Lime Binder Research Articles

Modification of Lime Mortars with Synthesized Aluminosilicates

The increasing attention for restoration of buildings of historical and architectural importance has increased the interest for lime-based binders, which could be applied for manufacturing repair mortars and plasters compatible with historical heritage. Different additives, admixtures or fibers may be incorporated to improve mechanical and thermal features of such materials. In this study synthesized aluminosilicates (SA) were applied as an additive for lime mortar. The technology of synthesis consisted in the deposition of aluminosilicates from a sodium liquid glass by the aluminum sulphate Al2(SO4)3. The goal of this investigation was developing a new method of aluminosilicates synthesis from a sodium liquid glass and using this new material as a component for a lime mortar. Aluminosilicates were precipitated from the solution of aluminum sulphate Al2(SO)3 and sodium silicate. SA were then used as an additive to calcareous compositions and their influence was tested. Mortars were prepared with commercial air lime and siliceous river sand. Air lime binder was replaced by 5 and 10 wt.% of SA. Calcareous composition specimens were formed at water/lime ratio 1.0. The following analyses were made: grain size distribution of SA, X-ray diffraction analysis (XRD), sorption properties, plastic strength and compressive strength of lime mortars. XRD pattern of the SA shows the presence of thenardite, gibbsite and amorphous phase represented by aggregate of nano-size cristobalite-like crystallites. Application of SA leads to increase of compressive strength after 90 days of hardening by 28% and 53% at SA content 5 and 10% respectively comparing to specimens without this additive. Contents of chemically bound lime in the reference specimens after 28 days of hardening in air-dry conditions was 46.5%, while in specimens modified with SA contained 50.0-55.3% of bound lime depending on filtrate pH. This testifies to high activity of calcareous composition. The new blended lime mortar was developed based on SA. SA in lime composites turned out to be effective as structure-forming additive, both plastic and compressive strength increased after addition of SA.

Analysis of the distribution of temperature and humidity in different variants of external walls made of hemp-lime composite

Proper design of the building component, which not only meets the legal requirements, but also provides comfort of using of buildings, requires knowledge of the materials and solutions. Since moisture is one of the main factors that can affect the building structure destruction, it is particularly important to be aware of hygrothermal properties of components. And this is the focus of the study. In this paper several variants of external walls were analysed, according to the requirements in terms of: heat transfer coefficient U, the risk of surface and interstitial condensation. Partitions were designed with composite based on shives from industrial hemp and lime binder, which is not yet widely used in Poland. The purpose of the analysis of this material was to prove the validity of using the natural materials in residential buildings.

A STUDY OF HEMPCRETE PROPERTIES USING NATURAL HYDRAULIC LIME – MIX DESIGN, MECHANICAL PROPERTIES, AND MICROSTRUCTURE

In the article, an analysis of tensile strength fiber hemp and hemp fiber linkage analysis in the cement matrix is presented. The average tensile strength of the fibers of untreated hemp amounts to 764 MPa and the calculated modulus of elasticity amounts to 30 GPa. A test of pulling fibers from the cement matrix has shown that when increasing the length linkage, the maximum pulling force increases while the clamping strength does not significantly change. In the laboratory, a mixture of hemp concrete where a portion of mineral aggregate was replaced with hemp hurd was prepared. Results of the examination of the microstructure of hardened lime binder have shown that the hardened NHL mixture is porous and vapor-permeable while the hardened HL mixture is thick and compact. The goal was to create a prototype hemp concrete mixture that can be used for production of prefabricated elements with tensile strength between 10 and 25 MPa.

The Application of Raw Materials Obtained from the Cultivation of Industrial Hemp in Various Industries

Abstract Subject and purpose of work: The raw materials which are the purpose of the current hemp cultivation (<0.2% THC) are fibre, seeds and shives. This study describes the characteristics the raw materials obtained from the industrial hemp and described in detail the possibilities of their applications in pulp and paper, textile, pharmaceutical, construction and food industries. Analysis of the issues: Hemp straw consists of a porous ligneous core, which may be cut into smaller pieces, called hemp shives and of the fibre around the core. Hemp cellulose is used to produce paper pulp or plastics. In the construction sector, hemp fibre is used to produce, among other things, thermal insulation materials. Hemp shives is used as a filler for a composite based on lime binder, which is used as a wall material with good hygrothermal conditions confirmed by proprietary research. Hemp seeds are used for the production of cooking oil. Hempseed oil is also used in the pharmaceutical industry, e.g. to produce skin creams. Conclusions: Raw materials obtained from industrial hemp have a variety of applications. Currently, new directions in hemp application are being sought and tested, like for example hemp lime composite and bio-composites. The positive environmental impact resulting from the cultivation of hemp should be the main reason for simplifying the procedures for the commencement of its cultivation in many countries, e.g. in Poland.

