Compressive Strength Of Mortar Research Articles

Integrated Effects of Metakaolin and Nano-silica in Superplasticizer-Free Mortar: An Analysis of Mortar Compressive Strength with Relative Strength, K-Factor and Clinker Savings

Integrated Effects of Metakaolin and Nano-silica in Superplasticizer-Free Mortar: An Analysis of Mortar Compressive Strength with Relative Strength, K-Factor and Clinker Savings

Study on the rheology, mechanical properties and microstructure of polypropylene fibers in different binder systems

To explore the effects of polypropylene fiber (PPF) on the properties of different binder materials, the effects of PPF on the rheology, shrinkage, mechanical properties and microstructure of alkali-activated mortar (AAM) and ordinary Portland cement mortar (PCM) were studied. The results showed that the addition of PPF reduced the fluidity of the mortar, and the lower the initial yield stress and plastic viscosity of the paste were, the more obvious the increase. PPF reduced the drying shrinkage of both the AAMs and PCMs by 7.63–12.85 %. The inclusion of PPF to the mortar had a limited effect on enhancing the mortar compressive and flexural strength, but it notably improved the mortar toughness. At a fiber content of 0.5 %, the samples from the cement and slag-steel slag systems exhibited a more compact of the interfacial transition zone (ITZ) between the fiber and paste. Conversely, the slag-steel slag-fly ash and slag-fly ash systems showed poorer compact of the ITZ, which was attributed to increased unreacted precursors and shrinkage cracks. This phenomenon primarily accounted for the superior residual stresses observed in the cement and slag-steel slag systems. This study provides an avenue for analysis the effect of the same fiber on different binder systems.

Pullout test for PC column-capital grouted rebar connection with corrugated duct

Double-beam precast concrete (PC) structures require large capitals to support a wide PC girder. In this study, a segmented PC column-capital system is developed to overcome the disadvantages of conventional PC columns in terms of manufacturing, transportation, and construction. In the proposed segmented PC column-capital system, large PC capitals are assembled with PC columns using the proposed corrugated rebar connections filled with grouted mortar. To verify the load-transfer capacity of the proposed corrugated rebar connections, pullout load tests are conducted under various test parameters, including the mortar compressive strength, curing time, bond length, and embedment length. To enable rapid construction, a relatively short curing time of 1–2 days is addressed. The test results indicate that the pullout performance of the proposed corrugated rebar connection is primarily affected by the mortar compressive strength fm’ and embedment length ld. When fm’ > 7.9 MPa and ld = 800 mm, the proposed corrugated rebar connection transfers tensile loads corresponding to construction loads. When fm’ > 21.0 MPa and ld = 800 mm, the proposed rebar connection can resist the tensile yielding load of the connected vertical rebar even after one-day of curing. However, when ld is less than 800 mm, bond-slip failure occurs because of the insufficient bond length. Based on the test results, a parametric analysis is conducted using a finite-element model. Similar to the experimental result, the numerical result shows that the bond strength of the proposed rebar connections is significantly affected by fm’ and ld. Hence, a bond-strength model of less-hardened grouted mortar with a bond stress of τb = 0.20 fm’ is suggested based on the previous and present test results as well as parametric analysis results.

The Use of Sargassum spp. Ashes Like a Raw Material for Mortar Production: Composite Performance and Environmental Outlook.

