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The integration of organic wastes into cement-based materials shows promise as a solution to mitigate environmental pollutants. It achieves this by minimizing waste sent to landfills and in some conditions decreasing Portland cement use. One of these organic wastes that produces positive effects when used in cement products is olive seed. In this study, the effect of a new generation bio-polymeric admixture on the physical and mechanical properties of cement mortars is examined in detail. The bio-polymeric admixture is prepared by grinding olive seeds in 0/125 μm sizes. The olive seeds have been used as bio-polymeric admixture in cement mortars at different rates, i.e., 0, 0.2, 0.35, 0.5, 1 and 1.5% of total weight. The olive seed is characterized by XRD, FT-IR analysis and by determining extracts, pectin, cellulose, hemicellulose and lignin content. The characteristics of hydration products were analyzed by SEM/EDS and XRD investigations. Effect of bio-polymeric admixture addition on the unit weight, flowability, setting time, compressive and flexural strength and capillary water absorption was analyzed. The results suggested that the bio-polymeric admixture hindered the cement hydration at low usage rates but promoted at high usage rates. Accordingly, 28 days compressive and flexural strength of test samples decreased. However, 1.5 wt% bio-polymeric admixture was associated with a slight increase of 150-days compressive strength. Bio-polymeric admixture improves the hydrophobicity property of the hardened mortar samples by declining effect on the water absorption. Another important effect of the bio-polymeric admixture contribution was also observed on the flowability property of the cement mortars. As the bio-polymeric admixture increased, the flow diameter values of the mortar were also significantly increased. The research outcomes suggested for the first time the beneficial effect of bio-polymeric admixture as a natural and bio-degradable alternative of chemical admixtures on especially flowability, set retarder and hydrophobicity of cement mortars with comparable mechanical properties. [ABSTRACT FROM AUTHOR]

A water-soluble ternary copolymer bearing carboxyl, sulfonic, and amide functional groups was synthesized using ammonium persulfate-catalyzed free radical polymerization in water, resulting in high monomer conversion. This copolymer was then complexed with aluminum sulfate, forming an admixture containing Al(SO4)(OH)·5H2O, which was subsequently combined with silica gel. Characterization revealed that the synthesized copolymer formed a large, thin membrane that covered both the aluminum compounds and the silica gel blocks. The introduction of this complex admixture, combining the copolymer and aluminum sulfate, not only reduced the setting times of the cement paste but also enhanced the mechanical strengths of the mortar compared to using aluminum sulfate alone. The complex admixture led to the formation of katoite, metajennite, and C3A (tricalcium aluminate) in the mortar, demonstrating significant linking effects, whereas pure aluminum sulfate could not completely transform C3S within 24 h. Further addition of silica gel to the complex admixture further shortened the setting times of the paste, slightly reduced compressive strength, but improved flexural strength compared to the initial complex admixture. The silicon components appeared to fill the micropores and mesopores of the mortar, accelerating cement setting and enhancing flexural strength, while slightly decreasing compressive strength. This study contributed to the development of new cementing accelerators with improved hardening properties. [ABSTRACT FROM AUTHOR]

Sustainability is becoming increasingly pivotal in the construction industry, prompting a shift toward the use of bio-sourced waste materials. This study presents a novel application of mint stem (MS) waste as an additive in mortar with the aim of harnessing its cellulosic nature to enhance thermal insulation. The mineralogical and chemical properties of the raw materials were examined to understand their inherent characteristics and suitability for mortar composite development. The modified mortars were subjected to thermal and mechanical evaluations with MS proportions up to 6% by cement mass. The hot disk method revealed a substantial reduction in thermal conductivity (over 50%), whereas compressive strength testing indicated a decrease with higher MS content. The water absorption increased slightly, implying changes in porosity. These findings suggest that MS can play a significant role in the development of energy-efficient building materials, despite trade-offs in mechanical strength. This study discusses the implications of these results for sustainable construction and the potential of MS-enhanced mortar. [ABSTRACT FROM AUTHOR]

This study investigates the potential of Layered Double Hydroxides (LDH) as additives to improve the durability and physical properties of cement-based mortars, with a focus on freeze-thaw resistance. Three LDH types—MgAl-LDH, CaAl-LDH, and ZnAl-LDH—were synthesized and incorporated into mortar at a 1/1000 w/w ratio. X-ray diffraction (XRD) and wavelength dispersive X-ray fluorescence spectroscopy (WDXRF) were used to characterize the LDHs, and the effects of the additives on mortar density, water absorption, and durability under 30 freeze-thaw cycles were examined. Results revealed that MgAl-LDH provided the best freeze-thaw resistance, likely due to its smaller crystallite size and enhanced cement hydration. CaAl-LDH offered moderate improvements, while ZnAl-LDH negatively impacted the mortar's mechanical integrity, leading to higher degradation. The study demonstrates the potential of LDH additives—particularly MgAl-LDH—in improving the durability of cementitious materials, although further optimization is required to enhance long-term performance and resistance to environmental stresses. [ABSTRACT FROM AUTHOR]

With the growing global concerns regarding sustainable development in the building and construction industries, concentration only on the engineering properties of building materials can no longer meet the requirements. Although some studies have been implemented based on the lifecycle assessment of lightweight cement-based materials, very few attempts have been made pertaining to multi-criteria optimization, especially when fly ash cenospheres are used as lightweight aggregates and nano additives are incorporated as modifying admixtures. This investigation utilized cenospheres as fine aggregates to produce green, sustainable, lightweight cement mortar. Multi-walled carbon nanotubes at 0.05, 0.15, and 0.45% were binarily added, together with 0.2, 0.6, and 1.0% of nano silica to improve the mechanical performance. Strength tests were conducted to measure the flexural and compressive behaviors, combined with a cradle-to-gate lifecycle assessment and direct cost analysis to assess the environmental and economic viability. Integrated indexes and the TOPSIS method were adopted to systematically evaluate the mortar mixes and determine the optimal mix. The outcomes show that nano additives worked synergically to enhance the mechanical properties of the mortars. The utilization of cenospheres effectively reduced environmental impacts and improved economic feasibility. Nano additives significantly affected the sustainability and economic viability; in particular, the utilization of multi-walled carbon nanotubes increased the material costs. To minimize the impact of the price of multi-walled carbon nanotubes, it is proposed to binarily use less expensive nano silica. In the multi-parameter optimization, the mix with 0.05% multi-walled carbon nanotubes and 0.02% nano silica was recommended to be the optimal mix. [ABSTRACT FROM AUTHOR]

For thousands of years, mortar-based materials — including bedding mortars, plaster floors, internal wall plasters, external wall renders and stuccos, and concrete — have been key construction materials in many cultures throughout the world. This paper gives an overview and examples of the use and development of mortar-based materials in cultures across the Middle East, Europe, Asia, and Mesoamerica, prior to the development of hydraulic cements in the late 18th and early 19th centuries. [ABSTRACT FROM AUTHOR]

