Non-hydraulic Lime Research Articles

Compressive and Flexural Strength of Non-Hydraulic Lime Mortar with Slag (GGBS)

Mortar for masonry is important because it provides the bond between masonry units so enabling the composite to behave as a single material. The type of mortar used determines the flexural and compressive strength of the masonry. Currently, most mortars used in construction are cement based. However, due to the heavy energy-intensive processes that are involved in its production the cement industry is responsible for up to 10% of global CO2 emissions; therefore, there are serious environmental implications with the usage and application of cement mortars. A sustainable alternative are lime mortars which have 30% less embodied CO2. Lime mortars confer benefits in comparison to cement based mortars such as accommodating a greater degree of wall movement and improved damp resistance. The main disadvantage with lime mortars is the longer setting time which can take up to 91 days in addition to the low strength. A way to overcome this is to add cement replacements e.g pozzolans or slag. This paper investigates the properties of non-hydraulic (lime putty) lime mortar containing up to 20% ground granulated blastfurnace slag (GGBS). Findings show a minimal amount of GGBS addition of 2% doubles the mortar strength to 2 MPa within 91 days with an eventual strength of over 15 MPa achieved with 20% GGBS. Strengths satisfying minimum requirements for all four mortar designations were achieved with between 2 - 16% GGBS addition, all within 56 days ageing; with designations (i), (ii), (iii) & (iv) strengths being satisfied within 28 days. Therefore, non-hydraulic lime mortars with GGBS offer a more sustainable alternative to cement based mortars without compromising setting time or strength whilst offering improved flexibility and breathability

Use of particle packing methods for development of lime fly ash-based mortars for repair of heritage structures

Lime is a sustainable alternative to cement as it requires less energy for production and it absorbs CO2 in the atmosphere for strength gain through carbonation. Non-hydraulic lime-based mortars have low strength and this can be enhanced using pozzolanic additions. However, densifying sand using particle packing theories in mortars for strength enhancement is one of the sustainable methods which is the main aspect of present study. In the current study, physico-chemical characteristics of two non-hydraulic lime binders Type-I and Type-II lime fly ash binders were prepared by replacing lime with fly ash from 0 to 30%. In addition, 5% gypsum was added to the binder mix for obtaining quicker setting. Two particle packing theories Modified Toufar Model (MTM) & J.D Dewar Model (JDD) and Indian Standard Codes (IS:650-2000 and IS: 383-2016) were considered for attaining different gradations of sand. Mix proportion 1:3 (Binder: Sand) lime-fly ash-based mortars were investigated for the flowability and compressive strength properties. The lowest minimum void ratio of 0.574 was attained for MTM proportioned sand. Compressive strengths of Type-I and Type-II lime fly ash-based mortars were highest for MTM particle packing sand with strengths 2.320 MPa and 0.738 MPa respectively after 28 days of curing. The compressive strengths were attained at 25% and 20% replacement levels of Type-I and Type-II limes with fly ash. The average flow values for Type-I and Type-II Lime fly ash-based mortars were obtained as 7.1 cm and 10.4 cm for MTM particle packing sand. From the study, it can be concluded that using Type-I lime fly ash-based mortar and MTM particle packing theory, repair mortars with reasonably good strength can be achieved.

Historical and Scientific Investigations into the Use of Hydraulic Lime in Korea and Preventive Conservation of Historic Masonry Structures

In addition to non-hydraulic lime, natural hydraulic lime (NHL) is a material widely used to repair and restore historic buildings. In Korea, although lime mortars have been used as important building materials for thousands of years, the sharing of information and technology with other countries has been relatively inactive. While not recognizing the suitability of NHL as a repair material, undesirable materials such as Portland cement have often been selected due to their high strength, ease of use, and hydraulicity, but unfortunately, this has resulted in the irreversible damage of existing elements, especially in historic masonry structures. This study aims to emphasize the need for hydraulic lime for the sustainable preservation of Korea’s architectural heritage. To justify its use, historical and scientific investigations were conducted. By reviewing literature written in the 15th century, it was found that dark limestone was used to manufacture building lime. Based on this, the chemical compositions of different-colored limestone were experimentally analyzed, and significant evidence was found that dicalcium silicate was formed in the quicklime manufactured by calcining blue-green and green-black limestone. Prior to the 19th century, it would have been impossible to record the chemical compositions of various types of limestone, except for visual observations such as color differences. Fortunately, this important information was recorded in royal documents and has been handed down to the present day. Thus, knowledge from 500 years ago could be scientifically interpreted using the latest technology. The link between the historical record and the experimental results shown in this study can contribute to the selection of a suitable material. This is a method for the preventive preservation of historic masonry structures, as it can significantly lower the possibility of future damages caused by efflorescence and freeze–thaw.