The accumulation of brown algae from the genus Sargassum has been increasing over the years in coastal regions of the Caribbean, Africa, Brazil, and Mexico. This causes harmful effects to the ecosystem, human health, the economy, and the climate due to gas emissions from its decomposition process. There is the possibility of this biomass being reused in civil construction, and some studies have been carried out on its application to common Portland cement mortar. As such, the objective of this study is to evaluate the potential of sargassum ash as a mineral addition to partially replace fine aggregates in Portland cement mortar. Characterization of the raw materials was carried out through X-ray fluorescence spectroscopy, loss on ignition, particle size distribution, Brunauer-Emmett-Teller (BET) analysis, real density, X-ray diffraction, scanning electron microscopy, and dispersion spectroscopy of electrons. The mortars were prepared by partially replacing the fine aggregate (sand) with sargassum ash at 0%, 5%, 10%, and 20%. Mortar performance was evaluated through water absorption, apparent porosity, apparent specific mass, and compressive strength 7, 28, and 63 days after curing. Lastly, a life cycle assessment was conducted in accordance with ISO standards 14040:2006 and 14044:2006. The results showed that replacing sand with sargassum ash increases water absorption and apparent porosity, and decreases the apparent specific mass and compressive strength as replacement increases. Nevertheless, the compressive strength results after 63 days for 5 and 10% replacement did not differ statistically from reference values. The life cycle assessment indicated that mortars with partial replacement of sand by sargassum ash show positive environmental impacts when compared to reference values for most categories, regardless of the scenario analyzed, especially for mortar with 10% replacement. As such, the use of sargassum ash at 10% does not alter the mortar's compressive strength values after 63 days, but does reduce its environmental impact. The application of this biomass in civil construction materials provides a destination for this algae, and that can be a solution to mitigate the social, environmental, and economic problems it has been causing.

Strength assessment of structural masonry walls: analysis based on machine learning approaches

ABSTRACT In conventional masonry buildings, masonry walls are key structural load-bearing elements. Likewise, masonry infill walls strengthen framed constructions against lateral stress. The material characteristics of brick units and mortar determine the compressive strength of structural masonry walls. In this study, advanced machine learning (ML) techniques were utilized to estimate the compressive strength of structural masonry walls based on the material properties of brick units and mortar. The Young’s modulus of brick units (Eu), compressive strength of brick units (Fcu), Young’s modulus of mortar (Em), and compressive strength of mortar (Fcm) were used as input parameters to model the compressive strength (Fc) of the structural masonry wall. Gradient Tree Boosting (GTB), Elman Neural Network (ENN), and Multivariate Adaptive Regression Splines (MARS) were developed using four diverse input and output (I/O) combinations to explore the effect of each input parameter on output estimation. The data used for modeling were obtained from prior studies published in the literature. The model’s performance was evaluated based on different statistical (error and efficiency) indices. For the third and fourth (I/O) combinations, the MARS model significantly outperformed other models. However, for the first I/O combination, the GTB model performed well. The study also revealed that the compressive strength of a structural masonry wall is more likely to depend on the strength and quality of the brick units than on the strength of the mortar.

Cement Mortars Based on Polyamide Waste Modified with Fly Ash from Biomass Combustion—A New Material for Sustainable Construction

The article presents an analysis of the possibility of using the waste of polyamide 6 modified with fly ash (in the amount of 5, 10 and 15%) from the burning of wood–palm kernel shells biomass as an addition to cement mortar. Fly ash from the burning of biomass in a circulating fluidized bed boiler (which currently has no practical use) was first used to produce polyamide 6, and then post-production polymer waste (added at 20, 40 and 60%) was used to produce ecological mortar. The use of this type of waste is both economically profitable and desirable due to the need to implement waste material management processes in a closed circuit. The addition of polyamide 6 waste containing 5% fly ash in amounts of 20 and 40% and waste containing 10% ash in 20% to cement mortars improves their mechanical properties. The compressive strength of cement mortars (after 28 days of maturation) containing 20 and 40% of polyamide waste containing 5% fly ash increases by 6.6 and 4.6%, respectively, and the flexural strength by 4.9 and 3.4% compared to the control mortars. However, the compressive strength of mortars with the addition of 20% polyamide waste containing 10% fly ash increases by 4.2% and the flexural strength by 3.7%. Cement mortars modified with waste are characterized by slightly lower water absorption and mechanical strength after the freezing–thawing process (frost resistance) compared to control mortars and do not have an adverse effect on the environment in terms of leaching metal ions.