The main objective of this study was to determine the impact of glass waste as a valuable additive in cement mortars. As part of this study, three mortars with different glass waste contents were designed with the addition of 10, 20, and 30% glass waste, as well as a reference mortar without the additive. The selected characteristics of the mixtures were determined, including the consistency, density, air content, and strength properties of the mortar. Strength tests (bending and compressive strength) were performed after 28 and 56 days of maturation. Mortars with the lowest waste content (MC10%) achieved flexural strength of 26% and compressive strength of 18% compared to the average value of standard mortar, whereas MC20% mortars showed a decrease in bending strength of 30% and compressive strength of 24%. Studies have also been conducted to determine the parameters of air trapped in the mortar microstructure and its possible impact on mortar durability in a freezing/thawing environment. A group of experimental studies involved microstructure studies aimed at assessing the changes that occur in mortars containing glass waste. The negative effects of glass waste on the compressive and bending strengths and the positive effect at low temperatures were clearly demonstrated. [ABSTRACT FROM AUTHOR]

In the article, the authors presented the results of research on the assessment of the effect of selected mineral additives on the strength properties of the standard mortar. The modification of the composition of the standard mortar made on the basis of CEM I 42.5R cement and quartz sand consisted of using seven selected mineral additives in the form of compacted microsilica, Mikrosill microsilica, limestone flour, glass flour, glass granulate, basalt flour, and fly ash in the amounts of 10 and 20% in relation to cement as its substitute. Reducing the share of cement in the standard mortar by 10% has a beneficial effect on improving the compressive strength by over 40% with the addition of microsilica, and in the case of bending strength, even by 10%. [ABSTRACT FROM AUTHOR]

In this study, the effect of ulexite substitution in cement mortar and its physical and mechanical properties on cement mortar properties were investigated. First of all, the pozzolanic activity of the ulexite material was determined. Then, cement mortars with ulexite additives at different rates (0.5%, 1%, 2%, 4%); Specific gravity, specific surface, setting start and end times, consistency and expansion tests, as well as 7 and 28 days flexural and compressive strength of the mortar samples were determined and compared with the control sample. As a result of the study, with the increase of the ulexite substitution ratio, the set start and set expiration times were extended, and all of the ulexite-substituted cement mortars provided the lowest mechanical strength required in related standard. It was observed that the cement mortars with 0.5%, 1%, 2% ulexite substituted cement mortars exceeded the reference sample and the best replacement rate was in the mortars with 0.5% replacement. However, depending on the increase in the ulexite substitution ratio, a decrease in mechanical strength was detected among themselves. According to the results obtained from the thermal conductivity tests, the thermal conductivity values of the cement mortars decreased with the ulexite substitution. Depending on the ulexite substitution rate, the thermal conductivity value decreased by approximately 50%. The lowest thermal conductivity value was measured in the test sample with 4% ulexite substitute. [ABSTRACT FROM AUTHOR]

This study aimed to comprehensively investigate the properties of a binder based on high-calcium fly ash and silica fume with a complex additive consisting of calcium nitrate and magnesium chloride. The strength characteristics, the characteristics of the hydration process, and the phase composition of the hydration products of the binder were investigated. Silica fume was used to suppress the expansion of fly ash during hydration. A complex additive (CA) consisting of Ca(NO3)2 and MgCl2 provided a higher strength of binder than each of these salts separately. When testing a mortar with sand, the CA additive ensured that the strength of the specimens was 43.5% higher than the strength of the mortar with the addition of Ca(NO3)2 and 7.5% higher than the strength of the mortar with the MgCl2 additive. Calcium nitrate greatly accelerated the process of heat release in the first 60 min of binder hydration, and subsequently, conversely, slowed it down. The addition of MgCl2 gave a significantly greater thermal effect than Ca(NO3)2. When the two salts acted together, even a small fraction of magnesium chloride (0.2 of CA) compensated for the retarding effect of calcium nitrate and provided heat release for the binder that was almost as good as that of MgCl2. [ABSTRACT FROM AUTHOR]

In this study, experimental and numerical investigations were conducted to examine the time-dependent creep and earthquake performance of the historical Plaka stone bridge, which was constructed in 1866 in Arta, Greece. During the original construction of the bridge in 1866, Khorasan mortar with an egg white additive was used between the stone elements. Furthermore, when the bridge underwent restoration in 2015, Khorasan mortar with an eggshell additive was employed between the stone elements. Consequently, two distinct 3D finite-difference models were developed for this study. In the first bridge model, egg white was used in the Khorasan mortar, replacing water at various proportions of 0%, 25%, 50%, 75%, and 100%. In contrast, for the second model, eggshell was incorporated into the Khorasan mixture at percentages of 25%, 50%, 75%, and 100%, relative to the lime amount. Subsequently, the mortars were subjected to curing periods of 1 day, 7 days, and 28 days, and their mechanical properties were determined through unconfined compression strength experiments. Taking into account the determined strengths of the mortars, the kn and ks stiffness values of the interface elements between the stone elements and Khorasan mortar were calculated. In the 3D model, each stone element was individually represented, resulting in a total of 1,849,274 stone elements being utilized. Non-reflecting boundary conditions were applied to the edge boundaries of the bridge model, and the Burger creep and Mohr–Coulomb material models was employed for time-dependent creep and seismic analyses, respectively. Subsequently, time-dependent creep analyses were conducted on the bridge, and seismic events that occurred in the region where the bridge was located were simulated to assess their impact. Based on the results of the time-dependent creep and seismic analyses, we observed that the use of 50% eggshell-mixed Khorasan mortar between the stone elements had a positive influence on the earthquake and creep behaviors of both restored and yet-to-be-restored historical bridges. [ABSTRACT FROM AUTHOR]

Crystalline admixture (CA) is an effective self-healing agent for mortar. However, the effects of crack parameters (i.e. crack width and cracking age) and the service environment on the self-healing behavior of CA-containing mortar are not well understood. Herein, the self-healing behavior of mortar containing a self-developed CA was assessed by testing strength recovery, impermeability recovery, and crack closure in pre-cracked specimens. Three initial crack widths (0.2, 0.3, and 0.4 mm), five cracking ages (3, 7, 14, 28, and 56 days), and four external exposure conditions (humidity chamber, air exposure, water immersion, and wet-dry cycles) are investigated. Furthermore, the influence of different external conditions on the healing products at the region of crack and the pore structure of hardened paste containing CA are studied. The results show that adding 4.54% CA into mortar allows rapid healing of 300 μm-wide cracks. Although wider cracks (400 μm) are more difficult to heal, the sorptivity coefficients of the mortars with 400 μm-wide cracks after healing decrease. When the cracks are produced at an earlier age, the pre-cracked specimens have higher recovery ratios of strength and impermeability after healing, and the specimens pe-cracked at a later age still have acceptable compressive strengths after healing. The analysis shows that the strengths and impermeabilities of pre-cracked mortars containing CA exposed to the four external conditions are all recovered. The best self-healing performance is observed for the specimens exposed to water immersion and wet-dry cycles conditions. Somewhat less good self-healing was observed in the specimens exposed to humid chamber condition, while the worst self-healing performance was in the specimens exposed to air exposure condition. This study provides a theoretical basis for the application of novel CAs in cement-based materials. [ABSTRACT FROM AUTHOR]

