Cement Volume Research Articles

Temperature dependance of 3D printed concrete produced with copper tailings

Abstract3D printed concrete is being applied in an increasing amount worldwide. While in theory, there are environmental and economic benefits associated with using this technology, in practice, the amount of cement in printable concrete is much higher than in a conventional one, leading to increased environmental and economic costs. Furthermore, cement's performance relies heavily on climate variables, specifically temperature. One way to solve this issue is to include local alternative low‐CO2 materials, such as processed mine tailings, as cement replacement. This paper presents an experimental approach to assess the use of copper tailings as cement replacement in printable concrete under different ambient temperatures. Three levels of cement volume replacement have been researched. The copper tailings' rheological effect has been measured using standard printability tests and a rheometer. Four mixtures have been printed in a controlled‐climate chamber to evaluate print‐ability, buildability and extrudability. The mechanical effect has been assessed with compressive and flexural strength tests of samples collected from the printed specimens. The results show that copper tailings are a promising alternative to cement in printable concrete in countries where this by‐product is abundant.

Effect of different cement distribution in bilateral and unilateral Percutaneous vertebro plasty on the clinical efficacy of vertebral compression fractures

BackgroundThe ramifications of osteoporotic fractures and their subsequent complications are becoming progressively detrimental for the elderly population. This study evaluates the clinical ramifications of postoperative bone cement distribution in patients with osteoporotic vertebral compression fractures (OVCF) who underwent both bilateral and unilateral Percutaneous Vertebroplasty (PVP).ObjectiveThe research aims to discern the influence of bone cement distribution on the clinical outcomes of both bilateral and unilateral Percutaneous Vertebroplasty. The overarching intention is to foster efficacious preventive and therapeutic strategies to mitigate postoperative vertebral fractures and thereby enhance surgical outcomes.MethodsA comprehensive evaluation was undertaken on 139 patients who received either bilateral or unilateral PVP in our institution between January 2018 and March 2022. These patients were systematically classified into three distinct groups: unilateral PVP (n = 87), bilateral PVP with a connected modality (n = 29), and bilateral PVP with a disconnected modality (n = 23). Several operational metrics were juxtaposed across these cohorts, encapsulating operative duration, aggregate hospital expenses, bone cement administration metrics, VAS (Visual Analogue Scale) scores, ODI (Oswestry Disability Index) scores relative to lumbar discomfort, postoperative vertebral height restitution rates, and the status of the traumatized and adjacent vertebral bodies. Preliminary findings indicated that the VAS scores for the January and December cohorts were considerably reduced compared to the unilateral PVP group (P = 0.015, 0.032). Furthermore, the recurrence of fractures in the affected and adjacent vertebral structures was more pronounced in the unilateral PVP cohort compared to the bilateral PVP cohorts. The duration of the procedure (P = 0.000) and the overall hospitalization expenses for the unilateral PVP group were markedly lesser than for both the connected and disconnected bilateral PVP groups, a difference that was statistically significant (P = 0.015, P = 0.024, respectively). Nevertheless, other parameters, such as the volume of cement infused, incidence of cement spillage, ODI scores for lumbar discomfort, post-surgical vertebral height restitution rate, localized vertebral kyphosis, and the alignment of cement and endplate, did not exhibit significant statistical deviations (P > 0.05).ConclusionIn juxtaposition with unilateral PVP, the employment of bilateral PVP exhibits enhanced long-term prognostic outcomes for patients afflicted with vertebral compression fractures. Notably, bilateral PVP significantly curtails the prevalence of subsequent vertebral injuries. Conversely, the unilateral PVP cohort is distinguished by its abbreviated operational duration, minimal invasiveness, and reduced overall hospitalization expenditures, conferring it with substantial clinical applicability and merit.

Increased stability due to symmetric cement volume in augmented pedicle screws? A biomechanical study.