Statistical assessment of the factors influencing fly ash reactivity

Siliceous fly ash is a pozzolanic supplementary cementitious material often used in cement and concrete production. The influence of the chemical, mineralogical and physical properties of 75 siliceous fly ashes on their reactivity was examined in this study. The reactivity was analyzed by relative mortar compressive strength and a rapid screening test (a version of the R³ test). A statistical data analysis was carried out to evaluate the factors influencing the reactivity of the ash. The screening test was found to be able to predict the reactivity within short periods of time, while the relative strength is not a good measure for reactivity. It was also found that the TiO2 and chloride content of the fly ash can serve as an indicator for its reactivity.

Synthesis, performance and mechanism of shrinkage-reducing agents with water-reducing function for cement-based materials

Three shrinkage-reducing agents (SRAs) possessing a water-reducing capacity with different structures were synthesized by aqueous free radical copolymerization. Their structures were characterized by Gel Permeation Chromatography (GPC), specific anion charge density, and Fourier Transform Infrared Spectrometer (FTIR) measurements. Their abilities to reduce surface tension and their adsorption and dispersing effectiveness in cement paste as well as their impacts on cement hydration and compressive strength, autogenous shrinkage, drying shrinkage, and pore structure of cement mortar were investigated. Results clearly showed that the three synthesized SRAs with a water-reducing function reduced the surface tension of pore solution, with the water-reducing SRA with butyl exerting the most significant effect due to its lower molecular mass. They enhanced the flowability of cement paste because of their adsorption on cement grains. The water-reducing SRA with dimethyl amino exhibited higher adsorption amounts on cement grains due to higher charge density, resulting in higher initial flowability of cement paste and more significant hydration retardation. Their presence decreased the autogenous shrinkage of cement mortar by reducing the surface tension of pore solution, delaying the cement hydration, and decreasing the capillary pore volume. Their addition also mitigated the drying shrinkage due to the synergistic effect of surface tension reduction, pore structure coarsening, and porosity (2.5–50 nm) reduction. Among the three, the water-reducing SRA with butyl demonstrated a higher capability of reducing the drying shrinkage and had a favorable effect on the compressive strength of mortar at later ages.

Out-of-plane behavior of masonry infilled Chuan-dou timber frames

The masonry infilled Chuan-dou timber frame is a traditional structural system widely used for non-engineered residential buildings in southwestern areas of China, where earthquakes are common. And the masonry is prone to out of plane (OOP) collapse due to the lack of an effective connection between the timber frame and the masonry. This paper discusses the OOP seismic performance of masonry infilled wall Chuan-dou timber frame. Considering the slenderness ratio and the compressive strength of mortar, three full-scale single-story specimens were subjected to airbag loading to investigate the out-of-plane seismic behavior of the structural systems. Two typical failure modes of the structural systems including one-way bending and shearing slip were observed in the study. The results indicated that the slenderness ratio of the infilled masonry was inversely proportional to the bearing capacity of the structural systems. The columns have a limited effect on the constraint of infill wall while the beam can prevent the wall from falling out of the frames. And the OOP seismic behavior of the infill wall can be improved by strengthening the connection between the infilled wall and the frame. At the same time, the formulas for peak OOP load are presented based on a two-hinged arching/rocking pier mechanism.

Experimental studies and symbolic machine learning aided prediction model of the mechanical properties of recycled waste slurry micropowder mortar

Ready-mixed concrete generates large quantities of concrete waste during production and transportation. The reuse of concrete recycled waste slurry in mortar and concrete is widely regarded as having significant potential and promising prospects. This study aims to investigate the impact of recycled waste slurry micropowder (RSP) on the microscopic structures and macroscopic mechanical properties of RSP mortar. A series of microscopic experiments and uniaxial compressive tests were conducted on RSP mortar at replacement rates of 0%, 10%, 20% and 30% of RSP for cement. The particle size, Scanning Electron Microscope (SEM), X-ray Diffraction (XRD) and Date Time Group (DTG) analyses of RSP show that RSP has weaker particle size uniformity, rougher surface, less mineral content and higher water content than cement, which leads to a lower comprehensive performance of RSP than cement. As the replacement ratio of RSP increases, the strength of RSP mortar gradually decreases. This study provides a new approach for the strength prediction of RSP mortar. The machine learning model based XGBoost and SHAP are introduced to quantify and rank the importance of the influencing factors of the compressive strength of RSP mortar. It is found that the influence of cement strength on the compressive strength of mortar is the most critical, followed by the importance of RSP replacement rate and particle size. Then, a symbolic regression is adopted to establish a prediction model for the compressive strength of RSP mortar, and the prediction process of pure data-driven method is transformed into a practical mathematical equation suitable for engineering application.

