Increase In Compressive Strength Research Articles

The Influence of Multi-Size Basalt Fiber on Cemented Paste Backfill Mechanical Properties and Meso-Structure Characteristics

As the mine enters the deep mining stage, there is a need to enhance the compressive strength and toughness of the backfill. The objective of this study is to examine the mechanical properties of cemented tailings backfill after the incorporation of multi-size fibers and to validate the toughening mechanism of basalt fibers (BFs). To achieve this, a series of basic mechanical property tests for multi-size BFs mixing were devised, accompanied by industrial computerized tomography (CT) scanning and discrete element simulation. This study shows that the compressive strength increases and then decreases with the increase of BF dosage at a certain percentage of each size, and the splitting tensile strength gradually increases with the increase of BF dosage. The compressive strength tends to decrease and then increase, and the splitting tensile strength increases and then decreases as the fiber size ratio changes. The distribution of cemented tailings backfill and BF within the discrete element model is random. A few BF cannot play a bridging role; however, a moderate amount of BF is relatively uniformly distributed in the model to form a network structure, which generates a bond between the particles and the matrix and can effectively limit the expansion path of cracks and enhance the toughness.

Research on axial compressive behavior of steel-fiber-reinforced recycled concrete-filled square steel tube slender columns

This paper presents an experimental and analytical study of the axial behavior of steel-fiber-reinforced concrete-filled square steel tube slender columns. A total of 25 axially compressive column specimens are manufactured to investigate the effects of the mass replacement percentage of recycled coarse aggregates (Rp), tube wall thickness (Ts), length-to-width ratio of columns (Lc), and steel fiber content (Vsf) on the performance of slender columns. The results show that the effects of Lc and Ts on the compressive behavior of the column specimens are significant owing to changes in the confinement effect and instability. In terms of the bearing capacity, the compressive strength increases by 12.45%–23.19% as Ts increases from 3 to 5 mm but decreases by 4.35%–10.65% as Lc increases from 6 to 12. However, the incorporation of steel fibers improves the post-peak load mechanical behavior of the slender columns by performing anchoring and bridging effects, and when Vsf reaches 1.2%, it tends to compensate for the reduction caused by changes in Lc and Ts. The synergistic action of the column specimens under axial compression is quantified based on an energy consumption indicator. In addition, predictions of the bearing capacity of the slender columns specified in the Eurocode 4, GB 50936-2014, and Han model are compared and discussed. An incremental iteration model is proposed, and the predicted values are similar to the experiment results with reasonable safety margins.

Optimization of the compressive strength of used tire/cement phase composite concretes using a full factorial design

The purpose of this work is to optimize the treatment conditions of rubber aggregates using a full factorial design. NaOH concentration and treatment duration and devulcanization were used as factors, while the compressive strength of the concretes was the response to the factorial design. The results indicated that NaOH concentration and treatment duration, as well as the interaction between NaOH treatment duration and devulcanization, have a significant influence on the compressive strength of rubberized concrete. 10% NaOH concentration, 60 min NaOH treatment duration and 30 s devulcanization were optimal treatment conditions. Under these optimal treatment conditions, an increase in compressive strength of 12.11% is observed compared with concretes incorporating untreated rubber aggregates.

Physicomechanical Behavior of High-Performance Concrete Reinforced with Recycled Steel Fibers from Twisted Cables in the Brittle State—Experimentation and Statistics

This research studied the effect of recycled steel fibers extracted from twisted cable waste on the fresh and hardened states of high-performance concretes. Accordingly, slump, water absorption (WA), compressive strength (CS), flexural strength (FS), and split tensile strength (STS) were measured in the laboratory using mixtures generated by the response surface methodology (RSM). The RSM-based central composite design (CCD) was used to assess the influence of water-to-binder (W/B) ratios from 0.27 to 0.31, length-to-diameter (L/d = 46 to 80) and steel fiber content (SFC) in the range of 19 to 29 kg/m3 on the behavior of high-performance fiber-reinforced concrete (HPFRC). The accuracy and validation of the generated models were evaluated by employing analysis of variance (ANOVA) and optimal parameters. The experimental findings revealed that the use of an L/d ratio of 63, a W/B ratio of approximately 0.28, and an SFC of around 22 kg/m3 resulted in high workability in terms of slump. While a notable increase in compressive strength was observed when employing an L/d ratio of approximately 70, a W/B ratio of around 0.28, and the maximum SFC of 29 kg/m3, as confirmed by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis.

