Properties Of Cement Mortar Research Articles

Análise comparativa entre aderência à tração e resistência à compressão em argamassas produzidas com vermiculita expandida

In the construction industry, the performance of building elements is a pertinent topic for scientific research. Sustainability and concern for non-renewable natural resources have stimulated the search for alternative materials that have the potential to improve the properties of cement mortars. Although it is a material that is still rarely used as an aggregate in mortars, expanded vermiculite has interesting properties, with the potential to replace natural sand, reducing the environmental impact caused by its extraction. The aim of this study was to analyze, based on physical and mechanical characteristics, the reduction in environmental impact caused by replacing natural sand with expanded vermiculite as an aggregate in coating mortars. In this study, we analyzed the compressive strength and tensile bond strength of coating mortars produced from a 1:1:6 mix by volume and with 10, 20, 30, 40 and 50% replacement of natural aggregate with expanded vermiculite, comparing them with a reference mix. The experimental stage consisted of characterizing the aggregates, making the mortars and testing them in the fresh and hardened state. According to NBR 13281-1 (ABNT, 2023), the mixtures can be classified in terms of compressive strength as P3 (AN100, VE10, VE40 and VE50, with strengths between 2.5 and 4.5 MPa) and P4 (VE20 and VE30, with strengths between 4.0 and 6.5 MPa). Based on the same standard, the mixtures can be classified in terms of tensile bond strength as RA1 (AN100, VE40 and VE50, for strength greater than or equal to 0.2 MPa) and RA2 (VE10, VE20 and VE30, for strength greater than or equal to 0.3 MPa). It should be noted that the results for the intermediate traits VE20 and VE30, with compressive strengths between 4.0 and 6.5 MPa and tensile bond strengths greater than or equal to 0.3 MPa, can be classified as P4 and RA2 respectively. All the mixes complied with NBR 13749 (ABNT, 2013), which stipulates minimum values of 0.20 MPa for internal walls and 0.30 MPa for external walls. VE10, VE20 and VE30 were suitable for external cladding, while VE40 and VE50 were suitable for internal cladding. In these last two cases, the mixture stands out for meeting the standard and causing less environmental impact.

Utilization of thermal plasma decomposed municipal solid waste bottom ash as partial cement and fine aggregates replacements on cement mortar properties

Utilization of thermal plasma decomposed municipal solid waste bottom ash as partial cement and fine aggregates replacements on cement mortar properties

Superhydrophobic Property of Cement Mortar with Polydimethylsiloxane Modifier and a Rough Surface

Superhydrophobic Property of Cement Mortar with Polydimethylsiloxane Modifier and a Rough Surface

Enhancing engineering properties of cement mortars through microbial self-healing and community analysis

Enhancing engineering properties of cement mortars through microbial self-healing and community analysis

The influence of adding B. subtilis bacteria on the mechanical and chemical properties of cement mortar

BackgroundThis study investigated the effect of B. Subtilis bacteria on the properties of cement mortar. This was done by using soil samples from Sharkia, Egypt, to isolate 48 bacterial strains, after which they were cultured using the Johnson method and various media. Bacteria were then added to the cement mortar in amounts of 5% and 10% by weight to evaluate their effect on the mechanical and chemical properties of the modified mortar.ResultsThe study examined the compressive and flexural strength of the modified mortar over time, as well as its microscopic properties and chemical composition after 28 days. The results indicated that bacterial additions of 5% and 10% increased the compressive strength of the mortar after 28 and 56 days compared to the control. A 5% bacteria concentration resulted in significant improvements in strength, showing the best concentration for increasing mortar strength. The addition of 5% bacteria significantly enhanced the early flexure strength, while the 10% showed superior long-term strength after 56 days. Scanning electron microscopy (SEM) revealed high CaCO3 deposits in the bacterial samples, indicating microbial-induced calcite precipitation that filled the small cracks and increased strength. Fourier-transform infrared spectroscopy (FTIR) confirmed the presence of hydroxyl, carbonate, and silicate groups, with bacterial samples having a higher carbonate content, indicating an increase in calcium carbonate formation and microstructure.ConclusionsThe ideal bacterial concentration was 5% as it improved the compressive and flexural strength while also promoting a more flexible microstructure. This study supports the employment of microorganisms in the production of more durable and environmentally friendly building materials, enhancing the sustainability of building practices.

