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The evolution of the science of the chemistry of admixtures besides the integration of various mineral additions in granular mixtures has metamorphosed the field of the concrete material. Thus, the produced mixtures are directly affected by the chosen combination of additions of mineral and organic. The disorders of industrial experience have often been associated with the dosages and interactions between the various additions used. The proposed study investigates the impact of the combination of different types of mineral and organic additions on the rheological properties of mortars. In this research work, mortars were made by varying the rate of substitution of cement by three types of mineral additions (limestone fillers, marble powder, natural pozzolan), in association with different dosages of a 3rd generation superplasticizer (polycarboxylates ), in order to study the evolution of shear thresholds and viscosities. In addition, a coaxial vane-type rheometer is used to study the rheological characterization of the mortars. The obtained experimental results revealed the effectiveness of the incorporation of inert mineral additions combined with polycarboxylates on the rheological parameters. [ABSTRACT FROM AUTHOR]

Clinker is the raw material used in the manufacture of cement. However, this material is very harmful to the environment, since it is estimated that for every ton of clinker produced, about 1.0 ton of CO2 is released into the atmosphere. For this reason, alternatives were sought for the use of other materials that are less harmful to the environment. This has led to the use of industrial by-products with the aim of increasing their use and thus reducing the amount of carbon released into the atmosphere. Blast furnace slag is a by-product used in the manufacture of some cementitious products. The aim of this research is to conduct a study on the use of slag as an additive for cement or concrete. The mortar samples were tested according to Brazilian, American and European technical standards. Physical, chemical and compressive strength tests were carried out which confirmed the possibility of using the slag without chemical or thermal activation. [ABSTRACT FROM AUTHOR]

Conservation of historical buildings has socio-economic impact and in order to conserve historic structures without disturbing its aesthetics, a precise characterization of raw materials is very much essential. In the present paper, the historical structure, Forest Research Institute (FRI), Dehradun, Uttarakhand, India, has been investigated as it is known as remarkable masonry structures using red bricks and lime mortar systems. Different samples of mortar and bricks of the building were analysed using different techniques such as Optical microscopy, Xray Diffraction (XRD), Field emission scanning electron microscopy coupled with energy dispersive (FE-SEM/EDX), X-ray spectroscopy (XRD), Thermo Gravimetric Analysis (TGA) and Infrared Spectroscopy (FT-IR). The analysis shows that bricks are made up of noncalcareous clay material and firing temperature was not exceeding above 900°C. All the brick samples analysed in this study have the water absorption, porosity and bulk density in the range of 10.9-18.5%, 15.5-32.2 % and 1.66-1.96 g/cm³, respectively, while the compressive strength of all the brick samples is found to be in the range of 7.8-14.2 MPa. Mortar samples are stiff, compact and hydraulic due to the presence of surkhi and brick aggregates. The petrological analysis revealed the presence of calcite and quartz, which is also confirmed by XRD and FE-SEM/EDX analysis. SEM micrographs shows needle-like structure of calcite mineral indicates the complete carbonation of the lime. Further, FTIR results indicating the use of organic admixtures in the buildings mortar samples. [ABSTRACT FROM AUTHOR]

The main aim of this article, carried out in relation to ash–cement mortars, is to determine the effect of complex additives of polyfunctional modifiers, including, in addition to superplasticizers, air-entraining and water-retaining additives, at different values of water–cement ratios. With the use of experimental–statistical models, the complex effect on the adhesive strength of cement–ash mortars of water–cement and ash–cement ratios, as well as complex additives of polyfunctional modifiers, including air-entraining and water-retaining additives, is considered. The extreme nature of the water–cement and ash–cement ratios on the adhesive strength of ash–cement mortars are established. Their optimal values are in the ranges of 0.7–0.75 and 0.35–0.4, respectively. The addition of a naphthalene-formaldehyde superplasticizer makes it possible to increase the adhesive strength of mortars by up to 40%. A positive effect is achieved along with the addition of a superplasticizer by introducing optimal amounts of air-entraining and water-retaining additives into the mortar mixtures. Quantitative parameters of mortar compositions that positively affect adhesive strength are established. The influence on the adhesive strength of the fly ash was also investigated, as well as on the binder–sand ratio. In addition, a positive effect on the adhesive strength of modified cement–ash mortars was experimentally shown by increasing the specific surface area of fly ash by regrinding it and increasing the cement–sand ratio. [ABSTRACT FROM AUTHOR]

The use of natural admixtures as a sustainable alternative to cement and chemical admixtures in concrete has gained significant attention. Eupatorium adenophorum Spreng (EAS), commonly known as the 'forest killer' in Nepal, is a perennial and herbaceous invasive plant. This prompted an experimental investigation aimed at assessing the potential utilization of its liquid and burnt ashes as additives in cement mortar. EAS leaves were dried, burnt at wooden coal fire, and sieved through a 90 μm sieve to obtain EAS powder. EAS liquid was produced by hammering the fragmented leaves, followed by squeezing and filtering. The control mortar had a water-cement ratio of 0.35 and a cement-sand ratio of 1.0. EAS powder content ranged from 0 % to 15 % and EAS liquid from 0 % to 0.4 %, by weight of cement. The optimal content (10 %) of EAS powder resulted in decreases in flow table value, density, and elastic modulus of mortar by 2.3 %, 4.2 %, and 10.6 %, respectively, while increasing compressive strength and water absorption by 2.3 % and 14.6 %, respectively. As for EAS liquid, its optimal content (0.3 %) led to increases in flow table value, density, compressive strength, elastic modulus, flexural strength, and splitting tensile strength by 11.0 %, 1.4 %, 13.0 %, 25.4 %, 28.4 %, and 33.0 %, respectively, while decreasing water absorption by 2.7 %. The observed increase in the compressive strength of mortar with the incorporation of EAS powder suggests its potential to substitute mineral admixtures. This can be achieved through improvements in the burning process, grinding to finer particles, and thorough micro-characterization, followed by detailed investigations into mortar properties. Additionally, the effectiveness of EAS liquid in replacing chemical admixtures to enhance various mortar properties has been confirmed. The collaborative use of EAS powder and liquid holds promise for supporting future sustainable infrastructure development, facilitating the production of eco-friendly green concrete. [Display omitted] • Eupatorium Adherephreng Spreng (EAS) is called forest killer in Nepal. • EAS powder reduces workability but boosts mortar compressive strength. • It also lowers elastic modulus and raises water absorption. • EAS liquid improves workability and all mortar mechanical properties. • Both EAS powder and liquid can substitute mineral and chemical admixtures. [ABSTRACT FROM AUTHOR]