Physico‐mechanical and thermo‐mechanical analysis of zinc borate filled glass fiber reinforced polymer composites

AbstractThe potential benefits of using zinc borate powder as filler material in the production of glass fiber‐reinforced composites were explored in this study. The epoxy matrix was filled with zinc borate powder at 5%, 10%, and 15% by weight, as part of the hand lay‐up approach followed by a compression molding process. Ultrasonication was used to mix the epoxy resin with zinc borate fillers. Both the elemental composition and morphological characteristics were studied using a scanning electron microscope and energy‐dispersive X‐ray analysis. The composite's density, tensile behavior, flexural behavior, impact resistance, and hardness were all measured experimentally. The potential incorporation of zinc borate particles resulted in a modest reduction in the void contents, in addition to enhancing the interfacial bonding in glass fiber‐reinforced composites as also a significant improvement in both the mechanical and thermal properties of the hybrid composites produced. The 10 wt.% zinc borate‐ filled glass fiber‐reinforced composites exhibited a significant rise in both ultimate tensile strength (227 MPa), ultimate compressive strength (239 MPa), and ultimate flexural strength (406 MPa) compared to the unfilled counterpart. The performance of the laminated composites was greatly improved by adding zinc borate powder particles to the matrix.Highlights In the present work glass fiber was reinforced with zinc borate to explore the morphological, mechanical, and thermal properties. Ultrasonication was used to mix the epoxy resin and zinc borate fillers and the composites were manufactured by compression molding process. The addition of zinc borate resulted in an increase in tensile strength, flexural strength, and compressive strength. The thermal stability of the composites was increased by the addition of zinc borate to the glass matrix. The good bonding between the matrix and fiber resulted in improvements in various properties.

Dynamic stress-strain relationship of steel fiber-reinforced rubber self-compacting concrete after exposure to high temperature

The purpose of this study was to investigate the dynamic compression characteristics of steel fiber-reinforced rubber self-compacting concrete (SFRSCC) after exposure to high temperatures by using the split Hopkinson pressure bar (SHPB) impact test. The study considered four parameters: strain rates of 55 s−1, 90 s−1, and 155 s−1; volume fractions of steel fibers of 0%, 0.5%, 1.0%, and 1.5%; volume fractions of rubber contents of 0%, 10%, 20%, and 30%; and temperatures of 25 ℃, 300 ℃, 600 ℃, and 900 ℃. Experimental results revealed that: (I) The toughening effect of rubber decreases after exposure to high temperature, which decreases the specimens' dynamic compressive strength and toughness index after high temperature with the increase of rubber content. (II) The dynamic compressive strength, toughness index, and dynamic increase factor (DIF) of the specimens increased with the increasing steel fiber content after exposure to the same temperature. (III) The dynamic compressive strength of the specimens decreased linearly as the temperature increased, and the toughness index initially increased and then decreased. However, the incorporation of steel fiber mitigated this reduction. (IV) The impact of strain rate on compressive strength, toughness index, and DIF-σ was more significant for specimens exposed to high temperatures than for those at room temperature Finally, a stress–strain curve prediction formula considering temperature, rubber content, steel fiber content, and strain rate of SFRSCC was proposed.

