Mortar Composites Research Articles

3D Printing of Continuous-Fibers Cementitious Composites

Significant developments in 3D concrete have been made over the past few decades. Yet, unreinforced printed components generally do not comply with existing construction standards or regulations and are therefore not used as load-bearing components. There is still a gap between research and use, and despite several proposals, standard commercial solutions for the reinforcement of 3D-printed structural members are still awaited. The proposed technology is inspired by the composites industry and called flow-based pultrusion for additive manufacturing. The reinforcement is provided by long and aligned fibers, and produces a transverse isotropic composite mortar. Here we show the first experimental setup, and the material tests performed on the printed material. An increase in tensile strength and ductility is shown. An industrial prototype, in collaboration with the company XtreeE, is being developed. This new equipment has made it possible to print beams of 1m50 whose intrados is reinforced with carbon fibres.

FLY ASH MORTAR FROM ASPHALT PLANT FOR 3D CONSTRUCTION PRINTING

Recent advancements in additive manufacturing have extended its application to the realm of civil construction, necessitating the formulation of specialized mortars tailored for this technology. The dependency of mortar properties on locally sourced raw materials presents a challenge in adopting mortar compositions developed in other countries. This paper introduces mortars designed for additive manufacturing, utilizing Brazilian materials and incorporating asphalt fly ash, a byproduct residue. The developed mortars were evaluated using a laboratory-scale 3D printer equipped with a helicoidal screw-based extrusion system. The incorporation of asphalt fly ash significantly enhanced the mechanical strength of the dried mortar and improved the cohesion of the fresh mortar. The fresh mortar exhibited minimal slump (ranging between 10mm and 15mm) and demonstrated a compressive strength of approximately 30 MPa upon hardening. These findings indicate that the fly ash-enriched mortar is well-suited for additive manufacturing applications in civil construction, offering a promising avenue for the utilization of industrial byproducts in sustainable building practices.

Assessment of mechanical properties with machine learning modeling and durability, and microstructural characteristics of a biochar-cement mortar composite

Rising CO2 emissions have become one of the biggest environmental challenges in recent years. Due to the rising carbon footprint of the building industry, CO2 emission regulation and mitigation have become perennial issues. The utilization of Biochar (BC) as a carbon-sequestering component in cement mortar is the novelty and main concern of this study. In this research, the effectiveness of BC in sequestering carbon was examined along with its effect on the mechanical, microstructural, and durability characteristics of the composite cement mortar. It includes a control and eight additional mixes prepared with 1%, 3%, 5%, and 8% BC by weight of cement added to mortar; the BC were prepared at two fixed temperatures of 300 °C and 500 °C. It also involves testing fresh properties, mechanical properties, durability properties, and microstructure analysis using scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDX). A Universal Testing Machine (UTM) was used to determine the mechanical properties of the cement mortar, such as its compressive and tensile strengths. The water permeability and rapid chloride permeability tests (RCPT) were used to evaluate the specimens' long-term stability as a measure of their durability. Based on the test results, it has been found that the inclusion of BC enhanced the strength and durability of cement mortar through its pozzolanic action. In addition, BC is a filler material whose porous structure fills the voids within the cement particles, decreasing water absorption and improving workability. BC sequesters carbon by carbonizing biomass. Its presence in cement mortar stores carbon that would otherwise be emitted into the atmosphere, which helps to reduce the environmental effect. According to the conclusion of the study, BC has the potential to be a sustainable component of cement mortar. In addition, the two distinct algorithms built upon machine learning applied in the analysis using adaptive boosting (AdaBoost) and linear regression (LR); both these analyses demonstrate that it is feasible to predict the characteristics of cement mortar accurately. The AdaBoost methodology outperforms the LR methodology because of its strong correlation value (R2).

