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Today, the construction industry has expressed its preference for the use of sustainable materials due tothe significant impact they have on the environment. Although concrete is widely used in construction due to itsdiverse properties, one of its main components, known as clinker, is a major contributor to CO2 pollution. Therefore,the feasibility of partially replacing this material with alternatives is being investigated. Among them, calcineddiatoms are presented as a promising option. These are an extremely fine and highly porous material, composedmainly of silica, which has a large specific surface area. The abundant presence of active silica improves theproperties of concrete, such as its strength, while the ultrafine particles of diatoms densify the concrete structure,thus achieving a concrete with greater durability. The objective of this study was to evaluate the properties ofconventional concrete, both fresh and hardened, by adding calcined diatomite in proportions of 5%, 10% and 15%,with the purpose of determining the optimum percentage of calcined diatomite to achieve adequate concretedevelopment. Test specimens were elaborated without the addition of calcined diatoms and with the addition ofcalcined diatoms, then immersed in water for 7d, 14d and 28d. Tests were carried out in the fresh state to obtainworkability, bleeding, setting time, air content, temperature, and unit weight. In the hardened state, tests were carriedout to obtain compressive strength, static modulus of elasticity and permeability. It was found that with a loweraddition of calcined diatomaceous earth, the concrete can develop as a normal concrete, and improvements incompression were obtained, increasing with respect to the control concrete. However, by increasing the percentageof calcined diatomite, the workability is reduced and in general, the properties do not show an improvement. Concretewith the addition of calcined diatomite can be used as a thermal insulator, since it presents

This article describes the work carried out to investigate the behavior of concrete by adding interlocking steel fibers in different proportions (0%, 1%, 1.5%, 2% and 2.5%) for rigid pavements, said addition was made in percentage as an addition to the concrete. With an f'c of 280 kg/cm2 for the standard concrete, the tests were carried out to determine its resistance to compression in 28 days, resistance to flexion in 28 days, and resistance to diametral traction in 28 days. It was obtained as results that the optimal percentage for the compression resistance test was 1%, reaching a resistance of 350 kg/cm2 at 28 days, for the flexion test the optimal percentage was 2.5%, the best The value obtained in the tensile test was the addition of 2.5% and finally in the ASTM C944 test it was obtained as a result that the percentage of 2.5% is the best of all where the wear is minimal by 0.010%. The rigid concrete used for concrete paving has a potential use in the construction of road infrastructures and applying the addition of interlocking steel fibers only improves some characteristics of the concrete, such as flexion and traction.

As an environmentally responsible alternative to conventional concrete, geopolymer concrete recycles previously used resources to prepare the cementitious component of the product. The challenging issue with employing geopolymer concrete in the building business is the absence of a standard mix design. According to the chemical composition of its components, this work proposes a thorough system or framework for estimating the compressive strength of fly ash-based geopolymer concrete (FAGC). It could be possible to construct a system for predicting the compressive strength of FAGC using soft computing methods, thereby avoiding the requirement for time-consuming and expensive experimental tests. A complete database of 162 compressive strength datasets was gathered from the research papers that were published between the years 2000 and 2020 and prepared to develop proposed models. To address the relationships between inputs and output variables, long short-term memory networks were deployed. Notably, the proposed model was examined using several soft computing methods. The modeling process incorporated 17 variables that affect the CSFAG, such as percentage of SiO2 (SiO2), percentage of Na2O (Na2O), percentage of CaO (CaO), percentage of Al2O3 (Al2O3), percentage of Fe2O3 (Fe2O3), fly ash (FA), coarse aggregate (CAgg), fine aggregate (FAgg), Sodium Hydroxide solution (SH), Sodium Silicate solution (SS), extra water (EW), superplasticizer (SP), SH concentration, percentage of SiO2 in SS, percentage of Na2O in SS, curing time, curing temperature that the proposed model was examined to several soft computing methods such as multi-layer perception neural network (MLPNN), Bayesian regularized neural network (BRNN), generalized feed-forward neural networks (GFNN), support vector regression (SVR), decision tree (DT), random forest (RF), and LSTM. Three main innovations of this study are using the LSTM model for predicting FAGC, optimizing the LSTM model by a new evolutionary a, Pavement Engineering

The use of waste materials has gained attention as a sustainable approach in various industries. Cigarette waste, which is typically discarded as a non-recyclable material, poses a significant environmental challenge due to its toxicity and slow decomposition rate. However, by incorporating this waste into ceramic bricks, new approaches for waste management and resource utilization are explored. This research work provides a detailed evaluation of the possibility of utilizing natural zeolite tuff incorporated with cigarette waste to produce sustainable ceramic bricks. Uniform powders are produced by milling various combinations of zeolitic tuff and cigarette waste using a planetary ball mill. The substitution ratios ranged from 0% to 12% by weight of the zeolitic tuff, with increments of 2%. Ceramic discs were formed by dry pressing and then subjected to sintering at different heat treatment temperatures (950–1250 °C). The impact of the inclusion of cigarette waste on the microstructural and technical features of zeolite tuff-based ceramic bricks has been thoroughly investigated. The results of the experiments demonstrate that incorporating cigarette waste into the development of ceramic bricks leads to improved thermal insulation properties, with thermal conductivity ranging from 0.33 to 0.93 W/m·K. Additionally, these bricks exhibit a lighter weight in a range of 1.45 to 1.96 g/cm3. Although the inclusion of cigarette waste slightly reduces the compressive strength, with values ranging from 6.96 to 58.6 MPa, it still falls within the acceptable range specified by standards. The inclusion of cigarette waste into zeolite tuff is an innovative approach and sustainable practice for reducing energy consumption in buildings while simultaneously addressing the issue of waste disposal and pollution mitigation., Dynamics of Micro and Nano Systems

The responsible management of construction and demolition waste is a critical issue, primarily due to the substantial volume of waste generated. Landfilling remains a prevalent method for disposal. This project explores the use of construction and demolition waste (C&D) as a substitute for coarse aggregate in cement brick production, with varying percentages (ranging from 0% to 100%). Various mix types were employed in the casting of these bricks. The study encompasses the evaluation of compressive strength at intervals of 7, 14, 21, and 28 days, as well as the implementation of water absorption tests, alternate drying and wetting tests, and examinations for sulphate and chloride attacks.

Waste tires have long been a challenge for waste disposal. In an effort to mitigate the impact of solid waste on the environment and recycle it as much as possible, research has been conducted into the possibility of using this waste in concrete mixes. However, the use of these waste materials in concrete is still not popular due to the lack of knowledge of the properties that can be obtained with this material. Hence, the aim is to use waste material in the production of concrete, and that concrete mixes with this material have satisfactory performance. The paper presents the results of research on concrete in which volume replacement of fine aggregate with crumb rubber was performed in the amount of 5%, and this concrete was compared with the control concrete mix and aerated concrete. All concrete are made with a water-cement factor of 0.45. The performance of fresh concrete was monitored for 10, 30 and 60 min. In the case of concrete with the addition of crumb rubber, after 60 min, higher values of air content were obtained, and lower values of volume mass of fresh concrete compared to the initial measurements. The obtained test results of hardened concrete indicate that concrete with crumb rubber has a lower compressive strength compared to the control concrete mix, while compared to aerated concrete, they obtain approximate compressive strength values.