Study on the Basic Mechanical Properties and Discrete Element Method Simulation of Permeable Concrete

Permeable concrete pavement material has many voids and a good water permeability, which can reduce surface runoff and alleviate the problem of urban water logging. It also has the functions of acting as a supplementary source of groundwater, purifying water, bodies reducing the urban heat island effect, reducing road noise, and so on. It is an effective solution for urban infrastructures. However, at the same time, because it has a large number of pores, this also affects the strength of permeable concrete. The main factors affecting permeable concrete are particle size and the shape of the aggregate, the content of the cement paste and aggregate, the compaction degree of the mixture, and so on. In this study, the single-factor test method was used to study the effects of aggregate size, slurry-to-bone ratio and loose paving coefficient on the basic mechanical properties and permeability of permeable concrete. Here, the numerical model for permeable concrete is established by using the particle flow discrete element (Particle Flow Code (PFC)modeling method, and a numerical simulation test is carried out. It can be seen from the test results that the permeability coefficient of 50% 5–10 mm + 50% 10–15 mm mixed aggregate permeable concrete is slightly lower than that of 5–10 mm and 10–15 mm single-size aggregate, but has a higher compressive and splitting tensile strength. With the increase in paste-to-bone ratio, the permeability coefficient of permeable concrete decreases, and the compressive strength increases. The loose paving coefficient has a significant effect on the mechanics and permeability of permeable concrete with the increase in the loose paving coefficient, the water permeability decreases and the compressive strength increases. The numerical simulation results show that under the condition that the loose paving coefficient is 1.10 and the slurry-to-bone ratio is 0.5, compared with the experimental results, the error of the numerical simulation results of the compression test is less than 3%. The reliability of the simulation is verified. The discrete element modeling method in this study can be used to simulate the shape of the aggregate in permeable concrete, and the numerical model can effectively simulate the crack development and failure form of permeable concrete in compression tests.

Variation of compressive strength characteristics of basic concrete with partial replacement of cement content

Fly Ash (FA) and Waste Glass Powder (WGP) are two waste products that are being evaluated as potential cement substitutes in this study. At first, characterization of both types of waste was conducted to check the similarity index and to what extent, if any. The cement content of basic or ordinary concrete has been partially replaced by using FA and WGP. A wide range of different combinations of mix design has been used by using both wastes. In order to check the performance of newly formed concrete, compressive strength analysis has been performed. The outcomes point unequivocally in the direction of a more efficient usage of both waste for fractional replacement of cement content in concrete. Maximum rate of increase in compressive strength was observed as 21.6% for the curing age of 7 days in case of Mx design 2, whereas equal amount of FA and WGP were used to replaced partial cement content from ordinary concrete. Characterizations show that FA and WGP can both function as a cement substitute. It was also determined that the innovative possibilities opened up by the recycling of trash in the construction industry had contributed to an improved economic climate.

Finite element analysis of RC beams strengthened with near-surface mounted reinforcement bars under pure torsion

This study’s primary objective is to investigate the pure torsional behavior of reinforced concrete beams with inadequate resistance to applied loads. The beam needs to be strengthened with a simple and effective technique, the near-surface mounted. This paper was conducted to check the validity and accuracy of experimental results. This numerical study included testing three specimens; one was control beams, while the remaining were strengthened beams with two configurations with NSM closed and U-stirrups steel stirrups and longitudinal NSM bars. Each beam has three variables: Remove NSM longitudinal bars, use concrete’s compressive strength (20,60) MPa, and Strengthen with NSM GFRP and CFRP bars. All beams have a cross-section (300x300 mm), and the length of the beam was constant (2100 mm). The numerical analysis showed close results to those obtained from the experimental work. This convergence was evident in failure and ultimate torque patterns and mechanisms. The ultimate torque increased when strengthening with four faces of NSM closed stirrups and three faces of NSM stirrups (U-shape) at a spacing of 130mm. On the other hand, The increase in compressive strength leads to an increase in the ultimate torque. Lowering compressive strength leads to more ductile behavior with lower ultimate torque. Removing the additional longitudinal reinforcement has a minor effect on behavior. The type of bars, steel, CFRP, and GFRP, have a marginal impact on the behavior with more ductile behavior for the steel reinforcement bar beams.