Development of ternary blend cement-free binder material for construction

This study aims to develop new ternary blend (TB) cement-free binder materials as an alternative to conventional cement by using Paper Sludge Ash (PSA) waste as the base material. During this research, the combined application of mechanical activation (grinding) and chemical activation by blending with pozzolanic: (silica fume; SF) and (rice husk ash; RHA), and high al-kalinity: (poultry litter fly ash; PLFA) and (cement kiln dust; CKD) materials were investigated. The research plan included four stages in which PSA was activated and replaced with the above-mentioned materials until reaching a ternary blend binder with the best performance (depending on the mortar compressive strength). Thereafter, the performance of this ternary blend binder was compared with the conventional cement by conducting compressive strength (at the ages of 3, 7 and 28 days) and Scanning electron microscopy (SEM) tests. The findings indicated that a cement-free binder material was developed by using a combination of 60% PSA that was blended with 20% RHA and 20% PLFA. The new binder has shown higher compressive strength than the conventional cement by about 12% after 28 days of curing.

Impact of Superabsorbent Polymer on Shrinkage and Compressive Strength of Mortar and Concrete

This article aims to study the effects of mixtures with superabsorbent polymers (SAPs) when using different mixing methods. The mixing methods used in this study are the dry mixing method and wet mixing method. Autogenous shrinkage, total shrinkage, drying shrinkage, compressive strength, and curing sensitivity index values are investigated. The results show that mixtures with SAPs have reduced autogenous shrinkage and total shrinkage. Shrinkage is more effectively reduced by the dry SAP mixing method than the wet SAP mixing method. The compressive strength derived by the dry SAP mixing method is higher than that derived by the wet SAP mixing method.

Experimental investigation into the potential of recycled concrete and waste glass powders for improving the sustainability and performance of cement mortars properties

This comprehensive experimental investigation delves into the world of sustainable mortar mixtures by introducing recycled concrete powder (RP) and waste glass powder (GP) as partial substitutes for conventional Portland cement (OPC). The primary goal is to assess how these substitutions affect the mechanical, physical, and durability characteristics of mortar. RP and GP are individually and jointly incorporated at substitution rates of 10 %, 15 %, and 20 % by weight of cement. The study encompasses a wide range of tests, including compressive and flexural strengths, acid resistance, workability, and microstructural analysis. The study shows that replacing 10 % cement with RP increases mortar compressive strength by 13.28 % after 90 days, and a combination of 15 % GP and RP improves mortar durability against chemical attack. Economic evaluations confirm cost savings exceeding 10 % for all blended mortars compared to OPC. The environmental perspective, explored through a carbon footprint assessment, demonstrates substantial reductions in CO2 emissions when RP and GP are employed in lieu of OPC. Overall, this study highlights the potential of utilizing recycled materials, to enhance the performance and durability of cement-based concrete production.

Numerical simulation of autoclaved aerated concrete masonry wall subjected to close-in explosion and the structural damage assessment

In this study, we investigated the destructive effect of autoclaved aerated concrete (AAC) masonry walls subjected to close-in explosions. First, full-size refined finite-element models of the AAC masonry wall were established, and the accuracy of the models was verified by comparison with the test results. The destruction pattern and damage characteristics of the AAC wall were studied, and the effects of block size, wall thickness, mortar compressive strength, and explosion distance on the destruction degree of the AAC masonry walls were analyzed. The results showed that the destruction pattern of the AAC masonry wall subjected to close-in explosion manifested as punching damage in the middle of the wall. When the scaled distance remained unchanged, the punching damage area of the AAC masonry wall was positively correlated with the block size and negatively correlated with the wall thickness and mortar compressive strength. When the explosive equivalent remained unchanged and the explosion distance increased, the punching damage area first increased and then decreased. According to the damage mechanism of the AAC masonry wall, a calculation method for predicting the punching damage area of the AAC masonry wall was established, and the accuracy of this method was verified by comparing it with the numerical results. In addition, the damage criterion based on the punching damage area was established to determine the destruction levels of AAC masonry walls.