In the world wide the usage of concrete is more in the construction industry which contains maximum volume of aggregates than cement due to this the natural aggregates are depleted day by day. In this project coarse aggregate is replaced with Mangalore tiles in self-compacting concrete ranging from 10%, 20%, 30%, 40%. Mangalore tiles are rejected tiles which are not in ideal size and shape. The various tests are carried out such as compressive strength, flexural strength and spilt tensile strength test at 7 and 28 days for cubes, cylinder and beams. Here the grade of the concrete is M50 and mix design is carried out. Mechanical properties, strength, durability and optimum percentage of crushed Mangalore tiles is observed. Self-compacting concrete is a concrete mix which has a low yield stress, good segregation resistance and moderate viscosity uniform suspension of solid particles during transportation and placement. Mangalore tiles waste is used as coarse aggregate for the present study which can be obtained in the rural areas where the major number of houses is built using these tiles for the roof. The demolition of these generates maximum roof tiles which will be wasted.

Disposable face masks and other personal protection equipment have been important for healthcare workers and ordinary people since the COVID-19 outbreak began. Disposable face masks have been in high demand to restrict and reduce the spread of SARS-CoV-2, which is the virus that causes COVID-19. All of those masks have an environmental cost. Healthcare workers must wear masks for the vast bulk of the time, even if the cases decrease in certain areas. To address the issue above, using disposable face masks as a construction material for building bricks could be a viable and long-term solution for managing a country's medical waste. This study utilized the quantitative-experimental research method while utilizing a purposive sampling technique.    The statistical treatment used for this study was Student’s T-Test to find out if there is a significant difference between the American Concrete Society for Testing and Materials (ASTM) standard of brick and bricks made with discarded disposable face masks in terms of compressive strength, water absorption and moisture content. The study used a questionnaire as the research instrument where researchers surveyed two groups of respondents, 5 Civil Engineers and 5 Chemical Engineers, to determine the level of acceptability of the brick in terms of construction materials, procedures and design, and content ratio. It indicates no significant difference between the American Concrete Society for Testing and Materials (ASTM) standard of brick and bricks made with discarded disposable face masks regarding compressive strength, water absorption and moisture content. Regarding compressive strength, the acquired mean of the ASTM is 37.9, while the Ecobrick acquired 36.87. The variance of ASTM was 136.66, while Ecobrick acquired 184.59. The T-computed value is -0.99. T-critical is 2.92 with an alpha level of 0.05 and degrees of freedom of 2.   Regarding water absorption, the acquired mean of the ASTM is 0.6, while

Ultrafine hydraulic binder grout injection is a technique utilised for repairing masonry, either to connect sections, seal joints, or fill voids due to its great capacity for penetration and higher mechanical strength than lime grout. In this research, the mechanical properties of ultrafine hydraulic cement grout are analysed considering the influence of the mould material for preparing the specimens and their geometry characteristics in the context of the specifications set out in several international standards. The test campaign to ascertain compressive and flexural strength in different circumstances is supplemented with a physical and chemical characterisation of both binder and fresh and hardened grout. Significant differences in mechanical properties between specimens prepared with absorbent or non-absorbent-water material are found due to the influence of drying shrinkage and decanting binder during the curing process. Furthermore, the slenderness of specimens is presented as an important factor in determining the compressive strength of mixtures.

Recycled concrete aggregates (RCAs) and supplementary cementitious materials (SCMs) may substitute some cement and natural aggregates (NA) in concrete manufacturing. However, their effects on recycled aggregate concrete (RAC) compressive strength are difficult to model. Reactivity, silica, and alumina modulus were examined for cementitious materials' chemical complexity. Random Forest approaches were developed to predict and analyze RAC compressive strength. Even with RCAs and SCMs, the RF model accurately estimated concrete compressive strength. The Variable Importance (VI) research examined how input factors affected RAC compressive strength. VI indicated that silica fume contributes most to RAC compressivestrength, followed by cementitious materials' reactivity modulus, cement content, silica modulus, fine natural aggregate content, and coarse naturalaggregate dosage. The water dosage, water/binder ratio, and RCA content lower the RAC compressive strength. As a result, to highlight, the amount of SCM was not significant, but its nature was (i.e., hydraulic, silica pozzolanic, or alumina pozzolanic)., Los agregados de concreto reciclado (ACR) y los materiales cementantes suplementarios (MCS) pueden sustituir parcialmente cemento y agregados naturales (NA) en la fabricación de concreto. Sin embargo, sus efectos sobre la resistencia a la compresión del concreto con agregados reciclados (CAR) son difíciles de modelar. Se examinaron los módulos de reactividad, sílice y alúmina para determinar la complejidad química de los materiales cementosos. Se desarrollaron enfoques de Random Forest para predecir y analizar la resistencia a la compresión de los CAR. Incluso con ACR y MCS, el modelo de RF estimó con precisión la resistencia a la compresión del concreto. El análisis de importancia de variable (IV) examinó cómo los factores de entrada afectaron a la resistencia a la compresión del RAC. IV indicó que el humo de sílice contribuye más a la resistencia a la compresión del CAR, seguido del módulo de reactividad de los materiales cementantes, el contenido de cemento, el módulo de sílice, el contenido de agregados naturales finos y la dosificación de agregados naturales gruesos. La dosificación de agua, la relación agua/cemento y el contenido de ACR reducen la resistencia a la compresión de CAR. Como resultado a destacar, la cantidad de MCS no fue significativa, pero sí su naturaleza (es decir, hidráulica, sílice puzolánica o alúmina puzolánica).

This study used digital image processing and an artificial neural network (ANN) to determine the compressive strength of concrete in reinforced concrete buildings without coring. First, 32 concrete samples were produced in the laboratory, with different water-to-cement ratios, aggregate types, amounts of binder, compression values applied to fresh concrete, and amounts of additive. Next, the locations of 192 cores were visualized, and the compressive strengths of their corresponding core samples were matched with the surface images of the concrete, which were then digitized by image processing. The digitized images were the input layer, and the training and testing procedures were performed using the ANN as an output layer. After testing, the model was validated in existing reinforced concrete buildings. For the verification process, 20 cores taken from randomly selected concrete buildings were used. Although the results obtained from the samples produced in the laboratory were satisfactory, the success rate of the samples taken from the field was limited. Finally, the findings of this study are compared against the literature on this subject, especially from the last two decades., En este estudio se utilizó procesamiento de imágenes digitales y una red neuronal artificial (ANN) para determinar la resistencia a la compresión del hormigón en edificios de hormigón armado sin tomar núcleos. Primero, se generaron 32 muestras de concreto en el laboratorio con diferentes proporciones de agua a cemento, tipos de agregado, cantidades de aglutinante, valores de compresión aplicada al concreto fresco y cantidades de aditivo. A continuación, se visualizaron las ubicaciones de 192 núcleos, y las resistencias a la compresión de sus correspondientes muestras se compararon con las imágenes de la superficie del hormigón, que se digitalizaron mediante procesamiento de imágenes. Si las imágenes digitalizadas fueron la capa de entrada, y los procedimientos de entrenamiento y prueba se realizaron utilizando la ANN como capa de salida. Después de las pruebas, el modelo se validó en edificios reales de hormigón armado. Para el proceso de verificación, se utilizaron 20 núcleos tomados de edificios de hormigón seleccionados al azar. Si bien los resultados obtenidos de las muestras producidas en el laboratorio fueron satisfactorios, el porcentaje de éxito de las muestras tomadas en campo fue limitado. Por último, se comparan los hallazgos del estudio con la literatura sobre este tema, especialmente de las últimas dos décadas.