The deterioration of mortar or concrete caused by the alkali-silica reaction (ASR) significantly depends on its susceptibility to moisture imbibition and exposure. This study investigated how applying hydrophobic materials in cement mortar prevents ASR-induced deterioration. Three hydrophobic materials were used, including a hexamethyldisilazane (HMDS) treated fumed-silica, a silane-based emulsion, and a silane-based cream. These hydrophobic materials were applied by directly coating the aggregates before mortar preparation or added directly to the mixture as admixtures. The effect of the applied hydrophobic materials on mortar properties was evaluated based on compressive strength, dynamic modulus, water absorption, and linear expansion. Furthermore, the microstructure and ionic distribution of alkalis from the aggregates interface were appraised using scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS) tests. The results were compared to a mortar with no admixtures and a mortar with 20% cement replaced by fly ash (a traditional method of ASR mitigation). Coating aggregates with hydrophobic fumed silica were more effective at reducing ASR-induced expansion than directly integrating the hydrophobic materials, although at a lower degree than fly ash. • Hydrophobic materials were incorporated in mortars through two methods: aggregate coating and direct using as admixtures. • ASR-induced expansion and cracking were reduced by hydrophobic aggregates. • EDS analysis via the line approach shows the impact of hydrophobic materials on the transport of alkali ions. [ABSTRACT FROM AUTHOR]

The addition of polymers in construction is a new tendency and an important step toward the production of structures with better functional properties. This work investigates the addition of polyurea (PU) as a polymeric material in mortars. Polymer mortars were manufactured with the addition of polyurea retained in different sieves (T50 and T100) and different concentrations (2% and 5%). The characterization of the, polyurea (PU)control mortar (PU0%) and manufactured polyurea mortars (PU2%T50, PU5%T50, PU2%T100, and PU5%T100) was conducted by means of morphological analysis, SEM, XRF, TGA, and a compressive strength test of hydraulic mortars. The results show that mortars with polyurea retained in sieve 100 with a particle size of 150 μm exhibit better thermal behavior and a greater resistance to compression with a concentration of 5% polyurea with respect to the other samples. The present work reveals that polyurea retained in sieve 100 can be considered as a polymeric additive for mortars, indicating that it could be a candidate for applications such as construction. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Utilization of various mineral admixtures in producing mortar decreases the porosity and capillarity, hence improves the durability in opposition to water and competitive solutions. In this research work, Ground Granulated Blast Furnace Slag is used to replace 30 percent, 60 percent, and 70% of ordinary Portland cement (OPC) (GGBFS). Mechanical property (compressive strength) and durability properties (permeability, porosity, and sorptivity) of high-performance concrete (HPC) are tested. Water permeability of M85 is measured using three cell permeability apparatus. Compressive strength, porosity, and sorptivity of the same mixes are also found. According to the test results of HPC, 30% replacement level of GGBFS gives higher compressive strength than 60% and 70% replacement levels of GGBFS. An equation is developed for permeability of HPC based on mechanical strength and porosity. It is found that coefficient of permeability of water for HPC mixes ranges from 5.1 × 10-11 cm/sec to 7.8 × 10-11 cm/sec. It is concluded that 30% GGBFS used in HPC produces less porosity, less permeability, and less sorptivity than compared to other replacement levels. [ABSTRACT FROM AUTHOR]

This article presents research on selected physical and mechanical properties of cement-based plasters and masonry mortars with consistency-improving additives, namely, traditional hydrated lime and a plasticizing and aerating mixture (APA), which, in practice, is often considered to be a lime substitute. Comparative analysis of the properties of mortars with alternative additives—lime or APA—was carried out, taking into consideration possible effects of cement, as two types of Portland cement were used for the research. For fresh mortar, mixture consistency, air content, resistance to segregation, and water retention were determined. Tests on hardened mortars included tests of porosity and impermeability, depth of penetration of water under pressure, drying shrinkage, as well as compressive and bending strength, modulus of elasticity, and adhesion of mortars to the base. In addition, research has shown that cement–lime mortars and cement mortars with APA admixture of similar consistency in the fresh state are characterized by significantly different properties. The results show, in most of the features analyzed, more favorable properties of mortars with the use of traditional lime. For shrinkage only, the use of admixture turned out to be more advantageous. [ABSTRACT FROM AUTHOR]

