Mechanical Properties Of Mortar Research Articles

Physical and mechanical properties of mortars containing date palm fibers

This paper presents the results of a study conducted to investigate the effects of incorporating Sefri Date Palm Leave Fibers (SDPLF) into the mortar. A total of seven mixtures were prepared and tested. SDPLF were collected from local farms. The fibers were then cleaned, dried, and cut to different sizes of 10 mm, 20 mm, and 50 mm, maintaining the same individual fiber width of approximately 5 ± 2 mm. The content of SDPLF in mortars was kept to 1% and 3% by mass. The physical and mechanical properties of SDPLF fibers and SDPLF mortars were investigated. The compressive strength at 7, 14, and 28 days was determined. The water absorption rate test was carried out on mortars containing 1% SDPLF fibers. The results showed that mortars with SDPLF have lower workability, lower density, and lower compressive strength as compared to control mortars. However, they are still acceptable for use in construction works. Mortars containing 10 mm and 20 mm SDPLF fibers by mass showed significant improvement in terms of water absorption rate as compared to the control mortar.

Effect of Surface Hydrophilized Plastic Waste Aggregates Made by Mixing Various Kinds of Plastic on Mechanical Properties of Mortar

Effect of Surface Hydrophilized Plastic Waste Aggregates Made by Mixing Various Kinds of Plastic on Mechanical Properties of Mortar

Sustainable cement mortar with recycled plastics enabled by the matrix-aggregate compatibility improvement

Use of recycled waste plastics (RWPs) as the aggregates of concrete has attracted increasing attention for sustainable concrete manufacture with great environmental benefits. However, the replacement of natural aggregates by RWPs always results in degradation of mechanical properties due to poor aggregate-matrix compatibility, which greatly limits the uses of RWPs in practical concrete manufacture. In order to overcome this shortage, polymer (ethylene–vinyl acetate, EVA) coated RWPs, i.e. polypropylene (PP) and polyamide (PA), were investigated to tune the aggregate-matrix interactions in cement mortars. Density, strength and ductility were measured to assess the physical and mechanical properties of mortars with RWPs. Microstructure was qualitatively and quantitatively analyzed using scanning electron microscopy (SEM) with backscattered electron (BSE) mode and energy-dispersive X-ray spectroscopy (EDS). Results showed that single EVA addition into cement mortars kept the mortar density, decreased the compressive and flexural strengths, but increased the deformation and energy absorption to an extent of 100% in mortars with high EVA content. While the addition of RWPs witnessed a reduction in density of about 13–16%. The dual mix of 10% RWPs and 5% EVA mitigated the reduction trend in compressive strength and provided a slight increase (1.5%) in flexural strength compared with the mortars with single mix of 10% RWPs. The EVA addition built organic–inorganic interfacial transition zones (ITZs), improving the matrix-RWPs adhesion and coordinate their deformations. The mechanisms of compatibility improvement of EVA on RWP-cement mortar were proposed towards future design and fabrication of green concrete.

Mechanical Properties and Durability of Mortars Made with Organic-Inorganic Repair Material

Abstract The purpose of this study was to evaluate the mechanical properties and durability of mortars made with organic-inorganic repair materials (OIRMs). The ratio between the main resin and hardener of the organic binder was fixed at 2:1 for the fabrication of OIRM mixtures, while the ratio of the inorganic binder was varied. For a performance comparison with OIRM mixtures, a mortar mixture was fabricated with a conventional cementitious repair material (CRM). The mechanical properties of mortars, such as flow, strength characteristics (compressive, flexural, and bonding strengths), drying shrinkage, and absorption, as well as the durability properties, such as freezing-thawing resistance and resistance to chloride ion penetration, were measured to evaluate mortar performance. The experimental results show that the OIRM mixtures had more favorable mechanical properties (except for compressive strength) and durability than the CRM mixture. In particular, the OIRM mixture with a 1:2:12 (resin:hardener:organic binder) ratio exhibited the most outstanding performances. In conclusion, based on the results of this study, OIRMs should be considered promising repair materials for degraded concrete structures in the future.