This study investigates the size effect on the compressive strength of foamed concrete at the mesoscale level combining X-ray computed tomography (X-CT) and a discrete lattice model. Image segmentation techniques and X-CT were employed to obtain virtual specimens comprising hydrated cement paste and air voids. The lineal-path function and pore size distribution was used to characterise the air void structure. A two-dimensional lattice fracture model of foamed concrete considering different wet densities was established. The model was verified experimentally at a wet density of 700 kg/m3 and then used to predict the strengths of specimens with wet densities of 600 and 800 kg/m3. Square and rectangular specimens (slenderness ratio = 2) with widths of 10, 20, 40, 70.7, and 100 mm were investigated. Results show that the air void structure significantly influences the observed size effect on the compressive strength in the investigated size range. A random forest regressor was used to predict the compressive strength of the foamed concrete; the regressor yielded satisfactory results. Finally, existing analytical size effect models were used to fit the simulated strength. Although good fitting was achieved, special attention should be given to the applicable range and physical meaning of fitted empirical parameters., Materials and Environment

The use of non-destructive tests for assessing the material status of concrete structures in the Netherlands remains relatively uncommon, despite the growing demand for the preservation of existing structures under the VenR policy of Rijkswaterstaat. Skepticism towards NDTs is reflected in the scarcity of documented case studies in publicly available literature and in the absence of rules and guidelines. In this research, following an extensive literature review on the current state of assessing the material status of reinforced concrete structures using NDTs, a large-scale non-destructive inspection was carried out on the Sluinerweg viaduct. The research aimed to address the practical challenges associated with these methods. These challenges serve to formulate a practical methodology to facilitate future inspections. Limitations include the use of specific NDTs: GPR, UPE, rebound hammer, UPV, half-cell potential, resistivity, and corrosion current density. Following the inspection, a data analysis was conducted, accompanied by a destructive verification of the methods. The integration of GPR with UPE technology showed promise for tendon duct inspections. However, a 12 mm borehole used for destructive verification proved to be too small to make accurate judgments. Additionally, the absence of grouting defects made evaluation of the method challenging. GPR provided a more accurate estimation of the cover depth compared to previous measurements conducted on the Sluinerweg viaduct using a standard cover meter. However, it was impossible to measure through the cathodic protection coating. The data's correlation with the provided drawings is promising, especially given that drawings are often unavailable. The key finding regarding the estimation of compressive strength using the rebound hammer and UPV is the strong recommendation to avoid using SonReb models unless they are specifically calibrated for the structure under inspection. No active corrosion, https://a1oost.nl/nieuws/2637251.aspx Information on the demolition of the Sluinerweg viaduct (in Dutch). https://repository.tudelft.nl/islandora/object/uuid:7d1fb21c-047e-4366-aea6-9a2abd06b22e?collection=education Handheld XRF measurements performed on the Sluinerweg viaduct., Liggerkoppen, Civil Engineering | Structural Engineering | Concrete Structures

The main problem facing the world today is pollution. In the construction industry, especially during the production of Portland cement, pollutants are emitted which lead to environmental pollution. in the present study, to make the geopolymer bricks, the ordinary Portland cement is fully replaced with fly ash and the fine aggregate is replaced with stone dust and alkaline liquids are used for the binding of materials. In this study an attempt is made to identify the optimum methodology of curing, by curing the red soil based geopolymer bricks with various curing temperature from 600c to 1200c with a variation of 100c for 24 hours in oven. From the optimum elevated temperature obtained, specimens are cured for 24 hours,48 hours and 72 hours in oven and also comparative study is carried out between elevation curing and ambient curing. The specimens are tested for physical and durable aspects.

The disposal of waste foundry sand (WFS) in landfills is a widespread issue, prompting the metal casting industry to explore reusing WFS. Concrete production offers a promising avenue for utilizing WFS as a substitute for M sand, potentially benefiting both the environment and construction costs. This project focuses on analyzing the physical properties of WFS, formulating concrete mixes for M25 grade concrete per IS 456:2000 standards and evaluating mechanical properties like compressive and split tensile strength. The aim is to determine the ideal formulation for concrete mixture by assessing the performance at different replacement levels of WFS (0%, 25%, 50%, 75%, and 100%). The experiment sourced materials from various locations, including cement, waste foundry sand, fine aggregate, coarse aggregate, and water. To assess the impact of replacing M sand with WFS on OPC mix properties, several laboratory tests were conducted. These tests encompassed particle size distribution analysis for fine aggregate, aggregate impact value assessment, workability testing, as well as evaluations of compressive strength, split tensile strength, flexural strength, and durability. The project aims to address the challenge of WFS disposal by exploring its potential as a substitute for M sand in concrete production, with the goal of optimizing mix designs and enhancing mechanical properties across different replacement levels.

The generation of industrial waste has been steadily increasing, necessitating sustainable waste management strategies. Quarry dust, a by-product of the aggregate production process obtained from crushing rocks in rubble crusher units, contributes to this waste stream. This study proposes using fine quarry dust waste, ranging from 50 to 100 ?m, as an additive or replacement in mortar to mitigate environmental and health hazards caused by this kind of waste. However, literature on the usage of very fine quarry dust waste (about 50-100?m particle sizes) as a partial sand replacement in mortar production is very limited. Therefore, this paper presents an experimental investigation on the effects of incorporating quarry dust waste as a sand replacement, with variations of 0%, 5%, 10%, 15%, 20%, 25%, and 30%, with a water-cement ratio of 0.5 to enhance mortar strength. The micro-structural analysis and compression tests were performed to evaluate the mortar samples. XRF analysis confirmed that silica oxide (SiO2) was the predominant element present in quarry dust waste. The compression tests were conducted on 50 mm x 50 mm x 50 mm mortar cubes. The tests were performed at 3, 7, 14, and 28-day intervals. The results revealed that, incorporating 25% quarry dust waste as a sand replacement produced the highest compressive strength of about 37 MPa on the 28th day curing duration. Hence, using this material as an environment-friendly sand replacement offers a promising solution for producing high-strength mortar. This finding highlights the potential of quarry dust waste as a supplemental cementitious material and emphasizes its viability in reducing the environmental impact associated with industrial waste.

This paper deals with the application of machine learning (ML) in the field of concrete technology. Two databases of test mortars and concretes were created from selected academic theses, which include mechanical properties in relation to their composition. These databases were used to develop two ML models that predict the mechanical properties of mortars and concretes depending on their composition. The mortar test database contains a total of 242 mechanical property records and the concrete test database contains 111 records. The materials in the database are CEM I, CEM II and CEM III cements combined with additives such as ground granulated blast furnace slag, high temperature fly ash and micro-ground limestone.

The building material that is most often utilised worldwide is concrete. In infrastructure projects, it is frequently employed. Due to the rapid speed of construction operations in India, the major goal of this study is to find other sources of cement that would lower the amount of cement needed for construction. Cement is partially replaced with metakaolin and fly ash. It has a variety of pozzolanic qualities that have beneficial impacts on the final characteristics of concrete. These characteristics lead calcium hydroxide, a byproduct of cement hydration, to chemically react with the active ingredients.The primary goal of this research is to partially replace OPC with Metakaolin and Fly ash. This research aims to examine the qualities of M-30 grade concrete, concrete manufactured with metakolin, and concrete made with fly ash while they are both fresh and hardened. The weight of cement has partially replaced metakoalin in the ratios of 5%, 10%, 15%, and 20%. The weight of cement has replaced a portion of the fly ash in the amounts of 7.5%, 15%, 22.5%, and 30%. Slump testing is done to investigate the new qualities. Compressive and split tensile strength tests are carried out on concrete after 28 and 56 days of curing to examine its hardened qualities.