Huge amount of water-based drilling cuttings (WDC) is generated during the drilling and exploitation of shale gas. In this study, WDC powder was used as a replacement of cement at different mass fraction (0, 10%, 30%, and 50%) to prepare cement mortars. The mechanical properties, water absorption, and heavy metals leaching of the mortars were then investigated along with the corresponding microstructures. The results showed that a higher porosity was formed within the WDC-blended mortars. For instance, the porosity of the control specimen was 16.7%, while the porosity increased to 20.6%, 21.4%, and 25.0% for the mortars blended with 10%, 30%, and 50% WDC, respectively. Therefore, the mechanical properties of the mortars decreased and their water absorption increased with the increase of WDC replacement ratio. For example, the compressive strength of the mortars blended with 10% and 30% WDC decreased from 33.11 MPa of the control specimen to 29.33 MPa and 21.48 MPa, respectively. Nevertheless, the blended mortars still satisfied the M20 strength grade according to the Chinese standard (JGJ/T 98–2010). The compressive strength of the mortar blended with 50% WDC was 11.33 MPa and then satisfied the M10 strength grade. The leaching test indicated that the water quality of leachates from the mortars blended with lower than 30% WDC remained as Grade I according to the Chinese standard (GB 3838–2002); the water quality of leachate from the mortar blended with 50% WDC was classified as Grade III, which, however, would not cause a safety issue to the environment. [ABSTRACT FROM AUTHOR]

The structures may be exposed to fire or high temperature conditionally or accidentally. Alteration in the behavior of concrete structure is prospective under the exposure of elevated temperature. There is an urge to find the materials that can resist the alteration in physiochemical and strength properties of cementitious materials under high temperature. In the present study, the effect of elevated temperature on cement mortar consisting of additives, i.e., accelerating admixtures, and stone waste, i.e., stone slurry powder, was investigated and compared with specimens at room temperature. The aim of the study was to examine the practicability of these additives under exposure to high temperatures. The mortar specimens were exposed to various temperatures, i.e., 150°C, 300°C, 450°C, and 600°C, for the duration of one hour and compared with unheated samples. The change in mass, strength, and micro-structure of mortar specimens at elevated temperature was studied. The environmental assessment and performance evaluation of various mortar mixes were also evaluated. The mass of mortar specimens reduced as the exposure temperature of specimens was raised. The residual strength of mortar increased up to a certain temperature; afterwards, it decreased. Stone slurry powder and calcium nitrate can be used individually and in combination to resist thermal changes. [ABSTRACT FROM AUTHOR]

In this study, roller compacted concretes were produced by using polycarboxylate-based third generation high-performance mortar and concrete admixture, which provides ultra-high range water reduction and long workability time. In roller compacted concrete production, the chemical admixture dosage was 1%, which was the maximum dosage recommended by the manufacturer, and the amount of water used was reduced by 10, 20, 30 and 40% compared to the concrete produced without the use of concrete admixture. The physical and mechanical properties of the roller compacted concrete specimens were investigated. When the ultra-high range water reducer was used as 1% of the cement weight in the production of roller compacted concrete, optimum values in terms of unit weight, compressive strength, water absorption, ultrasonic pulse velocity and dynamic modulus of elasticity were obtained by reducing the mixing water by 10%. Although the water/cement ratio decreased, further reduction in water amount resulted in a decrease in compressive strength and affected the concrete quality negatively. [ABSTRACT FROM AUTHOR]

We synthesized catechol‐conjugated chitosan (CCC) to study its usefulness as a construction material additive in cement mortar. The degree of catechol conjugation (DOCcat) of the synthesized CCC was determined to be approximately 14% by UV–vis and 1H NMR spectroscopy. Furthermore, the hydroxyl and amine groups in CCC could play a crucial role in hydrogen bonding, metal coordination, and cross‐linking processes via interaction with adducts from cement mortar. In this study, we observed an improvement in the compressive strength and absorption rate, suggesting that CCC is a promising candidate for high‐performance cement mortar. [ABSTRACT FROM AUTHOR]

We encountered a number of cases in the published archaeological studies where ashes and charcoal were used as aggregates in ancient lime mixtures. These mixtures were tested in a small number of experiments, and this paper presents the results. Our tests confirmed that charcoal retains moisture and can be used to help mortars retain water. It does not, however, increase a mortar's ability to retain moisture to the same degree that crushed ceramic does. Charcoal should be an additive to a mortar and not its sole aggregate, as it is brittle and the mortar produced would be weak. Mixtures of ash with lime seem to work best when spread on a single layer. When the ash is a small part of a mortar, it does not affect its behaviour significantly. The addition of ash does not increase the ability of lime mortars to retain water. Powdered ceramics also limit the effect of ash on lime. The paper concludes with suggestions for future research into these materials and mixtures. [ABSTRACT FROM AUTHOR]

In this study, the effect of the PCE main chain length variation on the admixture demand to provide the desired slump value (27±2 cm) and the consistency retention performance of mortar mixtures having different C3A content was investigated. For this purpose, a total of 12 mortar mixtures were prepared by using CEM I 42.5R type cement having four different C3A content (2%, 3%, 6%, 9%) and using PCEs having three different main chain lengths (27000 g/mol, 55500 g/mol, 78000 g/mol). According to the results, irrespective of the PCE type, the PCE requirement increased by an increment of the C3A ratio. This behavior was more pronounced in the mixture containing the cement having the highest C3A ratio (9%). Compared to the mixture containing PCE having medium main chain length, the admixture demand to provide desired slump value of the mixture containing PCEs having short and long main chains was obtained at 3.9-4.5 and 4.7-6.5 times higher, respectively. The shortness of the PCE's main chain reduces the adsorption and electrostatic effect of the admixture. The poor performance of the PCE having a long main chain may be due to the bridging effect and the intertwining of the long polymers. PCE having a medium main chain showed almost %21 lower consistency retention performance than the others. This is due to the greater admixture requirement to achieve target flow value in the mixtures containing admixture with short and long main chains compared to admixtures with medium chains. [ABSTRACT FROM AUTHOR]

