Mortar Composites Research Articles

Properties of 3D-Printed Polymer Fiber-Reinforced Mortars: A Review.

The engineering applications and related research of fiber-reinforced cement and geopolymer mortar composites are becoming more and more extensive. These reinforced fibers include not only traditional steel fibers and carbon fibers, but also synthetic polymer fibers and natural polymer fibers. Polymer fiber has good mechanical properties, good bonding performance with cement and geopolymer mortars, and excellent performance of cracking resistance and reinforcement. In this paper, representative organic synthetic polymer fibers, such as polypropylene, polyethylene and polyvinyl alcohol, are selected to explore their effects on the flow properties, thixotropic properties and printing time interval of fresh 3D-printed cement and geopolymer mortars. At the same time, the influence of mechanical properties, such as the compressive strength, flexural strength and interlaminar bonding strength of 3D-printed cement and geopolymer mortars after hardening, is also analyzed. Finally, the effect of polymer fiber on the anisotropy of 3D-printed mortars is summarized briefly. The existing problems of 3D-printed cement and polymer mortars are summarized, and the development trend of polymer fiber reinforced 3D-printed mortars is prospected.

Residual mechanical performance of lightweight fiber-reinforced geopolymer mortar composites incorporating expanded clay after elevated temperatures

This research provides an experimental investigation on the properties of fiber reinforced composite materials consisting of lightweight expanded clay aggregates (LECA) and polyvinyl alcohol (PVA) fibers. The influence of temperature (room temperature, 250°C, and 500°C) on the lightweight geopolymer mortar (LWGM) composite materials is also explored. LECA is used as a partial replacement to river sand with 60% and 80%. The base material utilized for LWGM is slag activated by a mixture of sodium silicate and sodium hydroxide solutions. The fresh properties in terms of workability and density were performed. A series of experiments, such as compression, flexural and uniaxial tensile strength tests, were executed to assess the mechanical properties of LWGM composite materials. In addition, the microscopic variations due to the elevated temperature were also evaluated by scanning electron microscopy (SEM) to understand the macro-scale behavior of the samples. The results indicated that increasing the level of LECA replacement caused a reduction in the density and compressive strength of the LWGM. Also, incorporating a 1% PVA fiber volume fraction significantly enhanced the flexural and uniaxial tensile behavior of LWGM composite materials. The compressive strength enhancements were observed at 250°C due to further geopolymerization, while compressive strength reductions were obtained at 500°C due to the vapor impact and difference in thermal expansion. In addition, the load-carrying capacity of all samples increased, and displacement capacity decreased under flexural tests at 250°C. However, the ductile behavior of the PVA incorporating specimens changed to brittle due to the melting of PVA fibers.

Modeling of carbonation, de-carbonation and re-carbonation processes of structural concrete subjected to high temperature heating

When structural concrete is exposed to a fire, various changes in chemical and mechanical properties proceed. The concentration of carbon dioxide CO2 rises to about 15% depending on the situation of fire accidents accompanying combustion of carbide. The self-healing of damaged concrete is expected by absorbing CO2 after fire. Thus, consideration of high temperature heating for carbonation is indispensable for performance assessment of structural concrete. This paper proposes a multi-scale thermo-chemo-physics model for carbonation, de-carbonation and re-carbonation processes during and after high-temperature heating. The proposed integrated model is experimentally validated by using the thermo-gravimetry experiments of cement paste and the strength of mortar composites immediately after high-temperature heating and after post-fire-curing. The CO2 concentration and the humidity are experimentally changed as the thermodynamic boundary conditions for wide-range verification and validation. The compressive strength is treated not as the material property but the computed structural capacity of a cylindrical solid in which the temperature, hydration degree and carbonation develop non-uniformly. The proposed model can capture the tendency of experimental results and allows practically reasonable assessment of fire-damaged and moist-cured concrete as a multi-scale composite.

A new method for detecting sticky rice in ancient mortar based on ELISA

AbstractAs a common organic additive in organic–inorganic composite mortar, sticky rice significantly augments the strength, toughness, and waterproof properties of the mortar. In China, sticky rice mortar has been used for more than 1,500 years. However, the traditional iodine‐starch method cannot achieve quantitative detection, and the colour of the mortar itself interferes with detection results, causing failures in detecting trace amounts of sticky rice in cultural relic samples. In this paper, we present a new approach where extracting and purifying protein from sticky rice and subsequently the enzyme linked immunosorbent assay (ELISA) is used to recognize sticky rice in the mortar. The studies performed showed that the ELISA detection limit based on sticky rice is two orders of magnitude lower than that of the iodine‐starch method and can identify traces of sticky rice in mortar.