The demand for and consumption of cement are rising as the building industry expands quickly. Cement manufacture takes a lot of raw resources, which results in carbon dioxide emissions into the atmosphere and other environmental issues. There has been a lot of research done in an effort to create substitute binders that are eco-friendly and aid in waste management. The bagasse, or fibrous waste product, is produced in large quantities by the sugar processing companies and dumped on open ground. Utilizing trash and its by-products as a disposal alternative has grown more appealing as environmental awareness has grown. Pozzolanic qualities are present in sugarcane bagasse ash, which mostly comprises silica and aluminium ions. During hydration, the silica in the bagasse ash interacts with the cement's ingredients. In the current development, an effort has been made to partially substitute cement with bagasse ash. The primary goal of this research is to examine the qualities of M-30 grade control concrete while it is both fresh and hardened. Bagasse ash has been substituted in concrete in amounts of 0%, 5%, 10%, 15%, 20%, and 25% by cement weight. Slump testing is done to investigate the new qualities. Compressive and split tensile strength tests are carried out to examine the hardened characteristics of concrete, and comparison research will be done.

One aspect that affects the strength of Portland cement mortars is the correction of moisture in the mix. Thus, standard techniques are usually used to obtain the absorption value in fine aggregates; one of them is the standard ASTM C128. However, the ASTM C128 presents variability associated with the identification of the saturated surface dry state in the fine aggregates. This research compares the water absorption of four types of Colombian aggregates obtained using the ASTM C128 and an innovative instrumental and analytical technique with the thermogravimetric balance of halogen light (TBHL), coupled with a software that reads the retained water data in real time. The strength of mortars designed on the basis of moisture correction is also evaluated. The absorption results show that TBHL presents lesser dispersion results (not exceeding 10%) than the standard method ASTM C128, indicating greater precision and less uncertainty. Additionally, resources are optimized through TBHL implementation, requiring 25% less time, 86% less energy consumption, and 98% less fine aggregate for a test. Furthermore, the strength of the mortars varies depending on the method used to determine the absorption, as well as the morphology of the aggregates. The accuracy of TBHL allows better correction of the water–cement ratio in the mortars; thus, leading to higher performance., Un aspecto que afecta la resistencia de los morteros de cemento Portland es la corrección por humedad de la mezcla. Se suelen utilizar técnicas estandarizadas para obtener el valor de absorción en áridos finos; una de ellas es la norma ASTM C128. Sin embargo, esta norma presenta una variabilidad asociada a la identificación del estado seco superficial saturado en el árido. En esta investigación se compara la absorción de agua de cuatro tipos de agregados colombianos obtenida mediante la norma ASTM C128 y una innovadora técnica instrumental y analítica con la balanza termogravimétrica de luz halógena (TBHL), acoplada a un software que lee los datos de agua retenida en tiempo real. También se evalúa la resistencia de los morteros diseñados a partir de corrección por humedad. Los resultados de absorción muestran que la TBHL presenta resultados con menor dispersión (no superior al 10%) en comparación a la ASTM C128, lo que indica una mayor precisión y menor incertidumbre. Además, se optimizan recursos mediante la aplicación del TBHL, requiriendo un 25% menos de tiempo, un 86% menos de consumo de energía y un 98% menos de áridos finos para un ensayo. La resistencia de los morteros varía en función del método utilizado para determinar la absorción, así como de la morfología de los áridos. La precisión del TBHL permite una mejor corrección de la relación agua-cemento en los morteros, lo que conduce a un mayor rendimiento.

The cerambycid insect Xylotrechus arvicola is considered a pest that affects the wood of the grapevine (Vitis vinifera) in the major wine areas of the Iberian Peninsula. The larva of this insect perforates the grapevine wood, resulting in structural and biomechanical failure of the vine plants. Vine samples from wood damaged by X. arvicola larvae were picked up from different vineyards and grape varieties. Compressive and flexural tests were performed in order to assess the mechanical behaviour of the wood samples. Total length of the cracks in wood samples (TLCWS) that appeared on the surface of the grapevine wood samples after the mechanical tests was measured. Compressive strength (CS) and flexural strength (FS) decreased with the increase of the cross-sectional area (CSA) of both branches and trunks, regardless of damage condition or water content. Moreover, the resistance was lower in damaged wood. In addition, this was verified through the linear regression coefficients of the interaction CS x CSA and FS x CSA. TLCWS in branches and trunks of damaged samples was greater that in undamaged samples. Also, TLCWS within the same damage condition and part of the plant was higher in dry samples than in fresh samples. The damaged wood would show a higher vulnerability to common mechanical stress suffered by the grapevines in the field including heavy winds, fruit overweight or harvesting machines shaking (when mechanically collected). Larvae of this insect altered the mechanical behaviour of the trunk and branches of grapevine wood. The mechanical strength of wood was more negatively affected when the CSA of the branches and trunks increased. Longer TLCWS was found in affected wood., El insecto cerambícido Xylotrechus arvicola se considera una plaga que afecta a la madera de la vid ( Vitis vinifera ) en las principales zonas vitivinícolas de la Península Ibérica. La larva de este insecto perfora la madera de la vid, provocando el fallo estructural y biomecánico de las plantas de vid. Muestras de vid de madera dañada por X. arvicolalas larvas se recogieron de diferentes viñedos y variedades de uva. Se realizaron ensayos de compresión y flexión con el fin de evaluar el comportamiento mecánico de las muestras de madera. Se midió la longitud total de las grietas en muestras de madera (TLCWS) que aparecieron en la superficie de las muestras de madera de vid después de las pruebas mecánicas. La resistencia a la compresión (CS) y la resistencia a la flexión (FS) disminuyeron con el aumento del área de la sección transversal (CSA) de las ramas y los troncos, independientemente de la condición de daño o el contenido de agua. Además, la resistencia fue menor en la madera dañada. Además, esto se verificó a través de los coeficientes de regresión lineal de la interacción CS x CSA y FS x CSA. TLCWS en ramas y troncos de muestras dañadas fue mayor que en muestras no dañadas. También, TLCWS dentro de la misma condición de daño y parte de la planta fue mayor en muestras secas que en muestras frescas. La madera dañada mostraría una mayor vulnerabilidad a los esfuerzos mecánicos comunes que sufren las vides en el campo, incluidos los fuertes vientos, el sobrepeso de la fruta o las sacudidas de las máquinas de cosecha (cuando se recolectan mecánicamente). Las larvas de este insecto alteraron el comportamiento mecánico del tronco y las ramas de la madera de vid. La resistencia mecánica de la madera se vio más afectada negativamente cuando aumentó la CSA de las ramas y troncos. Se encontró TLCWS más largo en la madera afectada. Las larvas de este insecto alteraron el comportamiento mecánico del tronco y las ramas de la madera de vid. La resistencia mecánica de la ma

