Proportions Of Cement Research Articles

The Prophylactic Effect of Single vs. Dual Antibiotic-Loaded Bone Cement against Periprosthetic Joint Infection Following Hip Arthroplasty for Femoral Neck Fracture: An Analysis of the German Arthroplasty Registry.

Antibiotic-loaded bone cement in arthroplasties is currently experiencing increased usage. Therefore, single and double antibiotic-loaded bone cements are commercially available and used in orthopedic surgery. The aim of this investigation was to compare the clinical use of single compared to dual antibiotic-loaded bone cement for implant fixation after femoral neck fracture. Further infection rates were to be compared in (partial) arthroplasty for the treatment of femoral neck fracture for both treatment options. On the basis of the German Arthroplasty Registry (EPRD), all cases of femoral neck fracture treated with hemiarthroplasty (HA), or total hip arthroplasty (THA) with single and dual antibiotic-loaded bone cement, were included into the data analysis. The infection risk was compared using Kaplan-Meier estimates. In total, 26,845 cases (HA 76.3%-THA: 23.7%) with femoral neck fracture were included. Within recent years, an increasing usage of dual antibiotic-loaded cement in Germany, with a current proportion of 7.30% in arthroplasty procedures for femoral neck fracture treatment, has been observed. In patients treated with HA, the proportion of dual antibiotic-loaded cement was 7.86%, while in those treated with THA, 5.46% of all prostheses were fixated with a two antibiotic component cement. For all arthroplasty procedures using single antibiotic-loaded bone cement after six months 1.8%, after one year 1.9%, and after five years 2.3%, of the cases failed due to periprosthetic joint infection (PJI), while in the same time period, in cases with dual antibiotic-loaded bone cement 1.5%, 1.5% and 1.5% suffered from infection (p = 0.34). A infection rate of 1.1% after HA with dual antibiotic-loaded bone cement was reported, compared to a 2.1% infection rate whilst using single antibiotic-loaded bone cement after five years (p = 0.098). The number required for treatment when using HA was 91. The use of dual antibiotic-loaded bone cement is increasingly used in arthroplasty procedures after femoral neck fractures. It demonstrates a reduction of PJI after HA and seems, therefore, to be a useful method for the prevention of infection, especially in patients with increased risk factors for PJI.

Microstructure and Strength Parameters of Cement-Stabilized Loess

In this study, cement was used as a component to provide a stabilizing effect in order to evaluate the hardness and stability of loess soil. To evaluate the strength properties of loess soil reinforced with cement, samples with four distinct cement concentrations (3%, 5%, 7%, and 9%) and three distinct curing durations (7, 14, and 28 days) were generated. During a series of tests, the flexural strength, direct shear strength, indirect tensile strength, and unconfined compressive strength were determined. An appropriate cement dosage was found, in addition to a durability index that could be used to quantify the effect of water absorption investigations on cement-stabilized loess. Both of these discoveries were made simultaneously. Scanning electron microscopy (SEM) and energy dispersive X-ray fluorescence spectrometry (XRF) examinations were carried out so that the fundamental mechanics of the materials could be comprehended. The results show that the cohesion of cement-stabilized loess is much more sensitive to structure than the friction angle of the material. The increase in shear strength after remoulding is due to cohesion. The SEM study showed that the cement interacted with the loess particles to produce a thick cement network that successfully covered the voids and boosted the mixture’s strength parameters. The 28-days UCS for the samples containing 7% cement was the greatest, at 3.5 MPa, while the UCS for those containing 9% cement was 4.78 MPa. The highest flexural tensile strength of 1.98 N/mm2 was determined after 28 days. The tensile strength after 7 days in samples containing 3%, 5%, 7%, and 9% cement reached a maximum force of 0.15 MPa, 0.23 MPa, 0.27 MPa, and 0.37 MPa, respectively, and increased with each passing day. To achieve the desired level of strength, it is necessary to adjust the proportion of cement. In addition, as the curing period progressed, we observed an increase in the resistance and stiffness of the cement-stabilized loess due to the interactions that take place between the structure and the mineral composition. It is believed that this event was caused by naturally occurring cementation. As a consequence of this reaction, the production of new cementitious materials takes place. The cation exchange that causes the hydration and pozzolanic reaction that leads to the creation of aggregates and interparticle flocculation is responsible for their production. These findings suggest that cement may be utilised as a simple and effective method of loess stabilization, ultimately resulting in improved performance of the loess. Therefore, this study revealed that cement may considerably enhance the microstructure and strength parameters of loess. This research provides important information on cement-stabilized loess that has ramifications for geotechnical investigation, construction, research, and testing to achieve a successful project.