The scientific identification of organic additives in plaster and mortars has become an appropriate principle in the preparation of compatible repair material. Besides the need to characterise inorganic components, the conservation of mural art is facilitated by the unabridged documentation of organic components particularly mixed in ancient decorative mud/lime plasters support. The review addresses the influence of organic additives in the historic artworks and analytical methods used for their investigation. The paper has considered, the various plant-based organic additives recommended by ancient Indian texts like the Vishnudharmottara purana, Samaranga sutradhara, Silparatna etc., which have been documented and reported. With regard to the mentioned historical texts, plant-based products such as fermented juice, gum, fibres, straw, husk, resin etc., were used as organic additives for the preparation of wall plaster which provides disparate attributes to the plaster thus making it crack free, durable, antioxidant, antibacterial and insect-resistant. Furthermore, the recently reported destructive and non-destructive characterisation techniques based on chromatography, spectroscopy, ionization, and microscopy have also been described here. The mentioned techniques contribute as a fundamental tool to identify proteins, polysaccharides, fatty acids, resinous materials, starch, plant product etc., extracted from the mud/lime plasters and mortars. [ABSTRACT FROM AUTHOR]

Supplementary cementitious materials (SCMs) have been used in the construction industry to mainly reduce the greenhouse gas emissions associated with Portland cement. Of SCMs, the petrochemical industry waste known as fluid catalytic cracking catalyst residue (FCC) is recognized for its high reactivity. Nevertheless, the binders produced using SCMs usually present low mechanical strength at early curing ages. This study aims to assess the effect of different accelerating additives (KOH, sodium silicate SIL, commercial additive SKR) on the mechanical strength of mortars containing FCC. The results show that after only 8 curing hours, the compressive strength gain of the FCC mortars containing SKR was over 100% compared to the FCC mortar with no additive (26.0 vs. 12.8 MPa). Comparing the compressive strength of FCC mortar containing SKR to the control mortar, the enhancement is spetacular (6.85 vs. 26.03 MPa). The effectiveness of the tested accelerators at 8–24 curing hours was KOH ≈ SIL < SKR, whereas it was KOH < SIL < SKR for 48 h–28 days. The thermogravimetric data confirmed the good compatibility of FCC and the commercial accelerator. [ABSTRACT FROM AUTHOR]

Ancient Chinese architecture drawing is a unique form of ancient Chinese art. Porcine blood hydrogels are distinctive ingredients used to prepare the composite material of the substrate layer for architecture drawing. This investigation was focused on the mechanism for porcine blood hydrogel formation. Based on the traditional Chinese recipe for the preparation of porcine blood-lime mortar, samples with different ratios of porcine blood and lime water were prepared, and the molecular-scale interactions between the lime water and proteins in the porcine blood were examined with FTIR spectroscopy, Raman spectroscopy, XRD, XPS, fluorescence spectroscopy, contact angle and rheology studies. The mechanical properties and morphological features of the samples were detected with a rheometer, universal material testing machine and SEM. The results indicated that an appropriate amount of lime water was required for gelation of the porcine blood. With the appropriate alkalinity, sufficient carboxyl groups on the fibrin chains were deprotonated, and coordination with Ca2+ ions formed enough cross-links for support networks within the structure of the porcine blood hydrogel. Complexation of deprotonated carboxyl groups on the fibrin chains with Ca2+ ions led to the formation of a hydrophobic surface due alterations of the fibrin conformation and increased the adhesive properties of the hydrogel. With the hydrogel used as an ingredient in the preparation of a substrate layer composite, it is suggested that the hydrophobic surface of the hydrogel facilitated mixing with hydrophobic tung oil during preparation of the composite material, and strong adhesion of the hydrogel increased the mechanical strength and crack resistance of the substrate layer. [ABSTRACT FROM AUTHOR]

The swiftness in the speed of construction work is the present scenario's need to meet the infrastructure demand due to rise in industrialization and urbanization. Various admixtures are being used to produce mortar/concrete with acceleration in stiffening of cement composites and requisite strength at early age. However, due to industrialization, the generation and dumping of stone wastes in different forms from stone industries has become menace to the ecosystem. To overcome their ill effects, a possible solution can be reuse of these wastes into the construction sector as it can absorb huge waste. This study used stone slurry powder as cement substitution; calcium nitrate and triethanolamine as additives in different proportions individually and in combination to investigate their practicality in cement mortar. The environmental assessment of additives in mortar mixes was also carried out along with the microstructural analysis. Results demonstrated that water cured specimens had higher compressive strength and air cured specimens had higher electrical resistivity values. The stone powder was predominant among all additives in the performance enhancement in terms of strength, chemical resistance and environmental assessment of mortar mixes as compared to other additives. [ABSTRACT FROM AUTHOR]

This study explores the efficacy of a sacrificial anode cathodic protection (SACP) system with an activated carbon-based conductive mortar in bridge structures. In the previous Part 1 study, various admixtures were compared to identify a conductive mortar for enhancing the performance of the SACP system, assessed through electrical conductivity, resistivity, cathodic protection (CP) potential and current, and 4 h depolarization potential. Part 2 extends the investigation by applying the developed conductive mortar containing activated carbon to an SACP system on an actual bridge structure in which corrosion has already been initiated. Before CP installation, the physical properties of the conductive mortar were evaluated to satisfy the standard requirements for concrete structure maintenance. Subsequently, zinc mesh and bulk anodes were installed on the bridge pier, followed by the application of a conductive mortar with an admixture ratio of 5%. Over a four-year period, performance was measured through regular 4 h depolarization potential checks and visual inspections. The SACP system with the conductive mortar demonstrated superior CP performance compared to the general mortar, confirming the effectiveness of the developed conductive mortar. Visual inspection after four years confirmed the workability of the SACP system with conductive mortar. [ABSTRACT FROM AUTHOR]