Olivine as a reactive aggregate in lime mortars

This paper presents the first investigation into the use of olivine as an aggregate material for calcium lime mortars. Lime binders provide many advantages when compared to cement binders such as higher vapour permeability and the ability to accommodate movement. They are undergoing a resurgence in their use in the conservation of historic buildings and in combination with environmentally friendly natural materials where these attributes are particularly important. Their ability to mitigate against global warming through the sequestration of CO2 by carbonation is a further advantage which will bring impact.The equilibrium reaction products between non-hydraulic lime and olivine were calculated using the thermodynamic software GEMS3 Selektor. Experimental mortar mixes were modelled with varying ratios of quartz sand aggregate and olivine sand aggregate. The software predicted phase assemblage at equilibrium comprising calcite, dolomite, magnesite and quartz, with mass percentages depending on the ratio of quartz to olivine.The mortars morphological, chemical and mechanical properties were evaluated using Scanning electron microscopy, X-ray diffraction (XRD), Raman spectroscopy, thermogravimetric analysis (TGA) and compressive strength testing. Significantly, this study has shown that the use of olivine based aggregates in finely divided form can enhance carbonation, and hence the CO2 absorption capacity of these mortars. Dolomite formed within the mortar from the reaction of olivine aggregate with lime and carbon dioxide in the presence of moisture is attributed to the superior mechanical properties observed increasing from 0.5 to 2.5 MPa.

Physic-Mechanical Properties of Cement Composites Consisting of Organic Raw Materials

The use of rapidly renewable raw materials in the building industry is seen as very promising with regard not only to the environmental issues but also to its economic aspects. A number of producers, not only in this country, have been trying to replace fine construction materials with secondary raw materials or rapidly renewable ones. As an example, technical hemp is a very promising material due to its good mechanical and thermal insulation characteristics. One of the possibilities is its use as filling component for non-constructional filling materials. Combining binders on the basis of non-hydraulic lime with hemp chaff yields a range of new construction materials. These products offer excellent work characteristics for permanent, environmentally sustainable buildings. These products as a whole form a natural composite construction material that can be used to build insulation walls, floor and roof insulation layers, and to obtain excellent heat and acoustic characteristics of buildings.

Possible Role of Simple Ionic Solutions on the Water Transport Kinetics and Mechanical Properties of Hydrated Lime Mortars

AbstractThe CL90 mortar (i.e., the nonhydraulic lime mortar) is dramatically more water retaining than any of the hydraulic mortars. This paper investigates the possible role of simple ionic solutions used as mix water on the water transport kinetics and mechanical properties of hydrated lime mortars. The results show that the addition of sulphate solutions as mix water does not only improve the transfer sorptivity and time to dewater, but also consistency and setting time of hydrated lime mortars. Compressive strength of hydrated lime mortars is significantly increased when potassium sulphate is used as mix water solution, and this is supported with microstructural analysis. The parameters studied in this paper form the main barriers to the use of hydrated lime mortars in construction practice; therefore, the use of hydrated lime mortars may be encouraged if the simple ionic solutions as mix water can improve the fresh and hardened properties of these mortars.

Raw materials used in ancient mortars from the Cathedral of Notre-Dame in Tournai (Belgium)

Abstract: Mortar samples from the Notre-Dame Cathedral at Tournai in Belgium have been investigated as part of a broader studyconsidering the transition of ancient cities and their rural territories from Roman to late Roman society and the transformation to theearly Middle Ages. Masonry mortars and mortars used for flooring have been studied from the Imperial Roman period, theCarolingian style period and the Romanesque style period (4th–11th century AD).A selected set of samples has been characterised using a combination of mineralogical, chemical and microscopical techniques.This characterisation enabled us to refine our knowledge of the mortar composition, of the original materials and of their provenance.It appears that both chalk and ‘‘hard’’ Tournaisian limestone were used to produce the lime. Both locally available materials can yieldeither hydraulic or non-hydraulic lime. The aggregates have a local origin. Additionally, several microscopical techniques wereapplied to identify the nature of the overburnt particles. The low abundance of this type of Binder Related Particles in the Gallo-Roman and Palaeo-Christian mortars suggests that technological knowledge, be it empirical or theoretical, was available.Key-words: ancient mortars, raw materials, provenance, lime binder, lime burning, hydraulicity, archaeometry.