Pedicle screw instrumentation has become "state of the art" in surgical treatment of many spinal disorders. Loosening of pedicle screws due to poor bone mineral density is a frequent complication in osteoporotic patients. As prevalence of osteoporosis and spinal disorders are increasing with an aging demographic, optimizing the biomechanical properties of pedicle screw constructions and therefore outcome after spinal surgery in osteoporotic patients is a key factor in future surgical therapy. Therefore, this biomechanical study investigated the stability of polymethylmethacrylate (PMMA)-augmented pedicle screw-rod constructions under a deviating distribution of PMMA applied to the instrumentation in osteoporotic human cadaveric vertebrae. We showed that PMMA-augmented pedicle screw-rod constructions tend to be more stable than those with non-augmented pedicle screws. Further, there appears to be a larger risk of screw loosening in unilateral augmented pedicle screws than in non-augmented, therefore a highly asymmetrically distributed PMMA should be avoided.

Interpretable Machine Learning Model to Predict Bone Cement Leakage in Percutaneous Vertebral Augmentation for Osteoporotic Vertebral Compression Fracture Based on SHapley Additive exPlanations.

Retrospective study. Our objective is to create comprehensible machine learning (ML) models that can forecast bone cement leakage in percutaneous vertebral augmentation (PVA) for individuals with osteoporotic vertebral compression fracture (OVCF) while also identifying the associated risk factors. We incorporated data from patients (n = 425) which underwent PVA. To predict cement leakage, we devised six models based on a variety of parameters. Evaluate and juxtapose the predictive performances relied on measures of discrimination, calibration, and clinical utility. SHapley Additive exPlanations (SHAP) methodology was used to interpret model and evaluate the risk factors associated with cement leakage. The occurrence rate of cement leakage was established at 50.4%. A binary logistic regression analysis identified cortical disruption (OR 6.880, 95% CI 4.209-11.246), the basivertebral foramen sign (OR 2.142, 95% CI 1.303-3.521), the fracture type (OR 1.683, 95% CI 1.083-2.617), and the volume of bone cement (OR 1.198, 95% CI 1.070-1.341) as independent predictors of cement leakage. The XGBoost model outperformed all others in predicting cement leakage in the testing set, with AUC of .8819, accuracy of .8025, recall score of .7872, F1 score of .8315, and a precision score of .881. Several important factors related to cement leakage were drawn based on the analysis of SHAP values and their clinical significance. The ML based predictive model demonstrated significant accuracy in forecasting bone cement leakage for patients with OVCF undergoing PVA. When combined with SHAP, ML facilitated a personalized prediction and offered a visual interpretation of feature importance.

Risk factor analysis of refracture in the same cemented vertebra after percutaneous kyphoplasty for Kümmell's disease.

The objective of this study was to evaluate the factors that affect refracture in the same cemented vertebra after percutaneous kyphoplasty (PKP) for Kümmell's disease (KD) and establish a risk prediction score. A total of 2932 patients who were treated with PKP for KD between January 2019 and December 2021 were retrospectively reviewed. After inclusion and exclusion criteria were applied, 191 patients were included in the study. According to the criteria for refracture, there were 50 patients in the refracture group and 141 patients in the no-refracture group. Twenty-five factors were analyzed. Patient demographics, medical history, imaging data, surgical data, and postoperative management were reviewed. Multivariate logistic regression modeling was used to identify the independent risk factors for refracture. Receiver operating characteristic (ROC) curve analysis was used to assess and establish a risk score system and further predict the risk of refracture. In this study, 50 (26.2%) patients developed a refracture. Through univariate analysis, bone mineral density (BMD) (p < 0.001), compression rate (p = 0.007), classification (i.e., the stages determined by the compression ratios) (p < 0.001), bone cement volume (p < 0.001), volume fraction (p < 0.001), distribution pattern (p = 0.007), non-PMMA endplate contact (p < 0.001), and anti-osteoporosis therapy (p < 0.001) were found to be significant factors for post-cement vertebral refracture after PKP in patients with KD. Three independent risk factors were found to be significant for refracture: small volume fraction, low BMD, and no anti-osteoporosis therapy. One point was assigned for each factor. The incidence rates of refracture in patients with scores of 0, 1, 2, and 3 were 3.7%, 4.4%, 42.0%, and 100%, respectively. The area under the ROC curve for this risk prediction score was 0.888 (p < 0.001), indicating moderate accuracy. Volume fraction, BMD, and osteoporosis therapy are the main factors influencing the refracture of the same cemented vertebra in KD. On the basis of these factors, the risk prediction score developed in this paper can be used to forecast the incidence of refracture.