Biodeterioration may take place due to the influence of microorganisms, leading to the deterioration or destruction of materials. This process involves distinct mechanisms of material breakdown, such as mechanical damage, decomposition, corrosion induced by microorganisms, and fouling caused by living organisms. Research and literature data on biological corrosion of polymer-modified cement materials (polycarboxylate resin) are ambiguous and even contradictory. Samples, 20x20x160 mm in size, made of cement-polymer mortar with 5% polycarboxylate resin were prepared for the test, with 6 specimens for each determination. The study determined the level of contamination of the material, using the culture method and COD, after 18 months of exposure to Penicillium and Cladosporium fungi. In addition to this, bulk moisture content, water absorption, flexural strength and internal structure were determined using a scanning microscope and EDS analysis was carried out. The beneficial role of polymers has been demonstrated, e.g. by sealing the structure of cement-polymer materials. However, there is also an increased development of biocorrosion associated with organic material as a food source, especially for molds that colonize materials in favorable conditions. The test results showed that there was a strong growth of mold fungi on the material and the mass humidity was high. However, the strength increased slightly, and after further exposure to a corrosive environment it decreased again. [ABSTRACT FROM AUTHOR]

This research primarily delves into a comprehensive investigation concerning the synergistic effects of fly ash (FA) with yellow pigment (YP) and red pigment (RP) in the workability, physical characteristics, and mechanical properties of colored mortars, both pre-and post-exposure to high temperatures. Within the experimental design, FA was employed as a 20% substitute for cement, while YP and RP were systematically incorporated into the cement mixtures at varying concentrations (1%, 3%, and 5% by weight). The specimens underwent controlled exposure to high temperatures, ranging from 300 °C to 800 °C. This study's outcomes unveiled that while the introduction of FA positively influenced mortar workability, including YP and RP adversely impacted spreading diameters (SD), resulting in a discernible reduction in overall workability. Despite these effects, FA emerged as a pivotal factor to enhancing the residual compressive strength (RCS) and residual flexural strength (RFS) of the colored mortars. For instance, after 90 days at 800 °C, the control concrete (R0) exhibited a notable 66.13% decrease in RCS, and the sample solely incorporating FA (R1) demonstrated a reduced reduction of 55.39%. Similarly, mortars with YP additives (R2–R4) and RP additives (R5–R7) showcased RCS reductions within the range of 53.32% to 55.12% and 54.51% to 56.04%, respectively. [ABSTRACT FROM AUTHOR]

Crystalline coatings are waterproofing systems used for additional protection against increased moisture and subsurface water ingress. Even though these crystalline materials are commonly used in moisture-protective systems, they have not yet been sufficiently scientifically described. The weakest link in the chain of interaction between crystalline coatings and underlying concrete is the transition zone. To increase knowledge of the interaction between these materials, a series of experiments was prepared using a specially formulated protective mortar as the final surface layer, with the function of additionally waterproofing the structure. An experimental study of the adhesion of surface layers based on secondary crystallization to provide additional protection to concrete structures loaded with moisture or ground water exposure is presented in this paper. The series of experiments carried out consisted of an analysis of protective crystalline mortar adhesion to concrete samples of identical composition. A set of experimental measurements under the influence of various boundary conditions was carried out to determine the bond strength between two different materials. For the experimental measurements, the materials were exposed to aggressive environments for which durability verification had not yet been performed. A modified protective mortar with crystalline admixture was used as an overlayed material. This mortar worked similarly to a crystalline coating after application. Over time, there was penetration of the underlaying concrete and a secondary hydration of the cement matrix which resulted in the waterproofing of the structure. The test samples were exposed to aggressive environmental conditions in the form of freezing–thawing cycles and a carbonation process. Pull-off tests were carried out on every test sample to determine the strength of the surface layers. The penetration of the crystalline agent into the base concrete was confirmed with an SEM observation. The results of the experimental program showed that exposure to the aggressive environment further reduced the strength of the modified mortar containing the crystalline admixture. However, the bond strength between the concrete and the modified mortar exceeded the tensile strength of the concrete. [ABSTRACT FROM AUTHOR]

One of the ways to modify selected parameters of lime mortars is the use of biopolymers of animal origin, such as bone glue, skin glue, bovine blood, eggs, and casein. These are protein-based biopolymers. Casein is an example of an organic polymer produced from cow's milk. The aim of the work was to investigate the possibilities of improving selected properties of mortars based on hydrated lime and metakaolin. The mixture was modified with powdered technical casein in amounts of 0.5%, 1.5%, 1%, 1.5%, and 2% as a partial mass replacement for the binding mixture. Additionally, the influence of increasing the amount of water on the properties of the mortar with a casein admixture of 2% was checked. This study examined consistency, shrinkage, water absorption, capillary action, porosity, flexural, compressive strength, and Young's modulus. The admixture of casein influenced the properties of the mortar, but not in all cases, and it was possible to determine a clear trend related to the variable amount of casein. Strength properties deteriorated as the amount of casein increased. When air bubbles were introduced into the mortar after the casein was dissolved, the porosity increased as the amount of admixture increased. The moisture properties improved; namely, casein led to a reduction in water absorption and water absorption caused by capillary action. No relationship was observed between the amount of casein and the drying shrinkage. Increasing the amount of water in the mixture led to the expected effects, i.e., an increase in porosity, shrinkage, and water absorption, and a decrease in mechanical strength. [ABSTRACT FROM AUTHOR]

In this work, the effect of cellulose ether (CE), tartaric acid (TA), and polycarboxylate superplasticizer (PCE) on the working performance and mechanical properties of cement-based self-leveling mortar is investigated. According to the orthogonal experiment analysis, TA is identified as the most influential factor affecting the working performance, as indicated by factors such as fluidity, fluidity loss, and viscosity. Upon conducting a comprehensive assessment of the working performance and mechanical properties, the optimal parameters are found to be CE = 0.6 wt.‰, TA = 0.5 wt.‰, and PCE = 2.0 wt.‰. A univariate test highlights that that the working performance improves with the higher TA dosages. Specifically, the exponential reduction of fluidity loss corresponds with an increased TA content. Regarding the mechanical properties of cement-based self-leveling mortar, the compressive and flexural strength exhibit enhancement when the TA dosage remains below 0.4 wt.‰ at the early stage, implying that TA has some influence on the hydration process. Impressively, the 1 d compressive and flexural strengths surpass 7 MPa and 2 MPa, respectively, ensuring the viability of subsequent construction activities. Through an analysis of hydration heat, the effect mechanism of TA on the cement-based self-leveling mortar is derived. The result shows that the addition of TA decelerates the hydration process within the initial 10 h, followed by acceleration in the subsequent 20 h to 30 h. Consequently, this delayed formation of the early hydration product, ettringite, contributes to a more porous structure in the slurry, with low friction leading to a better working performance. A large number of hydration products, such as alumina gel and calcium–silicon–hydrate gel, presented in the hardened paste results in the good mechanical properties at 1 d. This study may lay a foundation for the optimization of the dosage of chemical admixtures in the self-leveling mortar and high-performance cement-based materials, and also impart valuable insights for practical applications extending to the realm of building construction and decoration. [ABSTRACT FROM AUTHOR]