Modelling the effect of mortar constituents on rheological properties

AbstractConcrete is a widely used construction material whose potential has not yet been fully exploited due to the lack of knowledge about its rheological behaviour. The mix composition is assumed to play a key role in controlling the rheological properties of concrete. Due to the extremely high proportion of finer particles in concrete, the investigation of the rheological properties of the mortar and paste phases is of major importance in understanding the rheological behaviour of concrete. Therefore, this paper systematically investigates the impact of water‐to‐cement ratio, sand content, and maximum sand size on the rheology of flowable mortars. It also explores the applicability of existing models for modeling these mortars.The results, presented as a rheograph, reveal that a reduction of the w/c ratio and an increase in the sand solid content in the mortar leads to an increase in the rheological properties plastic viscosity and yield stress. Also, the addition of coarser sand in mortar compositions induces an increase in the maximum solid content and consequently a decrease in plastic viscosity. In addition, it shows that the Krieger‐Dougherty and Liu models are appropriate enough for modelling polydisperse suspensions.

Utilizing porcelain tile polishing residue in eco-efficient high-strength geopolymers with steel microfibers

Geopolymers are an alternative that produces low environmental impact binders with satisfactory mechanical properties. This research evaluated the influence of adding steel microfibers to a binary geopolymer matrix composed of metakaolin and ceramic tile polishing residue. Three mortar compositions (1:2, 1:3 and 1:4 cement:sand mass ratios) were produced with three microfiber concentrations (vf = 0.45, vf = 0.90 and vf = 1.35 % of total volume). The mechanical properties were evaluated by testing compressive strength, dynamic modulus of elasticity, flexural strength, and toughness. For 1:3 mortar, autogenous shrinkage measurements were performed for the 3 microfiber concentrations. Equivalent carbon dioxide emissions and binder intensity were also quantified. The mechanical properties classify the geopolymer concrete as high strength, achieving up to 95 MPa (composition 1:3) of compressive strength at 28 days and low binder consumption (9.82 kg.m−3. MPa−1). An improvement in flexural tensile strength was observed as the concentration of steel microfibers increased, reaching 20 MPa with vf= 1.35 %. For the concentration vf= 0.90 %, there was a reduction of ∼38 % of the autogenous shrinkage measurements about the reference (vf=0.0 %) at 28 days. In addition, regarding the CO2 intensity index, the lowest values were obtained for the 1:3 compositions, being minimum for vf= 0.90 % (9.01 [kg. ECO2-eq /m³ of mortar]/MPa), producing geopolymeric composites with low CO2 emissions, allowing the production of construction materials with low environmental impact.

Mechanical properties of cement mortar with gamma-irradiated recycled plastic powder, pellet, and fiber

This study aimed to investigate the impact of gamma irradiated recycled polyethylene terephthalate (PET) pellets, powder, and fibers on the mechanical performance and ductility of cementitious mortar. The sensitivity to gamma irradiation was explored by varying the irradiation rate and total dose. The recycled PET additives employed in this experiment consisted of pellets and their different application forms: powder and fiber, containing 30 % recycled raw materials polymerized through a chemically recycled method. For comparison, plain mortar composite and virgin PET mortar composite were used as controls. When PET pellets partially replaced the aggregate, the compressive strength of the composite decreased significantly as the volume fraction of pellets increased. Conversely, specimens partially replaced by PET powder showed an overall increase in compressive strength compared to the control specimens, regardless of the volume fraction of powder, gamma irradiation rate, or total dose, with no change in ductility. To assess changes in tensile strength and ductility of the recycled PET fibers under different gamma irradiation rates and total doses, direct fiber tensile tests were conducted. The gamma-irradiated fiber specimens exhibited a slight increase in strength and ductility. This information allowed for the calibration of the tensile material constitutive relationship of PET fibers, which was subsequently used in nonlinear finite element analysis. The study also investigated the variation in direct tensile, compressive, and flexural strengths with different volume fractions of fiber. The results indicated that the strength enhancement was minimal, but the direct tensile and flexural tensile analyses predicted an enhancement.

Ultrasonic Characterization of Polymer Based Sille Stone Powder Composite Mortars

The Sille stone mined in the Sille Region of Konya province in Türkiye, is an andesitic rock. This stone is a material used in the construction of traditional and modern buildings. The Sille stone is cut while being used in buildings. The Sille stone powder (SSP) is formed during this cutting process. The SSPs cause environmental pollution. Therefore, this study was carried out to produce durable and eco-friendly new restoration mortars from the SSP that can be used in the restoration of historical buildings. The SSP composites were prepared by contributing SSP into epoxy and polyester resins in varied ratios such as 60‒75 wt.%. The effect of resin types and SSP contribution ratios on the elastic properties of epoxy resin (ER)/SSP and polyester resin (PR)/SSP composites was investigated by the ultrasonic pulse-echo method. Additionally, the morphology of these composites was investigated by scanning electron microscopy (SEM). Experimental results figured out that both longitudinal and shear wave velocity values of the PR/SSP composites were higher than of the ER/SSP composites. Furthermore, a linear increase was observed in the elastic properties of obtained composites with the increasing amounts of SSP.