Mechanical Properties and Microstructural Features of Biomass Fly Ash-Modified Self-Compacting Coal Gangue-Filled Backfill.

To achieve sustainable utilization of a large amount of mine solid waste, this study investigated the performance of self-compacting coal gangue-filled backfill (SCFB) containing biomass fly ash (BFA) generated from biomass power plants as a supplementary cementitious material (SCM). The correlations between the physical structure and compressive strength of SCFB samples were obtained by ultrasonic pulse velocity (UPV). The failure process of the SCFB samples was monitored by the digital image correlation (DIC) technique, and the stress-strain relationship and failure pattern were also analyzed. The micro-morphological structure and hydration products of SCFB samples were evaluated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and backscattered electron imaging (SEM-BSE). The results show that the usage of 30~40% BFA in SCFB improves the physical structure and strength of the samples. The compressive strength and UPV value of SCFB samples with different water-to-cement (w/c) ratios showed a similar trend of increasing and then gradually decreasing as the proportion of ordinary Portland cement (OPC) replaced by BFA increased. BFA exhibits better reactivity and filling effect in SCFB samples with a high w/c ratio. The peak stress of SCFB samples gradually decreases, and resistance to deformation gradually weakens with the increase in w/c ratios, while the DIC results further verify the mechanical experimental results. Microstructural analysis revealed that reducing the w/c ratio and incorporating specific ratios of BFA can reduce the thickness of the interface transition zone (ITZ) and porosity. The results of the study will provide theoretical guidance for the modification, stability monitoring, and strengthening of SCFB.

Self-compacting concrete incorporating incinerated biomedical waste ash: a performance assessment

Rapid technological advancement is underway in the sphere of material science research. Several studies have been undertaken around the globe over the last four decades to improve the strength and durability performance of concrete. As a result of ongoing research and experimentation, concrete no longer just consists of the traditional materials of cement, aggregates and water but has transformed into an engineered custom material with efficient new ingredients in order to meet the demands of the expanding construction industry. In this experimental study, biomedical waste incinerator ash (BMIA) was employed as a partial substitute for cement in self-compacting concrete (SCC), designed for M30 grade. BMIA was partially replaced with cement in proportions of 0%, 5%, 10%, 15% and 20% by cement weight. This experimental work aimed to study the fresh, mechanical and durability characteristics of the SCC mixes incorporating BMIA. A suitable super-plasticizer was used to retain the rheological qualities of fresh concrete. To investigate the mechanical and durability characteristics, experiments on hardened concrete were performed. The results demonstrate that 5% of BMIA substitution for cement in the SCC mix had higher strength compared to all other mixes because BMIA’s fine particles filled the voids in the hardened concrete. Scanning electronic microscopy (SEM) and X-ray diffraction (XRD) analyses were performed to examine the microstructure of BMIA substituted SCC versus conventional SCC mix. The chemical composition test revealed that BMIA can be employed in the SCC mix up to 5% efficiently, which will result in waste utilisation and disposal.

Hydration and mechanical properties of FGD gypsum-cement-mineral powder composites

Solving the problem of environmental pollution caused by flue gas desulfurization gypsum (FGD gypsum) accumulation is conducive to improving FGD gypsum green and sustainable development. In this study, the ternary system was prepared by using FGD gypsum, cement,and mineral powder. The simplex-centroid design method was used to determine the optimal proportions of FGD gypsum, cement, and mineral powder. The optimal proportions of FGD gypsum, cement, and mineral powder were designed by the simplex-centroid design method. The effects of cement and mineral powder contents on the mechanical and hydration properties of the ternary system were analyzed by contour map. Furthermore, the phase composition and microscopic morphology of the ternary system were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Hydration processes of all samples were observed by the hydration heat. It was observed that the optimal proportions of FGD gypsum, cement, and mineral powder were 75%, 5%,and 20%, respectively by comprehensive considerations of strength, softening coefficient, water absorption, hydration, and microstructure. Compared with pure gypsum, both binary and ternary systems consisting of gypsum, cement, and mineral powder showed good water resistance. The softening coefficient at 28 d improved, reached 0.71 at the optimal proportion.