In this study, the effect of the PCE main chain length variation on the admixture demand to provide the desired slump value (27±2 cm) and the consistency retention performance of mortar mixtures having different C3A content was investigated. For this purpose, a total of 12 mortar mixtures were prepared by using CEM I 42.5R type cement having four different C3A content (2%, 3%, 6%, 9%) and using PCEs having three different main chain lengths (27000 g/mol, 55500 g/mol, 78000 g/mol). According to the results, irrespective of the PCE type, the PCE requirement increased by an increment of the C3A ratio. This behavior was more pronounced in the mixture containing the cement having the highest C3A ratio (9%). Compared to the mixture containing PCE having medium main chain length, the admixture demand to provide desired slump value of the mixture containing PCEs having short and long main chains was obtained at 3.9-4.5 and 4.7-6.5 times higher, respectively. The shortness of the PCE's main chain reduces the adsorption and electrostatic effect of the admixture. The poor performance of the PCE having a long main chain may be due to the bridging effect and the intertwining of the long polymers. PCE having a medium main chain showed almost %21 lower consistency retention performance than the others. This is due to the greater admixture requirement to achieve target flow value in the mixtures containing admixture with short and long main chains compared to admixtures with medium chains. [ABSTRACT FROM AUTHOR]

Building physical investigations of clay plasters stabilized and coated with linseed oil varnish Due to numerous prejudices against traditional building materials made from renewable raw materials, but in particular due to ignorance of the physical, structural and hygrothermal properties, the use of such building materials in building construction is still rare. This also includes the use of clay plaster outdoors. In two current research projects, the effect of linseed oil varnish used as a mortar additive was analyzed in laboratory tests. Laboratory samples with a proportion of 1 % linseed oil varnish in a percentage of the dry clay mass showed increased strength values and sorption capacity, whereas the water vapor diffusion resistance of these samples increased only slightly. An in‐situ monitoring of an ecologically sustainable wall construction with clay plaster and coating of linseed oil varnish was carried out over several years and evaluated. The required functionality and durability of the investigated clay exterior plaster were achieved through the use of linseed oil varnish coating. [ABSTRACT FROM AUTHOR]

The work relates to a composition of an additive mortar with a volumetric weight below 250kg/mc, the thermal conductivity coefficient below 0,08kcal/m×h×°C, mechanical strengths more than 7daN/cm² with self-cleaning effect after commissioning. In order to obtain a selfcleaning effect over time by eliminating chromatic deviations, the composition of ZnO, TiO2 and the three colored ceramics mixture is reformulated by optimizing the content based on color adjustment, by using a specialized software and CIE L*a*b* colorimetry for pressed bulk powders, at the medium one given by the patina. The composition optimization is performed by modifying, as appropriate, the addition rate of eggshell powder by a reformulated percentage related to the three fine colored ceramic powders. The freshly prepared mortar is applied to the restoration of the historical monument's facades through physical-structural and chromatic reintegration interventions. Depending on the conservation state of the apparent structures, two stages with differentiated specific operations are used: for surfaces without gaps, but chromatically degraded and with deposits of embedded dirt, it is spread with a trowel in the form of thin plasters on fiberglass mesh and in case of damage with deep lacunars areas the consolidation of the mobile structures will be first executed and grouting with a simple mortar based on river sand, expanded perlite, Portland cement and water in gravimetric ratio sand:perlite:cement:water = 2:1:2:5. After strengthen the same thin plasters will be applied on the fiberglass mesh. The new mortar allows the accomplishing of a series of advantages both in the processes of paste obtaining, as well as during commissioning and after, respectively within the period of integration in the tourist circuit. [ABSTRACT FROM AUTHOR]

A composite mineral admixture was prepared by steel slag and superfine blast furnace slag. The influence of superfine blast furnace slag content of the composite mixture on the mortar and concrete was investigated. The results show that the composite mineral admixture may decrease the strength of concrete at the early age but improve the strength development over time. Increasing the content of superfine blast furnace slag can reduce the degradation of the early strength. The reduction of the autogenous shrinkage and adiabatic temperature rise is significant when the composite mineral admixture is added. The reduction is more obvious when the water-to-solid ratio (w/s) is low. The results show that with steel slag and superfine blast furnace slag playing as complementary parts in the composite mineral admixture, it can be used as an effective substitute of cement. [ABSTRACT FROM AUTHOR]

To analyse the different mechanism of polycarboxylate superplasticizer and polyester fibre and its effect on cement mortar during freeze-thaw cycles, by taking cement mortar as main research object and the proportion of additive as variables, the varying pattern of the mechanical properties, size and distribution of the pores of the cement mortar during freeze-thaw cycles were studied by the NMR technology for the first time. The influence of different proportion of additive on the changes of the surface scaling, mass, compressive strength, splitting tensile strength and elastic modulus of cement mortar after 0, 25, 50, 75 and 100 times freeze-thaw cycles was studied. Meanwhile, the T2 spectra change law of the cement mortar under different freeze-thaw environment was analysed and the change rule between freeze-thaw cycle, additive proportion and the pore size within the cement mortar was obtained. Also, the relationship between the mechanical parameters and pore properties was studied. This study on the damage evolution mechanism of additive cement mortar during freeze-thaw process is of great theoretical and practical significance to the analysis and prevention of freeze-thaw disasters in cold area. [ABSTRACT FROM AUTHOR]

This paper focuses on producing a natural hydraulic lime (NHL) mortar with metakaolin, expanded perlite and tuff additives for the purpose of repairing historic masonry. The experimental study was based on laboratory tests for determining the mechanical and physical properties of NHL mortars with mineral additives, under standard and water curing conditions at 7, 28 and 90-day testing periods. Following preliminary tests for selecting most favourable materials; flexural strength, compressive strength, adhesion strength, modulus of elasticity and ultrasound tests were conducted for obtaining mechanical performance. Adhesion strength of mortars were determined by applying each mortar to the most common historic masonry materials. Physical performance of the pozzolan added mortars were investigated through; apparent density, bulk density, water permeability, capillary absorption, water vapor permeability, porosity tests. Regardless of mineral additive type; water cured mortars reached higher physico-mechanical properties in comparison with the ones cured in relative humidity. Overall, water cured natural hydraulic lime mortars with specific amounts of mineral addition are found promising for the repair of historic masonry. [ABSTRACT FROM AUTHOR]