Implementation of Alternative Mineral Additives in Low-Emission Sustainable Cement Composites.

The influence of four naturally occurring mineral additives (zeolite, diatomite, trass and bentonite) on the hydration and properties of cement pastes and mortars was investigated. The materials change the phase composition, heat of hydration (determined by calorimetry) and mechanical properties of composites. After 28 days, the amount of Ca(OH)2 was reduced by up to 23% and up to 35% more C-S-H was formed, as proved by TG measurements. Differences were observed in the kinetics of heat release, especially for 25% of the addition. In the calorimetric curves, an additional exothermic effect is observed, related to the alteration in the hydration of C3A in cement. From the point of view of beneficial influence on mechanical properties of mortars, the additives could be ranked as follows: bentonite < diatomite, zeolite < trass after 2 days and bentonite < diatomite < trass < zeolite after 28 days of curing. The highest compressive strength (58.5 MPa) was observed for the sample with a 10% addition of zeolite. Zeolite, trass, bentonite and diatomite are all pozzolanic materials; however, their activity varies to an extent due to the differences in their specific surface area and the content of the amorphous phase, responsible for the pozzolanic reaction.

Usability of a Natural Tuff as Admixture in Clinker and Its Influence on the Physico-Chemical and Mechanical Properties of Mortar

The mechanical and physical properties of TUFF from Korsimoro (Burkina Faso) were investigated for use as admixtures in clinker to make pozzolanic cement. Six different cement mortar specimens were prepared by replacing clinker with TUFF in ratios of 0%, 5%, 8%, 10%, 13% and 15% by mass. The flexural and compressive strengths of the specimens were determined at the ages of 2, 7, 28 and 60 days. The effects of the TUFF replacement ratio on workability, setting time and volume expansion were also examined. Based on the results, it was concluded that Korsimoro TUFF has pozzolanic activity and is suitable for use as an alternative adherent material in the cement industry.

Mechanical properties of hydraulic lime mortars and fired clay bricks subjected to dry-wet cycles

This paper examines the influence of moisture and chlorides on the mechanical properties of natural hydraulic lime mortars, fired clay brick materials and masonry components. Besides assessing three types of mortars incorporating limes with different hydraulicity levels, a cement-only mortar was also investigated for comparison purposes. The test results indicate that all the hydraulic lime mortars had mass accumulation in the range of 11–14% after being subjected to wet-dry cycles in a sodium chloride solution, whilst the mass uptake was in the range of 3–8% for those made of cement. Salt accumulation produced a denser material leading to compressive cube and flexural strength enhancements by factors ranging between 1.6 and 4.7 in comparison to those in ambient-dry conditions, with even higher factors obtained for compressive cylinder strengths and elastic moduli. In contrast, lime mortar subjected to water-only wet-dry cycles showed constant mass or mass loss, due to cracking. Uniaxial compressive strengths of cylindrical brick cores were about 8.5% higher due to wet-dry cycles in chloride solution, and by about 14.9% lower due to wet-dry cycles in water, compared to the ambient-dry case. Complementary compressive tests on masonry cylinders in ambient-dry conditions were also used to assess the adequacy of existing compressive strength assessment expressions. After modifying the expressions by a set of proposed calibration factors, these are employed to undertake a sensitivity study using the mechanical properties of mortars and bricks subjected to wet-dry cycling. The results of the sensitivity study, combined with strength ranges available in the literature, lead to an identification of a suitable range of materials that can be considered for rehabilitation of some forms of historic masonry.