• A series of semi-quantitative analytical procedures are proposed for the characterization of organic additives in ancient lime mortars and can be a preliminary screening method for further lab analysis. • The use of a microplate spectrophotometer reduced the detection limit by two orders of magnitude and decreased the sample consumption to 0.2 g for the detection of seven organic substances. • Twelve samples of ancient mortar from the Forbidden City in Beijing were analysed using the test procedure. To improve the performance of lime mortar, ancient craftsmen often added various additives to mortars, including inorganic and organic materials. The analysis of mortar additives plays an important role in the conservation and restoration of historical buildings. However, it is quite difficult to accurately identify the species of additives. This paper proposed a series of semi-quantitative analytical procedures to identify the organic additives in ancient lime mortars. By using reagents such as phenolphthalein, periodic acid, acetylacetone, anthrone, bicinchoninic acid (BCA), iodine-potassium iodide, chloramine T, etc., organic additives such as triglyceride, soluble sugar, starch, and protein (including blood, gelatine, and other unknown proteins) remaining in ancient lime mortar were accurately detected, respectively. The linear relationship of the standard curve was significant, and the detection limits for the target additives were below 7 µg/mL. The process is easy to operate within 6 h, and it is suitable for rapid in-situ testing. [ABSTRACT FROM AUTHOR]

The possibility of using composite fibers with phase change properties as a thermoregulating additive to dry building mixes (mortar mix) with the possibility of accumulating thermal energy under the action of sunlight and a high-frequency alternating magnetic field is studied. Composite fibers were obtained by adsorption of the organic phase-change material eicosane on fibers of microfibrillar cellulose modified with magnetite nanoparticles. The obtained composites demonstrated specific values of stored thermal energy in the range of 129-148 J/g, depending on the content of eicosane in their composition. It is shown that the addition of 10–15% wt. of composite fibers to the dry building mix makes it possible to store and release thermal energy in hardened samples in a temperature range of 27-43°C, corresponding to melting and crystallization of the eicosane in the structure of the composite fibers. It was shown that addition of the composites affects the dynamics of heating under the action of artificial sunlight and subsequent cooling: the samples with added fiber showed more intense heating and slower cooling compared with control samples when the temperature reached 35°C. Samples of the hardened mixture with addition of the composite fibers also exhibited the ability to accumulate thermal energy when exposed to a high-frequency alternating magnetic field with its subsequent sustained removal. [ABSTRACT FROM AUTHOR]

Nano-black carbon (NC) and partially de-aluminated kaolinitic clay (PDK) composite blend was investigated as an additive to mortar fabrication for improving of the compressive strength. PDK was obtained from aluminum sulphate of Egypt (ASCE). PDK was grounded with nanocarbon. PDK achieved a good pozzolanic activity, it reached 120 %. The experimental protocol included chemical and physical properties of the PDK/Nano-carbon (NCPDK) and the produced mortars. The effect of five weight ratios of NCPDK (0, 5, 10, 15 and 20 %) on the properties of the formed OPC mortars was investigated. Each ratio was tested with three contents of Nanocarbon (1, 2 and 3 %) by weight. The accelerating effect of NCPDK was clear on the initial setting time whereas it reduced by about 31 % and the final setting time reduced by 23 % at 10 % NCPDK. The reduction in the initial flowability of OPC mortar reached 2.7 and 6 % for 10 and 20 % replacement respectively of the OPC by NCPDK and After 60 minutes from mixing, the relative flowability loss was 68 % at 10 % NCPDK and 88 % at 0 % replacement. The compressive strength values of the produced mortars ranged between 46.2 and 50.7 MPa (EN 196-1), with a maximum improvement equal to 14.4 % using 10 % NCPDK. There was no significant change in the pH values of the mortar mixtures. According to the obtained results the composite NCPDK can be used as an additive material in mortar fabrication. The structure of the hardened mortar modified with 10% NCPDK was investigated by XRD, FTIR and TGA that assured formation of more CSH. Incorporation of Nano-carbon enhanced the compressive strength. [ABSTRACT FROM AUTHOR]

The influence of the components of plaster mortars on their properties is considered in a lot of studies at a qualitative level without searching for optimal compositions of these multicomponent composite materials. The purpose of this study was to obtain the experimental–statistical models based on the results of the designed experiment, allowing the influence of light fillers and polymer admixtures on the properties of the mortars to be evaluated and analysed; the compositions complying with specified requirements and compromised optimally by a number of properties should be found. The quantities of fine limestone and perlite as well as of the hydroxyethyl methyl cellulose and dispersible polymer were varied in the experiment. The effective viscosity and thixotropy of the mix, compression, tensile, adhesive strength, frost resistance, and density of hardened mortars were determined for 18 compositions according to the experiment design. The obtained models have allowed the individual and synergetic effects of mix components to be evaluated. The fine perlite has turned out to have the greatest positive effect on the properties. This porous filler increases the strength while decreasing the density of the mortars. It is shown how the composition complying with specified requirements—and the best based on several properties—has been found. [ABSTRACT FROM AUTHOR]

Absolute dating of plasters and mortars clearly represents a key information to study important structures and buildings that may have undergone a difficult story starting from their construction. This is for instance the case of the architectures in the archaeological site of Hierapolis (Denizli, Turkey). However, when discussing about the possibility to apply radiocarbon (14C) dating, in this site the presence of different sources of contaminants, due to the geological and geochemical conditions and to the used raw materials, prevents the binder dating. As an alternative, we thus decided to focus on the small fragments of straw that had been used as additives in the mortar/plaster matrices. The fragments were identified, selected and dated using a 14C experimental set-up specifically optimized for microgram-sized samples. The obtained results were satisfying, even though the measured 14C ages also pointed out some possible criticalities in dating such small samples collected from a carbonaceous matrix. [ABSTRACT FROM AUTHOR]

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This study presents the results of laboratory experiments conducted to determine the mechanical parameters for cement mortar with various quantities of waste fibers, polypropylene microfibers, and steel microfibers. Waste fibers were used as samples and obtained using an end-of-life car tire recycling process. For comparison, samples with the addition of steel and polypropylene microfibers were tested. The same degrees of fiber reinforcement were used for all types of fibers. Ultimately, 22 mixtures of cement mortar were prepared. The aim of this study is therefore to present and compare basic mechanical parameter values. Compressive strength, flexural strength, fracture toughness, and flexural toughness were of particular interest. A three-point bending test was performed on three types of samples, without a notch and with a notch of 4 and 8 mm. The results show that the use of steel microfibers in the cement mortar produces a product with better properties compared to a mixture with steel cord or polypropylene fibers. However, the cement mortar with the steel cord provides better flexural strength and greater flexural toughness factors compared to the cement mortar with polypropylene fibers. This means that the steel cord is a full-value ecological replacement for different fibers. [ABSTRACT FROM AUTHOR]