Improving damping properties of cement mortar using oxidized and methyl methacrylate-grafted coconut fibers

Improving damping properties of cement mortar using oxidized and methyl methacrylate-grafted coconut fibers

An ecofriendly approach to explore the physical and mechanical properties of cement mortar reinforced with Abutilon indicum fibres

An ecofriendly approach to explore the physical and mechanical properties of cement mortar reinforced with Abutilon indicum fibres

Measurement of viscosity during vibroextrusion of fiber concrete

Currently, the rheological properties of cement mortars containing dispersed reinforcement have not been studied enough, so it is important to develop a method for measuring the viscosity of fiber concrete mixtures that would simulate the technological process. To consider the flow process and calculate the rheological characteristics of fiber concrete mixtures during vibroextrusion, hydrodynamic theories were applied due to the fact that these mixtures behave like liquids in a vibration field. When solving flow problems, it is taken into account that vibrating fiber concrete mixtures are Newtonian systems. To obtain objective rheological characteristics of fiber concrete mixtures, it is proposed to measure viscosity directly during vibro-extrusion molding of flat products. The peculiarities of the flow of Newtonian fluids between flat fixed walls, which converge in a flat symmetrical rectangular narrowing channel, are considered. It is proposed to determine the reduction of the flow rate of the mixture in the rectangular channel compared to the flow between the plates by the braking coefficient. A graph of the dependence of the braking coefficient on the ratio of the sides of the cross section of the rectangular channel is plotted. 2 formulas are proposed for calculating the braking coefficient. The comparative analysis of the proposed formulas gives a good convergence of the calculation results, the average approximation error is equal to 0.0126%, which indicates a high level of coincidence of the regression equation with a more complex analytical formula. Taking into account the inhibition of the liquid flow in the end zones of the rectangular channel, a formula was proposed for calculating the viscosity of the fiber concrete mixture during the formation of flat products in the narrowing vibroextruder channel. The calculation formula contains the geometric dimensions of the channel, the density and the flow time of the fiber concrete mixture, and to determine the viscosity of the mixture, it is necessary to measure only the time of its complete flow during vibroextrusion. The proposed formula and methodology for calculating viscosity can be used to determine the rheological characteristics of any Newtonian fluids using a flat symmetrical rectangular narrowing channel. In the future, it is planned to continue researching the properties of fiber concrete mixtures under the influence of vibration.

Influence of hydroxypropyl methylcellulose on the mechanical properties of cement mortar reinforced by sawdust

This study explores the incorporation of Hydroxypropyl Methylcellulose (HPMC) and sawdust into cement mortar, focusing on their effects on the setting time and mechanical properties, such as compressive and flexural strengths. Various formulations were prepared by adding different proportions of HPMC (1% and 2%) and sawdust (2%) to a standard cement mortar mix. The setting time was assessed using the Vicat apparatus, while the compressive and flexural strengths were evaluated at 7, 14, 21, and 28 days of curing. Results showed that the addition of HPMC significantly improved the mortar's performance by reducing the setting time and enhancing both compressive and flexural strengths. At 28 days of curing, the mortar with 2% HPMC and 2% sawdust exhibited a compressive strength of 32.4 MPa and a flexural strength of 5.6 MPa, compared to the control sample, which had a compressive strength of 28.1 MPa and a flexural strength of 4.2 MPa. These findings suggest that incorporating HPMC and sawdust can be an effective way to improve the strength and sustainability of cement-based materials.

