 25%, 50%, and 75%. Water absorption, capillary uptake, weight variation, and drying from the fresh state up till one and two years were determined. The organic matter content and flaky seashell shape are responsible for the main differences observed between the mussel mortars and reference mortar. These two characteristics promote transport tortuosity paths and hydrophobic behaviour leading to reduced capillary uptake and increased drying resistance index. Furthermore, they enhance water retention, which increases the carbonation rate.

Fresh state properties of lime mortars with foam glass dust

Fine glass waste has been found to be a suitable addition to lime mortars because of the high amorphous content. The behavior of fresh air lime mortars and natural hydraulic lime mortars modified by foam glass dust is assessed with the purpose of exploring a new application of this waste dust as lime mortar admixture. The rheological parameters were correlated with relative density measurements, water retention abilities of mortars and air content in mortars. The effect of foam glass dust was found to be dosage-dependent. The fresh mortars behave generally as Hershel–Bulkley fluids with an evolution of the rheological parameters with admixture content. The replacement of lime by foam glass dust caused a reduction in mixing water reducing the yield stress simultaneously; however, the viscosity of the resulting mortars slightly increased. A change in behavior of mortars from shear-thickening to shear-thinning was observed. The natural hydraulic lime based mortars showed a gradual change from thixotropic to rheopectic behavior with increasing glass dust addition. The foam glass dust appears to be well suited to air lime plaster mixtures used in machine thin-layer rendering due to its plasticizing properties, and ability to increase water retention and reduce air content in the mortars.

Alkali-dolomite reaction in air lime mortar – implications for increased strength and water resistance

Abstract This paper investigates the origin of increased strength and water resistance of air lime mortar prepared by Triassic dolomite aggregate when exposed to humid or wet environments. The mortar specimens were exposed to various ageing conditions and analysed using petrographic and scanning electron microscopy equipped with X-ray microanalysis. Parallel to these analyses, X-ray powder diffraction and strength tests were performed on the specimens. It was revealed that reactions associated with the dedolomitisation process of the dolomite grains in the lime binder (hereafter alkali-carbonate reactions or ACRs) are the source of the improved strength and water resistance. An increasingly alkaline environment accelerated the ACRs substantially. Two parallel processes during the ACRs (dedolomitisation and CaCO3 dissolution/reprecipitation) were described in detail. Ageing temperature decisively influenced the kinetics of the dedolomitisation and dictated the path of the CaCO3 dissolution/reprecipitation process. After two years of ageing in a water-saturated environment at 60 °C, air lime mortar retained a great deal of its initial mechanical strength, and at 20 °C its strength was considerably increased. This somewhat unexpected observation was explained as being a result of microstructural changes and/or phase transitions.

Compatible Air Lime Mortars for Historical Tiled Facades: Bond and Mechanical Strength versus Tile–Mortar Interface Microstructure

AbstractExterior old glazed tiled facades have been a very important heritage testimony of Portuguese culture and traditions throughout the years. The adhesion of the mortars to the old tiles is a ...