Babassu carbohydrate fibers (BCF) are abundant and renewable materials that are currently underutilized. The present work evaluates the use of alkaline-treated BCF (TF − 0.6, 1.0, 1.4% w/w) as additive to cementitious mortars. Mass consistency, specific mass, water absorption, void ratio, and porosity, as well as compressive and indirect tension fracture strengths, were evaluated and compared to control mortars (without fiber addition). The results confirmed that the treated BCF can be an effective alternative as a potential reinforcement in cementitious composites. Furthermore, they are prepared by an alkaline treatment that is easy to operate, cost-effective, and efficient. The addition of BCF to the cement matrix decreased the water absorption capacity and void ratio, whereas increased compressive and tensile strength compared to mortars prepared in the absence of BCF. In particular, the addition of 1.0% of TF increased the compressive strength by up to 77%. Good interfacial adhesion of the alkaline-treated BCF with the rest of mortar components resulted in an increase in the values of mechanical properties. The studied fibers are potential materials for new sustainable mortars with improved properties. [ABSTRACT FROM AUTHOR]

Vegetable oils (e.g. linseed or tung) were used as lime mortar admixtures in order to increase the mortar durability (due to the water repealing effect) and/or to prolong the mortar's workability. The present paper aims to investigate the possibilities of thermal analysis to estimate the linseed oil content in a historic mortar. A set of model mortars containing Ca(OH)2, CaCO3 and variable amount of linseed oil was studied by methods usually used for mortars characterization: thermogravimetry with evolved gas analysis by mass spectroscopy (TG EGA-MS), FTIR spectroscopy (Fourier transform infrared spectroscopy) and XRD (powder X-ray diffraction). Oil admixed in lime mortar undergoes two principal transformations: saponification to Ca carboxylates and polymerization (drying). The products of the oil transformation are thermally decomposing during the thermal analysis experiment, but unfortunately in the same temperature range as Ca(OH)2—common mortar component—does. A calculation procedure which enables to determine content of both Ca(OH)2 and "oil products" on base of thermogravimetry was proposed. As an alternative, an estimation of oil content based on EGA-MS results for m/z 95 ion was developed. Finally, total organic carbon (TOC) may be also used if any other organics are not present. These three approaches were used for the oil content estimation in the sample of historic mosaic mortar. The result obtained by TG EGA-MS approach was found to be the most realistic. [ABSTRACT FROM AUTHOR]

The best known and effective methods for the reduction of the negative effects of an alkali–silica reaction in concrete include the application of mineral additives with an increased aluminium content and reduced share of calcium, as well as chemical admixtures in the form of lithium compounds. Because both aluminium and lithium ions increase the stability of reactive silica in the system with alkalis, it is possible to presume that the application of both corrosion inhibitors together will provide a synergistic effect in the ASR limitation. The paper presents the results of studies on the influence of combined application of metakaolin and lithium nitrate on the course of corrosion caused by the reaction of opal aggregate with alkalis. The potential synergistic effect was studied for the recommended amount of lithium nitrate, i.e., the Li/(Na + K) = 0.74 molar ratio and 5%, 10%, 15%, and 20% of cement mass replacements with metakaolin. The effectiveness of the applied solution was studied by measurements of mortars expansion in an accelerated test, by microstructure observations, and by determination of the ASR gels composition by means of SEM-EDS. The influence of metakaolin and the chemical admixture on the compressive and flexural strengths of mortars after 28 and 90 days of hardening were also analysed. The results of the studies revealed a synergistic effect for mixtures containing metakaolin at 15% and 20% cement replacement and lithium nitrate admixture in alkali–silica reaction expansion tests. It was found that corrosion processes in mortars with 5 and 10% levels of metakaolin became more severe after adding a lithium admixture to mortars with metakaolin only. The obtained results were confirmed by observations of the mortars' microstructures. There was no synergistic impact of lithium nitrate and metakaolin on compressive strength characteristics. The compressive strength of mortars containing a combination of metakaolin and lithium nitrate decreased both after 28 and after 90 days, compared to mortars with metakaolin alone. [ABSTRACT FROM AUTHOR]

Copyright of New Building Materials / Xinxing Jianzhu Cailiao is the property of New Building Materials Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper aims to analyze and evaluate the function of two types of ancient mortars in the bathhouse at al-Muwaqqar archaeological site in Jordan to promote the awareness level of cultural heritage conservation of ancient buildings and mortars in Jordan. The conservation of archaeological structures requires a thorough characterization and identification of the mortar components before carrying out the restoration, after the preserved results, and during the restoration process to decide how it responds. This work creates an experimental contribution through FTIR to study the influence of organic components on the mechanical performance of the mortar. The application of new techniques in terms of sustainability and compatibility is nowadays more and more important to preserve historical monuments, especially in the context of the increasing damage to the mortar joints in the al-Muwaqqar site. The paper presents new results concerning the identification of the binding materials of mortars, especially the organic parts as egg white or other organic components used in the bathhouse to connect the mosaics, and the collection of further information for compatibility challenges. The results will provide a new pioneering approach application in Jordan in the field of ancient restoration using mortar. The study concludes that it is easy to identify all the organic components of the mortar using Fourier Transform Infrared spectroscopy (FTIR) in the different bands of the organic material supported by thermogravimetric analysis TGA/SEMEDX. The investigations of both methods have provided accurate information about the technology of mortar production and have indicated a proteinaceous additive in the mortar. [ABSTRACT FROM AUTHOR]

Although biosorption is an effective technique for removing potentially toxic elements (PTEs) from wastewater, it causes secondary pollution in the form of used adsorbents ending up in landfills, leading to PTE leaching into groundwater. This study used two kinds of adsorption process waste ash - adsorbed paper ash (APA) and adsorbed mulch ash (AMA)- as an additive to mortar, which added an environmental and economic value through energy recovery during the ashing process following the ideas of the waste to energy and circular economy, in addition to immobilizing the PTEs into a cement matrix aiming to close the loop of pollution. This study focused on investigating the leaching of PTEs (Cd, Zn, Cu, and Pb) at five different artificial adsorption initial concentrations (0.5, 1, 5, 10, and 50) mg/L and three different mixing weight proportions of ash with cement, as well as their pH-dependent behavior, to ensure environmental safety. To detect the release of PTEs from the mortar ash mixes, the ICP-OES technique was used. The study concluded that the used adsorbent ashes potentially could be environmentally acceptable as an additive for mortar because their ability to stabilize PTEs based on leaching values of (Pb, Zn, and Cu) was below the permissible limit under the nonhazardous waste category. Only Cd leached higher than the regulatory limit in the case of very low acidity when pH was lower than 0. [ABSTRACT FROM AUTHOR]