Conductive carbon black Super-P (CSP) is a kind of nanomaterial, which is often used as conductive agent. It has excellent conductivity and low production cost. In this paper, CSP was used as the admixture to prepare composite mortar (with the specific gravity of cementitious material). The consistency, mechanical properties, electrical conductivity and temperature sensitivity of composite mortar were studied. The mechanism of CSP was analyzed by scanning electron microscope (SEM) and X-ray diffraction (XRD). The results show that the consistency of composite mortar decreases with the addition of CSP. The mechanical properties of composite mortar first increase and then decrease with the increase of CSP content. The addition of CSP greatly improves the conductivity of mortar. When the CSP content is 0.5–2%, the resistivity decreases rapidly and the seepage threshold appears. When the content of the mixture is large, the influence of different curing conditions on resistivity is small. SEM and XRD analysis show that CSP can fill micro pores and conduct electricity through tunnels, and does not change the composition of hydration products of composite mortar, and the formation of calcium hydroxide can be inhibited when the content is small. This paper explores the properties of CSP composite mortar, which provides theoretical and experimental basis for the preparation and application of conductive mortar. In this paper, conductive carbon black Super-P (CSP) was added into the mortar as an admixture to prepare composite mortar. It is found that when the CSP content was 0.5–2% of the cement quality, the seepage threshold appears and the temperature sensitivity decreases. [ABSTRACT FROM AUTHOR]

The self-healing capability of cracks plays an important role in improving the durability of concrete. This study investigated the the self-healing capability of mortar with crystalline admixture and fly ash under three conditions. The compressive strength, water absorption, and surface crack pattern were used to evaluate self-healing capability of mortar, and the composition of the healing products was analyzed by x-ray diffraction and scanning electron microscopy. The results indicated that the crystalline admixture could improve the self-healing capability of cementitious materials but caused a negative effect if adding too great an amount of fly ash (≥20%). The specimen that was immersed in water showed favorable self-healing capability of cracks. The healing products in cracks are mainly composed of CaCO3. [ABSTRACT FROM AUTHOR]

Raw clay is used in construction as a binder in mortars, in straw and shive-based composites, or in the production of unfired bricks. The problem with its use is its high susceptibility to drying shrinkage, low water resistance and low mechanical strength, which limits its use. The aim of the research was to assess the possibility of improving selected physical and mechanical properties of clay-sand mixtures by using methylcellulose (MC) in the amount of 0.2%, 0.4%, 0.6% of the clay mass. The glauconite clay used in the research is an industrial waste from the extraction of sand for the production of building materials. Selected properties of the fresh mixture and the parameters of the hardened material were examined, such as flexural and compressive strength, water resistance, shrinkage, drying kinetics, density and pore distribution. Additionally, SEM observation is described. The addition of methylcellulose thickened the mixture, retaining some of the mixing water. MC had a positive effect on reducing shrinkage by a maximum of 20.2%, reduced the weight loss after exposure to water by a maximum of 93.6%, and improved the flexural and compressive strength by a maximum of 22.8 and 34.9%, respectively, compared to the mortar without the admixture. The best results were obtained with an admixture of 0.4%, and increasing the content resulted in deterioration of the parameters. The beneficial effect of using MC can extend the use of glauconite clay in the unfired state, leaving the green in color. The results obtained prove that the developed mixtures can be the basis for making unfired bricks with load-bearing properties, mortars and plasters, including external ones. However, further research is necessary, such as moisture sorption and vapor permeability, which are important when using clay-sand mixtures as an external wall layer. • Glauconite clay mortar with methylcellulose admixture was investigated. • The working properties of the mixtures in their fresh state were tested. • Mortar density, porosity, pore size distribution, shrinkage, water resistance were studied. • Mortar flexural, compressive strength and Young's modulus were studied. • Selected amounts of methylcellulose admixture showed a positive effect on most of the tested mortar parameters. [ABSTRACT FROM AUTHOR]

Given the growing concern about environmental contamination risks, the management of sewage sludge (SS) from wastewater treatment plants is becoming more challenging. Thus, alternative pathways that offer value-added opportunities with minimal environmental impacts are needed. This study investigates the use of 0.5 2 wt% biochar (BC) powders generated from the pyrolysis of the SS in an N 2 or CO 2 environment, as an additive in cement mortar mixtures. The effect of dry and pre-wetted BC on the fresh properties, phase formation, compressive and tensile strength properties of cement mortar mixtures were assessed. Thereafter, life cycle assessment (LCA) of Plain and BC-modified mortar mixtures were evaluated, and the environmental impacts arising thereof were quantified. Results showed that whereas the BC had an infinitesimal effect on mix fresh properties, it caused approximately 17 34% and 10–18% increases in compressive and tensile strength, respectively. Regardless of the pyrolysis condition, pre-wetted BC had a superior impact on mechanical strength evolution. LCA results showed that except for minor, net increases in particulate matter/water consumption potential, the rest of the impact categories associated with the production of 1 m3 of cement mortar decreased with the addition of the BC. In terms of Global Warming Potential (GWP) per unit 28d compressive strength, the BC-modified mixtures yielded values that were lower than that of the Plain mortar by about 16 29%. Therefore, these research findings indicate that the use of SS-derived BC as a low-dose additive in cement composites could help the construction industry mitigate its negative environmental footprints. • Sewage sludge derived-biochar could be used as a cement additive in cement mortar. • The strength of BC-modified mortar was higher than that of the Plain mortar. • Relative to BC produced under an N 2 environment, BC-CO 2 was more effective. • BC mitigated most of the impact categories associated with mortar production. • GWP of BC-modified mortar was also lower than that of the Plain mortar. [ABSTRACT FROM AUTHOR]