Waste glass (WG), as a nonbiodegradable material, poses a threat to environmental protection. The reuse of WG as a raw material to replace cement or aggregate in concrete production is gaining attention for recycling purposes. However, the optimal proportion of WG in concrete mixtures and its particle size distribution are hard to determine. Large glass particles are prone to leading to the undesirable alkali–silica reaction (ASR) in concrete. Therefore, in this study, cement and aggregate in concrete mixtures are partially replaced by combinations of glass powder (<30 m) and glass beads (0.2–1.7 mm), respectively. Glass concretes (GCs) containing waste glass at various replacement ratios (0, 10, 15, 20, and 30%) are prepared, and their flowability and compressive strength are evaluated and compared. Finally, steel tubes filled by ordinary concrete (OCFSTs) and steel tubes filled by glass concrete (GCFSTs) are fabricated and tested in axial compression. The test results show that the slump and slump flow increase when the replacement ratio is lower than 20%, and the maximum slump value (250 mm) is achieved for concrete with the use of 20% waste glass. With regard to compressive strength, as the glass replacement percentage is increased, the compressive strength of GC continues to reduce. The maximum decrease of compressive strength (merely 70% of compressive strength for original concrete) is observed in GC mixed with 20% glass, which might be attributed to the smooth surface of glass, consequently weakening the interfacial bond strength between the glass and matrix. In terms of the bearing capacity of GCFSTs, the axial compressive strength of GCFSTs decreases as more GC is used. However, no obvious reduction is observed compared to OCFSTs (less than 10% for GCFSTs containing 30% GP). Moreover, GCFSTs show greater (no less than 25% more) deformational ability at peak strength over OCFST columns, demonstrating that GC is a promising alternative for normal concrete, Concrete Structures

Microwave radiation is widely utilized in construction practice, especially for drying building materials, remediating damp masonry, or sterilization of biotic pests that have infested building structures. The available scientific and technical literature reports that certain materials exposed to microwave radiation do not change their physical and mechanical properties, although this has not yet been adequately verified. This paper builds on many years of research in the area, adding to and refining existing information, providing new insights into the mechanical and physical properties of commonly available building materials that have been exposed to controlled microwave radiation, and comparing them with reference values. The experimental research on a set of clay brick samples is carried out using tests according to European standards, and it focuses on the effect of microwave radiation on compressive strength and water absorption. The experimental samples were compared to reference samples that had not been subjected to prolonged exposure to moisture and were subsequently treated with microwave radiation for dehumidification.

Microwave radiation is widely utilized in construction practice, especially for drying building materials, remediating damp masonry, or sterilization of biotic pests that have infested building structures. The available scientific and technical literature reports that certain materials exposed to microwave radiation do not change their physical and mechanical properties, although this has not yet been adequately verified. This paper builds on many years of research in the area, adding to and refining existing information, providing new insights into the mechanical and physical properties of commonly available building materials that have been exposed to controlled microwave radiation, and comparing them with reference values. The experimental research on a set of clay brick samples is carried out using tests according to European standards, and it focuses on the effect of microwave radiation on compressive strength and water absorption. The experimental samples were compared to reference samples that had not been subjected to prolonged exposure to moisture and were subsequently treated with microwave radiation for dehumidification.

This study addresses the evaluation of the confinement effect in the experimental determination of compressive strength in solid fired clay units. The experimental campaign has focused on two different types of solid fired clay bricks, namely mechanically extruded and handmade, with a total amount of 458 specimens. The research considers different standard specimens, such as whole or half brick, and 100 × 100 × 40 mm3 specimen, and nonstandard 40 × 40 × 40 mm3 specimen, subjected to different standard bearing surface treatments, i.e. grinding, capping with cement mortar or gypsum plaster, placing with birch plywood or fibreboard. Additionally, two novel bearing surface treatments are proposed, i.e. covering with gypsum powder, and placing two oiled PTFE leaves. The experimental campaign has focused on four main aspects. First, the evaluation of the compressive strength value in specimens with hardening response. Second, the influence of the cross section’s aspect ratio, defined as the ratio between the specimen’s length and width. Third, the influence of the bearing surface treatment on the determination of the compressive strength. Fourth, the evaluation of the standard compressive strength through the comparison amongst reference standards. The results highlight and quantify the different factors that influence the confinement, while detecting differences depending on the manufacturing process of the unit. In addition, the results reveal the use of oiled PTFE leaves as a promising and fast possibility of low boundary friction to obtain the strength regardless of the specimen shape., The authors gratefully acknowledge the financial support from the Ministry of Science, Innovation and Universities of the Spanish Government (MCIU), the State Agency of Research (AEI) as well as that of the ERDF (European Regional Development Fund) through the project SEVERUS (Multilevel evaluation of seismic vulnerability and risk mitigation of masonry buildings in resilient historical urban centres, ref. Num. RTI2018-099589-B-I00). Support from MCIU through a predoctoral grant awarded to the first author is also gratefully acknowledged., Peer Reviewed, Postprint (published version)

The increase of population results in more housing buildings and infrastructure, which increases the need for stable concrete structures that can safely accommodate people. In countries like Sweden, where temperatures are below zero for several months a year, housing construction cannot come to a halt. If a concrete structure is exposed to low temperatures, the phenomenon of early freezing can occur. This can damage the structure when forms are removed. To ensure that forms can be removed at the right time without causing damage, various methods have been developed by the industry, such as the prediction tool HETT 22. This program uses mathematical models to estimate when a safe form removal can be performed, considering factors such as concrete composition and surrounding conditions during casting and curing. A comparative study was conducted between obtained measurement data from two different building projects and simulations in the software. The results of wall simulations with HETT 22 were positive and show that the program can predict with good accuracy when the removal of formwork can be performed. However, the results from the floor slab simulations were indeterminate due to lack of documentation of infrared heating, making it difficult to draw a suitable conclusion about HETT 22:s capacity for floor slab simulations.

Microwave radiation is widely utilized in construction practice, especially for drying building materials, remediating damp masonry, or sterilization of biotic pests that have infested building structures. The available scientific and technical literature reports that certain materials exposed to microwave radiation do not change their physical and mechanical properties, although this has not yet been adequately verified. This paper builds on many years of research in the area, adding to and refining existing information, providing new insights into the mechanical and physical properties of commonly available building materials that have been exposed to controlled microwave radiation, and comparing them with reference values. The experimental research on a set of clay brick samples is carried out using tests according to European standards, and it focuses on the effect of microwave radiation on compressive strength and water absorption. The experimental samples were compared to reference samples that had not been subjected to prolonged exposure to moisture and were subsequently treated with microwave radiation for dehumidification.

This study determined how replacing sodium nitrate-based antifreeze admixture (AF) with belite-calcium sulfoaluminate (belite-CSA) cement affects the early age properties of ecological concretes based on ordinary Portland cement (OPC) and ground granulated blast-furnace slag (GGBFS). Concrete specimens were cured at −15 °C and treated in various ways before testing, i.e., no treatment, stored at 20 °C for 12 and 24 h. Generally, the addition of belite-CSA cement shortened the setting time due to the rapid formation of ettringite. The incorporation of 25 wt% of antifreeze admixture (AF) to the OPC-GGBFS concrete cured at −15 °C partially inhibited ice formation and enabled the continuation of hydration processes. This trend was observed for all samples, independent of the applied AF after freezing curing. On the contrary, the addition of 20 wt% of CSA failed to inhibit the ice formation and increased the risk of frost damage for concretes despite the treatment after freezing. These concrete specimens had lower hydration, lower strength, and a more porous binder matrix. The microstructure of the binder matrix was significantly affected by the amount of CSA and extreme negative curing, followed by no notable recovery post-curing at room temperature. Therefore, pre-curing at room temperature for at least 6 h has the potential to avoid frost damage. Concrete containing 25 wt% AF combined with 12 h and 24 h of curing at 20 °C after removal from freezing and prior to testing could enhance the compressive strengths of all concretes. The renewed hydration was indicated as the main influencing factor., Validerad;2023;Nivå 2;2023-09-25 (hanlid)