High‐performing mortar‐based materials from the late imperial baths of Aquileia: An outstanding example of Roman building tradition in Northern Italy

AbstractThis study provides the first detailed insight into the composition and properties of structural mortars used in a 4th‐century AD bath complex in Aquileia, the emblematic center of Roman culture in Northern Italy. Eighteen mortars, taken from different structures of the site, and three stone samples from the vaulting opus caementicium have been analyzed adopting a multianalytical approach integrating optical microscopy, X‐ray powder diffraction, X‐ray fluorescence, and scanning electron microscopy coupled with energy‐dispersive spectroscopy. The properties of the compounds are outstanding, as revealed by the formation of hydraulic phases (i.e., Al‐tobermorite and AFm) in most of the samples: the waterproofing capabilities of cocciopesto mortars are remarkable, as revealed by the formation of anthropogenic Al‐tobermorite (5.5 wt%) in pool coating samples; the lightweight of the vaults was guaranteed by the use of porous caementa and pozzolanic volcanic aggregates imported from the Gulf of Naples, as demonstrated by petro‐mineralogical features and chemical analysis of major and trace elements. This is the first proven case of trade in these building materials to the north of the Italian peninsula. These outcomes shed new light on the robust technical expertise of local artisans in Aquileia and indicate that the Cisalpina province was by no means a peripheral reality in the Roman Empire, as far as mortar‐based materials are concerned.

Improvement of mechanical strength of mortars by different morphological zinc oxide nanoparticles

This study presents novel nano-mixtures containing zinc oxide (ZnO) nanoparticles (NPs) to enhance the mechanical properties of cement mortars. Different morphological ZnO NPs were synthesised through the green sonochemical method, using tragacanth gum/Kappa carrageenan (TG/κ-C) and tragacanth gum/chitosan (TG/CS) as biopolymer matrices. The ZnO NPs were characterised using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, X-ray diffraction, Zetasizer and Brunauer–Emmett–Teller techniques. The intrinsic viscosities of TG/κ-C-ZnO and TG/CS-ZnO NPs were investigated to determine the miscibility of the polymeric blends in aqueous solution as affected by sonication time and composition ratios. The average diameters for the spherical and prism-like ZnO NPs were around 266 nm and 355 nm, respectively. Seven different cement mortar specimens containing TG/κ-C-ZnO and TG/CS-ZnO NPs were prepared in ratios of 0, 0.1, 0.5 and 1% by weight, and the flexural and compressive strengths of the specimens were determined at the ages of 7 and 28 days. The results indicate that there is a significant improvement in the mechanical performance of different morphological ZnO NP-based cement mortar composites. In comparison, it was observed that specimens containing TG/κ-C-ZnO NPs had much better results than TG/CS-ZnO NPs. Moreover, the workability problem encountered by using only ZnO NPs has been overcome with the presented biopolymers used in this study.

Digital image correlation applied to lime-based mortars: Shrinkage tests for durability evaluations in restoration works

Repair mortars applied to architectural heritage buildings for preservation, maintenance, restoration, and strengthening must be carefully studied regarding the many different compatibility issues. In the case of repair interventions, two closely related aspects are especially important: the mortar composition, and the method of its application, which can strongly influence the shrinkage phenomena during the setting and hardening phases. The aim of present experimental research is to set-up a procedure by Digital Imaging Correlation (DIC) technique to deepen shrinkage phenomena in lime-based mortars, thus comparing many different materials, wrongly considered to be similar in behaviour. The technique enable not only shrinkage measurement accuracy higher than standard tests, but also to understand its mechanisms of evolution over time, by evaluating locally strain stress before micro-crack appearing. The interpretation of a large number of test results represents a significant contribution to the development of operational tools to address material selection in specific contexts.