Successful AMS 14C Dating of Non-Hydraulic Lime Mortars from the Medieval Churches of the Åland Islands, Finland

Fifteen years of research on accelerator mass spectrometry (AMS) radiocarbon dating of non-hydraulic mortar has now led to the establishment of a chronology for the medieval stone churches of the Åland Islands (Finland), where no contemporary written records could shed light on the first building phases. In contrast to other material for dating, well-preserved mortar is abundantly available from every building stage.We have gathered experience from AMS dating of 150 Åland mortar samples. Approximately half of them have age control from dendrochronology or from 14C analysis of wooden fragments in direct contact with the mortar. Of the samples with age control, 95% of the results agree with the age of the wood. The age control from dendrochronology, petrologic microscopy, chemical testing of the mortars, and mathematical modeling of their behavior during dissolution in acid have helped us to define criteria of reliability to interpret the 14C results when mortar dating is the only possibility to constrain the buildings in time. With these criteria, 80% of all samples reached conclusive results, and we have thus far been able to establish the chronology of 12 out of the 14 churches and chapels, while 2 still require complementary analyses.

Effects of carbonation on the pore structure of non-hydraulic lime mortars

The pore structures of carbonated non-hydraulic lime mortars made with a range of different aggregates and concentrations of lime have been determined using mercury intrusion porosimetry (MIP). MIP data have been correlated with scanning electron microscopy images and other porosity data. During carbonation there is an increase in pore volume in the ∼ 0.1 μm pore diameter range across all mortar types which is attributed to the transformation of portlandite to calcite. Also there is a monotonic increase in the volumes of pores with diameters below 0.03 μm. A model is proposed for the changes in pore structure caused by carbonation. This attributes the increase in the volume of sub 0.03 μm pores to the attachment of calcite crystals to the surface of aggregate particles, and in some cases to the surface of portlandite crystals. This phenomenon may explain the continuing presence of portlandite in mortars that, apparently, have fully carbonated.

Mortar Dating Using AMS 14C and Sequential Dissolution: Examples from Medieval, Non-Hydraulic Lime Mortars from the Åland Islands, SW Finland

Non-hydraulic mortars contain datable binder carbonate with a direct relation to the time when it was used in a building, but they also contain contaminants that disturb radiocarbon dating attempts. The most relevant contaminants either have a geological provenance and age or they can be related to delayed carbonate formation or devitrification and recrystallization of the mortar. We studied the mortars using cathodoluminescence (CL), mass spectrometry (MS), and accelerator mass spectrometry (AMS) in order to identify, characterize, and date different generations of carbonates. The parameters—dissolution rate, 13C/12C and 18O/16O ratios, and 14C age—were measured or calculated from experiments where the mortars were dissolved in phosphoric acid and each successive CO2 increment was collected, analyzed, and dated. Consequently, mortar dating comprises a CL characterization of the sample and a CO2 evolution pressure curve, a 14C age, and stable isotope profiles from at least 5 successive dissolution increments representing nearly total dissolution. The data is used for modeling the interfering effects of the different carbonates on the binder carbonate age. The models help us to interpret the 14C age profiles and identify CO2 increments that are as uncontaminated as possible. The dating method was implemented on medieval and younger mortars from churches in the Åland Archipelago between Finland and Sweden. The results are used to develop the method for a more general and international use.

Chromatic behavior of inorganic pigments in restoration mortars (nonhydraulic lime, hydraulic lime, gypsum, and portland cement). A comparative study

AbstractSpectral diffuse reflectance was used to make a comparative study of the chromatic behavior (stability, coloring power and effects of time, thermal gradients, and high energy ultraviolet radiation) of the inorganic pigments ultramarine blue, green earth, molybdenum orange, zinc yellow, chrome yellow, chrome green, ochre, and natural sienna when mixed with the binders: nonhydraulic lime, hydraulic lime, Portland cement, and gypsum. The results show acute interference of the limes and the Portland cement, and, to a lesser extent, of the gypsum on the initial colors of ultramarine blue, molybdenum orange, and chrome yellow. The other pigments studied showed good stability in the four binders. Time, thermal gradients, and high energy ultraviolet radiation caused no appreciable color changes, except in the case of chrome yellow, which presented slight changes over time. © 2006 Wiley Periodicals, Inc. Col Res Appl, 32, 65–70, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20289

The use of tg to measure different concentrations of lime in non-hydraulic lime mortars

A high speed method of thermal analysis was developed to allow the carbonation profile of lime mortars to be followed within a convenient time-frame. The loss in mass on heating, up to 700°C, of lime/sand mixtures of different proportions was related to the known quantity of lime in each mixture. It was shown that a heating rate of 50°C min–1 produced data which had a very high correlation with known quantities of Ca(OH)2. Thismethod can be used to measure the extent of carbonation at varying depths through a limemortar. This can be repeated at intervals to give an insight into the shape and extent of the carbonation front as it develops over time.

