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In this article, the physico-mechanical properties and hydration processes of cement pastes containing three additives are introduced. Cement was replaced with pumice, trass, waste chalcedonite powder at 30% by mass and a combination of pumice or trass and waste chalcedonite powder in the amounts of 15% each. The main aim of this research was to assess the properties of two- or three-component binders to save cement in these binders. Rheological properties such as consistency, yield stress, viscosity and thixotropy were determined, in addition to porosity, 7-day and 28-day flexural and compressive strength and bulk density. Additionally, the heat evolution and degree of hydration of the tested pastes were compared. The use of all additives resulted in a reduction in the consistency of the tested pastes. The highest compressive strength measured after 28 days was observed for the cement paste with a 30% content of waste chalcedonite powder, which is related to it having the best pozzolanic activity of the materials used. The results of this research have confirmed that pumice, trass and waste chalcedonite powder can be used as components of blended Portland cements.

Although, the salt crystallization is one of the most common causes of the deterioration of lime-based mortars, testing of their resistance to the soluble salt action has not yet been standardized. The problems following the development of the globally accepted testing method are, among others: defining the type of mortar samples, ways of samples’ contamination, the type and the concentration of the salt solutions used, environmental conditions during testing, determination of the damage development and the durability assessment. Another task of the testing method is to explain and connect the processes developing in the materials when they are applied in laboratory and real conditions. In this paper, soluble salt resistance testing of lime mortars on the composite samples is presented. The main focus of the paper is on the determination of the salt distribution in this type of samples after the five wetting and drying cycles. Samples consisted of two lime rendering layers (inner – 1/3 and outer -1/1), both prepared according to the experiences found in the literature for these types of lime mortars when applied on historical structures, placed on the natural stone bases. They were cured in laboratory conditions for 90 days, before drying and exposing to soluble salts action. Two types of 10% salt solutions were used for the test: sodium-chloride and sodium-sulfate. Salt contamination was performed by capillary action only in the first cycle, while in the other cycles samples were wetted by deionized water. After the finalization of the cycles, the detached pieces of mortar and efflorescence were removed from the samples. One of the samples from both groups were then cut in two halves, from which one was used for X-Ray Fluorescence (XRF) and another for Scanning Electron Microscopy with Energy Dispersive X-Ray Analysis (SEM – EDX) characterization. For the XRF analysis samples were divided into four layers, and then crushed and sieved through 0.5 mm sieve before tes

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.

The subject matter of the work presented here is the development and evaluation of novel lightweight mortars that meet the functional and technical criteria imposed on repair mortars. In a broad experimental campaign, lime, natural hydraulic lime, and lime–cement mortars were designed and tested. Lightweight aggregate, expanded perlite, granules from expanded glass and zeolite were used as full replacements for quartz sand. The hardened mortars were tested at the ages of 28 days and 90 days. The conducted tests and analyses were focused on the assessment of structural, mechanical, hygric and thermal parameters. The salt crystallization resistance and effect of salt presence on the hygroscopicity of the investigated mortars were also investigated. The use of lightweight aggregates in the composition of mortars resulted in their high porosity, low density, satisfactory mechanical parameters, improved water vapor transmission capability and water absorption. The mortars with expanded perlite and glass granulate were ranked among thermal insulation mortars of classes T1 and T2, respectively. The use of lightweight aggregates enabled the development of mortars with great durability in terms of salt action, which was almost independent of binder type. The ability to accommodate water vapor was increased by the effect, i.e., the use of lightweight aggregates and the presence of salt in mortars increased porous space. Taking into account the compatibility, functional, and technical criteria, lime- and natural hydraulic lime-based lightweight mortarswere classified as repair mortars, providing improved thermal performance. The lime–cement lightweight plasters can be recommended only for repair of building structures where cement and lime–cement materials were original applied.