The thickness and properties of brash ice are usually compared with the properties of the surrounding level ice. The differences between these ice types are important to understand since the consolidated brash ice layer is typically assumed to have the same properties as level ice. Therefore, significant effort in the measurement campaign during the winters of 2020–2021, 2021–2022, and 2023 was made to develop a better understanding of the full-scale brash ice channel development. The channels were located near the shore in the Bay of Bothnia, Luleå, Sweden. The main parameters investigated were the snow, slush, and total ice thicknesses, including ice formed from freezing water and from freezing slush as well as the ice microstructure and strength. To our knowledge, this is the first paper to report the influence of snow in brash ice channels. It was observed that a significant amount of snow covered the brash ice channels between the ship passages. After each ship passage, the snow was submerged and formed slush-filled voids, which thereafter transformed into snow ice (SI) clusters frozen together with columnar ice. The SI content in the brash ice and side ridges was estimated from image analyses. The analyses showed that the snow ice content was 73% in level ice in the vicinity of the ship channel, 58% in the side ridges of the channel, and 21% in the middle of the test channel, whereas in the main channel, the SI contents were 54%, 43%, and 41% in each location, respectively., Validerad;2023;Nivå 2;2023-07-18 (sofila);Funder: TotalEnergies SE; Kolarctic CBC

The influence of waste glass powder (WGP) with fly ash in certain proportions on geopolymer concrete (GPC) was investigated by exchanging different proportions of molarity and WGP percentages in GPC. For this objective, fly ash was altered with WGP having percentages of 10%, 20%, 30%, and 40%, and the effect of molarity of sodium hydroxide (NaOH) was examined. The compressive strength tests, splitting tensile tests, and flexural strength tests were conducted. The workability and setting time were also evaluated. With the addition of WGP, the workability for molarities (M) of 11, 13, and 16 NaOH reduced by an average of 17%, 10%, and 67%, respectively. The findings showed that the slump values decreased as the molarity and WGP percentages increased. Molarity significantly affected the setting time, but WGP had no effect on the setting time. Although high molarity increased the capacity, this had a noticeable negative effect on the setting time and workability. This study demonstrated that WGP had a slight negative effect on the capacity and workability. Furthermore, when the combined effects of WGP and NaOH molarity were taken into account, the use of 10% WGP with M13 NaOH was recommended to obtain the optimum sustainable GPC considering both fresh and hardening properties. Scanning electron microscopy (SEM) analysis was done on the samples, too.

Plastic sand paver blocks (PSPB) provide a sustainable alternative by reprocessing plastic waste and decreasing reliance on environmentally hazardous materials such as concrete. They promote waste management and environmentally favorable building practices. This paper presents a novel method for estimating the compressive strength (CS) of plastic sand paver blocks based on gene expression programming (GEP) techniques. The database collected from the experimental work comprises 135 compressive strength results. Seven input parameters were involved in predicting the CS of PSPB, namely, plastic, sand, sand size, fiber percentage, fibre length, fibre diameter, and tensile strength of the fibre. Simplified mathematical expressions were used to figure out the CS. The results of GEP formulations showed that they were better in line with the experimental data, with R2 values for CS of 0.89 (training) and 0.88 (testing). The models' performance was evaluated using sensitivity analysis and statistical checks. The statistical evaluations show that the actual and predicted values are closer together, which lends credence to the GEP model's capacity to forecast PSPB CS. The sensitivity analysis showed that sand size and fibre percentage contribute more than 50% of the CS in PSPB. In addition, the results demonstrate that the proposed models are accurate and have a robust capacity for generalization and prediction. This research can improve environmental protection and economic benefit by enhancing the reuse of PSPB in producing green ecosystems., Validerad;2023;Nivå 2;2023-08-14 (joosat);Licens fulltext: CC BY LicenseFunder: Ministry of Higher Education of Malaysia and Universiti Teknologi Malaysia (FRGS grant 5F545); HiCoE research grant (4J224)

Plastic waste poses a significant hazard to the environment as a result of its high production rates, which endanger both the environment and its inhabitants. Similarly, another concern is the production of cement, which accounts for roughly 8% of global CO2 emissions. Thus, recycling plastic waste as a replacement for cementitious materials may be a more effective strategy for waste minimisation and cement elimination. Therefore, in this study, plastic waste (low-density polyethylene) is utilised in the production of plastic sand paver blocks without the use of cement. In addition to this, basalt fibers which is a green industrial material is also added in the production of eco-friendly plastic sand paver blocks to satisfy the standard of ASTM C902-15 of 20 N/mm2 for the light traffic. In order to make the paver blocks, the LDPE waste plastic was melted outside in the open air and then combined with sand. Variations were made to the ratio of LDPE to sand, the proportion of basalt fibers, and sand particle size. Paver blocks were evaluated for their compressive strength, water absorption, and at different temperatures. Including 0.5% percent basalt fiber of length 4 mm gives us the best result by enhancing compressive strength by 20.5% and decreasing water absorption by 50.5%. The best results were obtained with a ratio of 30:70 LDPE to sand, while the finest sand provides the greatest compressive strength. Moreover, the temperature effect was also studied from 0 to 60 °C, and the basalt fibers incorporated in plastic paver blocks showed only a 20% decrease in compressive strength at 60 °C. This research has produced eco-friendly paver blocks by removing cement and replacing it with plastic waste, which will benefit the environment, save money, reduce carbon dioxide emissions, and be suitable for low-traffic areas, all of which contribute to sustainable development., Validerad;2023;Nivå 2;2023-06-21 (hanlid);Funder: Ministry of Higher Education of Malaysia and Universiti Teknologi Malaysia (5F545, 4J224); Prince Sattam bin Abdulaziz University (PSAU/2023/R/1444)

High-strength concrete (HSC) is vulnerable to strength loss when exposed to high temperatures or fire, risking the structural integrity of buildings and critical infrastructures. Predicting the compressive strength of HSC under high temperature conditions is crucial for safety. Machine learning (ML) techniques have emerged as a powerful tool for predicting concrete properties. Accurate prediction of the compressive strength of HSC is important as HSC can experience strength losses of up to 80% after exposure to temperatures of 800°C–1000°C.This study evaluates the efficacy of ML techniques such as Extreme Gradient Boosting, Random Forest (RF), and Adaptive Boosting for predicting the compressive strength of HSC. The results of this study demonstrate that the RF model is the most efficient for predicting the compressive strength of HSC, exhibiting the R2 value of 0.98 and lower mean absolute error and root mean square error values than the other applied models. Furthermore, Shapley Additive Explanations analysis highlights temperature as the most significant factor influencing the compressive strength of HSC. This article provides valuable insights into the timely and effective determination of the compressive strength of HSC under high-temperature conditions, benefiting both the construction industry and academia. By leveraging ML techniques and considering the critical factors that influence the compressive strength of HSC, it is possible to optimize the design and construction process of HSC and enhance its resilience to high-temperature exposure.

