Cemented Components Research Articles

Sustainable innovations and future prospects in construction material: a review on natural fiber-reinforced cement composites.

There is a growing trend in the construction industry to adopt environmentally friendly practices, and innovative materials are becoming increasingly popular. Within the scope of this paper, the potential of natural fiber-reinforced cement composites (NFRCs) as an environmentally friendly building material is examined. This work introduces plant fiber aspects such as micromorphology, primary components, physical and mechanical properties, chemical components, thermal properties, and degradation mechanisms in cement composites. It explores how plant fibers affect concrete's mechanical performance, durability, and thermal qualities. It is responsible for increasing permeability and decreasing durability in concrete material because plant fibers have porosity and a weak interface. The purpose of this in-depth investigation is to investigate the features, sustainability (social, environmental, and economical) performance, and applications of NFRCs, with a particular focus on environmentally responsible innovation and potential future applications. The exhaustive study also addresses the difficulties associated with attaining the highest possible level of compatibility between fibers and matrixes. The physical and chemical treatments of natural fibers in cement components give more resistance to aging by reducing water absorption and increasing roughness at the surface. It is also possible to reduce the effect of alkalinity of the cement mixture through optimization of the binder component and curing regimes, which retard the breakdown of natural fibers. The purpose of this study is to present a summary of existing research, with a particular emphasis on the benefits, drawbacks, and prospective ways in which NFRCs could potentially improve throughout the construction industry in the future.

Mechanical processing of wet stored fly ash for use as a cement component in concrete

Wet storage effects on fly ash mean that processing may be necessary to achieve the physical properties required for use in concrete. This paper considers drying, de-agglomeration and milling of various wet stored fly ashes at laboratory and pilot/benchtop scales, towards meeting these. In the laboratory, different batch quantities and milling times with as-received/pre-screened materials were examined using a ball mill. Greater particle size reductions were obtained with increased milling time but at gradually reducing rates. Pre-screening and batch quantity had relatively minor effects on particle size reductions, with small differences also found between wet and dry stored fly ash. Extended milling time resulted in a darkening of colour; slight increases in loss-on-ignition, the main oxides content and crystalline components; reductions in water requirement (to a point); and greater reactivity. Similar effects were generally noted in concrete for the superplasticising admixture dose to achieve a target slump and compressive (cube) strength. At pilot/benchtop scale, a dryer-pulveriser and spiral jet mill were used, which gave general agreement with the behaviour noted in the laboratory, but with the effects tending to be less. Fineness levels in Standards were achievable, with subsequent performance in concrete, appearing to depend on the milling process used.

Valorization of Glycerol to Glycerol Carbonate and Glycidol by Different Dialkyl Carbonates Utilizing Tricalcium Aluminate Hexahydrate as Transesterification Catalyst

AbstractIn this study, we report a base‐catalyzed transesterification reaction of glycerol, a waste product of the biodiesel industry, with various dialkyl carbonates, which act both as reactants and solvents, to convert glycerol carbonate into an industrially useful molecular building block. The catalyst, being used for the first time, is also a waste product from industry, present in bauxite residues and in the Portland cement, simply known as tricalcium aluminate. Despite being well‐known and readily available, this solid is only extremely poorly researched catalyst, nevertheless, using dimethyl and diethyl carbonate, glycerol conversion rates >80% and glycerol carbonate yields >60% could be achieved in just 1 h (under air atmosphere and reflux). In a comparison of the performance with other catalysts commonly researched today, as well as with other components of red mud and cements, the results showed that tricalcium aluminate is excellent, cheap, and largely environmentally friendly material for this purpose. Reusability studies of the catalysts have also shown that they provide high conversion and product yields even after repeated use, although different material characterization techniques showed intense glycerol‐catalyst surface interaction and intermediate product formation, the deactivating side effects of which could be avoided by catalyst regeneration steps.

Calcined Clays as Concrete Additive in Structural Concrete: Workability, Mechanical Properties, Durability, and Sustainability Performance.