Flexural Toughening of Hooked-End Steel Fibers Reinforced Mortars

This paper investigated the effect of hooked-end steel fiber at varying fiber content on the flexural toughening of fiber reinforced cement mortars (FRCM) by using three-point bending tests. In particular, to preserve the mortar workability, three low weight fractions (0.3%, 0.5% and 0.7%) and two cement matrices (M10 and M15) were investigated. The results showed that the mechanical bending behavior of the FRCM increases significantly at increasing fiber content and cement plaster matrix. An important aspect that has been addressed is how the flexural toughening is varied at varying fiber content and the type of matrix. Especially, all composite mortars exhibited a toughness index (TI) in the range of 10–45, indicating a suitable strengthening and toughening effect supplied by the hooked-end fiber addition. The best TI value, equal to 44, was experienced for the M10-D7 batch characterized by 0.7 wt.% of hooked-end steel fibers and an M10 cement matrix. Furthermore, unlike unreinforced concrete where brittle and unexpected failure occurs dominated by a sudden and catastrophic propagation of tensile cracks, the FRCM samples exhibited a ductile behavior with a marked residual post-crack resistance even for composites mortars with low metal fiber content.

Silica aerogel added lightweight cement-based composite mortars for thermal insulation purposes in sustainable structures: A comprehensive study

It has been discovered in recent years that the use of silica aerogel in cement-based materials contributes to the thermal insulation properties of the materials, and studies on this subject have gained importance. However, it was determined that the studies mostly remained at the level of the thermal conductivity coefficient and the main physical and mechanical properties of the materials. In this study, a comprehensive research was carried out with the replacement of micro-sized aerogel particles with quartz sand in different ratios (0, 1, 1.6, 2.4, 3.2, 4 and 4.5 wt%) in lightweight cement-based composite mortar (LCCM) combinations. Specifically, the effect of silica aerogel granules (SAG) on flowability, fresh and hardened densities, porosity, water absorption, compressive strength, macro/microstructural properties (by optic microscope, SEM, XRD analysis), thermal conductivity, specific heat, thermal diffusivity and heat storage capability of LCCMs were investigated. While SAG could increase the flowability (up to 8.4 %) at low using rates, it decreased it at higher rates. It is very effective in reducing fresh and hardened densities. However, it highly increased porosity and water absorption, and greatly decreased compressive strength. On the other hand, generally the poor interfacial properties of the cement matrix and the aerogel were moderately improved in this study. The lowest thermal conductivity was determined as 0.155 W/mK in the highest SAG usage. SAG increased specific heat, decreased thermal diffusivity and decreased heat storage capability of LCCMs up to 45.23 %, 63.49 % and 46.32 %, respectively. As a result of the study, aerogel has been identified as a very suitable material that can be used to highly improve thermal properties in LCCMs.

RESEARCHING THE INFLUENCE OF PLASTICIZERS ON THE TECHNOLOGICAL AND PHYSICAL-MECHANICAL PROPERTIES OF COMPOSITE BINDING SUBSTANCES OF THE СаО – Al2O3 – SO3 – H2O SYSTEM