Depositional and diagenetic controls on the reservoir quality of Early Miocene syn-rift deep-marine sandstones, NW Saudi Arabia

Understanding the distribution of sedimentary facies, their texture and diagenetic alterations in deep-marine rift systems are critical for improved reservoir quality predictions in the subsurface. Syn-rift deep-marine sandstones of the Miocene Burqan Formation, deposited by various sediment gravity flow types in the Midyan Basin (Red Sea, Saudi Arabia) are characterized using detailed sedimentological and petrographic analyses. Six distinctive lithofacies (F1-F6) have been identified within the Burqan Formation and grouped into three broad facies associations namely proximal, medial, and distal facies of a submarine fan. The proximal fan facies consists of disorganized conglomerate (F1) and structureless sandstone (F2) . The medial fan facies are represented by graded bedded and channelized sandstone (F3) and sandstone dominated heterolithics (F4) . Deposits of distal fan facies consist of mudstone dominated heterolithics (F5) and structureless mudstone (F6) . The sandstones are predominantly arkoses and lithic arkoses with a low degree of diagenetic modification (Eo- and Telo-diagenesis; ≤ 2 km and ≤ 70 °C temperature) and low to moderate volumes of carbonate cement (mean = 7%). The structureless sandstone (F2), sandstone dominated heterolithics (F4) and mudstone dominated heterolithics (F5) have poor reservoir quality due to the presence of authigenic cement and matrix. Graded bedded and channelized sandstone (F3) lithofacies consists of excellent reservoir sandstone due to the least proportion of cement and virtual absence of detrital clay. The observed variability in composition and textural parameters within Burqan Formation indicates that sedimentological transport processes control the depositional reservoir quality which in turn dictates diagenetic modification in deep-marine sandstones with important implications for prediction of reservoir quality in deep-marine systems.

Cement Augmentation of Pedicle Screw Instrumentation: A Literature Review.

This literature review aimed to review the current understanding, indications, and limitations of pedicle screw instrumentation cement augmentation. Since they were first reported in the 1980s, pedicle screw cement augmentation rates have been increasing. Several studies have been published to date that describe various surgical techniques and the biomechanical changes that occur when cement is introduced through the screw-bone interface. This article provides a concise review of the uses, biomechanical properties, cost analysis, complications, and surgical techniques used for pedicle screw cement augmentation to help guide physician practices. A comprehensive review of the current literature was conducted, with key studies, and contributions from throughout history being highlighted. Patients with low bone mineral density are the most well-studied indication for pedicle screw cement augmentation. Many studies show that cement augmentation can improve pullout strength in patients with low bone mineral density; however, the benefit varies inversely with pathology severity and directly with technique. The various screw types are discussed, with each having its own mechanical advantages. Cement distribution is largely dependent on the filling method and volume of cement used. Cement composition and timing of cement use after mixing are critical considerations in practice because they can significantly alter the bone-cement and screw-cement interfaces. Overall, studies have shown that pedicle screw cement augmentation has a low complication rate and increased pullout strength, justifying its universal use in patients with a suboptimal bone-implant interface.

Clinical efficacy of modified percutaneous kyphoplasty (PKP) vs. conventional PKP for osteoporotic vertebral compression fractures: a single-center retrospective study.