Non-Hydraulic Lime Mortars

Lime-based mortars are now widely acknowledged as generally superior to cement-based mortars in the repair of appropriate historic infrastructure. Increasingly the benefits of hydraulic lime mortars are also being realized in new masonry construction. In order to standardize the expected performance of mortars, designers will specify the type of lime, the type of filler (aggregate), the proportions of each and quantity of water or the required workability. Limes can be non-hydraulic (calcium or dolomitic) or hydraulic (natural or artificial). This paper reports on results of tests conducted on non-hydraulic lime conservation repair mortars at early stages of curing. Results to date show that the type of both non-hydraulic lime and filler used have a significant effect on the early (up to 28 days) mechanical performance of a lime mortar. The mortars in the study were made using five non-hydraulic lime binders: dry hydrate; 4 month-old lime putty; 20 year-old lime putty; ‘hot’ lime; and dispersed hydrated lime. The fillers were silicate sand, crushed bioclastic limestone, and crushed oolitic limestone. No pozzolanic material was added to the mortars. Compressive strengths at 14 days ranged from 0.3 MPa to 2.5 MPa. Comparisons are made between the structural performance and rates of carbonation up to 28 days of each binder:aggregate combination. In conclusion, observations are made on factors to be considered when specifying non-hydraulic lime mortar mixes for repair work.

Influences Affecting Compressive Strength OfModern Non-hydraulic Lime Mortars Used InMasonry Conservation

Non-hydraulic lime based mortars are currently more and more often used for the repair of historic masonry. They are presumed to be compatible with the original mortarlmasonry and their properties are not always evaluated, mainly due to a lack of research into mortars produced in a traditional manner. Influences of curing conditions, quality of mixing and water content on compressive strength of a non-hydraulic lime mortar mix made of lime putty were reviewed and examined. The mortar specimens were prepared with various water contents, cured in outdoor and indoor conditions and tested after 1, 2, 4 and 6 months. Phenolphthalein pH indictor was used to measure the carbonation depth. The strongest mortar specimens were from the indoor ageing condition although the mortar was less carbonated. The addition of water into the fresh mix increased porosity and lowered the compressive strength, however there were other influences which affected this relationship.

Lime Mortars for Brickwork: Traditional Practice and Modern Misconceptions—Part Two

The revival in the use of traditional lime mortars for the repair, restoration and conservation of historic buildings in the United Kingdom over the past 25 years continues to gain momentum as designers and builders alike recognize the importance of using materials that are sympathetic to those originally used for the construction of such buildings. This work has tended to focus on the use of pure non-hydraulic slaked lime putties as the principal binder for all mortars, which has led both to the widely held belief that all historic lime mortars were prepared in this manner, and to a general perception that hydraulic limes are similar in behaviour to modem cements.These views are essentially inaccurate and contradict much of the written works on bricklaying mortars that reflect the thinking and practices of architects and knowledgeable master craftsmen from the seventeenth century onwards. This is especially so in relation to the city of London, from where such influence was to spread rapidly throughout the country and to the British colonies. The vast majority of brick buildings that are now in need of care and attention date from after this period, and it is therefore timely to reappraise traditional practice and modem misconceptions.

Lime Mortars for Brickwork: Traditional Practice and Modern Misconceptions—Part One

The revival in the use of traditional lime mortars for the repair, restoration and conservation of historic buildings in the United Kingdom over the past 25 years continues to gain momentum as designers and builders alike recognize the importance of using materials that are sympathetic to those originally used for the construction of such buildings. This work has tended to focus on the use of pure non-hydraulic slaked lime putties as the principal binder for all mortars, which has led both to the widely-held belief that all historic lime mortars were prepared in this manner, and to a general perception that hydraulic limes are similar in behaviour to modem cements.These views are essentially inaccurate and contradict much of the written works on bricklaying mortars that reflect the thinking and practices of architects and knowledgeable master craftsmen from the seventeenth century onwards. This is especially so in relation to the city of London, from where such influence was to spread rapidly throughout the country and to the British colonies. The vast majority of brick buildings that are now in need of care and attention date from after this period, and it is therefore timely to reappraise traditional practice and modem misconceptions.