Hydrophobization of Lime Composites with Lignocellulosic Raw Materials from Flax

ABSTRACTThe aim of the study was to evaluate the possibility of applying lime binder together with flax fibers and straw to the production of wall materials. Properties of the composites were modified by additives and admixtures. The following laboratory tests were performed: the analysis of the physical characteristics, compressive strength, a water droplet absorption test, water absorption of hydrophobized and standard samples, drying time, and analysis of the structure using scanning electron microscope (SEM). In the paper, there was examined the effectiveness of two formulations differing in the degree of hydrolytic polycondensation, viscosity, and concentration, as these are the factors that determine the final impregnation effect.

The Influence of Cement on Properties of Lime Mortars

The aim of this research is to investigate how cement affects the properties of lime mortars. The usage of pure aerial lime binders reduces the water resistance and mechanic durability of the material. It determines that pozzolan additives or cement have to be used in lime mortar. Mixed cement lime mortar (with increasing amount of cement) were synthesized and their properties tested: density, chemical composition, water absorption rate, compressive strength, resistance to soluble salts and frost resistance. Portland cement can be used as a suitable additive to mortars, to improve their compatibility with the hydraulic and historic mortars.

Hygrothermal performance of hempcrete for Ontario (Canada) buildings

Hempcrete is a bio-aggregate based composite material used for building envelopes which typically consists of hemp shiv (hurd), lime binder and water. Hempcrete has several distinct advantages including low thermal conductivity, effective moisture buffering, and high sound absorption, while having a high carbon sequestration “index”. This work investigates the impact of mix proportions on hempcrete properties and the hygrothermal performance of two proposed hempcrete wall assemblies for Ontario, Canada. The experimental results highlight the significant influence of the binder on the density and thermal conductivity of the final material. Thermal conductivity measurements ranged from 0.074 to 0.103 W/mK. Finally, hygrothermal analysis demonstrated that when using hempcrete in the Canadian climate a rain screen wall system is more suitable than a mass wall.

Archaeometric study of natural hydraulic mortars: the case of the Late Roman Villa dell’Oratorio (Florence, Italy)

This paper shows the results of a multidisciplinary study carried out on the mortars from the Late Roman Villa dell’Oratorio (fourth-sixth ad), an aristocratic mansion built in the lower Valdarno (Florence, Italy). Thirty-one bedding mortar and plaster samples were analysed through optical microscopy, thermogravimetric analysis, X-ray powder diffraction and scanning electron microscopy with energy-dispersive X-ray spectroscopy for determining the chemical, mineralogical and petrographic characteristics, while their main physical properties were measured by geotechnical procedures. The collected data indicates that the analysed mortars are made up of very fine to coarse river sand aggregate mixed with white to yellowish-white natural hydraulic lime binder mainly consisting of mixtures of prevailing calcite and hydraulic compounds. With regard to the origin of the raw materials, the aggregates were recognized to be selected Arno river sands, and the binders are the burning product of a local marly limestone (ex Alberese). Therefore, the mortars of the Late Roman Villa dell’Oratorio are one of the first uses of natural hydraulic lime in the lower Valdarno.