Supercritical, liquid, and gas CO[formula omitted] reactive transport and carbonate formation in portland cement mortar

In this study, we investigate carbonate formation and reactive transport rate in variably saturated portland cement mortars when high concentrations of gas, liquid, or supercritical CO2 flow through their pore network. X-ray computed tomography completed during CO2 flow is used to quantify the microstructural evolution as the mortar carbonates. After in situ tests, higher resolution scans, thermogravimetric analysis, and desorption isotherm analysis are performed to further quantify microstructural changes. We found that at dry conditions supercritical CO2 moves more rapidly through the pore space and precipitates more carbonates than liquid or gas CO2. However, at 50% degree of saturation (DOS) the CO2 state did not affect the rate of transport in that each specimen exposed to a different CO2 state carbonated within the first hour of CO2 exposure. When the pore space is at 50 or 100% DOS, supercritical CO2 did not react with hydration products more rapidly nor did it result in more carbonate formation during exposure compared to gas or liquid CO2. The amount of Ca(OH)2 that contributes to CaCO3 formation is correlated to the DOS. For the mortar composition analyzed, Ca(OH)2 contributes to approximately 40% of the carbonates formed in the 50% DOS specimens and 15% in the 100% DOS specimens. In other words, as the amount of moisture in the pore space increases, phases other than Ca(OH)2 contribute to more than 50% of the total CaCO3 formed.

Properties and durability of partially replaced cement-based composite mortars co-using powders of a nanosilica superplasticiser and finely ground plastic waste

This paper was about an experimental work on properties and durability of partially replaced cement-based composite mortars. Substitutions equal to 0, 2, 4 and 6% of finely ground polyethylene (PE) in association with a 3% nanosilica superplasticiser (SP) were used to cast the composite mortars. Fresh properties concerned setting as well as compressive strength versus porosity accessible to water whereas hardened durability properties were investigated by carbonation according to FT-IR, chloride corrosion of reinforcement, total chloride ion content, steel bars losses of mass and nitric acid attack. The superplasticiser and polyethylene powder inhibited the hydration of the cement while the compressive strength decreased with the rise of the polyethylene content but remained higher than the control mortar one for a (PE) content not exceeding 4%. Composite mortars were less porous and experienced a 2.08% average porosity. Under carbonation, composite mortars exhibited similar performance with the control mortar while corrosion and steel bar mass losses readings revealed the passive condition of the composite mortars and a total chloride content less than 0.4%. Composite mortars demonstrated better resistance to nitric acid attack with (PE) content increase. Correlation of the SEM images and X-ray evidence with the experimental records may be an indication of the feasibility of providing composite mortars with an optimal 2% (PE) for concrete constructions under severe environmental conditions.

Rubber Influence on the Performance of Thermal Insulating Quarry Sand Mortars-A Statistical Analysis

Abstract The purpose of this paper is to develop a framework for managing wastes resulting from the tire rubber valorization waste of quarry sand mortar. A research methodology was developed to achieve the abovementioned main objective. To create a framework for use of crumb rubber in the production of quarry sand mortars, with adequate physical and mechanical properties to be used in a variety of construction applications. Testing included strength and thermal conductivity properties of the various mixture composition subjected to varying by 5%. 10%. 15% and 20% by quarry sand substitution. The internal microstructure, and phase composition of all mixture mortars, were investigated using scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM/EDS). The results show that increasing incorporation rate of additives significantly improves thermophysical properties of based materials, the hardened properties of the various mortars made are analyzed and compared, the experimental results revealed that; the addition of crumb rubber waste in the quarry sand mortar is beneficial for physical properties (Mv) mass loss, The results of mechanics strength of the rubber based quarry mortar studied are also significantly reduced.The addition of 5% to 20% rubber crumb in matrix and the replacement of sand by 20% of rubber in quarry mortar record the low thermal conductivity properties including that appropriate QS and CR levels may change the pattern of quarry sand mortar. witch explain by a Larger pore and higher porosity produce a less rigid and uniform matrix, meaning that the sonic pulses must travel through longer and more miscellaneous paths which improvement of insulation. The good performance of new materials encourages us to integrate them into the building envelope.