Impact of replacing dune sand with ground date palm on the performance of cement mortar: dispersion analysis

This study investigates the effects of substituting dune sand with ground date palm at varying proportions of 0.5% to 2% on the mechanical and thermal properties of cement mortar. The findings indicate that this substitution enhances both the thermal and mechanical performance of the mortar, thereby improving its insulation capabilities. Notably, significant variations in compressive strength are observed, particularly at an early age of 7 days, with a reduction in variability as the mortar matures. Additionally, a high dispersion in measurement results is recorded. The application of the Weibull model facilitates the quantification of this variability and the assessment of material reliability, emphasizing the necessity of considering these fluctuations in the evaluation of sustainable construction materials. This approach not only underscores the potential of utilizing ecological resources but also paves the way for innovative practices in the construction sector. Overall, the study highlights the promising implications of incorporating alternative materials for enhancing the performance and sustainability of cement-based composites.

SEM analysis, durability and hardened characteristics of eco-friendly self-compacting concrete partially contained bentonite and waste walnut shells

Reusing waste materials as aggregate in self-compacting concrete (SCC) may reveal green construction materials. Walnut shell (WS) can be used in place of aggregate in SCC. This study utilized five dissimilar volume fractions of WS as fine aggregate ranging from 8% to 40%, containing bentonite clay powder constant as 10% of cement weight. The SEM analysis, fresh properties and hardened characteristics of all SCC mixtures were assessed. Additionally, the impact of a 5% concentration of H2SO4 and MgSO4 solution for a month on the compressive and splitting tensile strengths and density were studied. The workability of all the LWSCC mixes satisfied standard requirements except of L-Box result; nevertheless, as the WS content increased, the workability of the LWSCC mixtures declined. Following the exposure period for both sulphate attacks, all characteristics of LWSCC mixes were reduced. In contrast to the control mixture, the SEM analysis shows that when WS was added in greater amounts, the concrete became less dense and had more voids. Furthermore, the statistical analysis was performed by using two-way variance (ANOVA) technique which revealed that the effects of all independent variables on the strength and other properties of cement mortar were significant under all experimental conditions.

Feasibility Study of Magnesium Slag, Fly Ash, and Metakaolin to Replace Part of Cement as Cementitious Materials

To achieve the efficient utilization of magnesium slag, this study investigates the use of magnesium slag, fly ash, and metakaolin as partial substitutes for cement in cementitious materials. The reactivity of these materials is assessed based on the compressive strength of mortar. The response surface methodology is employed to explore the influence of material proportions on the strength performance of cement mortar. The mechanisms underlying strength development in the composite system are examined through XRD, SEM, TG-DTG, and BET analyses. Additionally, the effect of magnesium slag on the drying shrinkage properties of cement mortar is studied. The experimental results indicate that magnesium slag exhibits low reactivity and cannot be used alone as an active admixture. The optimal proportion of magnesium slag, fly ash, metakaolin, and cement is 10:10:10:70, achieving over 80% of the strength of pure cement mortar and approximately 1.5 times the strength of cement mortar containing 30% magnesium slag. Furthermore, magnesium slag helps mitigate the volume shrinkage caused by drying in cement mortar. Therefore, this study can facilitate the comprehensive utilization of magnesium slag in the construction sector, reducing its negative impact on the ecological environment.

Force-electric properties of smart cementitious composites reinforced with carbon fiber and conductive recycled fine aggregates