Designing good quality mortar of higher bond characteristics is essential for masonry construction, and for this purpose different types of chemical admixtures such as water reducer and set retarder are used. Sustainable construction needs developing natural admixtures instead of chemical ones and researches on this topic are in progress. The present study is an encouraging attempt to use different natural extract admixtures, acting mainly as flow and strength enhancers. The results obtained are interested and will encourage the concrete producer to design an eco-friendly sustainable mortar for masonry works. The natural admixtures attempted for cement mortar are grape extract, mulberry extract, pomegranate extract and date molasses. For this purpose, different properties of cement mortar were investigated to search for the true action of natural extracts used. It was observed that the addition of all natural admixtures in concrete mortar appreciably enhances compressive and flexural strengths and decreased water absorption. There is a chance for grape and pomegranate extracts to enhance flow of fresh mortar. Test data indicate that 0.4% grape extract is the optimum type of natural extract addition to improve mechanical and flow ability properties, but pomegranate extract enhanced well shear-bond strength when added by 0.3% reaching 155.9%. Based on SEM images, a refined and homogeneous microstructure of cement mortar with low pores and cavities is observed because of using natural extract admixture. • Important properties of mortar containing different natural admixtures were investigated. • Flow, mechanical properties, and shear-bond strength enhanced due to natural extract addition. • Grape and pomegranate extracts are good alternatives of chemical admixture for mortar. [ABSTRACT FROM AUTHOR]

This paper presents an innovative study on the partial replacement of lime binder with foam glass dust to explore a new application of this waste dust as a lime mortar additive. Standard air lime mortars and natural hydraulic lime (NHL) mortars were made by incorporating from 0% to 40% of foam glass dust in replacement to lime, and their mechanical performances, microstructure, and durability were determined. The waste foam glass dust showed an unusually high pozzolanic activity, predicting an improvement in the mechanical properties and durability of lime mortars. As the replacement level in air lime mortars increased, the performance properties of the mortars improved. The pozzolanic reaction of foam glass dust did not compensate for the loss of hydraulic binder in NHL mortars; therefore, these mortars have gradually lost their strength. The progress in mortars carbonation, as well as the pozzolanic reaction of foam glass dust, led to the formation of denser and more frost-resistant structure in air lime mortars, whereas the partial binder replacement in NHL mortars with foam glass dust had no significant effect on their frost resistance. The highly effective use of foam glass dust as a supplementary material was assessed to air lime mortars. [ABSTRACT FROM AUTHOR]

Linseed oil has been used as mortars admixture in times before the modern synthetic admixtures were introduced. The present study deals with influence of linseed oil on the engineering properties of air lime mortar. The composition of mortar was inspired by a mortar used for fixing of 1890' mosaic in Krásná Lípa (Czech Republic). The knowledge of complex influence of the oil on mortar's performance is important for the preparation of renovation mortars but also for possible application of the oil as sustainable mortar admixture, replacing the nowadays synthetic ones. The oil is reducing the yield stress of the fresh mortar (i.e. acts as plasticizer) and is increasing its air entrapment. The water-repealing effect is the most important impact of the oil admixing on the harden mortar; it was evaluated by measurement of water absorption coefficient. The higher air entrainment and water-repellence are resulting to the improved frost resistance of the mortar containing the oil. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate how the addition of shrinkage-reducing polycarboxylate superplasticiser (SRPC) affected the shrinkage of cement-based materials (CBMs). SRPCs can significantly reduce the surface tension of cement solutions. In this work, a new molecular structure of SRPC was synthesised; its surface tension was reduced to 34·1 mN/m, which is lower than that of ordinary polycarboxylate superplasticisers (PCEs). Compared with mortars without additives, the shrinkage-reducing ratios of mortars containing SRPC at 7 and 49 d were about 33 and 22%, respectively, for an SRPC dosage of 0·2% by mass of cement. The results showed that the SRPC reduced the shrinkage of CBMs more effectively than an ordinary PCE. Furthermore, the shrinkage mechanism of CBMs containing SRPC was assessed regarding three aspects: the change in the pore size distribution of the cement pastes with pore size below 50 nm, the reduction of the capillary pore pressure in the hardened cement pastes after the addition of a low-surface-tension SRPC and the reduction in the evaporation rate of moisture through SRPC aggregation on the gas–liquid interface in cement pastes. [ABSTRACT FROM AUTHOR]

A number of monosaccharides characteristic of plant gums were found in paint layers and preparation layers of samples of Maya mural paintings of 10 archaeological sites located in Campeche and Yucatan regions. This finding opens the question about the deliberate use of these organic polymers as additives for improving workability and mechanical properties in the preparation layer mortar and conferring cohesion to the pigments in the paint layer. The study performed by GC-MS has confirmed the presence, in significant amounts, of a series of monosaccharides, being glucose and mannose between the most abundantly found. Nevertheless, the low amount present in most of the samples hindered the quantification of the relative proportion of monosaccharides necessary for identifying the botanical species of the plant gum. According to the accepted methodology used by Maya artists for preparing painting materials, bark of trees containing plant gums was added to the slaked lime stored in pools and that should be consistent with the notable amounts of glucose, mannose and other monosaccharides forming the skeleton of hemicelluloses and cellulose found in most of the samples. Although organic matter can be present in paint samples exposed to the external environment in Mesoamerican region as result of the microbiological activity, marker compounds characteristic of products resulting from their metabolism were not found in the studied samples. [ABSTRACT FROM AUTHOR]