Retention Behaviour of Heavy Metals from Industrial Sludge Amended with Admixtures to Use Them as Liners for Landfill Facilities

The solidification of contaminants within the soil/waste has proved to be a versatile technique to de-contaminate them and make them usable for several applications. In this method, the development of binder provisions leads to the conversion of the environmentally unstable condition of waste materials into a nearly stable material. Further, these materials pose a minimum threat that can be absorbed into the environment. Normally lime/cement and other pozzolanic materials are used as binder materials. In this work, it is proposed to use the efficiency of binding fly ash to improve the unconfined compressive strength (UCC) of soils, particularly during the curing period. This is because improvement in strength is a reflection of the improvement of bonding soil particles. Fly ash as the main source material, in addition to a minor proportion of cement and lime, is used to determine the strength. UCC test results revealed that as the percentage of fly ash increases there is an increase in compressive strength. It is also observed that with an increase in lime content and an increase in cement content, the UCC strength also increases. The strength in cement-stabilized compacted specimens is more compared to lime-stabilized mixtures. To confirm that the improvement in strength is related to the solidification of contaminated metals, particularly for soils containing copper and chromium, the stabilized mixture is tested for the leaching of these metals. Leaching tests were conducted on various stabilized mixtures at different curing periods. The leachate was examined for metal ion concentration using Atomic Absorption Spectrophotometer. The leaching behavior of heavy metals from different proportions of soil matrix revealed that with an increase in lime or cement percentage, a decrease in leachability is observed. It is found that the leaching of heavy metals from cement-stabilized soils was lower than in lime mixture combinations. However, minimum strength improves the solidification and retention of heavy metals effectively.

Effect of UFC on the Microscopic Pore Structure of Cemented Soil in Humic Acid Environment

Peat soil is widely distributed in the Dianchi Lake area of Yunnan, and the effect of the cement deep-mixing method on peat soil foundation is mainly affected by humic acid (HA). In this paper, a composite cement curing agent is formed by adding different proportions of ultra-fine cement (UFC) to ordinary Portland cement (OPC) and used to cure the HA-containing cohesive soil. Mercury intrusion porosimetry (MIP), scanning electron microscopy (SEM), and X-ray powder diffraction (XRD) are used to study the influence mechanism of UFC on the micropore structure of HA-containing cemented soil. The unconfined compressive strength test (UCS) is used to verify it. MIP, SEM, and XRD results show that UFC can significantly improve the microscopic pore structure of the samples. The hydration reaction rate of cement increases with the increase in the proportion of UFC, and the generated hydration products can fill the pores of the samples. The filling effect of hydration products on macropores is enhanced, and the pores change from fibrous filling to cemented filling. The enhanced cementation of the hydration products improved the loose and overhead structure inside the sample. Enhancing the cementation of hydration products improves the loose and overhead structure inside the sample and the integrity of cemented soil. UCS verified that the increase in the UFC proportion increases the HA-containing cemented soil strength. It achieves the purpose of reducing the amount of cement when curing peat soil foundations and supports reducing carbon emissions in practical projects.

Experimental and Analytical Study on Performance of Fiber-Reinforced Self-Stressed Concrete

Expansive cement is a unique type of cement that, when mixed with water, produces a paste which expands in volume significantly more than standard Portland cement. This expansion nullifies the deficit of shrinkage that arises during concrete hardening. This paper presents the outcomes of two phases of experimentation. Phase I of the paper provides a summary of the performance of expansive cement concrete mixes prepared with various proportions of expansive cement, which partially supplements the ordinary Portland cement, and which is infused with varying amounts of PVA fibers of 0.5, 1, 1.5, 2, and 2.5%, as a form of reinforcement under compression, tension, and flexure. Concrete strength, curing effect, and PVA fibers are the variables in Phase I of the study. The Phase II findings provide the buckling behavior of the self-stressed concrete columns reinforced with PVA fibers when the optimum concrete mix obtained from the Phase I investigation was poured inside steel tubes of varying thicknesses of 2 mm and 2.5 mm to restrict the expansion of the concrete, thereby making it self-stressed concrete. The D/t ratio, inclusion of expansive cement, and PVA fibers are the variables for Phase II of the study. The self-stressed columns with 2% PVA fibers showed better performance than the other columns.