Problem statement. Composition of modern concretes and mortars includes surface-active substances that regulate processes of hydration, structure formation and, accordingly, properties of artificial stone. One of the types of surface-active substances are plasticizers, their main purpose is to reduce water consumption. When considering their influence, a wider range of changes in the properties of solutions and concretes can be noted. In this regard a particular attention should be paid to aluminate, sulfate and sulfo-aluminate binders. Therefore, the development of composite binders of the CaО – Al2O3 – SO3 – H2O system based on alumina cement and gypsum with the use of plasticizers requires research in this direction. The purpose of the article – to investigate the effect of plasticizers on the technological and basic physical and mechanical properties of alumina cement and composites based on it. Conclusions. A complex of experimental and statistical models of nanomodified compositions based on alumina cement and gypsum was obtained, and these models make it possible to determine influence of input factors on the growth of the main physical and mechanical properties. Research has established the ratio of the basic components of the composite based on 70 % alumina cement, 30 % gypsum and Sika VG Sika plasticizer = 0.10 ÷ 0.40; alumina cement = 69.72 ÷ 69.93; Gypsum = 29.88 ÷ 29.97. According to the manufacturing technology, the number of components was reduced to a minimum and a binder-filler-plasticizer system was obtained. From the economic point of view, depending on the customer’s requirements, it is possible to regulate the consumption of alumina cement and gypsum binder within the limits of approximately 10 %.

Analysis of pigments and mortars from the wall paintings of the Roman archaeological site of Las Dunas (San Pedro de Alcántara, Malaga S Spain)

This study aims to describe the composition, texture, and arrangement of mortars and pictorial layers from a newly excavated Roman archaeological site in the province of Baetica, southern Spain. Representative fragments with well-preserved pictorial layers were analyzed using optical imaging, spectrophotometry, Scanning Electron Microscopy with Energy-Dispersive Spectroscopy (SEM-EDS) mapping, and X-ray diffraction. The results reveal similarities to other well-studied Roman archaeological sites, particularly in the use of mixtures of natural (hematite, goethite, aragonite, phyllosilicates, and quartz) and synthetic minerals (cuprorivaite) used in classical Roman pigments. However, the mortar from the investigated site shows a distinctive use of ferromagnesian silicates (olivine and pyroxenes from local ultramafic rocks) as aggregate material, making this site unique among all Roman provinces. Additionally, the common occurrence of Mg in the binder of the mortars under the form of brucite, hydromagnesite and magnesium silicate hydrates, indicates the use of a magnesian (dolomitic) lime that, according to the chemical analyses, was obtained by adding up to 15 wt% of powdered dolomitic marbles from nearby Roman quarries to the limestone. We speculate that this addition might be intended to improve the workability and mechanical resistances of the mortar in combination with the abundant ferromagnesian silicates used as aggregates, some of them showing chemically reactive rims in contact with the binder. In conclusion, this study provides further evidence of the advanced knowledge and skills achieved by Roman craftsmen who were able to adapt traditional recipes to suit local resources, obtaining materials of excellent quality and durability.

Technology and Composition of the Mortar and Origin of the Stone and the Smalta Tesserae of the Early Christian Mosaics from Parthicopolis. The Beginning of Database on the Ancient Mosaics from Middle Strymon

The article presents the results of a study on the mortar and tesserae made of marble, sandstone, brick, and smalta in the mosaic pavement of the exonarthex of Basilica No. 2 in Parthicopolis. This basilica served as an important episcopal center in the province of Macedonia I. The methods employed include macro- and micro-analysis, as well as SEM-EDS and XRD analysis of the mineral phases. It has been established that the mosaic was laid on a mortar layer without a statumen and rudus. The study of the mortar revealed the presence of a fine fraction among the tesserae, as well as lumps of lime in the mortar composition, which were reinforced with a fine brick powder. The brick and stone tesserae, including marble and sandstone, originated locally, while the smalta used for the glass tesserae was imported, possibly undergoing secondary processing on-site. The analysis of the smalta composition identified several technological processes, including secondary heating, a significant presence of small air bubbles, and unwanted crystalline impurities. These phenomena likely occurred during the melting, molding, annealing, or secondary processing of sodium-lime-silicate glass. This suggests the possibility of imported manufactured production being remade in situ, demonstrating the utilization of local materials and techniques. The study revealed that the mosaicists possessed a profound understanding of the craft, including a deep knowledge of the underlying processes and a diverse range of technical skills. With this expertise, they were able to successfully achieve the desired result by utilizing local materials.