Physical, mechanical properties and durability of cement mortars containing fly ash from the sewage sludge incineration process

Pursuant to European Union regulations, waste generated during municipal sewage treatment should be managed in an environmentally friendly manner. In order to eliminate the risk to human health and to the environment, and also to minimise the volume of the resulting sludge, it is subjected to thermal treatment. The resulting ash contains heavy metals, and thus proper management is required. Since it is known that products of cement hydration reactions have a potential ability to immobilise heavy metals, a preliminary verification was conducted of the possibility of disposing of this type of waste by including it in cement composites. For this purpose, suitable tests were carried out on the mechanical properties and durability of cement binders containing ash from the incineration of sludge produced from municipal sewage (Sewage Sludge Ash – SSA). The tests were conducted for a standard mortar composition based on Portland cement CEM I and on ash obtained on a technical scale in a sewage treatment plant at a temperature of about 850 °C. This mineral addition was used to replace 10%, 20%, 30% and 40% of the cement by weight. The physical and mechanical characteristics were measured, such as compressive and flexural tensile strength after 14, 28 and 90 days of curing as well as durability characteristics such as total porosity, the ability to transport chloride ions and resistance to sulphate ions. The results obtained confirm that replacing 10% of the cement with this admixture has a beneficial effect on the mechanical and durability characteristics, but greater amounts are reflected in a clear deterioration of these characteristics.

Flexural and Impact Behaviors of Mortar Composite Including Carbon Fibers.

This study investigated the flexural and impact performances of mortar composite made with carbon fibers (MCCF). Four mortar composites (MCCF1, MCCF2, MCCF3, and MCCF4) were produced, using 1%, 2%, 3%, and 4% carbon fibers by volume, respectively. Another mortar composite without any carbon fibers (MCCF0) was prepared for its use as a control mix. The freshly mixed mortar composites were tested for inverted slump cone flow time to ensure they had an adequate workability to cast test specimens under vibration. In addition, all fresh mortar composites were examined for density and air content. The hardened mortar composites were tested for their first-crack flexural strength, ultimate flexural strength, first-crack impact resistance, and ultimate impact resistance. Moreover, the first-crack flexural toughness, ultimate flexural toughness, first-crack impact toughness, and ultimate impact toughness were determined for all hardened mortar composites. The correlations among the hardened properties of the mortar composites were also sought. Finally, the optimum fiber content was defined from the overall test results and considering the costs of the mortar composites. The test results showed that the workability and density of the fresh mortar composite decreased, whereas its air content increased due to the inclusion of carbon fibers. However, MCCF3 possessed the highest density and lowest air content among all MCCF mixes. It also had a higher workability than MCCF4. In the hardened state, the first-crack flexural strength and impact resistance, as well as the ultimate flexural strength and impact resistance of mortar composite, increased significantly with the increasing volume content of carbon fibers. In addition, the first-crack flexural toughness, ultimate flexural toughness, first-crack impact toughness, and ultimate impact toughness increased greatly with the higher volume content of carbon fibers. Strong correlations between the flexural strength and impact resistance, and between the flexural toughness and impact toughness of the mortar composites, were observed. Above all, excellent flexural strength, flexural toughness, impact resistance, and impact toughness values were observed for MCCF4 (4% carbon fibers). The 28-day ultimate flexural strength and impact resistance of MCCF4 increased by 4.6 MPa and 134 blows, respectively, as compared to MCCF0. Moreover, the 28-day ultimate flexural toughness and ultimate impact toughness values of MCCF4 were higher than that of MCCF0, by 3739.7 N-mm and 2703.3 J, respectively. However, MCCF3 (3% carbon fibers) also exhibited a good performance under flexural and impact loadings. Based on the costs of all mortar composites and their performances in both fresh and hardened states, MCCF3 was derived as the best mortar mix. This implies that 3% carbon fibers can be defined as the optimum fiber content in the context of the present study.

Mortars on binding alkaline activation

Objective. The problems of the negative impact of the carbonate technology for the production of Portland cement are hotly discussed at many scientific sites and the world community is striving to create more environmentally friendly and less energy-intensive binders. The development of clinker-free technology will allow solving many problems of a global scale, and the use of recycled or substandard material will expand the raw material base and reduce the burden on the environment.Method. When designing formulations for building mortars, it is necessary to take into account the compliance with the requirements for all mortars in general, both for plastering and for masonry, finishing, repair, etc. The study of the compositions of mortars was carried out by standard methods using a verified and certified equipment. Result. The paper presents the results of many years of work on the development of building composites based on binders of alkaline activation. Grades of solutions M75 - 150 were obtained, with the mobility of the mortar mixture Pk 1-2, shelf life of 33-120 minutes, with high adhesive strength of 0.62- 0.71 MPa. Conclusion. The proposed mortar compositions will make it possible to perform plastering, masonry and repair work requiring quick setting, and with proper adherence to the proposed recipes and methods for making mortars, it will be possible to obtain high-quality and durable material.