Mechanical properties of the semi-rigid subgrade of roads for the replacement cement with pyrolysis residues of oil sludge

The pyrolysis residues of oil sludge, as the industrial solid waste of the oil extraction process, have a large output. There are also social and environmental problems of piling and pollution. Pyrolysis residues of oil sludge contain many active ingredients, which can partially replace cement and be added to road building materials for application. However, the mechanical properties are unknown for the replaced subgrade of roads. Through physicochemical and mechanical tests, the effect of the pyrolysis residues of oil sludge was studied based on the mechanical properties of road subgrade by replacing the proportion of the base cement of cement stabilized macadam (CSM) (10 %, 20 %, and 30 %). The recommended alternative ratio was proposed for replacing the cement of oil sludge stabilized macadam (COSM) base based on the correlation between mechanical indices and the technique for order preference by similarity to ideal solution (TOPSIS). The results suggest that an appropriate alternative ratio can optimally enhance the mechanical properties of the semi-rigid subgrade of conventional roads. Pyrolysis residues of oil sludge are easily excited in an alkaline environment, and its porous structure and carbon nanotube composition contribute to the combination with cementitious products to form a nail-carrying effect. Moreover, the hydration promotion effect on cementitious materials can increase the cleavage strength of materials. The replacement of cement with pyrolysis residues of oil sludge can enhance the mechanical properties of the material and increase the toughness of the material. The optimal moisture content of the material is positively correlated with the alternative ratio, and the maximal dry density is negatively correlated with the alternative ratio. The low alternative ratio is conducive to the increase of the early cementing effect of the material, and the high alternative ratio contributes to the increase of the later cementing impact of the material and the improvement of the later strength of the material. The range of alternative ratios to adjust the material to a reasonable range of the pressure-resistant resilience modulus was obtained as 12.6 %–31 %. The correlation analysis and technique for order preference by similarity to ideal solution method suggest that the reasonable alternative ratio of the pyrolysis residues of oil sludge is 10 %–30 % for the cement of stabilized macadam base, and the comprehensive mechanical properties of the 10 % replacement ratio are better than those of the control group. The results of this study can provide a reference for applying the pyrolysis residues of oil sludge in roads.

The effects of long-term freezing-thawing on the strength properties and the chemical stability of compound solidified/stabilized lead-contaminated soil.

Solidification/stabilization (S/S) is the prevalent remediation technology for the treatment of heavy metal contaminated soils (HMCS). However, under the stress of complex surrounding environments, S/S effectiveness tends to deteriorate and freezing-thawing is one of the most influential natural forcings. The different proportions of cement, lime, and fly ash were used as the compound curing agents to treat solidified/stabilized HMCS with varying levels of lead contamination. The resulting samples were subjected to up to 180 freeze-thaw cycles (F-T) (1day per cycle). Unconfined compressive strength (UCS) tests and semi-dynamic leaching tests were performed after F-T to explore the strength evolution of compound solidified/stabilized lead-contaminated soils (Pb-CSCS) and the chemical stability of the lead within. The results show that the F-T duration changes the strength deterioration mechanism of Pb-CSCS under F-T. There has been a shift in the main influencing factor from the promoted curing agent hydration by short-term F-T to the structural damage of the specimen induced by prolonged F-T. The variations in leachate pH, lead leachability, and diffusion ability with progressing F-T revealed a degradation effect of the changes in the physical states of water and crack propagation brought by F-T. These unfavorable changes in soil structure and chemistry reduce the acid resistance of Pb-CSCS. Notably, fly ash and cement facilitate the strength maintenance of Pb-CSCS under long-term F-T conditions. Curing formulations that included both cement and fly ash significantly increased the UCS of treated soils by up to 80.5% (3 F-T) under short-term F-T. In contrast, the curing formulation without fly ash lost 51.8% of its strength after 180 F-T conditions. For lead stabilization, cement and especially lime are favored. The results showed a 25% increase in the total proportion of lime and cement in the curing agent formulation, leading to a 41.4% reduction of lead leaching risk.

Design and Study of Physical and Mechanical Properties of Concrete Based on Ferrochrome Slag and Its Mechanism Analysis

In this study, high-carbon ferrochrome slag powder produced by grinding was used to replace different proportions of cement, and the effect of the amount of ferrochrome slag powder on the physical and mechanical properties of ferrochrome-slag-cement composites was analyzed. Water-cooled ferrochrome slag with a particle size of <5 mm was optimized to replace part of river sand as fine aggregate, and air-cooled ferrochrome slag with a particle size of >5 mm was used to completely replace coarse aggregate to prepare ferrochrome-slag-based concretes. The microstructure of ferrochrome-slag-cement composites was analyzed by X-ray diffraction, scanning electron microscopy, and thermogravimetry–differential scanning calorimetry analysis. The compressive strength, water absorption, and aggregate–slurry interface bonding properties of ferrochrome-slag-based concrete were studied. The results demonstrate that a ferrochrome slag powder amount of 15% leads to the highest performance of ferrochrome-slag-cement composite material, and the fluidity ratio of ferrochrome-slag-cement mortar is 103, higher than reference samples. Furthermore, the compressive strengths of ferrochrome slag concretes are 15.8% and 3.6% higher than conventional concrete, and the water absorption of ferrochrome slag low-carbon concrete is better than that of conventional concrete. The interface bonding structure between concrete aggregate and slurry was optimized. This research can provide a reference for studying the application of ferrochrome slag, both the feasibility of high-carbon ferrochrome slag powder as supplementary cementitious material and the application of ferrochrome slag as concrete aggregate, and it can help to achieve the purpose of saving energy and reducing carbon emissions.