Cement, water and fine aggregate mixture is called mortar. Mortar samples suitable for the desired purpose can be obtained by adding various additives to the mortar samples. In this study, instead of standard sand, blast furnace slag (BFS) was used at 10%, 20% and 30% by weight in mortar samples. In order to determine the mechanical properties of the samples, compressive and flexural strength tests were applied. For the electrical resistivity values, a device with constant 30V voltage was prepared and the electrical resistivity values were measured. To determine the freeze-thaw resisting properties, it was applied sodium sulfate experiment. As a result, it was seen that the best values were obtained from 30% BFS additive samples in all series. The highest resistivity values are in the sample with 30% BFS doped with 0.1856 ohm.m and 0.268 ohm.m values. The highest freeze-thaw resisting value was seen in the sample with 30% BFS with 1.35%. [ABSTRACT FROM AUTHOR]

Featured Application: In this contribution, the applications of the hydrotalcites and hydrotalcite-like materials in the building materials, cements, mortars, and concretes are summarized. Hydrotalcites are layered double hydroxides displaying a variety of stoichiometry caused by the different arrangement of the stacking of the layers, ordering of the metal cations, as well as the arrangement of anions and water molecules, in the interlayer galleries. The compounds of the hydrotalcite group show a wide range of the possible applications due to their specific properties, such as their large surface area, ion exchange ability, the insolubility in water and most of the organic sorbents, and others. Affordability, wide possibilities of manufacturing, and presence of sufficient natural deposits make hydrotalcites potentially very useful for the construction industry, as either a building material itself or an additive in mortars, concrete or in polymers composites used in constructions. Similar possible application of such material is in leakage control in a radioactive waste repository. The effect of use of these materials for ion exchange, anti-corrosion protection, radioactive ions containment, and similar purposes in building materials is examined in this review. [ABSTRACT FROM AUTHOR]

In this study, the effect of silica fume and fly ash on the fresh and some hardened state properties of mortar mixtures containing plain, binary and ternary cementitious systems and air entraining admixture (AEA) were investigated comparatively. Within this regard, different mortar admixture combinations were prepared by using a CEM I 42.5R type cement, a type of polycarboxylate-ether based water reducing admixture, air entraining admixture, silica fume and fly ash. In addition to the control mixture containing no mineral admixture, three series of mortar mixtures were prepared. In the first and second series, silica fume and fly ash were replaced by 30% and 10% of cement, respectively. In the third series, both silica fume and fly ash were used as 30% and 10% of cement weight. Within all mortar mixtures, water/cement ratio, sand/binder ratio and flow values were kept constant as 0.485, 2.75, 270±20 mm, respectively. Time-dependent flow values, 90-day water absorption values, 3, 7, 28 and 90-day compressive strengths and compressive strengths values after 0, 50, 100, 150, 200 freeze-thaw cycle of mortar mixtures were measured. According to the results, the use of mineral additives in cement mortars containing air-entraining admixture had a positively effect on the fresh state properties of the mixtures. While mixtures containing mineral admixture exhibited lower strengths at early ages compared to the control mixture, they had higher compressive strength values than the control mixture at the end of 90 days. The 90-day water absorption values of the mortar mixtures were observed to be less with the use of mineral admixture compared to that of control mixtures. In terms of freeze-thaw cycles, the most successful mixture was determined to be K-UK-SD-HSK mixture having ternary cementitious system and containing both fly ash and silica fume. [ABSTRACT FROM AUTHOR]

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Lime mortar with organic additives is one of the most widely used building materials in ancient China and continues to play an important role in historic structure restoration. This study investigated the erosion of ordinary aerial lime and sticky-rice mortars under the cyclic actions of wetting–drying (WD) and dilute sulfate acid (DSA). Comprehensive experimental tests were conducted to study the mechanical properties, quality, microstructure and pore structure of the mortars according to cyclic WD and DSA actions. Results showed that both the WD and DSA actions can significantly degrade the compressive and shear strengths of the mortars. The DSA softens the mortar matrices more severely than the WD by a leaching mechanism. Apparently, sticky rice does not change the micro morphology, pore structure and packing pattern of the mortar matrices, but it inhibits the carbonation of the lime. Both the WD and DSA actions can erode the ordinary aerial lime and sticky-rice mortars, causing more porous matrices and coarser particles. The results of this study make it possible to clarify how the WD and DSA actions affect the durability of partially matured aerial lime mortars with or without sticky rice, with potential uses in the restoration of ancient buildings. [ABSTRACT FROM AUTHOR]

Gypsum efflorescence on clay brick masonry is a growing problem, leading to a persistent grey-white staining of masonry facades. Gypsum efflorescence has been reported in the United Kingdom, the Netherlands and Belgium, with a specific occurrence on masonry facades erected over the last few decades. This article investigates the origin of this recent occurrence of gypsum efflorescence, with accelerated testing of the gypsum efflorescence sensitivity of separate and combined masonry components. It is demonstrated that both brick and mortar may provide a gypsum source, respectively, via the dissolution of anhydrite and the carbonation of ettringite. Neither does however directly result in gypsum efflorescence, as the released gypsum commonly subfloresces below the brick surface. The efflorescence is instead triggered by mortar admixtures, the application of which has indeed risen strongly in recent decades. Avoiding gypsum efflorescence on clay brick masonry hence requires an inert alternative for the mortar admixtures. [ABSTRACT FROM AUTHOR]

We investigated the physico-mechanical properties of mortar mixed with copolymers based on polyvinyl alcohol (PVA) and 2-ethylhexyl acrylate (2-EHA) and synthesized by grafting using ammonium persulfate (APS) as an initiator. Increasing the amount of 2-EHA in the copolymer from 4% to 8% reduced the water/cement (W/C) ratio, the initial and final setting times, and the water absorption of mortar, while it increased its compressive strength. [ABSTRACT FROM AUTHOR]