Effect of the use of diatomite as partial replacement of sand on thermal and mechanical properties of mortars

This article is devoted to studying the feasibility of using Moroccan diatomite as replacement of sand in mortars. The principal objective is to value the use of this type of lightweight aggregates in insulating concrete. The diatomite is characterized by means of physical and chemical analyses, to determine its potential use in mortars, and then seven formulations of mortar with different amounts of diatomite are tested. The effect of this type of aggregates on the density, porosity, thermal conductivity and diffusivity, thermal effusivity and capacity, compressive strength, flexural strength and water absorption, is presented herein. The thermal characterization shows that the incorporation of diatomite in mortar improves significantly its thermal insulation potential. Thus, the lightning results in a net reduction of thermal conductivity and diffusivity. In the mechanical characterization, it is noted that despite the decrease in the compressive and flexural strengths with the addition of diatomite, the results obtained are satisfactory to use this type of mortar as insulating concrete. The water absorption test brings to light the increase of hygroscopic aspect with increasing diatomite ration.

Characterization and Analysis of the Carbonation Process of a Lime Mortar Obtained from Phosphogypsum Waste.

This work addresses the reuse of waste products as a raw material for lime putties, which are one of the components of mortar. 1:3 Lime/sand mortars very similar to conventional construction mortars were prepared using a lime putty obtained from the treatment of phosphogypsum with sodium hydroxide. The physical, rheological and mechanical properties of this phosphogypsum-derived mortar have been studied, as well as the mineralogical composition, microstructure by scanning electron microscope (SEM) and curing process by monitoring carbonation and ultrasonic propagation velocity. Considering the negative influence of sulphates on the hardened material, the behaviour of the material after sulphates precipitation by adding barium sulphate was additionally tested. Carbonation progressed from the outside to the inside of the specimen through the porous system by Liesegang rings patterns for mortars with soluble sulphates, while the carbonation with precipitated sulphates was controlled by diffusion-precipitation. Overall, the negative influence of low-sulphate contents on the mechanical properties of mortars was verified. It must be highlighted the importance of their precipitation to obtain adequate performance.

Experimental and numerical investigation on the rheological behaviour of bituminous composites via DSR testing

Mastic and mortar are two bituminous composites which play a fundamental role in defining bituminous mixes’ properties. Therefore, the main purpose of this paper is to study the behaviour of these materials according to time and frequency with three different approaches: Experimental, analytical, and numerical. To characterise bitumen, mastic, and mortar, a Dynamic Oscillatory Test was carried out on bituminous composites using DSR. Numerically, mortar mechanical properties were assessed by applying a heterogeneous finite element (FE) modelling. Analytical methods such as Generalised self-consistent schemes (GSCS) and Shift-Homothety-Shift and time Shift (SHStS) have succeeded in predicting mastic and mortar properties. Numerical simulation presented a virtual DSR test able to examine stress and strain distribution in the digital model’s microstructure. Since studying the response of the internal structure to an applied stress or strain is complicated using other methods. Thus, aiming to optimise the material formula and improve its mechanical properties.

The effect of graphene oxide on the mechanical properties, impermeability and corrosion resistance of cement mortar containing mineral admixtures

Graphene oxide (GO) is one of the nanomaterials that have attracted the most attention of researchers in recent years. Because of its excellent mechanical, thermal and electrical properties, it is widely used in the fields of energy, photoelectric, catalysis and materials, and it has shown broad development prospects. For the high demand of cement-based materials in buildings, as a new cement composites reinforcement agent, GO has been widely studied by researchers. Based on previous studies, cement, silica fume (SF) and fly ash (FA) were used as composite cementitious materials in this experiment, and the effects of different GO contents (0.00%, 0.01%, 0.03%, 0.05%, 0.07%) on the mechanical properties of mortar were analyzed. In addition, the impermeability and sulfate resistance of the modified mortar were studied. The results showed that under the same curing conditions and ages, when the GO content is 0.05%, the flexural strength of the specimens after 28 days of curing is the highest, reaching 10.8 MPa, and the improvement rate is 16.1%. When the GO content is 0.03%, the compressive strength of the specimens after 28 days of curing is the highest, reaching 64.5 MPa, and the improvement rate is 12.4%. In addition, when the dosage of GO is 0.03%, the durability of the mortar is also extremely improved. The impermeability of the mortar is 80% higher than the reference specimens. The strength retention rate under the action of sulfate corrosion is also the highest, which is 11.3% and 6.7% higher than the compressive strength and flexural strength of the reference specimens that corroded for 3 months. GO was proved to be an excellent reinforcement agent for cement-based materials. Through SEM and XRD analysis, it was found that GO promoted the hydration reaction, and it played a filling effect and template role in the mortar matrix. Its two-dimensional lamella structure regulates the morphology of hydration products and enhances the interface adhesion between the matrix and the aggregate. In addition, its nano-filling effect eliminates a large number of micro-pores in the mortar and increases the density of the matrix.