Calcined clays (CCs) as supplementary cementitious materials (SCMs) can be a promising option to reduce clinker content and CO2 emissions in eco-friendly concretes. Although CCs as components of composite cements in combination with Ordinary Portland Cement (OPC) and limestone powder (LSP) have attracted industry interest, their use as concrete additives is limited. This study investigates the effects of the addition of CCs on the fresh and hardened properties of industry-standard ready-mixed concretes. Four concrete mix designs, each with three superplasticizer dosages, were tested, resulting in 12 variations. The CCs used, which are typical of 2:1 bentonite clays with low metakaolin content, reflect the clays available in Germany. The results showed that CCs significantly influenced the workability, which could be controlled with a high superplasticizer dosage. Increased CC contents reduced bleeding tendencies, which was beneficial for certain structural applications. Early age strength decreased with CCs, but the 28-day strength exceeded that of pure OPC concretes up to 30 wt% CCs. Resistance to CO2-induced carbonation decreased with higher levels of CCs but was comparable up to 15 wt%. Freeze-thaw damage decreased, and chloride migration resistance improved due to a denser microstructure. The global warming potential (GWP) of the concretes tested is in line with that reported in the literature for concretes made from highly blended cements, suggesting that CCs can improve the sustainability of concrete production.

Numerical study on the influence of cemented components on the mechanical properties of Xiyu Conglomerate

Xiyu Conglomerate is a common type of weakly cemented gravel stone formation found in northwestern China. This material is mainly composed of mud, mud–calcium, and calcium cement, possessing mechanical properties that are superior to those of soils but significantly weaker than those of rocks. Assessing these properties is crucial in ensuring the successful implementation of hydraulic engineering projects involving this material. This work establishes a microscale contact bonding model with a mud–calcium transition by surveying Xiyu Conglomerate’s material composition in a typical engineering area. The particle flow code method is used to investigate the influence of cemented materials on the mechanical properties of the conglomerate. After appropriate model calibration, numerical results show that the difference between the vertical and lateral contact forces becomes increasingly significant as the proportion of mud cement decreases and the content of calcium cement increases. The bond breakage process within the cemented material can be divided into three stages: no bond breakage, rapid bond breakage, and differential bond breakage development. When the mud cement content exceeds 50 %, the characteristics tend toward a soil-like behavior, while it resembles a soft rock behavior if the calcium cement content exceeds 50 %. Mud cement connects particles internally, whereas calcium cement strengthens the structure, both contributing to the randomness, heterogeneity, and discontinuity of Xiyu Conglomerate. The results can serve as a reference for future construction and engineering practices in the region.

Nanocrystalline Cellulose to Reduce Superplasticizer Demand in 3D Printing of Cementitious Materials.

One challenge for 3D printing is that the mortar must flow easily through the printer nozzle, and after printing, it must develop compressive strength fast and high enough to support the layers on it. This requires an exact and difficult control of the superplasticizer (SP) dosing. Nanocrystalline cellulose (CNC) has gained significant interest as a rheological modifier of mortar by interacting with the various cement components. This research studied the potential of nanocrystalline cellulose (CNC) as a mortar aid for 3D printing and its interactions with SPs. Interactions of a CNC and SP with cement suspensions were investigated by means of monitoring the effect on cement dispersion (by monitoring the particle chord length distributions in real time) and their impact on mortar mechanical properties. Although cement dispersion was increased by both CNC and SP, only CNC prevented cement agglomeration when shearing was reduced. Furthermore, combining SP and CNC led to faster development of compressive strength and increased compressive strength up to 30% compared to mortar that had undergone a one-day curing process.