Effect of solid content on the piezoelectric properties of porous (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 ceramics

The influence of the solid content of porous (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 (BCZT) ceramics on the pore morphology and mechanical and piezoelectric properties was systematically investigated. The results show that with an increase in solid content, porosity and pore size decreased, and ceramic connectivity increased, leading to an increase in compressive strength. The best ferroelectric performance was achieved with an Ec of 2.40 kV/cm2 and a Pr of 2.01 μC/cm2 at a solid content of 30 vol%. When the solid content increased, the relative dielectric constant and the piezoelectric constant increased, which affected the piezoelectric energy harvesting performance. At a solid content of 20 vol%, g33 and FOM33 reached maxima of 43 × 10−3 Vm/N and 6.7 p.m.2/N, which were 2.40 times and 1.8 times those of the other solid contents, respectively. This work provides new ideas for the design of porous piezoelectric ceramics and the improvement of their piezoelectric properties for future piezoelectric energy harvesting applications.

Study on strength, durable and flexural behaviour of partial replacement of sugarcane bagasse ash over cement

Tonnes of cement are produced and used due to boom in infrastructure sector. During the process of production of cement, lot of CO2 has been emitted. It is estimated around 4%–8% of CO2 has been emitted from cement production. There is high need for address this issue. Because of its renewable nature and high silica content, Agriculture waste ash is gaining popularity as a viable alternative to traditional cementitious materials. It has been found by (Hernandez et al ) that Sugarcane bagasse ash shows good pozzolanic activity. Sugarcane bagasse ash (SCBA) is a waste-free renewable energy source made from sugarcane fibres. Many attempts have been made to study the SCBA as partial replacement for cement. The same has been checked in this study with extension for structural members have been done. The results of tests on concrete and concrete containing a partial replacement of cement made from sugarcane bagasse ash (SCBA) are the most important details in this text. The substitution of 10% SCBA resulted in the greatest increase in compressive strength, followed by a modest increase in split tensile strength maximum strength. The study findings allow for the conclusion that the Concrete that was built has high durability qualities. The flexural behaviour also showed very good performance. The use of Bagasse Ash shows improved performance due to is micro grain size and crystallographic nature. The replacement of 10% SCBA results in overall better performance.

Influence of carbon dioxide on shrinkage behavior and compressive strength of AAC in accelerated tests

AbstractBackgroundThe German application standard DIN 20000‐404:2018‐04 for the use of AAC according to DIN EN 771‐4:2015‐11 describes a method to determine the long‐term resistance due to carbonation. Thus, the total value of the drying shrinkage as specified in DIN EN 680:2006‐03 must not exceed 0.40 mm/m. This threshold was evaluated using empirical methods.ObjectiveIn order to verify the above threshold, additional studies were carried out in this paper on AAC blocks from different manufacturers.ExperimentalDeviating from the standard climate according to DIN EN 680:2006‐03, a parametric study was carried out under laboratory conditions. All AAC specimens were stored at a relative humidity of 80% and a carbon dioxide concentration of 0.5% by volume. In addition to the shrinkage behavior, the compressive strength behavior of the AAC specimens with increasing carbonation progress was investigated.ResultsThe degree of carbonation of the individual AAC types progresses at different rates. AAC that carbonates faster shows a greater change in length (up to about 5.2 mm/m) and a significant loss in compressive strength (up to about 50%). In some cases, the compressive strength initially increases before decreasing again. AAC containing fly ash only shows an increase in compressive strength with progressive carbonation.ConclusionsThe determination of the total value of drying shrinkage according to DIN EN 680:2006‐03 appears to be the most suitable method so far to identify AAC blocks with an increased risk towards carbonation with a manageable effort. The accompanying compressive strength tests indicate that the specified limit value of 0.40 mm/m according to DIN 20000‐404:2018‐04 is also appropriate.