Effect of GGBFS and lime binders on the engineering properties of clay

Although lime is one of the most suitable binders in soil improvement projects, the associated environmental impact and some accompanying mechanical deficiencies should not be ignored. Partial substitution of lime with other binders is one of the ways of reducing the associated harm and improving the engineering properties of lime. This study investigated the effect of the partial substitution of lime with ground granulated blast furnace slag (GGBFS) on the strength and mechanical properties of lime stabilised clay by performing a total of 246 volumetric shrinkage strain (VSS), unconfined compressive strength (UCS) and ring shear (RS) tests. The VSS results demonstrated that the addition of GGBFS to lime is very effective in reducing the volumetric shrinkage of lime stabilised clay, and that the reduction in volumetric shrinkage behaviour is linearly related to curing period. The UCS results revealed that the partial replacement of lime with GGBFS led to significantly higher compressive strength for all ageing periods. The ring shear results also demonstrated that the partial replacement of lime with GGBFS led to a greater shear strength. Moreover, microstructural studies were performed to better understand the reactions of the mixtures. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) carried on selected specimens revealed that the addition of GGBFS in a lime stabilised clay results in production of the cementitious products in a faster rate. X-ray powder diffraction (XRD) test results revealed that the main hydration products are cementitious products such as calcium silicate hydrates (CSH), calcium aluminates (CAH).

Modyfikacja spoiwa wapiennego gipsem oraz metakaolinitem

Wapno od tysięcy lat wykorzystywane jest jako materiał budowlany. W dzisiejszych czasach, z uwagi na jego niską wytrzymałość mechaniczną i małą odporność na warunki atmosferyczne zmniejszono lub nawet zaniechano jego wykorzystanie w budownictwie. Ten naturalny budulec korzystnie wpływa na mikroklimat wewnątrz budynków, a dzięki zasadowemu odczynowi zapobiega powstawaniu pleśni. Stosowanie wapna jako zamiennika tradycyjnych materiałów, do których można zaliczyć np. cement przyniesie korzyści nie tylko ekologiczne ale i ekonomiczne. W pracy opisano badania własne podstawowych właściwości fizyko-mechanicznych modyfikowanych spoiw wapiennych. W celu podwyższenia niekorzystnych parametrów wapna, zmodyfikowano spoiwo zmienną ilością gipsu w ilościach 10 %, 15 %, 20 % masy spoiwa oraz różną zawartością wody poprzez wskaźnik woda/spoiwo W/S: 0,65, 0,7, 0,75 dla mieszanki z 15 % zawartością gipsu. W wszystkich recepturach zastosowano stałą ilość metakaolinitu równą 10 % masy spoiwa. Przeprowadzono test wytrzymałości na zginanie i ściskanie po 7 dniach oraz badania gęstości, porowatości i nasiąkliwości spoiw. Przy wzroście zawartości gipsu odnotowano wzrost parametrów wytrzymałościowych i spadek nasiąkliwości przy niewielkich zmianach porowatości. Dużo większe różnice zaobserwowano przy modyfikacji W/S: wraz z jego spadkiem wzrastała wytrzymałość spadała nasiąkliwość i porowatość.

Assessing Local and Long-Range Structural Disorder in Aggregate-Free Lime Binders

For aggregate-free, calcite-containing lime binders, we correlate long-range crystallinity parameters from X-ray diffraction measurements (lattice constants, crystalline domain sizes, and microstrain fluctuation values) with short-range structural parameters from extended X-ray absorption fine structure data (coordination environments, attenuation factors, and fit stabilities). In doing so, we reveal a correlation between unit cell contraction and a more ideal local calcite structure. Using Fourier transform infrared spectroscopy and X-ray absorption near edge spectroscopy, we rule out the possibility of contributions from amorphous calcium carbonate and show that the structural disorder is likely related to localized regions of incomplete carbonation. Thus, by using data from this judicious combination of structural characterization tools, we demonstrate that short-range structural distortions occur in calcitic lime binders and that these distortions can be detected even in multiphase mixtures.

Unveiling the Use ofCretain Roman Plasters: Analysis of Clay Wall Paintings FromBrixia(Italy)

The paper describes the analysis of a particular kind of plaster from the walls of the Roman Sanctuary (first half of the 1st century BCE) in the centre of Brixia (now Brescia, Italy), which is an outstanding example of Roman Republican architecture. The walls were plastered and painted with different patterns, imitating marble panels and curtains. Optical microscopy on thin sections, X-ray diffraction, and infrared spectroscopy were performed on several samples of the plaster in order to reveal the execution technique. The palette consisted of glauconite, celadonite, Egyptian blue, and red and yellow ochres. In some cases, an organic compound, possibly a lipidic compound, was present in the external paint layer, as a surface treatment. The plaster contains two superimposed coats: the render coat with lime binder and sandy aggregate; the finish coat with a clay fraction (illite, chlorite, kaolinite), together with calcite from slaked lime and grains of quartz, silicate and carbonate rocks. Although Vitrivius’ De Architectura reported the use of creta (clay) as daub smeared on reed vaults, the Sanctuary of Brixia represents the first documented use in Roman buildings in a painted plaster laying on a stone masonry wall.