A type of intelligent cement mortar was created in the laboratory to achieve higher piezoresistive sensitivity for self-health monitoring of concrete structures and to address the reduction in mechanical properties caused by using recycled fine aggregate (RFA). It is a type of cement-based material that natural fine aggregate is partially replaced with highly conductive modified recycled fine aggregate (M-RFA) treated with graphite powder-agar gel impregnation, and a small amount of carbon fibre (CF) was uniformly distributed in the M-RFA mortar to construct a three-dimensional conductive network. The paper studied the intelligent cement mortar's workability, mechanical properties, conductivity, and piezoresistive performance. The results show that the content of M-RFA has little effect on the working performance of the composites, and CF significantly affects the working performance of the composites, which can meet the requirements after adding a superplasticizer. The addition of M-RFA will reduce the mechanical properties of smart cement mortar, but the multi-doped carbon fibre can restore the reduction of mechanical properties caused by M-RFA. Since CF helps M-RFA to be embedded in a conductive network by directly connecting M-RFA or tunnelling effect, conductive mortars doped with CF and M-RFA can significantly reduce resistivity, improve piezoresistive sensitivity, and improve signal stability. The loading rate affects the piezoresistive properties of cement mortar, and the strain sensitivity is negatively linearly correlated with the loading rate. It is worth noting that the conductive mortar with 0.24 vol% carbon fibre and 80 % M-RFA content achieves the highest strain sensitivity (836.9), lower resistivity (150.1 Ω•cm), and the best economy.

Mechanical and Physical Properties of Cement Mortar with Recausticizing Solid Byproduct

Mechanical and Physical Properties of Cement Mortar with Recausticizing Solid Byproduct

Lavender and Black Pine Waste as Additives Enhancing Selected Mechanical and Hygrothermal Properties of Cement Mortars.

The paper presents the mechanical and hygrothermal properties of cement mortars containing bio-powders made from lavender waste and black pine wood. The wastes were mechanically ground with a hammer mill to a fraction not exceeding 0.5 mm and then dried in air-dry conditions. The influence of bio-additives in amounts of 1.5% and 2.5% of the overall mortar volume was tested. The aim of the paper was to determine the impact of bio-additives on the mechanical and hygrothermal properties of the tested cement mortars. This publication included tests of compressive and flexural strength, elastic modulus, water absorption, absorption due to capillary rise, sorption and desorption properties, thermal properties, microstructural tests using mercury intrusion porosimetry and SEM, and EDS. The main conclusions of the research indicate that mortars with both 1.5% and 2.5% bio-powders are characterized by strong bactericidal properties, lower sorption properties at high air humidity, lower thermal conductivity, reduced compressive strength by 22-27%, no significant effect on the flexural strength, and significant reduction in capillary action of mortars both with short-term and long-term water exposure.

Preparation and characterization of core-shell structured CaCO3-SiO2 and hollow silica nanoparticles and evaluation of their effects on cement mortar properties

CaCO3-SiO2 particles having a core-shell nanostructure were produced by a modified Stöber process using CTAB as a surfactant. Then, a porous structure composed of a silica shell was formed after the removal of the CaCO3 cores as templates from the nanocomposite. To evaluate phase constitutions and microstructures of prepared nanoparticles, XRD, TEM, and FESEM–EDX techniques were utilized. The main aim of this work was to examine the usability of prepared CaCO3-SiO2 and SiO2 hollow shell nanoparticles instead of OPC in structural applications. In this way, the mixtures of cement mortar were made by partial replacement of 1% of cement mass with prepared nanoparticles. The amounts of calcium hydroxide (CH), bound water, and calcium carbonate for the prepared mortars have been calculated after 7 and 28 days of hydration through thermal analysis of TG/DTG. The results indicated that the CH content decreased by adding prepared nanoparticles as a cement replacement. As CaCO3-SiO2 and hollow SiO2 nanoparticles were used, the compressive strengths of mortars were enhanced by 34 and 59%, respectively, after 28 days, which were higher than the increasing influences on flexural strengths (29 and 55%). The increasing intensity of the XRD peaks related to the C-S-H phases and the decline of the orientation index of CH in a mortar containing silica shell suggest that hydration was further completed, leading to a strength improvement. The SEM micrographs indicated that the addition of prepared nanostructures improved the interface properties inside mortar and caused the microstructure to be denser.