Performance Assessment of Compressive Strength Property of Concrete Made with Hong Soybeans Hull Ash and Groundnuts Shell Ash in the Production of Ternary Concrete

Rapid urbanization through infrastructural development has resulted in depletion of natural resources leading to effects of flooding, global warming with incidents of health issues. A more ecofriendly way to solve this problem is through the adoption, use and invention of more ecofriendly concrete composite. Therefore, this research investigated the effect of replacing blended mix of soyabeans hull ash (SBHA) and groundnuts shell ash (GSA) in concrete production. A total of 108 cubes of 100mm x 100mm x 150mm were cast. The study specifically determined the physical and chemical properties of Soybean hull ash and groundnut shell ash, setting time and the compressive behavior of the concrete cubes. 6 mixes were produced with identities T0, T10, T20, T30, T40 and T50, the cubes were cured in water at 7, 14, 28 56, 90 and 180 days. The result shows an increase in compressive strength with increase in days of hydration. On 28 days curing, the strength of the ternary composites cured in water were in the range of 83% to 87% strength of the control cubes. The compressive strengths of the ternary concrete at 28 days were T0: 25.5N/mm2, T10: 21.1N/mm2, T20: 22.2N/mm2, T30: 24.2N/mm2 , T40: 22.2N/mm2 and T50: 24.3N/mm2 indicating a slow level of formation of SiO2 at the early stage of curing however at a latter age of 56 days curing there was a rapid increment in the compressive strength with all the concrete cubes attaining higher strength than the control concrete cubes while T50 possessed the highest compressive strength of 27.5N/mm2. Therefore, this study recommends T50 composing of 80%OPC + 12.5 %SBHA + 7.5% GSA for use for structural elements in Hong, LGA Adamawa for construction purposes.

Effect of Rise in Temperature (250°C) on the Physico-Mechanical Properties of Rubber Mortars

Abstract The recovery and use of waste in the field of civil engineering, particularly in construction materials, is one of the most prominent solutions for preserving the environment. In order to evaluate the results obtained, it is necessary to study the evolution of the properties of these new materials in the different environments where they can live or be exposed, and why not develop an effective method of treatment of such materials for the possibility of their use even in the field of precast concrete. The objective of this work is to study the effect of the increase in temperature as a living environment or as a treatment on the physico-mechanical properties of a crumbled mortar, a potential source of many environmental and economic problems. Hence the screening and the possibility of using these new mortars with sufficient physico-mechanical properties for masonry and why not for prefabrication. The formulation of the mixtures based on the substitution of dune sand by crumb rubber, at different weight contents 10, 20 and 30%. Consequently, prismatic specimens (4x4x16) cm3 subjected to the temperature (250°C), with a speed of 2°C/min followed by a one-hour plateau at the target temperature then cooling to the ambient temperature. The results obtained show that the maximum mass loss is 5% for 30% substitution and that for 10% substitution the absorption by total immersion decreased by more than two thirds and the porosity accessible to water decreased by more than half. The compressive strength increases by 8.9% for 10% substitution and the minimum decrease in tensile strength by bending is at the same substitution of an order of 26.9%. Using the analysis of variance, the influence of the substitution of dune sand by rubber crumbs and of the rise in temperature to 250°C on the behavior of the mortar acquired. Patterns developed by response surface methodology were significant for all p-value substitutions <5%. The results of the numerical optimization showed that the best mixture could obtained by replacing 30% of dune sand with rubber crumb and subjecting the hardened mortar obtained from this mixture to the temperature of 135°C.