Mechanical properties, phase composition and microstructure of activated Metakaolin-slaked lime binder

In the present paper mechanical properties, microstructure and phase composition of binder produced by mixing Metakaolin (MK) and slaked lime in 4:1 proportion by weight have been studied. Anhydrous Gypsum was mixed as an activator in different percentages of 0%, 5%, 10%, 15% and 20% by weight of the binder. The study measures the changes in the physical properties, flexural and compressive strengths of the mortar at different ages of curing varying from 2 to 28 days. Binder and sand were mixed in 1:1.5 proportion for the mortar preparation. Superplasticizer Glenium 51 was added by 1% weight of the binder. The curing of demolded mortar specimens were done at room temperature for 2 to 28 days. The optimal dosage of anhydrous gypsum was found as 5% by weight of the binder at which bulk density, compressive and flexural strengths of mortar were maximum and the total porosity and water absorption were minimum. Addition of 5% anhydrous gypsum increases the compressive and flexural strengths by 68.5% and 72.1% respectively. The composition and microstructure of the mortar confirm the trend of variation of mechanical properties of the mortar.

Raman scattering or fluorescence emission? Raman spectroscopy study on lime-based building and conservation materials

This work presents an in-depth study on Raman spectra excited with 1064 and 532nm lasers of lime binders employed in the past as building materials and revealed today as valuable conservation materials. We focus our interest on the bands of strong intensity, which are present in the spectra of all binders acquired with laser excitation at 1064nm, but absent in the corresponding spectra acquired with laser excitation at 532nm. We suggest, that the first group of spectra represents fluorescence phenomena of unknown origin and the second true Raman scattering. In our studies, we also include two other phases of lime cycle, i.e. calcium carbonate (a few samples of calcite of various origins) and calcium oxide (quicklime) to assess how structural and chemical transformations of lime phases affect the NIR-Raman spectral profile. Furthermore, we analyse a set of carbonated limewashes and lime binders derived from old plasters to give an insight into their spectral characteristics after excitation with the 1064nm laser line. NIR-Raman micro-mapping results are also presented to reveal the spatial distribution of building materials and fluorescent species in the cross-section of plaster samples taken from a 15th century chapel. Our study shows that the Raman analysis can help identify lime-based building and conservation materials, however, a caution is advised in the interpretation of the spectra acquired using 1064nm excitation.

Characteristics of Hydraulic Lime using Low-grade Dolomitic Limestone

This study aims to produce dolomitic hydraulic lime (D-NHL) using domestic low grade dolomitic limestone and to determine the effect of adding blast furnace slag (BFS) and gypsum as part of an investigation of the hydration properties of D-NHL to increase the mechanical properties. The main mineral phases of D-NHL as a hydraulic lime binder were Ca(OH)₂, Mg(OH)₂, C₂S, C₃S, and MgO residues. Ca(OH)₂ transformed into CaCO₃ in D-NHL paste over the period of 28 days, but the carbonation of Mg(OH)₂ and the hydration of C₂S did not occur until hydration, after 28 days. Through an investigation of the hydration properties of D-NHL pastes mixed with BFS and gypsum, Al-based compounds such as calcium aluminate hydrates (C₄AH 13 ) and ettringite were observed at early hydration time. The compressive strength was improved due to the increased quantities of these hydration products. These results show that good performance results from the application of dolomitic hydraulic lime and that a high value product can be made from domestic waste materials.