An Experimental Study on the Performance of Materials for Repairing Cracks in Tunnel Linings under Erosive Environments

Addressing the current lining cracking problem in coastal tunnels, this paper independently introduces a novel type of repair material for tunnel lining cracks—the composite repair material consisting of waterborne epoxy resin and ultrafine cement (referred to as EC composite repair material). Through indoor testing, we have analyzed the change rule of the mass change rate, compressive strength, flexural strength, and chloride ion concentration of the repair material samples in erosive environments, with the dosage of each component in the EC composite repair material being varied. We have also investigated the working performance, mechanical properties, and microstructure of the repair material. The results of this study show that when the proportion of each component of ultrafine cement, waterborne epoxy resin, waterborne epoxy curing agent, waterborne polyurethane, defoamer, and water is 100:50:50:2.5:0.5:30, the performance of the EC composite repair material in a chloride ion-rich environment is optimal in all aspects. When the mixing ratio of each component of the EC composite repair material is as stated above, the repair material exhibits the best performance in a chloride ion erosion environment. With this ratio of components in the EC composite repair material, the fluidity, setting time, compressive strength, flexural strength, and bond strength of the repair material in a chloride ion erosion environment can meet the requirements of relevant specifications, and it is highly effective in repairing tunnel lining cracks. The polymeric film formed by the reaction between the waterborne epoxy resin emulsion and the curing agent fills the pores between the hydration products, resulting in a densely packed internal structure of EC composite repair material with enhanced erosion resistance, making it very suitable for repairing cracks in tunnel linings in erosive environments.

Silica Quartz Characteristics from Local Silica Sand on Compressive Strength of Mortar

Many minerals, including quartz sand, granite, and feldspar, contain silica (SiO2), a substance that performs the same function as quartz. Silicate (SiO2), the primary mineral found in silica sand, can be added to concrete mixtures to boost strength. This means that silica sand can be employed as a cementitious component in concrete because it is believed to have pozzolanic and amorphous qualities. This study is part of a series that tries to use silica sand from an area in Indonesia. The purpose of this research was to manufacture and describe quartz silica (QS) from Kolaka silica sand, which was acquired from Southeast Sulawesi province in eastern Indonesia. In order to improve the characteristics of mortar mixtures that use composite Portland cement as a binder, it is advised to combine the X-ray diffraction process with an evaluation of the impact of addition (QS) on their physical and mechanical properties (volume weight and compressive strength). Laboratory experimentation is being conducted here. Water, cement, and silica sand are used to make mortar specimens. Red and white silica sand is the type of silica utilized. The specimens were created with a 50 mm diameter and a 100 mm height. Tests on mortar's compressive strength were performed after 7, 14, and 28 days. The study's findings indicated that the amounts of quartz formed in red and white silica sand were 45.05% and 91.87%, respectively. The volume weight that results is approximately 2.78 gr/cm3. Red silica sand was tested for compressive strength at ages 7, 14, and 28 days, and the findings were 20.73, 23.32, and 24.61 MPa, respectively. White silica sand has compressive strengths of 21.83, 24.67, and 26.52 MPa. We are aware of no prior studies examining the use of crystalline silica from Kolaka silica sand to enhance the mechanical qualities of cement mortar. Doi: 10.28991/CEJ-2024-010-08-010 Full Text: PDF

The influence of implant factors on patient outcomes in primary total knee arthroplasty