Mechanical properties and microstructure of the heterogeneous DZ2 axle steel under high-strain-rate compression at ambient temperature

This study aims to clarify the mechanical properties and deformation characteristics of the newly-developed DZ27CrNiMo (DZ2) axle steel for the China standard electric multiple units under dynamic loadings along the diameter direction of the axle at room temperature. The DZ2 axle steel has a heterogeneous band structure consisting of equiaxed grain and lath morphology tempered martensite. When being impacted at the strain rate range from 500 s−1 to 2440 s−1, its yield strength, compressive strength, and plastic strain increase. The flow stress upturn after yielding mainly depended on the strain rate effect rather than the work hardening due to the suppressed dislocation cross-slip. Meanwhile, the steady plasticity was consistent with the presence of uniformly distributed dislocations and microbands within the heterogeneous laminates. Although the nanoscale adiabatic shear bands (ASBs) and micro-cracks were found to initiate at the high strain rate of 2440 s−1, their propagation could be inhibited by the hard-tempered sorbate laths. As a consequence, an excellent resistance for impact-induced fracture was realized in DZ2 axle steel. Taking the thermal activation damage evolution into account, a modified Zerilli-Armstrong (ZA) constitutive model was proposed to describe the dynamic mechanical behavior of DZ2 axle steel. The modeling results were consistent with the experimental data, indicating a high prediction accuracy and good application availability in the operation and maintenance of DZ2 axle.

Effect of processed sugarcane bagasse ash on compressive strength of blended mortar and assessments using statistical modelling

There is much agriculture and non-agricultural waste that contains pozzolanic material, which can be recommended to use as a partial replacement for Ordinary Portland Cement (OPC). One of the waste products from sugar industries, which possess pozzolanic properties, is Sugar Cane Bagasse Ash (SCBA). Because of the negative impact associated with cement production, OPC is being replaced by several supplementary cementitious materials / pozzolanic materials. In the current study, an effort has been made to use the SCBA by partially replacing the OPC for mortar studies. SCBA has been processed to enhance the chemical and physical properties. OPC is partially replaced by Processed Sugar Cane Bagasse Ash (PSCBA) up to 30% by a 5% increment. PSCBA blended cement mortar contains different proportions of PSCBA blended cement: river sand as 1:3, 1:4, and 1:5 with different water-to-binder (W/B) ratios based on the flow studies. Experimental research was done to determine the effects of the W/B ratio, river sand, and PSCBA on the formation of the cube compressive strength of PSCBA blended cement mortar for curing times of 7, 14, 28, 56, and 112 days. An increase in compressive strength about 6.4%, 9.3%, and 8.2% for 1:3, 1:4 and 1:5 with different W/B ratios for 28 days is reported. Based on the investigational results, the coefficients of strength for various relationships proposed by different researchers have been calculated for the binder: sand ratio as 1:3 and 28 days curing period. Various relationships, including Abraham, Feret, Singh, and Bolomey law are used to validate the mixes of the PSCBA blended cement for different water-to-binder ratios and different curing periods. A novel relation has been developed through the extension of studies to forecast the compressive strength of PSCBA blended mortar mixes with various W/B ratios for various curing times.

Effect of modified nano-SiO2 on properties and microstructure of the high-performance cementitious composites

The effect of modified nano-SiO2 (MNS) on the performance of high-performance cementitious composites (HPCC) was investigated and the underlying mechanism was revealed by various microscopic analysis and testing methods. Results indicated that the fluidity of HPCC initially increased and then decreased with the increase of MNS content. Meanwhile, The HPCC with 0.8% MNS exhibited a 25% increase in compressive strength at the curing age of 3 days, while the HPCC with 0.8% nano-SiO2 showed a 10% increase. Compared with the reference mixture, the durability and autogenous shrinkage of HPCC with MNS were significantly improved, the chloride diffusion coefficient of HPCC with 0.8% MNS decreased by 25.9%. Furthermore, the quantitative analysis results of hydration process and hydration products show that the inclusion of nano-materials accelerated the hydration rate of cementitious composites, resulting in increased cumulative heat release. HPCC with MNS exhibited a higher generation of amorphous phases and greater consumption of calcium hydroxide compared with reference mixture. Moreover, the addition of MNS effectively refined the pore size of HPCC and converted some harmful pores into less harmful or harmless pores, enhancing the microstructure of HPCC with MNS and improving the interface transition zone. This optimization was mainly attributed to the effect of filling, nucleation of crystal and pozzolanic reactive of nano-materials, which further benefit from the good dispersion of MNS, resulting in excellent mechanical properties and durability of HPCC.