Sustainable cement and clay support in Ni–Cu/Al2O3 catalysts for enhancing hydrogen production from methanol steam reforming

Sustainable cement-clay composite is used as the support of bimetallic Ni–Cu/Al2O3 catalysts for hydrogen production from methanol steam reforming (MSR) reaction. The results indicate that higher methanol conversion and hydrogen yield can be obtained using composite supported catalysts. The cement-clay composite possesses CO2 absorption capability, which can enhance MSR performance. In the cases of a large proportion of cement, the CO2 concentration in the product is decreased by 1–2% where methanol conversion and hydrogen yield are not reduced. By varying the catalyst compositions such as Ni content, Ni–Cu/Al2O3 loading, and the weight ratio of cement and clay, 100% methanol conversion can be achieved as Ni content and Ni–Cu/Al2O3 loading increase. However, the CO concentration also increases due to the enhanced reverse water gas shift reaction. The results of the prepared 12 cement-clay-supported cases show the best performance with methanol conversion of 100%, hydrogen yield of 2.85 mol·(mol CH3OH)−1, and CO concentration of 5.90%. The scanning electron microscope images indicate no sintering of the spent catalyst, and the thermogravimetric analysis shows low coke formation on the catalyst surface. Overall, cement-clay replacing metal components in catalysts can efficiently reduce costs and intensify hydrogen production.

Effectiveness of EPS Bead Size and Cement Proportions on the Strength and Deformation of Light-Weighted Soil

The current study investigates the deformation and strength of Light-Weighted Soil (LWS) comprised of silt, Expanded Polystyrene (EPS) beads, cement, and water. The EPS bead sizes employed in this study are 4, 5, and 6mm in diameter with densities of 0.011, 0.009, and 0.006g/cm3 and cement concentrations of 10% and 15%. The effects of different EPS bead sizes and cement proportions on the mechanical properties (strength and deformation) of LWS are evaluated by Unconfined Compression Strength (UCS) tests. The findings show that the EPS bead sizes significantly impact the strength and deformations of the LWS. The smaller the EPS bead size, the higher the observed strength, but, on the other hand, bigger EPS bead sizes have lower strength and higher ductility. It was also revealed that the strength of LSW is entirely dependent on the cement concentration. High cement content in the LWS has more strength and brittleness, but it is more prone to deformation. The cost can be decreased by increasing the EPS bead size, and thus the prescription of mixed soil can be enhanced. The use of EPS beads with a diameter of 4-6mm is recommended in the construction process, especially in backfill for retaining walls. Each EPS bead size provides advantages in different context, depending on engineering applications and field conditions.

Visible light-responsive photocatalytic-based sustainable construction material for environmental remediation

The present study proposes a unique idea of utilizing cementitious materials incorporating iron-rich industrial waste products (IWPs) to support nano-photocatalyst like Titanium dioxide (TiO2) to fabricate a visibly active Fe–TiO2 composite exhibiting antibacterial property. The novelty of the present study lies in formulating a natural doping concept over the conventional techniques to facilitate the photocatalytic properties of the proposed sustainable construction material. To assess the structural performance of the prepared cementitious material, i.e., cement mortar, different physical (porosity, water absorption, and density) and mechanical (compressive strength, flexural strength, and split tensile strength) properties were performed. The results show that the cement mortar mixture FB5F having 15% (10% FA and 5% BS) proportion of conventional cement performed better in terms of workability and durability than other mix designs. Also, the stability and potency of the Fe–TiO2 composite were analyzed using FESEM, EDS, elemental mapping, UV–vis DRS, and XRD. The characterization tests confirmed the iron-titanium (ITO) bond formation with shifting TiO2 from UV to visible light spectrum (Eg = 2.52 eV). The Fe–TiO2 composite was also subjected to an antibacterial check using an aliquot of E. coli bacterial suspension. The composite attained an E. Coli count of about 0.541 log reduction at the end of 45 min and thus, exhibited bacterial disinfection quality. Thus, the Fe–TiO2 composite material proposes an eco-friendly concept which satisfies the requirement for a sustainable and low carbon footprint future which can additionally be used to treat different indoor and outdoor organic contaminants.