To investigate the clinical efficacy of using a standardized modified percutaneous kyphoplasty (transverse process‑pedicle approach to percutaneous kyphoplasty, TPKP) approach for the treatment of osteoporotic vertebral compression fractures (OVCFs) and to explore the possibility that it may become the preferred option in the future. A retrospective analysis was conducted on a total of 81 patients (TPKP group, 43 cases; PKP group, 38 cases) with OVCFs who underwent TPKP and PKP at the Department of Spine Surgery, Wuhan Fourth Hospital, from May 2021 to October 2021. We evaluated the patients' demographic information, intraoperative data (volume of cement injection and, duration of surgery), clinical outcomes at different time points (Visual Analog Scale, Oswestry Dysfunction Index), and radiographic data (Cobb angle, anterior vertebral body height). Statistical analysis was performed to assess the efficacy of the procedure, both within and between the two groups before and after surgery. The difference in preoperative general information between the two groups of patients was non-statistically significant (p>0.05), and they were comparable. Additionally, no statistically significant difference (p>0.05) was found between the TPKP and PKP groups in terms of operative time, length of hospital stay, recovery of injured spine height, Cobb angle, and cement leakage rate. However, significant statistical differences (p<0.05) were noted between the two groups regarding cement volume, distribution pattern, 1-day postoperative VAS scores, 1-day postoperative ODI scores, and loss of height of the injured spine. TPKP demonstrated superior performance compared to PKP in these specific areas. TPKP offers the same surgical safety as the conventional approach, with better cement distribution and better pain relief, as well as the advantage of maintaining the height of the operated vertebral body. The technique is easy to master and use when guided by standard puncture procedures.

Toothbrushing effects on the surface roughness and cement volume loss of bonded enamel-ceramic interface.

Thirty enamel and thirty ceramic blocks were bonded with cementing materials to produce the samples that were bonded with three types of cementing materials: 1- RelyX Ultimate resin cement (REXU), 2- RelyX Unicem 2 self-adhesive resin cement (REU2) and 3- heated Z100 restorative composite (60°C). Bonded interfaces of the samples were toothbrushed and the surfaces of the 3 cementing materials were evaluated for roughness (RG, in µm), roughness profile (RP, in µm), and volume loss (VL, in µm3) (baseline and after 20,000 and 60,000 toothbrushing cycles). Data were evaluated by Generalized Linear Analysis (two factors: "material" and "toothbrushing cycle") and Bonferroni test (α=0.05). REXU and Z100 exhibited lower RG than that presented by REU2, except after 60,000 toothbrushing cycles when only Z100 differed from REU2. The increase in toothbrushing cycles increased the RG and RP for all materials. REU2 also showed higher RP than those showed by REXU and Z100 when it was analyzed regarding the enamel. The VL of Z100 was the lowest with 20,000 toothbrushing cycles, regarding the enamel and ceramic. For 60,000 cycles, REXU showed the lowest VL regarding the ceramic, and REU2 had the highest VL regarding the enamel and ceramic. In general, REXU and Z100 showed the best results regarding the evaluations performed and the REU2 exhibited the highest RG, RP, and VL.

Characteristics analysis of long afterglow phosphor with SiO2 coating and evaluation its influence on the properties of self-luminescent cement-based materials

The long afterglow phosphors (LP) and reflective powders (RP) can be used in the preparation of self-luminescent cement-based materials (SLCM). However, the hydrolysis instability of LP combined with limited amount of LP and RP in SLCM have a degradation effect on the luminescent performance. This study proposes a solution by modifying the surface of LP as well as increasing the maximum amount of LP and RP to tackle this problem. Based on the modified Andreasen and Andersen model, the mix proportion of SLCM was firstly designed by 51% RP volume and replacing the cement volume (5%, 10%, 15% and 20%) by LP. The water resistance and morphology of LP with and without surface modification were examined. Furthermore, the surface modification and replacement level of LP on the compressive strength, luminescent performance and hydration kinetics were monitored. The phase assemblage, pore structure and morphology were also evaluated using XRD, MIP and SEM-EDS. The characteristics of LP showed that the surface modification not only changed its geometric shape but also improved its hydrolysis stability. Incorporating LP with optimal replacement and SiO2 modification in SLCM promoted the hydration process. The excessive addition of LP with surface modification was still inevitably detrimental to the development of strength, but it was favourable to strengthen the luminescent performance. Microstructure analysis showed that due to the low hydrolysis degree and well hydration process, the optimal replacement and surface modification of LP was more beneficial in pore refinement and microstructure compactness. Overall, incorporation of optimal amount of modified LP and RP in SLCM displayed excellent luminescent performance without compromising the hydration process and strength evolution.