Composition and characterisation of ancient lime mortar of Gopal Krishna temple, Alandi, India

Composition and characterisation of ancient lime mortar of Gopal Krishna temple, Alandi, India

Numerical investigation on the high-velocity impact resistance of textile reinforced composite mesh designs inspired by spider web

The need for thin and highly deformable textile reinforcements is constant in sectors like thin composites, catching nets, and complex construction designs (like dome-shape). The conventional rectangular-patterned meshed wovens are used in thin composite structures as reinforcement at the commercial level. These woven textiles are bidirectional and exhibit approximately the same strength along both axes. However, these conventional rectangular-patterned mesh designs show poor impact stress distribution capacity. Interestingly, very thin and fine mesh designs are available in nature. One such example is the spider web structure. These structures have evolved with time and optimised their mesh pattern design for better impact damage resistance and load transfer. In this study, the basalt fibre reinforced mortar textile composites are considered for the investigation due to their growing interest in civil and construction applications. To demonstrate how the mesh geometry in textiles significantly influences the stress transfer, energy absorption, and deformation of reinforcements under various impact situations, three different geometries, (a) square shape mesh, (b) diamond-shaped mesh, and (c) bio-inspired spider web mesh, are modelled and meshed based on the reference geometry’s meshing pattern and dimensions. The results of numerical simulations show that a meshed reinforcement design inspired by spider-orb-web has improved mechanical features compared to conventional square and diamond shape mesh designs under high velocity impact loading.

Reliability prediction of alkali-activated mortar during flexural loading using Weibull analysis

This study uses the Weibull analysis to predict the robustness of various mortars based on a fracture process analysis through a flexural test recorded by an acoustic emission sensor. Alkali-activated materials (AAMs) are an alternative to Portland cement that can decrease the amount of emitted CO2. This study aimed to characterise and compare the properties of AAM cement mortars to those of the commonly used ordinary Portland cement (OPC) mortars using the Weibull distribution to clarify the reliability and robustness of the prepared AAM cements; four different AAM cement mortar compositions—with fly ash (F), ground-granulated blast-furnace slag (G), and microsilica (M) alkali activation (sodium hydroxide (NaOH) and sodium silicate (Na2SiO3))—were considered in this study. The fracture process under a flexural loading of AAMs was based on four combinations of F/G/M activated by the alkaline solution—AAM-IV, AAM-V, AAM-VI, and AAM-VII, with OPC as control. The Weibull analysis showed that AAMs were more robust than the OPC mortar and possessed minor fractures compared to the OPC mortar.

Penetration resistance and damage characteristics of cementitious mortar with partially replaced waste tire rubber as a filler against high-speed impact loading

Concrete, as the sole construction material, demonstrates an inadequate performance against high-speed impact loading. Resistance to such loading can be increased by adding rubber from the waste tire industry. In this study, the performances of cementitious mortar with the addition of waste tire rubber (WTR) powder were investigated against the strike of a high-speed projectile. By setting the target flow above 110 % and air content within a range of 5–7%, mortar with 30 % WTR was selected for high-speed impact test. Selected mortar specimens demonstrated significantly high resistance to damage and penetration against a high-speed projectile at impact speeds of 300 m/s and 420 m/s. Further, an experimental study revealed the contrasting behaviour of mortar specimens with WTR powder from that of conventional specimens, where typical compression occurred due to triaxial stress at the tunnel circumference formed by the intrusion of the projectile. Recommendation is made for composite mortar containing a less-stiff material such as rubber for new variables to be defined in the existing formulae, to quantify penetration in high-speed loading; given that the penetration resistance of specimens with 30 % WTR was larger than that of the control specimen, even with its lower compression strength.

Cytotoxic-Ag-Modified Eggshell Membrane Nanocomposites as Bactericides in Concrete Mortar.

Against the backdrop of escalating infrastructure budgets worldwide, a notable portion-up to 45%-is allocated to maintenance endeavors rather than innovative infrastructure development. A substantial fraction of this maintenance commitment involves combatting concrete degradation due to microbial attacks. In response, this study endeavors to propose a remedial strategy employing nano metals and repurposed materials within cement mortar. The methodology entails the adsorption onto eggshell membranes (ESM) of silver nitrate (ESM/AgNO3) or silver nanoparticles (ESM/AgNPs) yielding silver-eggshell membrane composites. Subsequently, the resulting silver-eggshell membrane composites were introduced in different proportions to replace cement, resulting in the formulation of ten distinct mortar compositions. A thorough analysis encompassing a range of techniques, such as spectrophotometry, scanning electron microscopy, thermogravimetric analysis, X-ray fluorescence analysis, X-ray diffraction (XRD), and MTT assay, was performed on these composite blends. Additionally, evaluations of both compressive and tensile strengths were carried out. The mortar blends 3, 5, and 6, characterized by 2% ESM/AgNO3, 1% ESM/AgNPs, and 2% ESM/AgNPs cement replacement, respectively, exhibited remarkable antimicrobial efficacy, manifesting in substantial reduction in microbial cell viability (up to 50%) of typical waste activated sludge. Concurrently, a marginal reduction of approximately 10% in compressive strength was noted, juxtaposed with an insignificant change in tensile strength. This investigation sheds light on a promising avenue for addressing concrete deterioration while navigating the balance between material performance and structural integrity.