Deterioration of natural hydraulic lime mortars, II: Effects of chemically accelerated leaching on physical and mechanical properties of carbonated materials

Masonry using lime binders is very common in all regions of the world. Models for the future climate in northern regions predict conditions conducive for the materials used in mass masonry being saturated for longer periods and therefore at higher risk of binder leaching and consequent deterioration. Following work on uncarbonated lime mortars, ammonium nitrate leachant was used to accelerate the deterioration of carbonated mortars containing natural hydraulic lime binders. Leaching of binder significantly reduced the strength of the mortar and slightly increased its sorptivity. The resistance to deterioration increased in the order NHL2<NHL3.5<NHL5 binder, in line with the increasing hydraulicity of the binder. Carbonated mortars are more resistant to binder leaching than the corresponding uncarbonated materials.

Microscopic techniques and a multi-analytical approach to study the fire damage of the painted stuccoes from the Petruzzelli Theatre (Bari, Southern Italy)

This paper reports a study of the effects of fire on the decorative stucco elements consisting of painted mouldings and decorations in the Petruzzelli Theatre in Bari (Southern Italy). The theatre was built at the end of the nineteenth century. In 1991 a fire caused serious damage to both materials and structure.Visible damage to the decorations included various deterioration patterns. The fire-related effects on both plaster and painted surface layers were subjected to in-depth investigation under laboratory conditions by focusing on mineralogical, chemical and microstructural alterations. Methods used included Optical Microscopy, Environmental Scanning Electron Microscopy coupled with X-ray microanalysis, X-ray Diffraction, Fourier transform infrared spectroscopy and simultaneous Thermogravimetry–Differential Scanning Calorimetry.De-hydration of the gypsum binder and oxidation of the iron compounds caused new mineralogical phases to form in the stucco plaster. In some cases, microscopic observation suggested that calcination of the lime binder may have occurred in thin layers under the surface. Significant microstructural modifications were detected in the form of cracks and microcracks, due to thermal shock and gypsum dehydration. Phase transformations affected the structural integrity and the colour properties of the stucco plaster to different extents, up to a maximum depth of around 2.5cm, while fissuring due to thermal shock penetrated to greater depths.Fire-related damage in the surface paint consisted of colour changes and/or disruption of the painted layers due to thermally-induced chemical reactions involving mineral pigments; detachment and burning of the painted layers from the direct action of flames, as well as accumulation of combustion deposits on the surface were also observed.

Chemical Characterization of Lime-Based Binders in Historic Buildings of Latvia

The aim of this research is to investigate the chemical composition of stone materials of several local historic buildings with a purpose of elaboration of restoration strategy, including the choice of restoration materials. Most of the examined mortars are lime- based hydraulic mortars, characteristic of the architecture of 19th/20th century. Pure aerial lime binders show reduced compatibility with historic materials, that is why lime binders with pozzolan additive (cement) are an appropriate choice for restoration. In order to examine the changes of hydraulicity (i.e. the property of binders to harden when exposed to water) of perspective restoration binders, a series of blended lime-cement mixtures were synthesized with growing content of cement (up to 10% by weight). A significant relationship between cement content and hydraulic properties has been shown.

Characterization of 6–11th century A.D decorative lime plasters of rock cut caves of Ellora

The historic decorative lime plasters of Ellora caves, dated back to 6–11th century A.D have been investigated for their mineralogical, micro-structure and chemical characterization. The analytical studies were performed by means of optical microscopy, XRF, laser particle size analyzer, FTIR, XRD, Raman Spectroscopy, Scanning Electron Microscope and thermal analyzer. Traditional lime plaster is applied in 2–3 layers above the host rock but interestingly the techniques differ at India’s Ellora cave. From the analytical data it appears that all the lime plaster is composed of mixture of feebly dolomitic lime binder (aerial lime) mixed with fine to medium grained siliceous aggregates with addition of Cannabis sativa (Canabeacease) as an organic filler. The finding indicates that hempcrete technology was known to the ancient Indians in 6th century A.D and probably this is the first authentic report about the use of cannabis as filler in ancient lime plaster.

Comparison of different binders in sintering

The production of iron-ore sinter using lime and polymer binder is experimentally studied. The supply of lime to the batch (in doses of 30 kg/t) is comparable in efficiency with the use of polymer binder (in doses of 150 g/t). Better results are obtained when lime is supplied to wet concentrate, with subsequent storage, than when polymer is employed.