Quantitative Comparison of Vertebral Structural Changes After Percutaneous Vertebroplasty Between Unilateral Extrapedicular Approach and Bilateral Transpedicular Approach Using Voxel-Based Morphometry.

To compare unilateral extrapedicular vertebroplasty (UEV) and bilateral transpedicular vertebroplasty (BTV) by quantitatively calculating the structural changes of fractured vertebral body after percutaneous vertebroplasty (PVP) using 3-dimensional voxel-based morphometry (VBM). We calculated bone cement volume (BCV); vertebral body volume (VBV); leaked intradiscal BCV; and spatial, symmetric, and even bone cement distribution (BCD) in and out of 222 vertebral bodies treated with 2 different PVPs using VBM and evaluated the incidence of subsequent vertebral compression fracture (SVCF). Statistical analyses were conducted to compare values between the 2 different PVPs. Relative BCV, which is a potential risk factor for SVCF, was higher in the BTV group based on the data using VBM (0.22±0.03 vs. 0.29±0.03; p<0.001, t-test); however, the SVCF incidence between the 2 surgeries was not significantly different (UEV, 24.7%; BTV, 31%; p=0.046, chi-square test). Spatial, even, and symmetric BCD along the 3 axes was not significantly different between UEV and BTV using VBM (x, y, z-axis, p=0.893, p= 0.590, p=0.908 respectively, chi-square test). Contrary to intuitive concerns, UEV can inject a sufficient and more optimal BCV than BTV. Additionally, it can inject bone cement spatially, symmetrically, and evenly well-distributed without an increased rate of intradiscal leakage and SVCF compared with BTV based on VBM. Therefore, UEV could be a superior alternative surgical method with similar clinical effectiveness and safety, considering the above results and the consensus that UEV is less invasive.

Preoperative planning of compact zone trajectory is necessary in treating osteoporotic vertebral compression fracture with endplate involvement: A prospective randomized controlled study.

This prospective randomized controlled study compares the clinical and radiological outcomes between reduction methods with or without compact trabecular bone during percutaneous kyphoplasty in osteoporotic vertebral fractures. The cohort of 100 patients who underwent percutaneous kyphoplasty was randomly divided into groups A (guide pin and balloon introduced directly into fracture site) and B (guide pin and balloon inserted away fracture site). The surgery duration, clinical and radiological outcomes postoperatively and at follow-up, and complications of cement leakage and adjacent fracture were recorded. Patients were followed up for an average of 20.18 months. The clinical outcomes were assessed using the Oswestry disability index and visual analogue scale. The 2 groups had similar patient demographics, surgery times, and volume of cement injected. The method using elevation of the collapsed endplate indirectly had no significant influence on radiological outcomes but significantly decreased the occurrence of intradiscal cement leakage and improved 1- and 12-month postoperative functional outcomes. Elevating and reinforcing the collapsed endplate rather than just filling the defect during percutaneous kyphoplasty is safe and effective. This technique decreased pain and improved function with lower rates of further collapse of the osteoporotic vertebrae compared to defect-filling alone.