BackgroundThe influence of implant factors on patient-reported outcome measures (PROMS) after total knee arthroplasty (TKA) has previously been studied but findings are often inconsistent, restricted in scope and biased by confounding factors. This study aims to determine the association between implant-related factors and early post-operative PROMs after TKA. MethodsUsing data from the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) PROMs program, the study included 9487 primary TKA procedures performed in 43 hospitals from July 31, 2018 to December 31, 2020. Data included baseline demographic data, surgical details and PROMs collected pre- and 6 months post-operatively. Seven prosthesis characteristics were incorporated in the multivariable model, with proportional odds ordinal regression analysis used to assess their effects on post-operative Oxford knee score (OKS) and joint pain. Adjustments were made for pre-operative OKS and joint pain, as well as potential patient confounders. ResultsAt six months, fixed bearing implants showed higher odds of better OKS compared to mobile bearing implants (odds ratio [OR] = 1.20, 95 % confidence interval [CI] 1.06–1.37. p < 0.004). Similar findings were found with the use of image derived instrumentation (IDI) (OR = 1.27, 95 % CI 1.11–1.46, p < 0.001), robotic assisted vs. non-navigated knees (OR = 1.21, 95 % CI 1.06–1.38, p < 0.005) and no patella resurfacing (OR = 1.10, 95 % CI 1.01–1.20, p < 0.032). For lower pain scores at six months, the use of highly crosslinked polyethylene (OR = 1.12, 95 % CI 1.02–1.22, p < 0.015), cemented femoral components (OR = 1.11, 95 % CI 1.01–1.22, p < 0.024), IDI (OR = 1.20, 95 % CI 1.05–1.37, p < 0.009) or no patella resurfacing (OR = 1.10, 95 % CI 1.01–1.20, p < 0.034) were associated. ConclusionUtilizing a fixed bearing or robotic assistance correlated with improved OKS scores, whereas highly crosslinked polyethylene or cemented femoral components were associated with improved pain scores. At six months, the use of IDI compared to non-navigated TKA, and patellar resurfacing showed both improved OKS and pain scores.

Prediction of alkali–silica reaction expansions of mortars containing glass waste

The majority of existing findings regarding expansion (EXP) risks in concretes containing waste glass stem from experimental studies. There is a need for rapid assessment methods to ensure safer recycling of glass waste in cementitious composites. In this study, an artificial neural network (ANN) model was developed to accurately predict alkali–silica reaction EXP/mitigation resulting from the integration of glass waste in mortars. The analysis considered glass incorporation either separately as waste glass powder (WGP) and waste glass aggregates (WGAs), or in combination, at contents of up to 100% for WGA and 30% for WGP. A set of 175 mixtures was analysed, considering five distinct variables, which encompassed different mix proportions, involving varying components of cement, natural aggregates, WGP and WGA, in addition to the duration of environmental exposure. The results show that the EXP of WGA mortars decreased with the increased incorporation of WGP. The EXP values obtained from validation and experience confirm the high accuracy of the developed ANN model, with validation coefficients reaching up to 98.061% and a small value of the mean square error.

Periprosthetic Fractures: A Rising Tide of Hip Arthroplasty Failure Noted in the American Joint Replacement Registry and the Preventative Role of Cemented Stems

BackgroundThis investigation examined cemented femoral component use in total hip arthroplasty (THA) and its impact on the incidence of periprosthetic fractures (PPFx), a common failure mode in THA. The study leverages data from the American Joint Replacement Registry (AJRR) to assess trends in cemented femoral component usage over time, its association with PPFx rates, and compares the survivorship and 90-day complication rates between cemented and cementless femoral component THAs. MethodsPrimary THAs, captured in the AJRR, in patients aged 65 years and older from 2012 to 2021 were analyzed. Variables considered included age, sex, race, region, teaching status, year, Charlson comorbidity index, and institution bed size. Analysis compared fixation types for THA on all-cause linked revision and PPFx. Logistic regression models analyzed the odds ratios for all-cause linked revision and PPFx for any follow-up time as well as for 90-day revision. The models were adjusted for the listed variables. ResultsDuring the study period, the rate of cement utilization as a percentage of primary THAs performed and reported to the AJRR increased from 4.4 to 8.3%. The rate of THA failure from PPFx increased from 11.4 to 33.3%. When both fixation groups were compared in the univariate analysis, there was a statistically significant difference in all demographic variables (P < .001). To account for this, multivariable logistic regression models were applied. In our models, cemented stems showed a 54.4% (odds ratio: 0.456; 95% confidence interval: 0.347 to 0.599; P < .0001) and 65.8% (odds ratio: 0.342; 95% confidence interval: 0.237 to 0.493; P < .0001) lower risk of PPFx linked and PPFx early linked revision, respectively. ConclusionsPeriprosthetic fractures are becoming a leading failure mode for THAs in the AJRR. Given cemented fixation’s relative resistance to this failure mode compared to cementless fixation, we should consider increasing the utilization of this technique.