Investigations on the rheological properties of cement mortar based on fine aggregate characteristic and its extended prediction model

The rheological property of mortar is significantly influenced by its contained fine aggregate morphology characteristic and capable predictive models are limited. This work aims to expand the film thickness theory by developing an index that integrally represents variations in grain shape, gradation, and mix proportions, and elucidates the impact and the mechanism of these multifactorial differences on rheological performance. The quantitative analysis of the aggregate gradation and particle shape differences were performed, which was used to assess the impact of these variations and different mix ratios on the rheological performance of mortars. A correlation between aggregate differences and film thickness was established using specific surface area and void ratio. The result shows that variations in aggregates are accurately assessed by image analysis and consistently reflected in specific surface area and void ratio metrics. Since variations in rheological performance are predominantly governed by differences in film thickness, the disparities among aggregates can be quantified in terms of their impact on rheological properties by considering specific surface area and void ratio, thus translating into variations of film thickness. The differences in rheological properties due to variations in grain shape, gradation, and mix proportions can be comprehensively represented and controlled through an expansion of the film thickness model.

An environmental approach to cement admixtures: Utilization of waste olive seed powder as a bio-polymeric admixture.

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 0/125μm 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, 28days 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.

Studying of Mechanical Behavior of Waste Materials Modified Cement Mortar

Large-scale environmental problems have been triggered by ceramic tiles from demolished buildings and animal bone waste. Therefore, optimizing their potential for reuse and recycling is an important goal of sustainable solid waste management. The primary objective of this study is to evaluate the feasibility of partial replacement of the fine aggregates in cement mortar with a combination of natural animal bone powder and industrial waste materials which is wall tiles ceramic powder. This study measures thermal and mechanical characteristics. Recycling construction waste is one of many ways to deny waste material from entering landfills and create new eco-friendly material that reduces energy consumption in buildings. Modified mortar cement specimens with 5% up to 25% mixtures were combined using a 1:3 ratio and a 0.5 W/C ratio to see how the ratios would affect the material’s properties. The addition of a superplasticizer boosted the cement mortar’s workability and compressive strength. The compressive strength, flexural strength, density, and thermal conductivity were evaluated for each mortar mixture ratio. Results showed that compared to regular cement mortar, cement mortar combined with 20% bone and ceramic powder wastes reached the optimal replacement percentage. Compressive strength increased by 54% and flexural strength by about 67%. At the 28-day mark, thermal insulation was lowered by 25%.It is concluded from this study that it is possible to use bone waste as a natural material with ceramic waste as an industrial material to modify the insulation and mechanical properties of cement mortar.

The Use of Waste Synthetic Hair Fibre in Cement Mortar

Cement mortar has low tensile strength and fracture strain; therefore, fibres are used to reinforce cement mortar. Synthetic hair is one of the most neglected of all the residual wastes that cause environmental problems in many developing countries. Therefore, this study used waste synthetic hair fibre in cement mortar production as a way to reduce the environmental effect generated by waste, and also to enhance the strength of the mortar for construction application. The study aimed to investigate the properties of cement mortar reinforced with waste synthetic hair fibres. 0, 2.5, 5, and 7.5% of synthetic hair fibre were used as a replacement for cement by weight in mortar. 100 × 100 × 100 mm cube, and 100mm diameter and 200mm length cylinder specimens were prepared, cured, and tested at ages 7, 14, and 28 days for tensile and compressive strengths, density, and water absorption. The highest compressive strength for the synthetic waste hair fibre reinforced mortar was 8.57N/mm2 as compared to 10.84N/mm2 achieved for the control at 28 days of curing. The synthetic waste hair fibre reinforced mortar achieved the highest tensile strength of 1.80N/mm2 as compared to 1.67N/mm2 achieved by the control at 28 days of curing, representing an increase of about 11% in tensile strength of the synthetic hair fibre reinforced mortar over the control. The highest density for the synthetic hair fibre reinforced mortar was 2114 kg/m3 as compared to the control of 2144 kg/m3. The lowest water absorption for the synthetic hair fibre reinforced mortar was 2.48% as compared to the control of 2.04%, respectively. It is concluded that the properties of cement mortar reinforced with waste synthetic hair fibres are acceptable for construction application and recommended that practitioners use 2.5% waste synthetic hair as a partial replacement for cement in producing mortar.