A comparison of indices used to evaluate asphalt-filler interactions

Based on the physicochemical reactions between asphalt and filler, the structural asphalt film is formed. The interaction can significantly affect the strength of structural asphalt film and the mechanical properties of asphalt mastic. The strength of asphalt-filler interaction is hard to intuitively characterize. Hence, we need the index to evaluate the ability of interaction. To select the optimum evaluation index to characterize filler-asphalt interactions, we compared the rationality and reliability of six interaction indices (Palierne C, complex shear modulus coefficient ΔG*, Einstein coefficient ΚE, complex viscosity coefficient Δη*, Ziegel-B and Luis Ibrarra-A). This comparison was based on the complex modulus, phase angle and viscosity of asphalt mastics manufactured from four asphalt binders and nine mineral fillers comprising different fractions of filler volume. Comparing the sensitivity of the evaluation indices to changes in asphalt performance, filler type, and filler volume fraction, respectively, the complex shear modulus coefficient index (ΔG*), Einstein coefficient (KE) and complex viscosity coefficient (Δη*) of the filler volume fraction is the dominant factor, and as the filler volume fraction increases, the values of the indices increase. This observation of interaction indices growing with filler volume fraction is inconsistent with the physical–chemical interactions between asphalt and filler. Therefore, these indices cannot be applied to evaluate the filler-asphalt physical–chemical interactions. When the filler volume fraction changes from 0.23 to 0.68, the range of Palierne C index values is 0.84 ∼ 1.42. The higher the filler volume fraction, the smaller the Palierne C value. When the filler volume fraction is below 0.53, the Palierne C varies little. This changing rule of Palierne C is consistent with the adsorbed asphalt layer theory. Hence, Palierne C was ultimately selected as the optimum interaction index based on the relationship between adsorbed asphalt layer on mineral filler and filler volume fraction. We applied Palierne C to evaluate the interaction between different asphalts and mineral fillers.We used the Palierne C index to analyze the effects of asphalt, filler type and filler volume fraction on the asphalt-filler interaction. The results showed that SBS modified asphalt had the greatest effect on the filler-asphalt interaction, followed by high viscosity modified asphalt, SK 90 matrix asphalt, and finally, KL70 matrix asphalt. We also found that although the filler-asphalt interaction increases as the proportion of cement and hydrated lime increases, the cement and hydrated lime demonstrated an insignificant effect on the interaction. The effects of the hydrated lime-asphalt interaction were stronger than that of cement. The higher the filler volume fraction, the lower the value of Palierne C.Finally, gray system theory was used to analyze the correlation between the asphalt-filler interaction and the composition of filler and asphalt. The correlation degrees of the Palierne C index with filler composition were MgO > GaO > K2O > Fe2O3 > SiO2 > AL2O3 > P2O5 > MnO > Na2O > Ga(OH)2 > TiO2. Results indicate that the filler composition has a stronger effect on the filler-asphalt interaction than the asphalt composition. This result is consistent with previous research. The filler particles absorb the polar composition of asphalt, and the reactions occur between the filler alkaline group and the asphalt acid group. The results showed that the composition of MgO and GaO fillers most significantly affected the filler-asphalt interaction. And this conclusion further confirms the feasibility of using the Palierne C index to evaluate the filler-asphalt interaction.

ДОСЛІДЖЕННЯ ЕФЕКТИВНОСТІ ВИКОРИСТАННЯ СТАБІЛІЗАТОРІВ ДЛЯ УКРІПЛЕННЯ ҐРУНТІВ

Introduction. One of the main causes of deformation on roads is the deconsolidation of soils of the working layer of the subgrade and the non-strengthened lower layers of road structures. To eliminate this problem the technology of soil strengthening is used. Soil strengthened by the binder is an artificial monolithic material, which is formed by hardening the soil, after treatment with the binder, due to the physical and/or chemical processes after compaction and curing under specified conditions, and satisfies the standard requirements for physical and technical indicators in the project intermediate terms. Soil mass stabilizer is a modifier of the soil particles surface, which affects the value of the hydrogen index in which the soil structure is formed, improves the physical and mechanical properties of the soil. Problem statement. During road construction and repairing, the problem of unsatisfactory bearing capacity of subgrade appears quite often. For rational solving of this problem, the possibility of strengthening or stabilizing the soil is considered. Purpose. The purpose of the work is the analysis of laboratory tests data and determination of the effectiveness of soil stabilizers use. Materials and method. Analysis of information sources on foreign and domestic experience of soil stabilizers use. Results. The result of the work is established physical and mechanical properties of the soil with and without the use of stabilizer. Conclusions. When using soil stabilizers, the key to the effective use of capital investments in the construction or reconstruction of roads by increasing the strength of the road structure we see in a clear understanding of the functional orientation of the additive, the choice of appropriate technology, the selection of the optimal mix design and type of stabilizer. The research carried out at the State Enterprise «DerzhdorNDI» on the expediency of using a polymer-based stabilizer for the complex strengthening of sandy loam to increase the strength of the embankment base soil found that the obtained proportions of additive and cement have achieved a positive result.