Autogenous self-healing of post-fire damaged concrete enables structure performance auto-recovery leading to reduced repair costs, less generated waste, and lower CO2 emissions. In this paper, to improve the efficiency of this process and understand the underlying mechanism, the self-healing of 0.1 wt% MWCNT-modified and pure cement paste subjected to novel environmental stimulators was tested. High-temperature damage was induced at 200 °C and 400 °C, followed by a self-healing cyclic treatment with water, a mixture of water with phosphate-based retarding admixture, and limewater. The self-healing efficiency of the proposed solutions were compared based on crack closure, strength regains, porosity, and chemical composition changes. The surface crack closure after 200 °C varied between 33% and 60%, whereas for 400 °C, only retarding admixture exposure obtained over 50% crack closure and the most considerable decrease in average crack width of 33% for MWCNT-modified paste. The highest values of compressive strength recovery, equal to 18% and 14%, exceeding the intact specimen's compressive strength, were observed for the MWCNT-modified paste healed in water and limewater. Water exposure with an extended wetting phase enhanced the compressive strength recovery of the MWCNT-modified materials. Strong (r = 0.87) and moderate (r = 0.52) positive correlations were observed between temperature loading and compressive and flexural strength recovery parameters, respectively. Higher porosity and interconnected crack network, caused by high temperature, facilitated the self-healing process. Porosity changes before and after healing were pronounced in contrast to the amount of unhydrated cement, which did not exhibit noticeable changes. The healing mechanism included three processes: calcite formation, further hydration inside the cracks, and rehydration of the bulk cement paste.Previous article in issue, Validerad;2023;Nivå 2;2023-05-10 (joosat);Licens fulltext: CC BY License

Detta examensarbete utvärderar ett absorptionshämmande tillsatsmedel för att möjliggöra användningen av krävande ballast vid betongtillverkning. Den huvudsakliga anledningen till att ballasten benämns som krävande är att den har ovanligt hög absorptionsförmåga. Studien undersöker hur betongens egenskaper påverkas av olika halter absorptionshämmare. Dels studerades glimmerrikt bergkrossmaterial, som på grund av sin höga halt glimmermineral har en hög vattenabsorption vilket försämrar betongens arbetbarhet. För att minska transportavstånd och därmed klimatpåverkan är det viktigt att kunna använda närliggande täkter, även om bergmaterialet innehåller glimmermineral. Utöver glimmerkrossen studerades även återvunnen betong som ballast. Återvunnen betong har också en hög vattenabsorption vilket är en av de största utmaningarna för att kunna använda det som ballastmaterial. Då betong sällan hanteras cirkulärt i byggprocessen utan ofta läggs på deponi är den återvunna betongen som ballast en intressant tillämpning för att öka den cirkulära användningen. Den största delen av arbetet bestod av en laborativ del där den färska betongens egenskaper, såsom sättmått och värmeutveckling, och den hårdnade betongens egenskaper, såsom tryckhållfasthet, utvärderades hos betongen med krävande ballastmaterial och olika halt absorptionshämmare. För den glimmerrika bergkrossen varierades även vattencementtalet, och för återvunnen betong varierades halt återvunnen betong medan vattencementtalet var konstant. En del av arbetet bestod av en teoridel där standarder och krav kring användning av återvunnen betong som ballast utreddes. Resultatet från studien visade generellt att absorptionshämmaren förbättrar arbetbarheten hos betongen. Dock gav absorptionshämmaren en svagt retarderande effekt på hårdnandet, vilket syntes både i kalorimetrimätningarna av värmeutveckling och i tryckhållfastheten efter 24 tim-mar. Efter 28 dygn fanns inga tecken på retardation från absorptionshämmare. Gällande sta, This master thesis evaluates an absorption-inhibiting admixture to enable the use of demanding aggregate materials in concrete production. This was achieved by investigating how the properties of concrete were affected by different levels of absorption inhibitor. Firstly, mica-rich aggre-gate material was studied, which, due to its high mica mineral content, has a high water absorption rate that impairs the workability of concrete. In some locations, aggregates need to be transported over long distances. To reduce environmental impact and transportation costs, it is desirable to be able to use nearby quarries, even if the rock material contains mica minerals. In addition to mica aggregate, recycled concrete was also studied as an aggregate. Recycled concrete also has high water absorption, which is one of the biggest challenges in using it as an aggregate material. Since concrete is rarely handled in a circular manner in the construction process and is often disposed of in landfills, using recycled concrete as aggregate is an interesting application to increase its circular utilization. Most of the work in this project consisted of a laboratory part where fresh properties such as slump and heat development, as well as hardened properties such as compressive strength, were evaluated for concrete with demanding aggregate materials and different concentrations of the absorption inhibitor. For the mica-rich rock aggregate, the water-cement-ratio was varied along with the concentration of the absorption inhibitor. For recycled concrete, the concentration of both the absorption inhibitor and the recycled concrete itself were varied while keeping other variables constant. A theoretical part of the work focused on investigating Swedish standards and requirements related to the use of recycled concrete as aggregates. The results of the study generally showed that the absorption inhibitor improved the workability of concrete. However, the absorption inhibitor had a slightly r, Denna studie visar att användningen av återvunnen betong och krossat berg med vattenuppsugande egenskaper kan öka i betongtillverkningen om dessa behandlas med ett medel som förhindrar vattenuppsugningen. Detta är fördelaktigt då mindre betong behöver läggas på deponi och transportutsläppen kommer minska då fler täkter med krossat berg kan användas. Betongindustrin står för ett flertal utmaningar i och med att kraven på minskade utsläpp skärps för att uppnå klimatmålen. Betong tillverkas idag av cement, vatten och stenmaterial, som också kallas ballast. Minskningen av cementproduktionens stora utsläpp är på god väg med metoder som koldioxidinfångning och ersättning av en del av cementet med mer klimatvänliga alternativ. Ballasten, som både återvunnen betong och krossat berg kan användas som, har länge bortprioriterats men blir nu allt viktigare att hantera ur klimatsynpunkt. I Sverige är betonghus vanliga, och när dessa hus ska rivas hamnar betongen oftast på tippen. Ibland blir betong också över från gjutningar. Sådan betong hälls ut för att stelna och användningen av den är begränsad. Helt enkelt finns mycket betong utan användningsområde. Genom att ersätta en del av stenmaterialet i betong med återvunnen betong ökar den cirkulära användningen av betongen vilket ligger i linje med klimatmålen. Svårigheten med materialet är dock att det absorberar mycket fukt vilket ger en trög betong. Oftast används krossad sten som ballast i betong. Beroende på varifrån stenmaterialet kommer har det olika innehåll. På vissa ställen innehåller berget mineralet glimmer som gör att stenmaterialet suger upp mycket vatten. Om användning av berg som innehåller glimmer kan möjliggöras innebär det att transportutsläppen för ballast kan minska då fler bergtäkter kan användas. Detta är viktigt då det är stora volymer stenmaterial som krävs i betongen, och därför stora lass som transporteras. I studien har betong gjutits dels med krossat berg med glimmermineral, dels med återvunnen betong.

Portland cement (OPC) and steelmaking industries exhibit high pro- duction levels and are expected to continue in the near future. Their industrial processes are not considered environmentally friendly and are estimated to be responsible for 4–7% of worldwide CO2 emissions. To mitigate their negative externalities, they introduce several improvements in their processes. The steel- making industry generates a large volume of solid waste, mainly slags. Electric arc furnace slag (EAFS) and ladle furnace slag (LFS) shows exciting properties to be used as construction material. Currently, only EAFS is valorized, mainly as a granular material for different pavement layers. Instead, LFS presents tech- nological barriers (low cementing activity and expansive problems) that prevent them from being valorized and finally deposited in landfills. This work explores a safe/high-value application for LFS as a supplementary cementitious material (SCM). Pastes/mortars were produced to study the effect of varying the LFS- content replacement. Chemical/mineralogical characterization of raw/hydrated samples and fresh/hardened state properties were tested at different ages to study the physical-mechanical performance and microstructure evolution. Our results suggest that LFS has good potential as SCM, modifying the fresh/hardened per- formance depending on LFS content: by decreasing workability, accelerating the setting time, and lowering the strength. Also, it increases the potential volumetric instability issues. The compressive strength gap decreases with time, reaching over 30 MPa for 25/50 wt% replacements at 28–98 days. Finally, the microstructure evolution shows a shift in the typical OPC hydration reactions, producing higher AFm-AFt products due to the higher calcium-aluminates reactive phases in the slag., Peer Reviewed, Postprint (published version)