Study on mechanical properties of mortars containing steel shot and sea sand as fine aggregate replacement

In this study, the use of solid waste known in the metallurgical market as steel shot that is generated in the production of metallic elements has been analyzed. Normally the destination of this solid waste is the sanitary landfills of the cities or the security cells since it is classified as hazardous waste. In addition, the use of materials with high availability and that were not previously used in the construction industry, such as sea sand was used in the manufacture of mortar cubes as a fine aggregate. A granulometric analysis of each of the filling materials followed by the casting of 63 mortar cubes with four different fine aggregate replacement ratios (0%, 30%, 70% and 100%) were carried out. After the curing period, the compressive strength and the weight of the resulting mortars have been determined. The results from this study indicated that by completely replacing the fine aggregate with the steel shot waste the density and the compressive strength of the resulting mortars were increased, which indicates that this new material can be used in the construction industry.

Research on the Thermal Properties of Fireplace Concrete Materials Containing Various Mineral Aggregates Enriched by Organic and Inorganic Fibers.

This work presents a summary of research on concrete fireplace materials made of various mineral aggregates and enriched with steel and organic fibers. To determine the optimal applications of such concretes, their ability to accumulate heat and their other physicochemical parameters were tested and analyzed. Studies on the behavior of concrete materials during cooling are reported, and the ability of such materials to accumulate heat is evaluated using calculations. In addition, tests were performed on the loss of mass during heating, as well as on the mechanical bending strength and microstructures of these materials. Studies have shown that the behavior of concrete materials at high temperatures can be modified and adapted for specific purposes. The addition of fibers to concrete improves both the mechanical properties of mortars and the heat flow in concrete materials.

Influence of concrete mixer washing waste water on the chemical and mechanical properties of mortars

The world's population will be facing water shortage problems by 2050. Recycling and treatment of residual water and reusing it in real life applications may help to solve this problem. However, the total cost of the treatment processes is estimated to be very high. The reuse of concrete mixer washing waste water without previous treatment may contribute to a significant reduction in the cost associated with the treatment process. This process may also reduce the consumption of drinking water, which is used by default in concrete fabrication and for washing purposes in concrete plants. This research paper studies the feasibility of reusing washing water of concrete mixer trucks without treatment to fabricate cementitious matrices and evaluates its influence on their chemical and mechanical properties. An experimental program was conducted by using 3 different types of waste water from washing concrete mixer trucks. The hydration kinetics of cement pastes was evaluated by isothermal calorimetry. Mortar workability was studied by the consistency index. The properties of mortars in the hardened state were evaluated by determining their porosity, tensile and compressive strength. Results showed that the waste water did not significantly influence the hydration kinetics nor the properties of the fresh and hardened state of mortars, indicating its possible use as mixing water to produce cement mixtures with no previous treatment. This research presents a promising sustainability key either for elimination of treatment cost or for water shortage that threatens many regions in the world.The following specific conclusions may be derived from the results obtained in this experimental program:

Properties and mechanism of the compound MgO expansive agent(CMEA) produced by calcining the mixture of dolomite and serpentine tailings

Ordinary MgO expansive agent is produced by calcining magnesite, a valuable and not abundant mineral. The objective of this paper is to propose a new method to produce a compound MgO expansive agent (CMEA) by calcining the mixture of dolomite and serpentine, both cheap tailings. The calcium in dolomite combines with the silicon in serpentine to form C2S, while magnesia in these two minerals is left out to act as expansive composition. The composition and microstructure of the clinkers were investigated by X-ray diffraction (XRD)-Rietveld quantitative analysis, X-ray fluorescence (XRF), second electron image (SEI) and backscattered electron image (BSEI) of scanning electron microscopy (SEM). The hydration process of CMEA was investigated by isothermal calorimetry. The expansive and mechanical properties of mortars containing CMEA were also investigated. Results indicate that the reaction of dolomite and serpentine is based on the contact of solid phase, the generating quantity of MgO and C2S in the CMEA clinker increases, but the hydration activity of CMEA decreases with the rise of calcining temperature during the range of 950℃~1150℃. Incorporating 20% CMEA into cement decreases its mechanical strength slightly, but generates a volume expansion significantly. The expansion rate and speed of mortars containing CMEA is controlled by the calcining temperature of CMEA clinker. For common concrete components, the preferential calcining temperature of CMEA clinker should be in the range of 1050℃-1150℃ to ensure an efficient expansive ability of CMEA.

Strengthening mechanism and microstructure of fibre-reinforced coral mortar and concrete

The effects of different dosages and lengths of carbon fibre (CF), sisal fibre (SF) and polypropylene fibre (PPF) on the microstructure and mechanical properties of mortar and concrete made with coral sand were studied through mechanical tests and scanning electron microscopy. In total, 37 groups of coral mortar and concrete specimens with the addition of CF, SF and PPF in four different dosages and three different lengths were tested. Based on mechanical tests and microstructure analysis, the strengthening effect and strengthening mechanism of fibre in coral mortar and concrete, and the mechanical properties of coral mortar and concrete were investigated. It was found that – compared with normal mortar and concrete – the workability of the coral mortar and concrete was poor due to its light weight, high porosity and rough surface. The strengthening effect of the fibres was reduced due to difficulty in dispersing the fibres evenly in the mortar and concrete. The addition of fibres significantly enhanced the flexural strength and toughness of the coral mortar and concrete, but an excessively high fibre dosage and the use of extra-long fibres significantly reduced its working performance due to the fibre curling and clustering, especially for CF. The optimal length and content of the different fibres were also investigated. The addition of SF was found to have the best strengthening effect.

Synthesis of novel chitosan/modified zeolite nanocomposites and their effect on the mechanical properties of cement mortars

In this paper, a novel nanocomposite containing biodegradable chitosan [CS] and modified zeolite [mZeo] was introduced as a cement eco-nano additive and its effects on the mechanical properties of cement mortars were evaluated. The proposed nanocomposite was prepared by using a synergistic sonication-microwave method. The surface morphology and chemical compositions of mZeo and CS/ mZeo nanocomposites were determined using SEM, FTIR, XRF, and BET. Compressive and flexural strength of cement mortars containing mZeo and CS/mZeo in ratios of 0%, 0.2%, 0.5%, 1% and 2% by mass, were investigated. Experimental results showed a significant improvement in the mechanical properties of mortars containing the proposed nanocomposite. The use of nanoscale zeolite in cementitious composites was attempted for the first time within this study and the results so far have been very promising. Therefore, it is concluded that the proposed nanocomposite has great potential to be used as an alternative eco-nano additive, for cementitious composites.