A quantitative study of the influence of cement matrix impregnation on yarn pullout strength using combined confocal microscopy and double resin impregnation.

The complex impregnation of a multifilament yarn by a cementitious matrix leads to a difficult prediction of the mechanical behaviour of textile reinforced concrete and its less spread use than steel-reinforced concrete. To solve this problem, several models were established but they are not based on direct observations of the embedded yarn or quantification of its impregnation. In order to improve those models, a double resin impregnation process followed by confocal microscopy was set up, after pullout test was performed on each sample. Several parameters were then computed from the obtained images, which enables to quantify the impregnation of the yarn for each sample and to compare it with the pullout mechanical results. The number of fully impregnated filaments is found to be the crucial point to explain the pullout maximum load. The type of failure is also defined using those same parameters, computed along the embedded length, and it was found that the shape of the extracted volume of yarn is cylindrical and so the failure of the filaments is not telescopic. A pre-existing model was then improved, considering all those conclusions obtained by microscopic observations, and a good match between the numerical and the experimental results was found. Multifilament yarns are a continuous and flexible textile structure composed of hundreds of filaments that are maintain together using a chemical product called sizing. Those multifilament yarns can be used to reinforce mortar or concrete, like steel in steel-reinforced concrete. The performances of those types of composites depend strongly on the strength of the reinforcement/mortar bond. In case of textile /mortar composite, this bond depends on the level of penetration of the mortar into the yarn, so the impregnation of the yarn by the mortar. Since they are both very heterogeneous material, this impregnation is random and incomplete. Consequently, it is very difficult to predict the strength of this bond and so, the strength of the yarn/mortar composite. As a result, this type of composite cannot be widely used. Some models were established to predict the strength of those composite; however, they are not based on direct observation of the textile/mortar bond. To improve those models, a new visualisation method of the impregnation of the yarn by the mortar was set up. A double moulding of the impregnated yarn by the mortar was manufactured, using resins and two different fluorescent dyes, after underwent a mechanical test of pulling out the yarn from the mortar (pullout test). First, a resin with a red fluorescent dye was used for the moulding of the yarn shortly after the test, and, second, after dissolution of the mortar around the yarn in acid, a resin with a green fluorescent dye. A number of cross sections of the yarn is observed using a microscope that detects those two dyes and the obtained images are analysed allowing a clear differentiation, location and counting of fully impregnated filaments of the yarn by the mortar and those partially or not impregnated. The results are compared to the mechanical parameters of the pullout test. The number of fully impregnated filaments is found to be crucial to explain the strength of the composite. The behaviour during the pullout test is also explained using parameters computed along the length of the yarn in the mortar. It is found that filaments extracted by pulling-out take a cylindrical shape and so the pullout behaviour is not conical shape as it was suggested in a number of models. Considering all those conclusions obtained by observations, a pre-existing model is improved, and a good match between the numerical and experimental results is found.

Design of Fly Ash-Based Alkali-Activated Mortars, Containing Waste Glass and Recycled CDW Aggregates, for Compressive Strength Optimization.

Alkali-activated mortars and concretes have been gaining increased attention due to their potential for providing a more sustainable alternative to traditional ordinary Portland cement mixtures. In addition, the inclusion of high volumes of recycled materials in these traditional mortars and concretes has been shown to be particularly challenging. The compositions of the mixtures present in this paper were designed to make use of a hybrid alkali-activation model, as they were mostly composed of class F fly ash and calcium-rich precursors, namely, ordinary Portland cement and calcium hydroxide. Moreover, the viability of the addition of fine milled glass wastes and fine limestone powder, as a source of soluble silicates and as a filler, respectively, was also investigated. The optimization criterium for the design of fly ash-based alkali-activated mortar compositions was the maximization of both the compressive strength and environmental performance of the mortars. With this objective, two stages of optimization were conceived: one in which the inclusion of secondary precursors in ambient-cured mortar samples was implemented and, simultaneously, in which the compositions were tested for the determination of short-term compressive strength and another phase containing a deeper study on the effects of the addition of glass wastes on the compressive strength of mortar samples cured for 24 h at 80 °C and tested up to 28 days of curing. Furthermore, in both stages, the effects (on the compressive strength) of the inclusion of construction and demolition recycled aggregates were also investigated. The results show that a heat-cured fly ash-based mortar containing a 1% glass powder content (in relation to the binder weight) and a 10% replacement of natural aggregate for CDRA may display as much as a 28-day compressive strength of 31.4 MPa.