The mechanical and physical properties of volcanic tuffs from central Anatolian province were investigated for use as admixtures in pozzolanic cement. Five different cement mortar specimens were prepared by replacing cement with volcanic tuff in ratios of 0, 15, 25, 35 and 45% by mass. The flexural and compressive strengths of the specimens were determined at the ages of 7, 28 and 56 d. The effects of the tuff replacement ratio on workability, setting time and volume expansion were also examined. Based on the results, it was concluded that central Anatolian volcanic tuff has pozzolanic activity and is suitable for use as an alternative adherent material in the cement industry. [ABSTRACT FROM AUTHOR]

Addition of the waste tire rubber powder to the cement-based products is a solution for the waste problems and protecting environment. Cement-sand mortar is an integral part of masonry buildings and has an important effect on the integrity of the masonry walls. In the current research, mechanical properties and microstructures of the rubberized mortar have been investigated over various lifetimes and the cement content of the mortar was optimized by Pareto solutions. Portland composite cement (PCC) was used for making the rubberized mortar. The amount of rubber additive to the mortar specimens is considered to be 5%. The cement and water content were the variable parameters in the mixture designs while the ratio of W/C was fixed and equalled to 0.6. The microstructure analysis of the test specimens showed that the adherence of the rubber powder particles in the mortar mixture would be more effective with increasing of the cement content, and the negative effects of using rubber powder on the mortar structure can be minimized by choosing the appropriate mixture design. Also, it shows that by increasing the amount of cement in the mixture design of rubberized mortar, the compressive, tensile and flexural strengths of the mortar would be very close to the plain mortar specimens, and in some cases, the tensile and flexural strength of the mortar specimens would be increased regarding the plain mortar specimens. [ABSTRACT FROM AUTHOR]

Maintenance of the present concrete infrastructure is of great concern, because a great many concrete structures are approaching the end of their service lives. Considerable attention in contemporary research is focused on advanced technologies, such as self-healing processes. One the oldest is the use of crystallizing treatments, which improve the impermeability of the concrete and contribute to prolonged durability. This work deals with the reduction of concrete surface permeability properties by using a repair mortar with a crystallizing admixture for penetrating the concrete. The evaluation was based on the chloride migration test, water penetration test and initial surface absorption test (ISAT). The mortar was polished prior to testing to eliminate the barrier effect of the applied mortar and assess the quality of the penetration. The performed experiments confirmed significant improvement of the surface concrete layer based on all the permeability procedures over time. After a year of the program, the permeability of the treated concrete surface was decreased by approximately by 40%, but the greatest sealing effect was recorded during the first two weeks. [ABSTRACT FROM AUTHOR]

A number of monosaccharides characteristic of plant gums were found in paint layers and preparation layers of samples of Maya mural paintings of 10 archaeological sites located in Campeche and Yucatan regions. This finding opens the question about the deliberate use of these organic polymers as additives for improving workability and mechanical properties in the preparation layer mortar and conferring cohesion to the pigments in the paint layer. The study performed by GC-MS has confirmed the presence, in significant amounts, of a series of monosaccharides, being glucose and mannose between the most abundantly found. Nevertheless, the low amount present in most of the samples hindered the quantification of the relative proportion of monosaccharides necessary for identifying the botanical species of the plant gum. According to the accepted methodology used by Maya artists for preparing painting materials, bark of trees containing plant gums was added to the slaked lime stored in pools and that should be consistent with the notable amounts of glucose, mannose and other monosaccharides forming the skeleton of hemicelluloses and cellulose found in most of the samples. Although organic matter can be present in paint samples exposed to the external environment in Mesoamerican region as result of the microbiological activity, marker compounds characteristic of products resulting from their metabolism were not found in the studied samples. [ABSTRACT FROM AUTHOR]

Graphene oxide is an excellent substrate for pre-concentrating and recovering uranium in water. However, the need for scalable and affordable methods for producing graphene oxide has hindered its field applications. Besides, a sustainable strategy is required to recycle spent adsorbents and prevent them from entering the waste stream. In these contexts, this paper describes the application of graphene oxide aerogel (GOA) produced from graphite through a single-step combustion route for pre-concentrating and recovering uranium in water. The method allows GOA production in bulk quantity at 8–10 times less cost than prevalent Modified Hummer's graphene oxide (HGO). The paper also demonstrates using spent GOA as an active admixture in mortar to improve its mechanical properties. The physicochemical properties of the GOA and mechanistic details of uranium surface bindings were studied thoroughly. GOA showed enhanced uranium adsorption capacity (278 mg/g) compared to HGO due to abundant hydroxyl, carboxyl, and epoxy groups on GOA. However, the presence of HCO 3 − in water reduced uranium uptake due to highly water-soluble uranium-carbonate complexes such as (UO 2) 2 CO 3 (OH) 3 − , UO 2 (CO 3) 3 4 − , and UO 2 (CO 3) 2 2 − . The addition of the spent GOA improved the cement mortar's compressive strength by 15 % compared to the pristine cube and arrested the leaching of residual uranium. The GOA addition and associated enhancement in compressive strength help to save cement and lower CO 2 emissions. In short, the present work addresses the critical challenges of using GOA in pre-concentrating and recovering aqueous uranium, such as bulk production, production cost, and spent materials disposal. [Display omitted] • Affordable and scalable production of graphene oxide aerogel. • A reusable substrate for aqueous uranium pre-concentration and recovery. • The mechanism of removal of uranium by graphene oxide aerogel. • The use of spent graphene oxide aerogel as a valuable cement admixture. • Compressive strength of spent graphene aerogel-modified mortar and uranium leaching. [ABSTRACT FROM AUTHOR]