UTILIZATION OF MARBLE-CEMENT POWDER MODIFIED WITH GRAPHITE CARBON PARTICLES ON CONCRETE CONSTRUCTION FOR BUILDINGS IN SEASIDE AREAS

This research aims to utilize marble industrial waste which is not utilized optimally and reduce air pollution as a result of cement production in cement industrial factories which produce a lot of CO2 emissions. The results of this research indicate that the use of 25 % Graphite Carbon Marble Particle Powder, to replace 25 % of the cement volume in making concrete with quality plans K-250 or fc’ 20,75 MPa. The results obtained are higher concrete quality than the quality of each concrete planned for the DCT type = 22,39 MPa &gt; 20,75 MPa, DCL type = 22,76 MPa &gt; 20,75 MPa, WCT type = 22,14 MPa &gt; 20,75 MPa and WCL type = 22,89 MPa &gt; 20,75 MPa. The compressive strength testing process is caried out based on ASTM C 39/C 39M – 05. Meanwhile for workability based on the results of the slump test, a slump value of 12 cm is obtained with the testing process referring to SNI 1972:2008 and ASTM C143/C143M-12.

The relationship between pain relief and the amount and distribution of injected cement in kyphoplasty for osteoporotic vertebral fractures.

This study aimed to compare the relationship of pain relief with the amount and distribution of injected cement in kyphoplasty for osteoporotic vertebral fractures. This cohort study was conducted on 90 patients with osteoporotic vertebral fractures who needed chronic pain medication. Patients underwent kyphoplasty balloon surgery, and polymethylmethacrylate (PMMA) or bone cement was injected into the created cavities and the volume of injected cement was recorded. After the surgery, the distribution of cement was measured using a computed tomography (CT) scan in the coronal, sagittal, and axial axes of the vertebra, and the percentage of cement distribution was evaluated using Photoshop software in these three axes, followed by the pattern of cement distribution. The cement was measured in the entire vertebra. The patients were evaluated over a period of 6 months, and the amount of pain improvement was measured by the VAS scale in 24 hours, two weeks, six weeks, and six months after surgery. In this study, the data of 90 patients with a mean age of 72.5±10.9 years were included in the study. The mean volume of cement injected was 1.2±5.8 cc, followed by the mean percentage of cement distribution (47.7±7.4%); the mean pain score before the operation (8.7±1.3), the mean pain score 24 hours after the operation (7.7±1.4), the mean pain score 2 weeks after the operation (4.8±1.3), the mean pain score 6 weeks after the operation (3.6±1.2) and the mean pain score 6 months after the operation (3.5±1.4) were evaluated after collection. The pain intensity 24 hours after the operation had a significant positive correlation with the percentage of cement distribution and pain intensity before the operation. The intensity of pain 2 weeks after the operation was positively correlated with the age of the patients and the intensity of pain before the operation. The pain intensity 6 weeks after the operation was significantly correlated with the age of the patients and the pain intensity before the operation. The intensity of pain 6 months after the operation was positively linked to the age of the patients and negatively correlated with the percentage of cement distribution. The pain reduction has changed significantly in the 4 measured intervals, and during a period of 6 months, there was a significant improvement in the pain level of the patients continuously. It was found that the rate of recovery of the patient's pain has increased by increased distribution of injected cement. Although this reduction in pain during the 6-month period was not significantly related to the variables of gender, smoking, history of corticosteroid use, and the volume of injected cement. The balloon kyphoplasty is a safe and successful method for treating symptomatic vertebral fractures. Kyphoplasty is associated with significant pain relief, improved quality of life, and kyphosis correction. The volume of cement injected had no effect on reducing patients' pain after the operation, but a higher percentage of cement distribution was associated with a better response in patients.

A Review on the Application of Lignocellulosic Biomass Ash in Cement-Based Composites.