The application of locally available component materials (lime putty and zeolitic rock as pozzolanic admixture) in two types of rendering mortars (designed for inner and outer render layer), was assessed through TG/DTA, XRD and MIP analysis and by testing the compressive strength, dynamic modulus of elasticity, water transport behavior and open porosity of mortars cured under two different regimes.Higher levels of lime replacement with fine natural zeolite (40% and 50% by mass), for both render layers,led to 1.5 to 2.5 times higher values of compressive strength when cured in humid conditions. The changes in zeolite content led to different pore size distributions of mortars and influenced their water transport behavior and open porosity. Overall, mortars with 40% and 20% of zeolite addition for the inner and outer layer (by mass), respectively, showed the best agreement of properties, when cured in humid conditions.

Cellulose-based viscosity-modifying admixtures are used on daily basis in a wide range of building materials, dominantly in pre-mixed mortar systems. Lately, alternative admixtures such as different “gums” have emerged. In building materials, the gums have similar viscosity-enhancingeffects as cellulose ethers with different efficiency. Various ways of production, as well as diverse working mechanisms of the biopolymers are to be considered while choosing the most suitable admixture for the intended use. Influence of alternative admixtures in several doses on the microstructure of lime mortars was studied in this paper. Mortars were prepared with the same workability and the air content in fresh mortar was determined, for it can have notable impact on microstructure of hardened mortar. Hydroxypropyl derivative of chitosan showed air entraining ability, while the carboxymethyl derivative reported slight decrease in amount of air entrained into the mixture. In the case of diutan gum, the most water-demanding admixture, the percentage of entrained air dropped with growing dose. Admixture addition increased the volume of pores in diameter lower than 0.1 m, and in region of pores around 10 m. Only the diutan gum affected the distribution of capillary pores, which are typical for lime mortars. Hygric properties were in correlation with air content values.

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.

In this study, the comparison of lava sand, pumice, and natural zeolite as lightweight aggregate in air lime mortars, natural hydraulic lime mortars, and cement-lime mortars has been investigated with emphasis on the resistance of salt and ice crystallization. The lava sand and pumice improved frost resistance of the mortars while natural zeolite mortars remained without this effect due to their high water absorption. Salt crystallization resistance of the mortars was improved by using lava sand and natural pumice, while the mortars with natural zeolite were not resistant to crystallization of sodium chloride. The mortars have relatively little resistance to the reacting of Na2SO4, where gypsum and calcium sulfoaluminates were formed breaking the structure of the mortars. The best results were obtained using natural pumice.

In this paper, crushed lava granulate was used as full silica sand replacement in composition of repair mortars based on hydrated lime, natural hydraulic lime, or cement-lime binder. Lava granules were analyzed by X-ray fluorescence analysis (XRF), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Particle size distribution of both silica and lava aggregates was assessed using standard sieve analysis. Hygrothermal function of the developed lightweight materials was characterized by the measurement of complete set of hygric, thermal, and structural parameters of the hardened mortar samples that were tested for both 28 days and 90 days cured specimens. As the repair mortars must also meet requirements on mechanical performance, their compressive strength, flexural strength, and dynamic Young’s modulus were tested. The newly developed mortars composed of lava aggregate and hydrated lime or natural hydraulic lime met technical, functional, compatibility, and performance criteria on masonry and rendering materials, and were found well applicable for repair of historically valuable buildings.

Viscosity enhancing admixtures, widely used to improve characteristics of concrete and ready-mix mortars, are mainly different derivatives of cellulose. Due to the nature of cellulose processing, the environmental-friendlier alternatives should be studied in order to reduce the impact of the building industry on the environment. The rheological study of natural hydraulic lime (NHL) grouts modified by four different biopolymers is carried out to investigate their behaviour in the NHL-based mortars. The biopolymers studied are of seaweed (sodium salt of alginic acid (ALGNA) and carrageenan (CG)) and microbial (diutan gum (DG) and xanthan gum (XG)) origin. The effect of addition of these admixtures in the doses of 0.1%, 0.5%, and 1% was studied using hybrid rheometer with DIN concentric cylinders geometry. The flow properties as well as viscoelastic properties were studied. The addition of any of the admixtures led to the increase in yield stress, with DG being the most effective admixture. Desirable increase in consistency coefficient was observed within the pastes with CG and DG addition having growing dosage dependency, the ALGNA addition also increased the coefficient noticeably, but it was furtherly decreased with growing dose of admixture. The fluidity index lower than 1 expressed shear-thinning behaviour of studied pastes, except the pastes with highest dose of admixtures, and all of the XG pastes. The addition of CG and DG supported the stability of the grout expressed as the increase in critical strain, thus prolongation of linear viscoelastic region. The flow strain was increased by all of the studied admixtures promoting the gel-like behaviour of the pastes. Complex modulus and viscosity measured at 1Hz frequency were unaffected by the DG addition while they were increased notably by addition of other admixtures with ALGNA and XG supporting the resistance to deformation of the grouts studied. Correspondingly to complex modulus increase, the loss tangent is d