Many engineering problems are caused by the destruction of cement-based materials through the combination of salt mixtures and freezing/thawing. To improve the performance of cement-based materials under harsh environmental conditions, mortar was selected as a research object, and its mechanical and phase transformation characteristics were investigated by adding nano-CaCO3, silica fume, epoxy resin, and mixtures of these components. Laboratory tests were conducted on salt mixtures and freeze/thaw cycles, and the compressive strength and mass loss rate of the mortar recorded before and after freezing/thawing were compared. Subsequently, the effects of the type and amount of additive on the compressive strength and mass loss rate of the mortar were analyzed. The microstructural characteristics of the modified mortar were investigated using scanning electron microscopy, and the mechanisms of the physical and mechanical properties of the mortar modified by additives were revealed. Furthermore, the phase transition properties of water and salt in the modified mortar were studied using differential scanning calorimetry, and the crystallization amount, unfrozen water content, supersaturation ratio, and crystallization pressure in the mortar were calculated on the basis of heat balance and mass balance. The results indicate that during the cooling process, the solution in the internal pores of the mortar undergoes a crystallization phase transition, and the maximum crystallization pressure can reach a value of 30.1 MPa. The additive forms a compact structure inside the mortar to prevent harmful ions from infiltrating the mortar, thereby mitigating the damage caused to the mortar. The apparent deterioration reduced and the compressive strength of the modified mortar improved after several salt and freeze/thaw cycles, and an improvement rate of 15% for the epoxy resin was the most prominent result. The variation in temperature in this study was defined to model cold regions in northwest China and there are similar saline soils in cold regions in other parts of the world, such as the Mediterranean Basin, California, Southeast Asia, Arctic coast, and Central Siberia (Hivon and Sego 1993; Serrano and Gaxiola 1994; Bohren and Albrecht 1998; Shaterian et al. 2005). Therefore, cement-based materials worldwide suffer damage from salt erosion and freeze/thaw cycles. Although there are differences in temperature and salt concentration in different regions of the world, this research has practical reference value for improving the quality of mortar. For the additives considered in this study, all mass loss ratios of the improved mortar significantly reduced. In soil containing sodium chloride, a mixture of silica fume and epoxy resin is suggested to improve the durability of mortar based on reduced crystallization inside pores. In soil containing sodium sulfate, adding a mixture of na-CaCO3 and epoxy resin can improve the physical and mechanical properties of mortar by reducing salt and ice crystallization in pores. Although the improvement of mortar under the action of salt and freeze/thaw cycles was investigated in this study and the internal mechanisms of mass loss rate and compressive strength enhancement were discussed, the relationship between freeze/thaw cycles and actual environmental temperature changes has not yet been established, and phase changes in porous materials are closely related to the speed of temperature variation. The manner in which freeze/thaw cycles correspond to an actual environmental cycle and the improvement and phase transformation of mortar under ultralow temperatures (below −20°C) are worth studying in the future. Furthermore, the volume of a specimen has a significant influence on the transition temperature, in which supersaturation and supercooling decrease as the volume of soil increases (Wan et al., 2021). Furthermore, the effects of volume on the law of phase transition in mortar remain to be addressed in future studies. [ABSTRACT FROM AUTHOR]

Clay mortars are characterized by low mechanical strength and lack of resistance to water. Due to these weaknesses, the possibilities of their use in construction are limited. It is possible to modify the composition of the mortar to improve some properties, but it may adversely affect other important properties. One of the possible directions of research is the modification of the mortar with an admixture of biopolymers of natural origin. In this study, the scientific goal was to check the influence of the admixture of gum arabic (GA) in various amounts (1 %, 2 %, 3 % of the clay weight) on selected physical and mechanical properties of the clay mortar. Consistency, drying shrinkage, drying kinetics, pore size distribution (MIP), water resistance, flexural and compressive strength, and Young's modulus were examined. In addition, SEM microscopic analysis was performed. The admixture of gum arabic significantly increased the flexural strength (by 81.8–150 %) and compressive strength (by 84–170 %) in relation to the reference mortar. The strength increased with the increase in the amount of GA. The biopolymer reduced total porosity by 10.4–12 % and also reduced the average pore size by 11.9–18.1 %. A positive effect of the mortar modification was the improvement in water resistance. The weight loss of GA samples after 7 minutes of soaking in water was lower by about 52–79 % compared to the reference mortar. With the increase in the polysaccharide content, the water resistance of the mortar increased. The GA admixture did not significantly affect the consistency of the mortar. The shrinkage of the modified mortars did not exceed 1.3 %. The beneficial effect of using gum arabic can be extended to the use of clay mortar, e.g. as external plaster, mortar in load-bearing walls or as a mixture for making unfired bricks. The test results may be an inspiration for further studies regarding, for example, sorption and vapor permeability. • Clay mortar modified with gum arabic in various amounts was studied. • Air content, consistency, water retention of the fresh mixtures were investigated. • Compressive and flexural strength, pore size distribution, shrinkage, water resistance of hardened mortar tested. • SEM analysis of mortar samples were made. • The presence of gum arabic showed a positive effect on the strength and water resistance of clay mortars. [ABSTRACT FROM AUTHOR]

This study investigates the synergistic effects of incorporating carbon fiber with industrial wastes such as mill scale and red mud on the mechanical and electromagnetic properties of mortars. Carbon fiber is introduced at a volume fraction of 0.5 %, while mill scale replaces the crushed stone aggregate, and red mud replaces the cement at volume and weight ratios of 10 %, 20 %, and 30 %, respectively. The results reveal that incorporating mill scale and red mud generally reduces compressive strength. Mill scale's high density and coarse particle size can disrupt the mortar matrix, while replacing cement with red mud reduces the overall binder content, further weakening the mortar. Compared to the control sample, which does not include any conductive additives, mill scale causes approximately a 55 % reduction in compressive strength, while red mud results in about a 35 % decrease. Electromagnetic interference (EMI) shielding properties show substantial improvements with the inclusion of both mill scale and red mud in carbon fiber-reinforced mortars. Mortars containing these additives exhibit significant Shielding Effectiveness Transmission (SET) values across the 8–12 GHz frequency range, surpassing control samples that do not include admixture. Specifically, carbon fiber-reinforced mortars with 10 %, 20 %, and 30 % mill scale achieve SET values of 12–17 dB, 18–24 dB, and 25–34 dB, respectively. Similarly, mortars with 10 %, 20 %, and 30 % red mud achieve SET values of 8–11 dB, 14–27 dB, and 22–34 dB, respectively. Analysis of Shielding Absorption (SEA) values indicates that mortars with 10 %, 20 %, and 30 % mill scale and 0.5 % carbon fiber achieve SEA values of 11–15 dB, 16–23 dB, and 23–32 dB, respectively. Likewise, carbon fiber-reinforced mortars with 10 %, 20 %, and 30 % red mud achieve SEA values of 5–8 dB, 11–12 dB, and 21–31 dB, respectively. Despite the reduction in compressive strength, both additives effectively improve EMI shielding, demonstrating the feasibility of using industrial wastes for multifunctional mortar applications. • Synergistic effects of carbon fiber, mill scale, and red mud in mortars are investigated. • Material: 0.5 % carbon fiber (vol.), mill scale replacing aggregate, and red mud replacing cement at 10 %, 20 %, and 30 % ratios. • Reduction in compressive strength with mill scale and red mud inclusion is noted. • Substantial improvements in EMI shielding properties with mill scale and red mud is reported. [ABSTRACT FROM AUTHOR]