CONSTRUCTION AND OPERATIONAL PROPERTIES OF CONCRETE ON MODIFIED BINDER

The most important tasks of science in the field of construction: facilitating reinforced concrete structures, accelerating and reducing the cost of technological processes, in particular, abandoning heat treatment of products, increasing the durability of concrete can only be solved by giving special properties to binders. The way to solve this problem lies through the expansion of the range of complex mineral additives. Natural and man-made substances in a dispersed state, insoluble in water and characterized by grain size less than 0.16 mm, are used as mineral additives for binders and concretes. Despite the different effectiveness, mineral additives have a similar qualitative chemical composition (oxides of silicon, aluminum and others). The differences are in their mineralogical composition, the ratio of components and the degree of dispersion, which determine the predominant mechanism of their action in cement systems. Depending on the properties of the mineral additive, it is possible to obtain multicomponent binders for concretes with special properties: fast-hardening, high-strength, sulfate-resistant and others with significant savings in the cement component. The effectiveness of superplasticizers in dispersed systems can be increased due to a different procedure for their introduction or by combining them with finely ground mineral fillers of various chemical nature. The article presents the possibility of obtaining heavy concretes with specified construction and operational characteristics using a complex mineral additive, which includes waste from the tailings of the Balkhash mining and Processing plant and silica, as well as superplasticizers of various natures: MasterGlenium 305, Master Rheobuild 1000K and Master Air 200.

QUALITY IMPROVEMENT EFFECTIVENESS OF ROAD SLABS PRODUCED USING MICROSILICA AND FIBER

Here we present the results of testing the concrete physical and mechanical properties for road slabs reinforced with bulk fiber, including polypropylene macro- and microfibers. We have analyzed the effect of the use of macrofibers and microfibers in the concrete composition. There was established the impact of low-modulus synthetic fibers on the characteristics of strength, density, water resistance and frost resistance of concrete for road pavement. It was established that polypropylene macrofibers impact on the physical and technical characteristics of concrete, increase compressive and bending strength, and polypropylene microfibers improve the structure of the cement component of concrete, optimize the pore space, increase the frost resistance and water resistance of concrete. It has been experimentally proved that owing to the combined use of various sized fiber fibers, it is possible to produce concrete that has good characteristics in strength, density and frost resistance. It was established that with the combined concrete fiber reinforcement with microsilica addition, we get the possibility of increasing bending strength up to 35%, frost resistance up to F375 and water resistance up to W14. The research results make it possible to recommend multi-dimensional polypropylene fibers for volumetric reinforcement and microsilica to create additional crystallization centers and reduce the pore space in the concrete body at road slabs manufacture.

Assessing the climate effects of clinker production: A statistical analysis to reduce its environmental impacts

Building materials and components account for about 10% of the world's anthropogenic greenhouse gas emissions. Carbonate decomposition and fuel combustion from the cement production process are responsible for almost 7% of carbon dioxide emissions. Since clinker is the most impacting component of ordinary Portland cement, this paper presents a statistical analysis of the life cycle impacts of 41 recipes of grey clinker produced in Europe from 2015 to 2023 to identify the consumption impact categories (e.g., fossil fuels, renewable and non-renewable secondary fuels) which better explain the assessment of the Global Warming Potential (GWP), typically exploited to quantify the environmental impact of clinker production. More in detail, several regression methods are applied to the available dataset to build predictive models for GWP and to determine the most relevant impact categories. The regression models are then compared with respect to their statistical accuracy and goodness of fit. The results provide information that can support cement producers in developing low-impacting cement recipes.