Development optimization and performance evaluation of mineral capsules based on magnesium oxide expansive agent

Mineral capsules could improve the self-healing ability of cement-based materials by avoiding the premature reaction of minerals. This study mainly optimized the preparation process of mineral capsules and comprehensively evaluated the influence of mineral capsules on the mechanical and self-healing properties of cement-based materials. By incorporating different contents of magnesium oxide expansive agent, the basic properties of mineral capsules were investigated and the optimal dosage of healing agent was determined. The encapsulation effects of polyvinyl alcohol and epoxy resin were compared to identify the better wall material. Then the mechanical and self-healing properties of the mortar mixed with different amounts of mineral capsules were comprehensively analyzed. Results from the healing potential, granule strength and soundness of mineral cores indicated that the optimal dosage of magnesium oxide expansive agent was 60 wt%. Compared with polyvinyl alcohol, mineral capsules encapsulated with epoxy resin had higher granule strength and better alkali resistance. Although the addition of mineral capsules had a negative impact on the compressive strength of mortar, the self-healing performance was significantly improved. With increasing contents of mineral capsules, the cracked mortar obtained more pronounced crack closure and impermeability recovery.

Geopolymer using different size fractions of recycled brick-based mixed demolition waste

The hike in CO2 emission from the cement industry calls for an alternative binder to cement. On the other hand, constructionand demolition waste management is a global concern. This research aims to demonstrate the complete applicability of brick-based demolition wastes in geopolymer mortar and concrete. Ground Granulated Blast Furnace Slag (GGBS) was used with brick waste to improve performance. 3 M, 4 M and 6 M NaOH were used for mortar preparation, and 6 M NaOH was used for concrete tests. The performance of the geopolymer binder and mortar was compared with the control specimen. 5 % to 20 % incorporation of demolition waste powder (DWP) with GGBS was explored to find the optimum binder combination. A 10 % incorporation for 3 M and 15 % for 4 M and 6 M was found optimum. Then, 10 % to 100 % incorporation of brick sand was studied to examine the influence of brick-based demolition waste on the fresh and hardened properties of mortar. Sand: Binder: Alkaline activator was taken 3.375: 1: 0.45 for mortar. The workability of mortar varied with the increase of brick sand content. The flexural and compressive strengths were decreased with an increase in brick sand content for all molarities of NaOH; consequently, the water absorption increased with brick sand content. The maximum mortar compressive strength of 27 MPa was found for 10 % demolished sand with a 6 M alkali concentration. However, consistent results were obtained with a 4 M concentration. Geopolymer concrete from brick-based demolition waste was prepared using 6 M NaOH. The UPV result indicates the regular quality of the concrete cube, with acceptable capillary water absorption after 24 h. However, the compressive strength of geopolymer concrete could be useful for non-structural works, and therefore, further studies with higher strength of NaOH for geopolymer concrete are recommended.

Effect of gypsum content in cement on its adaptability to alkali-free accelerator at different temperatures