It is widely recognized that external earthen renders are susceptible to accelerated degradation caused by environmental factors. Therefore, chemical stabilization has become a common approach to address this issue. This study focuses on the stabilization of earth renders by heat treatment, considering criteria such as energy efficiency and the judicious use of resources. Different earth rendering mortars with additives such as wheat paste and horse dung were investigated. These were subjected to surface heat treatment at 400 °C for one minute. Changes in mechanical properties, including shear strength, adhesion and water erosion resistance were examined. The results showed that surface heat treatment at 400 °C improved water erosion resistance but negatively affected shear strength and adhesion to the adobe substrate. Interestingly, the mortar containing wheat paste showed the least reduction in shear strength and adhesion, with a 16 % decrease, while it experienced a water erosion resistance. The phenomenon was observed in all specimens and is attributed to the microstructural changes induced by the irreversible processes of dehydration and dehydroxylation, which alter the clay components on the surface of the earthen render. Overall, heat treatment shows promise for improving the durability of earthen renders against environmental degradation. [Display omitted] • A process of superficial in situ heat treatment for earth render was developed. • Stabilization of earth renders was achieved by heat treatment at 400 °C. • Water resistance of earth renders was enhanced by that treatment. • A novel and energy efficient process to protect earth renders was developed. [ABSTRACT FROM AUTHOR]

Many efforts have focused on the deterioration of historic buildings, and natural hydraulic lime mortar without admixture is less resistant to environmental agencies than a lime mortar with admixtures. A research study has been carried out to study the effect of carboxymethyl cellulose (CMC) and alccofine (AF) with the natural hydraulic lime mortars in improving the hydraulic properties, durability properties, and freeze–thaw resistance. The performance of lime mortars was evaluated with various additives. The experimental results indicated the combined effect of CMCs and AF in lime mortars' compression testing in different stages. In blended mortars, the early compressive strength was increased. Also, mixed mortar exhibits stronger freeze–thaw resistance with a long healing period. These findings indicate that AF and CMC combination played an essential role in lime mortar (LM) properties, which is generally advantageous for restoration and conservation purposes, especially in historic structures in cold regions. [ABSTRACT FROM AUTHOR]

The presented research is focused on the complex assessment of three different types of diatomaceous earth and evaluation of their ability for application as pozzolana active admixtures applicable in the concrete industry and the production of repair mortars applicable for historical masonry. The comprehensive experimental campaign comprised chemical, mineralogical, microstructural, and physical testing of raw materials, followed by the analyses and characterization of pozzolanic activity, rheology and heat evolution of fresh blended pastes, and testing of macrostructural and mechanical parameters of the hardened 28-days and 90-days samples. The obtained results gave evidence of the different behavior of researched diatomaceous earth when mixed with water and Portland cement. The differences in heat evolution, initial and final setting time, porosity, density, and mechanical parameters were identified based on chemical and phase composition, particle size, specific surface, and morphology of diatomaceous particles. Nevertheless, the researched mineral admixtures yielded a high strength activity index (92.9% to 113.6%), evinced their pozzolanic activity. Three fundamental factors were identified that affect diatomaceous earth's contribution to the mechanical strength of cement blends. These are the filler effect, the pertinent acceleration of OPC hydration, and the pozzolanic reaction of diatomite with Portland cement hydrates. The optimum replacement level of ordinary Portland cement by diatomaceous earth to give maximum long-term strength enhancement is about 10 wt.%., but it might be further enhanced based on the properties of pozzolan. [ABSTRACT FROM AUTHOR]

In recent decades, layered double hydroxides (LDH) have been proposed as innovative corrosion inhibitors for reinforced concrete. Their protective action is based on the ability to intercalate specific anions in the interlayer and on their ability to exchange the intercalated anion. In the present study, an organically charged LDH, with sebacate anions in the interlayer (LDH-S), is proposed as a water-repellent additive for mortar. The waterproofing efficiency of LDH-S and the associated corrosion inhibition ability has been evaluated in reinforced mortar samples. A 42% decrease in the water capillary absorption coefficient has been estimated when 3% LHD-S is added to a mortar. Both the passivation processes of the steel rebars during the curing period and the initiation of corrosion due to chloride exposure have been studied by electrochemical measurements. Three different mortars have been evaluated: reference mortar (REF), mortar with Mg-Al LDH (LDH), and mortar with LDH-sebacate (LDH-S). The latter has shown an important protective capacity for preventing the initiation of corrosion by chloride penetration, with an inhibitory efficiency of 74%. The presence of LDHs without sebacate in the interlayer also improved the performance of the mortar against rebar corrosion, but with lower efficiency (23% inhibitory efficiency). However, this protection is lost after continued chloride exposure over time, and corrosion initiates similarly to the reference mortar. The low corrosion current density values registered when LDH-S is added to the mortar may be related to the increased electrical resistance recorded in this mortar. [ABSTRACT FROM AUTHOR]

Multiwalled carbon nanotubes obtained via the Catalytic Chemical Vapor Deposition method were covalently functionalised by maleic anhydride – α-octene copolymer via 'grafting from' approach using a sonochemical method to obtain the additive for improving the mechanical properties of cement mortar. The catalyst and oxidising agent used for nanotube synthesis and surface activation through the formation of the functional groups in a mild condition were Fe – Co / Al2O3 and potassium permanganate, respectively. These functional moieties were used for the consequent functionalization of the nanotubes with the copolymer. The instrumental techniques like Transmission Electron Microscopy, Scanning electron microscopy, Fourier transform infrared spectroscopy, X - ray powder diffraction, and Raman spectroscopy were used to characterise the obtained nanostructures. The used techniques revealed the success of the surface functionalization in the formation of the strengthening additive. The results obtained from the compressive strength tests for the strengthening additive included cement mortar composites revealed the positive effects of the additive on the mechanical properties of the cement mortar over the reference material. The use of the 'grafting from' approach to covalently functionalise the multiwalled carbon nanotubes with maleic anhydride – α-octene copolymer via the sonochemical method to obtain strengthening additive for cement mortar is the novelty of the work. [ABSTRACT FROM AUTHOR]