The growth of cities and industrialization has led to an increase in demand for concrete, resulting in resource depletion and environmental issues. Sustainable alternatives such as using recycled concrete aggregate (RCA) and industrial waste have been proposed to meet construction material demands while adhering to building codes and promoting sustainability. However, compressive strength (CS) is a crucial property of concrete, and the design parameters have different effects on CS for various grades. Recently, researchers have focused on partially replacing natural coarse aggregate (NCA) with RCA in concrete to achieve sustainability goals. This study aims to examine the influence of design parameters (w/c: water-cement ratio, w/b: water-binder ratio, A/c: total aggregate-cement ratio, FA/CA: fine-coarse aggregate ratio, SP: superplasticizer, w/s: water-solid ratio and RCA%) on concrete CS and address controversies in the insights gained from pairwise comparisons using Pearson's correlation coefficient (PCC) analysis. Additionally, five techniques (M5P, RF, SVM, LR, and ANNs) were used to predict the CS of high-performance self-compacting concrete (HP-SCC) with RCA, and the results were compared with an ANNs-based model as was the commonly used one in literature. The approaches were assessed based on their accuracy measured using correlation coefficient (CC), mean absolute error (MAE), Root Mean Square Error (RMSE), Mean absolute percentage error (MAPE), Scatter index (SI), and comprehensive measure (COM) indicators. Accordingly, the analysis indicated that SVM-PUK-based model is the most appropriate and effective technique to predict the CS of HP-SCC for the given datasets, with CC = 0.894, 0.900, MAE = 1.721, 3.813, RMSE = 5.137, 6.306, and MAPE = 4.5%, 7.6% for the training and testing stages, respectively. The uncertainty analysis results were 21%, 20.7%, 19%, 22%, and 19% for M5P, RF, SVM, LR, and ANN-based models, respectively, whereby all of them were under, QC 20230901

Betong är ett av världens mest använda byggnadsmaterial, men kan också vara en stor miljöbov. Cementklinker är en betydande beståndsdel i betong som vid tillverkning frigör stora mängder koldioxid, av den anledningen optimeras betongrecept idag genom att ersätta en del av cementen med flygaska som är en restprodukt från kolkraftsindustrin. I takt med att samhället rör sig mot en fossilfri produktion beräknas tillgången till flygaska att avta och material med liknande egenskaper undersöks som alternativa bindemedel i betong. Syftet med studien är att, genom litteraturstudier och laboratoriska tester, undersöka huruvida naturliga puzzolaner kan ersätta mängden flygaska i en cementsammansättning utan att försämra betongens hållfasthetsegenskaper. Tryckhållfastheten samt hållfasthetsutvecklingen har undersökts hos 150x150x150 mm provkuber med varierande mängd flygaska samt vulkanaska av isländsk pimpsten respektive jordanska tuffer. Målet med studien är att minska mängden, eller helst ersätta hela andelen flygaska i en klimatförbättrad betongsammansättning. De laboratoriska testerna har utförts enligt svensk standard där totalt 48 provkroppar gjutits. Referenskuben i undersökningen består av 80% portlandkalkstencement och 20% flygaska. Totalt har 6 olika kombinationer av provkuber gjutits där andelen flygaska ersätts med 20%, 15% eller 10% vulkanaska. Vardera provkub har utsatts för tryckhållfasthetsmätning efter 2, 7 samt 28 dygn. Resultatet av provtryckningen visade att provkuberna innehållande isländsk pimpsten gav en ökad eller oförändrad hållfasthet vid samtliga mätningar, jämfört med referenskuben. Provkuberna innehållande jordanska tuffer medförde däremot en reducering av hållfastheten vid samtliga mätningar, jämfört med referenskuben. Provkuberna innehållande vulkanaska från isländsk pimpsten gav högst sluthållfasthet då ingen flygaska förekom i sammansättningen och något sämre värden vid inblandning av flygaska, till skillnad från provkuberna innehållande vu, Concrete is one of the most widely used building materials in the world, but it can also be a major environmental culprit. Cement clinker is a significant component of concrete that releases large amounts of carbon dioxide during production. For this reason, concrete recipes are now optimized by replacing some of the cement with fly ash, which is a byproduct from the coal power industry. As society moves towards fossil-free production, the availability of fly ash is expected to decrease, and materials with similar properties are being investigated as alternative binders in concrete. The purpose of the study is to investigate, through literature review and laboratory tests, whether natural pozzolans can replace the amount of fly ash in a cement composition without deteriorating the strength properties of the concrete. The compressive strength and strength development have been studied on 150x150x150 mm test cubes with varying amounts of fly ash and volcanic ash from Icelandic pumice and Jordanian tuffs. The goal of the study is to reduce the amount, or preferably replace the entire portion, of fly ash in a climate-improved concrete composition. The laboratory tests have been performed according to Swedish standards, where a total of 48 test specimens have been cast. The reference cube in the study consists of 80% Portland limestone cement and 20% fly ash. A total of 6 different combinations of test cubes have been cast, where the proportion of fly ash is replaced with 20%, 15%, or 10% volcanic ash. Each test cube has been subjected to compressive strength measurement after 2, 7, and 28 days. The results of the compression testing showed that the test cubes containing Icelandic pumice provided increased or unchanged strength at all measurements, compared to the reference cube. However, the test cubes containing Jordanian tuffs resulted in a reduction of strength at all measurements, compared to the reference cube. The test cubes containing volcanic ash from Icelandic

The high consumption of Portland cement (OPC) has a significant impact on the environment due to the generation of greenhouse gases and the use of non-renewable raw materials during its manufacturing. Therefore, the search for alternative materials to reduce cement consumption is crucial in the pursuit of sustainability. For this reason, copper slag (CS) as a supplementary cementitious material (SCM) in the production of mortars with lower OPC content is an option to create a sustainable environment. This study investigated the influence of CS on workability, compressive strength, and flexural strength at different curing ages. Mortars were prepared with 0%, 10%, 20%, 30%, 40%, and 50% CS as partial replacement for OPC, where mortars with CS demonstrated increased flowability. The mechanical properties were monotonically affected during the initial evaluated ages (7, 28, and 90 days), with mortars containing higher CS content showing the greatest loss of strength. However, at 150 days of curing, the 10% CS mixture exhibited a compressive strength of 43.6 MPa, which was 7.6% higher than the reference mixture., La demanda de cemento Portland (OPC) impacta de gran manera el medio ambiente, debido a la generación de gases de efecto invernadero y el consumo de materias primas no renovables durante su fabricación. Por tal razón, la búsqueda de materiales alternativos para disminuir el consumo de cemento es vital en la búsqueda de la sustentabilidad. Por esta razón, la escoria de cobre (EC) como materia cementicio suplementario (SCM) en la elaboración de morteros con menor contenido de OPC es una opción para generar un ambiente sostenible. Este estudio, investigo la influencia de la EC frente a la trabajabilidad, resistencia a la compresión y resistencia a la flexión a diferentes edades de curado. Morteros con 0%, 10%, 20%, 30%, 40% y 50% de EC como reemplazo parcial de OPC se elaboraron, donde se evidencio una mayor fluidez en los morteros con EC. Las propiedades mecánicas, se vieron afectas de manera monotónica en las primeras edades evaluadas (7, 28 y 90 días), donde los morteros con mayor contenido de EC presentaron la mayor perdida de resistencia. Sin embargo, a los 150 días de curado, la mezcla 10% EC presento una resistencia a la compresión de 43,6 MPa, 7,6% mayor que la mezcla de referencia.