ДОСЛІДЖЕННЯ ЕФЕКТИВНОСТІ ВИКОРИСТАННЯ СТАБІЛІЗАТОРІВ ДЛЯ УКРІПЛЕННЯ ҐРУНТІВ

Introduction. One of the main causes of deformation on roads is the deconsolidation of soils of the working layer of the subgrade and the non-strengthened lower layers of road structures. To eliminate this problem the technology of soil strengthening is used. Soil strengthened by the binder is an artificial monolithic material, which is formed by hardening the soil, after treatment with the binder, due to the physical and/or chemical processes after compaction and curing under specified conditions, and satisfies the standard requirements for physical and technical indicators in the project intermediate terms. Soil mass stabilizer is a modifier of the soil particles surface, which affects the value of the hydrogen index in which the soil structure is formed, improves the physical and mechanical properties of the soil. Problem statement. During road construction and repairing, the problem of unsatisfactory bearing capacity of subgrade appears quite often. For rational solving of this problem, the possibility of strengthening or stabilizing the soil is considered. Purpose. The purpose of the work is the analysis of laboratory tests data and determination of the effectiveness of soil stabilizers use. Materials and method. Analysis of information sources on foreign and domestic experience of soil stabilizers use. Results. The result of the work is established physical and mechanical properties of the soil with and without the use of stabilizer. Conclusions. When using soil stabilizers, the key to the effective use of capital investments in the construction or reconstruction of roads by increasing the strength of the road structure we see in a clear understanding of the functional orientation of the additive, the choice of appropriate technology, the selection of the optimal mix design and type of stabilizer. The research carried out at the State Enterprise «DerzhdorNDI» on the expediency of using a polymer-based stabilizer for the complex strengthening of sandy loam to increase the strength of the embankment base soil found that the obtained proportions of additive and cement have achieved a positive result.

Mechanical Strength and Water Transport Properties of Concrete Containing Treated Recycled Aggregates

Objective: The objective is to determine the effect of treated RCA on the mechanical strength of hardened concrete, and determine the influence of treated RCA on water transport within the matrix of hardened concrete. Aim: The study aims to use pozzolanic concentration of cement and RHA slurry to pretreat coarse RCA for full replacement of NCA for sustainable concrete production. Background: One of the common modes of disposal of construction waste is strained landfills. This study proposes a constructive way of recovering the coarse aggregates of recycled aggregates from laboratory concrete waste taken through a focused treatment process with pozzolan. The study aims to replace the proportions of the cement slurry to treat and replace with rice husk ash (RHA) for the modification of recycled concrete aggregate (RCA) and replace fully natural coarse aggregate (NCA) for sustainable concrete production. One of the main challenges of recycled concrete aggregate (RCA) is the fractured surface, which often results in reduced strength and loss of concrete durability. The strength of concrete with RCA is principally influenced by the fractured hardened paste attached to the surface, predominantly characterized by voids and gaps resulting from its production using a mechanical method. High water penetration within and around the aggregate matrix due to the presence of micro- and macro-cracks results in strength and durability deterioration of concrete. Methods: This study addresses these problems by specifying aggregate treatment with a pozzolanic slurry of cement and RHA. This was conducted in two (2) phases; first, to determine the optimum proportion of cement slurry concentration (0, 20, 40, 60, 80, and 100%), and second, to increase the silicate formation in cement slurry by substituting the proportions of cement with RHA (0, 5, 10, and 15%). The performance of concrete was evaluated by mechanical strength (compressive and split tensile strength) at 7, 28, and 56 days and water transport within the concrete (surface suction and submergence) at 28 and 56 days of curing age. Results: The use of cement slurry treatment at various concentrations generally increased compressive strength at 28 days compared to untreated RCA. The findings show that at a 20% concentration of cement slurry, the increase in compressive strength is 38.4%. Upon replacement of cement in treatment slurry of RCA with 5% RHA, the increase in compressive strength was 61%, while the split tensile strength increased by 10.2%. The amount of water absorbed was observed after 30 minutes of full submergence in water, indicating that samples with 20% cement concentration at 28 days resulted in the lowest water absorption of 2.01%. However, with the replacement of 5% RHA, the water absorption slightly increased to 2.3%, but still less than the requirement of 3.5%. The corresponding test results for water suction by capillarity, initial and secondary sorptivity coefficients (Si and Ss) were found to be 0.0330mm/√sec. (1.98mm/√hr.) and 7.95×10−4mm/√sec. (0.04mm/√hr.) respectively, all less than 6mm/√hr requirement. This improved performance was attributed to the increased strength and structure of the interfacial transition zone (ITZ) around the RCA. Conclusion: Based on the results of mechanical strength and water transport, characteristics of the new concrete were improved when coarse RCAs were pretreated with 20% pozzolanic concentration containing cement and RHA. The use of a pozzolanic treatment slurry containing 15% cement and 5% RHA to treat coarse RCA can produce concrete with characteristics similar to those of natural concrete aggregates. This study presents a methodological utilization and improvement of RCA wastes for field application.