The rheological behaviour and mechanical properties of lightweight lime-brick powder mortars with combined expanded clay-sand aggregates are presented in this paper. The rheological investigation included the characterization of flow properties and viscoelastic properties of the fresh mortars. Flexural and compressive strengths were determined at 7 and 28 days. These mortars are Non-Newtonian thixotropic liquids with conversion from shearthickening to shear-thinning behaviour depending on expanded clay aggregate (ECA) content. Yield stress and consistency coefficient of mortars significantly increase with decreasing amount of ECA; the mortars become more rigid and more viscous. Some of the mortars reached higher flexural strengths than similar lime mortars with metakaolin and higher compressive strengths than pure lime mortars. The lightweight lime-brick powder mortar with the mass ratio of 1:1 between gravelous sand and ECA was identified as the best among the analyzed mortars.

This article is focused on modern plasters with improved thermal insulating ability. The studied plasters were composed of lime, cement, ceramic powder, expanded perlite and silica sand. Regarding the matrix, three kinds of binders were used. Lime was partially replaced by ceramic powder. These waste materials show good pozzolanic reactivity and thus bring economic and ecological benefits. Portland cement was added as a third component to the mixture for the purpose of improving mechanical performance of the studied plasters. In this article, mechanical properties of designed plasters are presented. It was proved that matrix strengthening brought positive effect and eliminated the deterioration of mechanical behaviour; the final values of compressive strength were over 3 MPa. Due to desired high porosity of the studied plasters, their durability can be strongly affected by presence of the water. Therefore, in this article, the hygric parameters were studied too. Namely, the water absorption coefficient, apparent moisture diffusivity, the water vapour diffusion resistance factor and sorption and desorption isotherms belong among studied hygric characteristics. In this article, pore size distribution curves, which affect the discussed parameters, are presented.

Viscosity enhancing admixtures are widely used to improve the properties of concrete and ready-mix mortars. This study focuses on the influence of biopolymer (sodium salt of alginic acid, carrageenan, diutan gum, gellan gum, and xanthan gum) in doses of 1, 5, and 10 ‰ on the rheological properties of aerial lime-based pastes. The measurements were carried out on the Discover HR-1 hybrid rheometer with DIN concentric cylinders geometry. On the pastes the flow properties as yield stress, fluidity index and consistency coefficient as well as the viscoelastic properties (complex modulus, loss tangent, critical and flow strain) were studied. All pastes studied expressed shear-thinning behaviour and the flow curves indicated rheopectic character of samples. The significant differences in effectivity of admixtures used were observed. Xanthan and gellan gums were found less effective than the three others in influencing the rheology of aerial lime-based paste while diutan gum was so effective, that the future research with lower doses of the admixture are recommended to better explain its impact on the rheological properties.

The properties of alkaline activated brick dust mixed with water glass with a silicate modulus (Ms) of 1.0 were studied in fresh mixtures as well as hardened products in connection with the particle size of the dust. The brick dust (ground waste brick) was separated into 5 fractions according to particle size. The influence of particle size on the rheological properties of the fresh mixtures was studied via measurements of the yield stress and viscosity. The flexural and compressive strengths of the hardened products were determined after storage under laboratory conditions for 7, 14 and 90 days; the influence of 7 days of curing at 65°C on strength was evaluated as well. The microstructure of the hardened products was studied by means of porosimetry and SEM.