Study on effect of mechanical sand on mechanical properties and fractal characteristics of mortar pore structure

The influence of stone powder content, fly ash and other factors on mechanical properties, pore structure and fractal dimension of machine-made sand mortar were studied, and the relationship between fractal dimension and mechanical properties of mortar was explored. The research shows that with the increase of the content of stone powder, the mechanical properties of mortar and the fractal dimension of pore structure of different sizes increase; the porosity and average pore size of the mortar decrease, and the ternary of cement-fly ash-stone powder The micro-particle system can effectively optimize the pore structure distribution of the mortar; the fractal dimension of the mortar using ordinary river sand is significantly smaller than that of machine-made sand under the same conditions; with the increase of the fractal dimension of the pore structure, the compressive strength and flexural strength of the mortar continue to increase Large, the fractal dimension and the macroscopic mechanical properties of the mortar show a good correlation.

Utilization of Recycled Concrete Powder in Cement Composite: Strength, Microstructure and Hydration Characteristics

Recycled concrete powder (RCP) is used more and more in cement-based materials, but its influence on the hydration process is still unclear. Therefore, this paper studied the influence of recycled concrete powder (RCP) on the hydration process of cement and provides a theoretical basis for the hydration mechanism of cement composite materials. The hydration heat method was used to systematically analyze the thermal evolution process of cement paste with or without RCP. Hydration products were identified using X-ray diffraction (XRD) and thermal analysis (TG–DSC). The pore structure change of cement pastes was analyzed by mercury intrusion porosimetry (MIP) method. The mechanical properties of mortar were also evaluated. Four recycled concrete powder (RCP) dosages, such as 10%, 20%, 30% and 40% are considered. The results indicate that with the increase of RCP content, the hydration heat release rate and total heat release amount of paste decreased, but the second heat release peak of hydration reaction advanced; the proportion of harmful pores and more harmful pores increases, the total porosity and the most probable pore size also increase; the fluidity and mechanical strength of mortar decrease, but the crystal type of hydration products does not change. When the content of RCP is less than 20%, it has little effect on the mechanical strength of mortar. When fly ash and silica fume are mixed, the fluidity difference of mortar decreases, and when the content of fly ash is the highest, the fluidity of mortar is the highest, which is 15mm higher than that of the control group. When RCP content is 15%, fly ash and silica fume content is 15% (FA:SF = 3:2), the hydration heat of the clean pulp is the highest among all the compounding ratios, and the hydration reaction is the most complete; the proportion of harmless pores increased by 9.672%, the proportion of harmful pores and more harmful pores decreased, and the compactness of material structure increased; the compressive strength and flexural strength of mortar reached 50.6 MPa and 9 MPa respectively, both exceeding those of control mortar.

Cavitation properties of rendering mortars with micro silica addition

Micro-silica is a highly efficient mineral additive whose role is reflected in improvements of microstructure packing, strength and durability of non-shaped composite building materials such as concrete and mortar. A comparative study of performances of rendering mortars with different quantities of micro silica was conducted. The experimental program included production of reference mortar based on Portland cement and quartz sand (CM) and three mortars with 5, 10, and 15 % addition of micro silica (SCM-5, SCM-10, and SCM-15). The effect that micro silica addition has on the thermal behavior and mechanical properties of mortars was discussed. Hydration mechanisms and thermally induced reactions were studied at temperatures ranging from ambient to 1100 ?C by differential thermal analysis. The results were supported by X-ray diffraction analysis. The cementing efficiency of micro silica was assessed by cavitation erosion test. The changes in the morphology of mortar samples prior and upon cavitation testing were monitored by means of the scanning electron microscope imagining. It was found that 5 % of superfine micro silica (SCM-5 mortar) has positive effects on mechanical strengths (15 % increase in compressive strength) due to microstructure densification arising from the successive filling of voids by the micro silica. Addition of micro silica also improved the cavitation erosion resistance in comparison with reference cement mortar (SCM-5 showed cavitation velocity as low as 0.09 mg/min). This qualifies mortars with micro silica addition as building materials which can be safely employed in potential hydro-demolition environment.