Cement mortar composites including 1-tetradecanol@PMMA Pickering emulsion particles for thermal energy management of buildings

In this study, a poly(methyl methacrylate) (PMMA) shell 1-tetradecanol core microencapsulated phase change material (MPCM) was produced using the Pickering emulsion technique. Characterization tests of the produced MPCMs were performed using Fourier transform infrared (FT-IR) spectroscopy, particle size distribution (PSD) analysis, differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA) techniques. The latent heat, melting temperature and encapsulation rate of MPCM were determined and they were found as 108.4 J/g, 33 °C, and 46.7 % for heating period, respectively. The effect of 1-tetradecanol@PMMA MPCM on the physical, mechanical, and thermal performance properties of cementitious mortars was also investigated in the study. For this reasons 1-tetradecanol@PMMA MPCMs are included in mortar mixes at 5 %, 7.5 %, and 10 % by weight of cement. As the MPCM ratio increased, the water absorption rate and porosity increased, while the workability, unit weight of the mortar, ultrasonic pulse velocity, flexural strength and compressive strength parameters decreased. The compressive strength of the mortar containing 10 % MPCM on the 28th day was measured as 34.74 MPa. The highest thermal storage capacity was found in mortars containing 10 % MPCM. When the thermal performance of the reference and 10 % MPCM-containing mortars were compared, the indoor temperature differences at the end of the heating and cooling periods were measured as 4.7 °C and 3.9 °C, respectively. The results showed that MPCM produced by the Pickering emulsion technique has the potential to increase thermal comfort in buildings, reduce fuel consumption used for heating purposes and, accordingly, reduce carbon emissions.

Medical Waste Incineration Ash Waste: Impact On Environmental Health And Its Potential To Be Used For Paving Blocks

ABSTRACT : It is known that medical waste has increased in recent years due to the Covid-19 pandemic, which was followed by an increase in ash from burning medical waste processing using incinerators. The objective of this study is to determine the impact of using medical waste incineration ashes on health and the environment, as well as the potential for using solidification techniques to make the ash into paving blocks. The ash used was obtained from a medical waste processing facility in Surakarta, Indonesia's Central Java. The test object was created using seven different combinations of ash, sand, and cement with a water-cement ration of 0.5 and cured for 28 days. The optimum compressive strength condition was determined as the basis for the composition of medical waste incineration ash as a mixture of paving block raw materials, which was then tested for the content of heavy metal compounds using the SNI 8808: 2019 method. According to research, the ash from medical waste incineration contains heavy metal compounds such as Pb, Ni, Cu, and Cd and has the potential to be used as a mortar mixture. Six of the seven mortar compositions with the addition of incineration medical waste ash met the compressive strength requirements of SNI 03-0691-1996 for category D paving blocks to be used in parks and other places.

Analyses of the Structure Formation of Constructional Complex Mixtures Developed on a Local Raw Basis and their Behaviour in a Chemically Aggressive Environment

The article presents the physical, mechanical (strength, density), and chemicalcharacteristics of complex M100 water-resistant mortar compositions, which include crushedlimestone (0.16–1.25 mm) and granite-crushed sand. Additionally, stone masonry mortar mixtureswith a grain size of up to 5 mm have been developed using local raw materials for the restoration ofwall constructions in building structures.The relationship between the density and chemical stabilityof the hardened samples was determined using the results of complex research on the structuringprocess of the test samples obtained with the modifiers used to improve the workability of theprocessed lime mortars.