Impact of partial replacement of coarse aggregate with electronic plastic waste on compressive strength of concrete

The need for infrastructure development, electrical equipment, and plastic-manufactured goods has increased exponentially with the arrival of the twenty-first century. Demand growth was followed by a notable increase in construction debris and electronic-plastic (e-plastic). Due to its nonbiodegradability and dangerous metallic waste, e-plastic waste, which consists primarily of wires and discarded plastic components from TVs, refrigerators, and other electronic devices, poses a serious ecological threat. Being the primary component of construction waste, cement considerably contributes to CO2 emissions, which cause global warming.. Situations become more distressing for towns with a large population when such waste is dumped or burned, either of which pollutes the environment. Thus, the purpose of the article is to evaluate whether e-plastic waste can substitute some of the coarse aggregates in concrete. In the experiment, the compressive strength of an M40 concrete mix with weight replacements of coarse aggregates of 5 percent, 10 percent, 15 percent, and 20 percent made from e-plastic waste was measured and compared to a control mix. In the experiment, e-plastic wastes were made up of acrylonitrile butadiene styrene (ABS), a high-density polymer plastic, and polypropylene (PP), a low-density plastic primarily found in electronic gadgets. For efficient test results, a total of 30 cube specimens with varying proportions of cement, fine aggregate, coarse aggregate, and eplastic were created. According to the conclusions drawn from tests carried out in accordance with Bureau of Indian Standard (IS), a noticeable increase in compressive strength was seen at a 5 percent replacement of e-plastic. Nevertheless, a further rise in replacement showed a fall in compressive strength.

Study on Temporal and Spatial Distribution and Transport Characteristics of Dust in New Composite Spraying Slurry

In view of the problems of traditional spraying technology, such as complex processes, high costs, large dust amounts, and poor air leakage effects, a new composite spraying slurry is proposed in this paper, which takes clay as the main base material and uses water pressure and wind pressure to ensure intrinsic safety. Firstly, the airtightness, bending resistance, and viscosity of the spraying material were measured in the laboratory; secondly, the gas–liquid–solid three-phase flow process involved in the spraying process was simulated by using the CFD-DPM method, adopting the Eulerian two-fluid model for continuous gas–water two-phases and the discrete phase DPM model for dust generation, and the transport, diffusion, and full space-time distribution characteristics of dust generation were studied. The research shows that: (1) the new composite slurry spraying material made of clay as the main material is made by adding a small proportion of cement and engineering fiber to increase the toughness of the material, and finally, determining the mass ratio of the composite material as follows: clay: cement: additive: engineering fiber = 84:14:1.85:0.15. It has good sealing and bending resistance and good adhesion; (2) the water phase distribution under the action of spray determines the distribution of solid-phase dust, and the distribution area of dust is similar to that of the water phase; (3) under the action of spray, the area at the bottom of the roadway is covered by dust flow, and the dust in this area is obviously stratified. The particle size of the dust gradually decreases from bottom to top. The large particle size dust is deposited at the bottom, while the small particle size dust is suspended at a certain height, and the diffusion area gradually increases; (4) the effect of spray angle on dust is mainly manifested in the initial dust flow shape and dust diffusion time. The larger the spray angle, the faster the diffusion; (5) when the water velocity at the nozzle outlet is large, the dust concentration is low in the whole area, but in areas higher than 1.5 m, the PM2.5 concentration also increases with the increase in water flow. The dust suppression effect of larger a water flow is mainly reflected in the bottom area, and the disturbed surrounding airflow can make PM2.5 diffuse to higher areas.