Molecular insights to in vitro biocompatibility of endodontic Pulpotec with macrophages determined by oxidative stress and apoptosis

Pulp therapy has been emerged as a one of the efficient therapies in the field of endodontics. Among different types of new endodontic materials, pulpotec has been materialized as a recognized material for vital pulp therapy. However, its efficacy has been challenged due to lack of information about its cellular biocompatibility. This study evaluates the mechanistic biocompatibility of pulpotec cement with macrophage cells (RAW 264.7) at cellular and molecular level. The biocompatibility was evaluated using experimental and computational techniques like MTT assay, oxidative stress analysis and apoptosis analysis through flow cytometry and fluorescent microscopy. The results showed concentration-dependent cytotoxicity of pulpotec cement extract to RAW 264.7 cells with an LC 50 of X/10-X/20. The computational analysis depicted the molecular interaction of pulpotec cement extract components with metabolic proteins like Sod1 and p53. The study revealed the effects of Pulpotec cement's extract, showing a concentration-dependent induction of oxidative stress and apoptosis. These effects were due to influential structural and functional abnormalities in the Sod1 and p53 proteins, caused by their molecular interaction with internalized components of Pulpotec cement. The study provided a detailed view on the utility of Pulpotec in endodontic applications, highlighting its biomedical aspects.

Hydration of a 2-component CSA-OPC-mix – timing of component blending &amp; setting on demand

With the ongoing development of new technologies like 3D printing, the requirements for the performance of cementitious materials become more complex. Setting on demand, while the workability of the material is retained until placement, is an important aspect of this usage. A ternary CSA-OPC-C$ system was developed to achieve setting on demand in a 2-component setup, where two retarded cementitious components were mixed after specific times of storage. The kinetics of the individual systems and the blend were examined by heat flow calorimetry, quantitative X-ray diffraction and pore water analysis. The rheological development was monitored by a penetration test method. The results show that the performance of the blend is independent of the storage time of the individual components and can be tailored by changes in the retarder dosage in the individual components. The initial reaction in the blend is characterized by the simultaneous dissolution of ye'elimite and C3S, resulting in the formation of ettringite as the sole detectable hydrate phase. The fate of silicon remains unclear as with the methodology at hand no silicon incorporating hydrate phase can be identified.

Synergetic optimizing particle size distributions of aggregate and cementitious materials: Toward lower chloride diffusivity of concrete

Particle size distributions (PSDs) of aggregate and cementitious material dominate the microstructure and properties developments of concrete. Optimizing the proportion of aggregate can mitigate chloride ingress pathways, leading to a significant increase in surface area and augmented generation of the interfacial transition zone (ITZ). Overemphasis on aggregate proportion can compromise workability of fresh concrete due to limited cement paste lubrication. Although gap-graded distribution benefits cementitious material hydration, accurately classifying cementitious components for broad implementation is challenging. This study designed the aggregate proportion and PSD based on a proposed diluted packing region with low estimated chloride diffusivity. The gap-graded distribution at the cementitious material scale was conveniently achieved by incorporating fine ground blast furnace slag and coarse fly ash into commercial Portland cement. Consequently, dual-scale designed concretes, taking into account PSDs at both aggregate and cementitious material scales, were proposed. These concretes exhibited chloride diffusion coefficients ranging in (1.26–1.46)×10−12 m2/s, with aggregate proportions spanning 52 % to 74 %. Their compressive strength was comparable with Portland cement concrete, even with 60 % supplementary cementitious materials (SCMs). The improved properties of the dual-scale designed concrete can be attributed to the high aggregate proportion with rational PSD, which does not result in a significant rise in the ITZ proportion. Efficient hydration of the cementitious material is beneficial to microstructure densification and chloride binding capacity improvement, helps to increase the chloride diffusion distance and hinder the penetration of chloride. This study provides insights into designing chloride-resistant concrete with less Portland cement reliance.