Effect of Adding Hydrogen Peroxide (H<sub>2</sub>O<sub>2</sub>) and Sodium Dodecyl Sulphate (SDS) to the Properties of Fly Ash (FA)-Based Geopolymer Mortar

Geopolymer is an alternative cementitious material produced by rich aluminosilicate mineral materials (Si-Al) combine with an alkaline activator. The objectives of this study are to study the effect of adding hydrogen peroxide (H2O2) and sodium dodecyl sulphate (SDS) as foaming and stabilizing agents, respectively to the fly ash (FA)-based geopolymer mortar properties. The geopolymer mortars were synthesized with a mixture of FA, alkaline activator and SDS with different H2O2 content. The geopolymer mortars were analyzed using compressive strength test, porosity test and Scanning Electron Microscopy (SEM) analysis. Geopolymer mortar with 1 wt% H2O2 content and 0.5 wt% SDS has the lowest compressive strength (8.67 N) compare to the other geopolymer mortar composition. As H2O2 content increase with presence of SDS, the formation of the pores also increased hence resulting in the low compressive strength of geopolymer mortar.

Development of Dry Sand-Lime New Multicomponent Mortars into the Historical Cultural Monuments Applied on Local Raw Basis

The visual and instrumental research of the technical condition of historical cultural constructions and their stone additions, documentation of their existing damages, as well as complex development and implementation of further collapse preventing measures and construction durability ensuring measures are presented. Application of processed sand-lime complex mortars based on local raw is offered for blockage of composition cracks during the rehabilitation work taking into consideration some averaged indices of Mape Antique I, Italian “Mapey” firm, similar injection mortar orientation basic characteristics (physical and mechanical characteristics, leakage, viability) and complete laboratory detailed examination results of the component mineralogical and physical and mechanical characteristics of the substances originally used in the construction. The data on local based raw processed sand-lime construction complex mortars (blockage mortar, injection mortar) physical and mechanical characteristics, thermographic dilatometric properties dependence on composition and fastening conditions of mortars are presented

Chemical and Mineralogical Compositions of Mortar Mixes of Architectural Monuments of Uzbekistan of the IX-XII Centuries

The article covers the research of the chemical and mineralogical compositions of mortars used in the construction of architectural monuments of Uzbekistan in the 9th-12th centuries, which is based on the study of chemical composition, X-ray and differential thermal analyzes. Comprehensive study of the building materials used in mentioned monuments will allow development of identical modified solutions to preserve the value of architectural monuments.

New sustainable mortar compositions containing perlite waste

New sustainable mortar compositions containing perlite waste

A Study on Tensile Behavior According to the Design Method for the CFRP/GFRP Grid for Reinforced Concrete.

In the present study, fiber-reinforced plastics (FRP) grid-reinforced concrete with very rapid hardening polymer (VRHP) mortar composites were fabricated using three types of design methods for the FRP grid (hand lay-up method, resin infusion method, and prepreg oven vacuum bagging method), along with two types of fibers (carbon fiber and glass fiber) and two types of sheets (fabric and prepreg). The FRP grid was prepared by cutting the FRP laminates into a 10 mm thick, 50 mm × 50 mm grid. The tensile behavior of the FRP grid embedded in composites was systematically analyzed in terms of the load extension, fracture mode, partial tensile strain, and load-bearing rate. The CFRP grid manufactured by the prepreg OVB method showed the best tensile behavior compared to the CFRP grid manufactured by the hand lay-up and resin infusion methods. The load-bearing of each grid point was proportional to the height from the load-bearing part when reaching the maximum tensile load. In addition, finite element analysis was conducted to compare the experimental and analysis results.