With the development of society, the demand for cement-based composites is increasing day by day. Cement production significantly increases CO2 emissions. These emissions are reduced when high volumes of cement are replaced. The consideration of sustainable development has prompted people to search for new cement substitutes. The lignocellulosic biomass ash obtained from burning lignocellulosic biomass contains a large number of active oxides. If lignocellulosic biomass ash is used as a partial cement substitute, it can effectively solve the high emissions problem of cement-based composites. This review summarizes the physicochemical properties of lignocellulosic biomass ashes and discusses their effects on the workability, mechanical properties, and durability (water absorption, acid resistance, etc.) of cement-based composites. It is found that appropriate treatments on lignocellulosic biomass ashes are beneficial to their application in cement-based composites. Meanwhile, the issues with their application are also pointed out.

Use of irradiated PET plastic waste for partially replacing cement in concrete?

Portland cement used in the manufacture of concrete is responsible for an estimated 5–8% of the global CO2 emissions. Recently published work (Schaefer et al., 2018) claims that γ-irradiated PET waste powder can be used as a partial replacement of cement in concrete for reducing its CO2 footprint. More specifically, exposure of PET to γ-irradiation at a dosage of 100 kGy alters its crystal structure and chemical composition, which in turn leads to a smaller reduction in concrete strength compared to non-irradiated PET waste. Hence, making it possible for irradiated PET waste to be used as a raw ingredient in the manufacture of concrete while at the same time diverting significant quantities of PET waste from landfills. The aim of this research was to independently assess and verify the above claims. For this purpose, the effect of different low irradiation dosages (0, 10 and 100 kGy) and different replacement levels (2.5 %, 5 % and 10 % by volume) of cement by PET waste on the consistency and mechanical strength of pastes and mortars was determined in a laboratory investigation. XRD, TGA and DSC were also used to study the effect of irradiation on the microstructure of raw PET waste and the microstructure of paste and mortar samples containing irradiated PET waste powder. Our results indicate that use of γ-irradiated PET waste (exposed to an irradiation dosage of up to 100 kGy) for partially replacing cement does not lead to a significant recovery of mechanical strength lost when non-irradiated PET waste is used.

Concrete Blocks Using HDPE Solid Waste as Aggregate

The objective of this study was to analyze the addition of plastic as a partial component of the coarse aggregate in concrete, for the design of ecological blocks, establishing a linear equation that estimates the compressive strength of the block, varying the volumes of cement, sand, gravel and plastic. For the design of blocks, volume in three proportions were considered (cement/fine aggregate/coarse aggregate), thus four types of mix proportions were made (1/1/1, 1/1.25/2.5, 1/1.5/3 and 1/2/4). Coarse stone aggregate as a partial aggregate component was replaced by flake HDPE type plastic HDPE in proportions of 0, 25 and 50% coarse stone replacement. The compressive strength and unit weight of the concrete was measured after 30 days of curing. The research methodology was of a quantitative type of descriptive experimental design. The results showed that the addition of 25 and 50% plastic as a coarse aggregate reduced the unit weight of the concrete to 9.7 and 12.02% respectively. However, in this case, the reduction in compressive strength was up to 29.17 and 48.5% respectively for its best effectiveness, reducing only the unit weight of the parts.

Performance of slag based recycled coarse aggregate concrete with steel fibers

Designers may lessen the impact of concrete on the environment while yet ensuring enhanced performance and higher durability by using slag cement, which has proven long-term performance advantages. However, in actual practice, concrete constructions use slag to replace OPC up to 30 to 50 percent of the time, depending on the uses. By using M sand in place of river sand, this study shows differences in the strength and durability parameters of concrete manufactured using 100% with slag cement. Mechanical and durability study was made on replacement of natural coarse aggregates (NCA) with 30, 45 and 60% of recycled coarse aggregates (RCA); Based on the study optimum percentage of recycled aggregates for slag based concrete is 45%. Thus to study effect of fiber on concrete 45% of natural aggregates replaced by recycled aggregates with and without Nano silica.This reduces the consumption of natural resources and adds some additional benefits from a structural and financial standpoint. Steel fibers are added at a rate of between 0.5, 1 and 1.5 percent by volume of cement to give it strength. In order to obtain the optimum percentage of steel fibres using slag cement, concrete grades M20, M25, M30 and M35 were used. Testing techniques such as the compression test, flexural test, spill tensile test, Rapid Chloride penetration test used to assess properties recycled aggregate concrete and also performed the life cycle assessment. From the experimental study 1% Steel fibers was optimum for both with and without Nano silica.