Evaluation of the Performance of Pervious Concrete Inspired by CO2-Curing Technology

Urban runoff is acidic in nature and mainly consists of heavy metals and sediments. In this study, the pervious concrete samples were cured in a CO2-rich environment and their performance under runoff conditions was evaluated by passing different solutions containing clay particles, heavy metal ions, and acid species. The compressive strength of these samples was reduced by up to 14% when they were cured in water instead of a CO2 environment. Heavy metal ions, including lead and zinc, in the simulated runoff were adsorbed in these pervious concrete samples by up to 96% and 80% at the end of the experiment, but the acid species in this runoff could leach calcium ions from the cement components during passage. Clay particles in the runoff were trapped in the flow channels of samples, which marginally reduced the percolation rate by up to 14%. Concrete carbonation reduced the release of calcium ions under runoff conditions, and zinc removal was relatively lower because of the nonavailability of hydroxyl sites in the interconnected pore structure. The weight and strength losses in the carbonated concrete samples were relatively lower at the end of the acid storage experiment, suggesting that CO2 curing reduces cement degradation in aggressive chemicals. The SEM and tomography images revealed the degraded microstructure, while the XRD results provided data on the mineralogical changes. CO2 curing improves the strength gain and service life of pervious concrete in runoff environments.

Identifying potentially low value surgical care: A national ecological study in England.

High variation in clinical practice may indicate uncertainty and potentially low-value care. Methods to identify low value care are often not well defined or transparent and can be time intensive. In this paper we explore the usefulness of variation analysis of routinely-collected data about surgical procedures in England to identify potentially low-value surgical care. This is a national ecological study using Hospital Episode Statistics linked to mid-year population estimates and indices of multiple deprivation in England, 2014/15-2018/19. We identified the top 5% of surgical procedures in terms of growth in standardised procedure rates for 2014/15 to 2018/19 and variation in procedure rates between clinical commissioning groups as measured by the systematic component of variance (SCV). A targeted literature review was conducted to explore the evidence for each of the identified techniques. Procedures without evidence of cost-effectiveness were viewed as of potentially low value. We identified six surgical procedures that had a high growth rate of 37% or more over 5years, and four with higher geographical variation (SCV >1.6). There was evidence for two of the 10 procedures that surgery was more cost-effective than non-surgical treatment albeit with uncertainty around optimal surgical technique. The evidence base for eight procedures was less clear cut, with uncertainty around clinical- and/or cost-effectiveness. These were: deep brain stimulation; removing the prostate; surgical spine procedures; a procedure to alleviate pain in the spine; surgery for dislocated joints due to trauma and associated surgery for traumatic fractures; hip joint replacement with cemented pelvic component or cemented femoral component; and shoulder joint replacement. This study demonstrates that variation analysis could be regularly used to identify potentially low-value procedures. This can provide important insights into optimising services and the potential de-adoption of costly interventions and treatments that do not benefit patients and the health system more widely. Early identification of potentially low value care can inform prioritisation of clinical trials to generate evidence on effectiveness and cost-effectiveness before treatments become established in clinical practice.

OPTIMIZING FINE AGGREGATE AND CEMENT REPLACEMENT WITH STONE DUST: IMPACT ON CONCRETE COMPRESSIVE STRENGTH

The utilization of stone dust in concrete presents a promising avenue for reducing environmental impact through decreased dependence on traditional fine aggregate and cement components, primarily focusing on the properties of fresh and hardened concrete. This study delves into the direct integration of stone dust sourced from stone companies, particularly as random samples collected during the sawing phase of stone manufacturing. Through meticulous analysis, the replacement of stone dust is thoroughly examined to assess its influence on the fresh and hardened characteristics of concrete, aiming to optimize the mix for superior performance. Experimental investigations reveal that quarry dust can effectively substitute for fine aggregate and cement, albeit with the caveat that a comprehensive chemical analysis of the stone dust is imperative prior to integration to ensure compatibility with the concrete mix. Moreover, the study quantifies the compressive strength of concrete across varying percentages of stone dust, evaluating its impact on the concrete class. By analyzing replacement percentages ranging from 5% to 12.5% for fine aggregate and optimal cement replacement, the research explores mix design preparation, fresh property assessments, and hardened concrete sample evaluations, with a particular focus on compressive strength comparisons against reference concrete formulations.