The setting times and early strength of shotcrete are greatly affected by the gypsum content of the cement used. In this work, the setting times, compressive strength and microscopic analysis (X-ray diffraction quantitative analysis, thermogravimetric analysis and scanning electron microscopy) were used to determine the effects of changes in gypsum content on the hydration and mechanical properties of cement mixed with an accelerator at different temperatures. The results showed that an increase in the gypsum content of the cement promoted the formation of ettringite (AFt) and decreased the setting times of the cement pastes at 0°C, 20°C and 40°C. Mortar compressive strength tests showed that, after curing at 0°C, 20°C and 40°C, the highest compressive strength was exhibited with a final molar aluminate-to-sulfate ratio (C3A/SO3; henceforth called the MASR) of 0.84, 0.84 and 1.18, respectively. The mechanical properties of the hardened cement pastes were adversely affected by MASRs that were too high or too low. When the MASR was too high, the conversion of AFt to monosulfate (AFm) was facilitated and C3S hydration was slowed. Conversely, when the MASR was too low, this enabled large amounts of AFt to occupy the space where calcium silicate hydrate (C-S-H) gels were formed, resulting in decalcification of the C-S-H gels.

Impact of Graphene on Microstructure and Compressive Strength of Cement Mortars Utilizing Two Different Dispersion Methods

Impact of Graphene on Microstructure and Compressive Strength of Cement Mortars Utilizing Two Different Dispersion Methods

Effects of Adding Coal Ash vs Rice Husk Ash on Compressive Strength of Mortar

Coal is widely used as an energy source in several industries, especially for power plants (PLN), but on the other hand this causes waste problems or environmental impacts. Several studies have been carried out to utilize coal ash waste (fly ash) as an additional material [or as a partial substitution material] in making mortar. This research aims to determine the effect of adding coal ash and rice husk ash with variations of 5%, 10% and 15% of cement weight respectively (at ages 3 days, 7 days, 14 days, 21 days and 28 days). on the 'compressive strength' and 'absorption capacity' values of the mortar. This research uses quantitative methods through a series of experiments on 60 samples or test objects with the addition of coal ash (fly ash) and rice husk ash in the mortar mixture with reference to the Indonesian National Standard (SNI 03-6825-2002). Next, a series of tests were carried out at the age of 3 days, 7 days, 14 days, 21 days and 28 days to calculate the ' strong ' value. press' and ' power absorb' mortar. The research results showed that with the addition of coal ash and rice husk ash, the mortar experienced a significant increase in 'compressive strength' when compared to ordinary mortar, the strength of the mortar reached the optimum level at a variation of 15% addition of the cement weight, reaching 240.96 kg /cm 2 . Meanwhile, with the addition of husk ash in the same variation, the compressive strength of the mortar reached 204.82 kg/cm 2 .

Fracture behaviour assessment of high-performance fibre-reinforced concrete at high strain rates using interpretable modelling approaches

High-performance fibre-reinforced concrete (HPFRC), a type of cementitious composite material known for its exceptional mechanical performance, has widespread applications in structures exposed to severe dynamic loading conditions. However, understanding nonlinear HPFRC fracture behaviour, particularly under high strain rates, remains challenging given the complexities of assessment procedures and cost-intensive nature of experiments. This study presents an interpretable framework for modelling and analysing HPFRC fracture strength at high strain rates. A wide range of machine learning methods, including ensemble techniques, were employed to capture multivariate effects of eight essential input features (e.g., mortar compressive strength, fibre physical and mechanical properties, cross-sectional area, and strain rate) on fracture strength response. To assess the derived models, a novel evaluation procedure was proposed involving a data-based analysis, employing established metrics (i.e., coefficient of determination, root mean squared error, and mean absolute error via K-fold cross-validation) and a domain experts-involved evaluation utilising global sensitivity analysis to discern first-order and higher-order interactions among input factors. The proposed approach efficiently yielded both quantitative and qualitative insights into crucial input factors governing HPFRC fracture strength with limited experimental data. The obtained findings highlight the significance of multivariate effects, such as the interaction between strain rate and fibre tensile strength, and between fibre volume and fibre diameter, on fracture behaviour. The proposed interpretable framework aims to provide a powerful tool for proactive material failure analysis by understanding fracture behaviour and identifying potential weak and strong interactions among input factors of HPFRC-based samples. Moreover, the utilisation of the proposed approach enables researchers and civil engineers to efficiently focus on the most critical input parameters during the early design stage and ensuring the structural integrity and safety of HPFRC-based constructions.