Effects of graphene nanoplatelets inclusion on microstructure and mechanical properties of alkali activated binders

This paper presents a study investigating for the first time the effects of the inclusion of graphene nanoplatelets (GNPs) on the mechanical and microstructural properties of alkali activated binders produced with fly ash and slag and using superplasticizer for the GNPs dispersion in the mixing water. Compressive strength and water absorption of mortar cubes, flexural strength of mortar beams, X-ray computer tomography scanning and mercury intrusion porosimetry, Fourier transform infrared spectroscopy, scanning electron microscopy with Energy Dispersive X-Ray Spectroscopy, and X-ray diffraction, were carried out on samples cured either at room temperature or at 40 °C. Results showed that the inclusion of GNPs at a dosage of 0.05% provided a considerable increase in compressive strength at both curing conditions. Microstructural observations suggested that the presence of GNPs improved the formation of hydrated gel, and the research demonstrated through porosity measurements the shift from the capillary to the gel pore region due to the inclusion of GNPs. This study represents a step forward in understanding the effects of GNPs inclusion on alkali activated binder microstructure.

Evolution of the pore structure of pumice aggregate concrete and the effect on compressive strength

Abstract China possesses abundant pumice resources and thereby makes the utilization of pumice in the preparation of pumice aggregate concrete (PAC) a significant strategy for environmental protection and resource conservation. To obtain the effect of pumice pore structure variation on the compressive strength of PAC, PACs with strength classes LC20, LC30, and LC40 were prepared. Moreover, the pore structure of PAC was characterized using nuclear magnetic resonance to investigate the effect of pore structure variation on the compressive strength of PAC. Results showed that the higher the coarse aggregate content of PAC, the higher the percentage of large capillary and non-capillary pore sizes of PAC, corresponding to higher porosity and lower compressive strength. The hydration products in PAC continuously fill in the pore structure, the proportion of large capillary pores and non-capillary pore size gradually decreases, the proportion of small capillary pores and medium capillary pore size gradually increases, the pumice concrete matrix gradually becomes dense, and the compressive strength increases. The prediction model of the pore structure and compressive strength is established based on gray theory, and the relative error between predicted and tested values is not significant, which can effectively predict its compressive strength. It provides effective guidance for the engineering practical application of PAC.

Determination of optimum blast furnace slag ash and hemp fiber ratio in cement mortars

This study aims to investigate the effect of incorporating hemp fibers into cement mortars to enhance their mechanical properties. Additionally, the study examines the use of blast furnace slag (YFC) as a substitute for cement to reduce costs. The findings demonstrate that adding 1%, 2%, and 4% hemp fibers to cement mortars yields the best results in terms of density, water absorption, compressive strength, bending strength, compressive strength after bending, and flexural strength. In conclusion, the study reveals that incorporating hemp fibers enhances the workability of YFC-blended mixtures while reducing the spreading diameter as the hemp fiber content increases. Additionally, an increase in YFC substitution leads to a decrease in compressive strength; however, the addition of 1% hemp fiber to the Y15 mixture results in a approximately 12% increase in compressive strength, indicating improved matrix strength and reduced crack formation. Moreover, the study shows that the flexural strength increases with the addition of hemp fibers, with the highest flexural strength observed in the mixture containing 4% hemp fiber and 10% YFC substitution. The results highlight that the combination of YFC and hemp fibers can produce strong, durable, and environmentally friendly composite materials. These materials offer a lower environmental impact and cost-effectiveness compared to traditional construction materials.