Numerical investigation of the impacts on the primary cement in a new thermal approach for plug and abandonment operations

The advancement of Plug and Abandonments (P&A) procedures is pivotal for reducing the costs associated with current operations. A novel technology concept proposes a heat emitter that will produce enough energy to melt the casing steel without critically affecting the cement layer. However, recent studies concerning this proposal have not given enough attention to the potential impact on the primary cement, which is a crucial material to guarantee the plug's integrity. This study models the heat emitter as a thermite mixture with constant volumetric heat generation, and the oil well structure was approached as a 2-D axisymmetric domain. The finite volume method with a static melting/solidification model is employed to solve the governing equations numerically. A C++ code was developed and compared with the commercial software Ansys® Fluent was performed to verify the present code. The thermal parameters of the heat emitter, including density (1983.6 and 2192.4 kg m−3), specific heat (919.6 and 1016.4 J kg−1 K−1), conductivity (5 and 15 W m−1 K−1), latent heat (1267.79 and 1147.05 kJ kg−1), volumetric heat generation (104.59 and 115.6 MW m−3), and reaction time (71.25 and 78.75 s), are evaluated through a 26 factorial design. The responses analyzed are the maximum melted volume of steel and the volume of cement critically affected. The high variability associated with thermal conductivity indicated a strong dependence on this parameter. Most importantly, this study highlights that melting the casing steel could unintentionally degrade the cement layer, increasing potential leakages paths and integrity problems.

Which head element is more effective for cement augmentation of TFNA? Helical blade versus lag screw

BackgroundEarly fixation and rehabilitation is the gold standard treatment for intertrochanteric femur fractures. Cement augmentation through perforated head elements has been developed to avoid postoperative complications such as cut-out or cut-through. The purpose of this study was to compare two head elements in terms of cement distribution using computed tomography (CT) and to examine their initial fixation and clinical outcomes.MethodsElderly patients who had intertrochanteric fractures were treated with a trochanteric fixation nail advanced (TFNA) helical blade (Blade group) or a TFNA lag screw (Screw group). In both groups, 4.2 mL of cement was injected under an image intensifier (1.8 mL of cement was directed cranially and 0.8 mL each caudally, anteriorly, and posteriorly). Patient demographics and clinical outcome were investigated post-operatively. Cement distribution from the center of the head element was evaluated with CT. Maximum penetration depth (MPD) were measured in the coronal and sagittal planes. On each axial plane, the cross-sectional areas in the cranial, caudal, anterior and posterior directions were calculated. The sum of cross-sectional areas (successive 36 slices) was defined as the volume of the head element.ResultsThe Blade group included 14 patients, and the Screw group included 15 patients. In the Blade group, MPD in the anterior and caudal direction was significantly greater than that in the posterior direction (p < 0.01). In the Screw group, volume in the cranial and posterior direction was significantly greater than that in the Blade group (p = 0.03). Subsequently, the total volume in the Screw group was significantly larger than that in the Blade group (p < 0.01). No significant correlation was detected between bone mineral density, T score, young adult mean, and total cement volume. Change in radiographic parameters and clinical outcome such as Parker score and visual analog scale were similar in both groups. No patients suffered from cut-out / cut through or non-union.ConclusionsThe position of cement distribution through the lag screw is different from that through the helical blade, and the total volume of the head element is significantly larger in the lag screw. Both groups had similarly effective results in terms of mechanical stability after surgery, postoperative pain and early phase of rehabilitation.Trial registrationCurrent Controlled Trials ISRCTN45341843, 24/12/2022, Retrospectively registered.