El presente artículo de estudio analizó la resistencia al fuego del concreto con adición de cenizas de cascara de arroz (CCA) y bagazo de caña de azúcar (CBCA). Se adoptó un método experimental como diseño de investigación, que produjo setenta y dos probetas cilíndricas (72) y cincuenta y cuatro vigas (54), para ensayos a compresión y flexión respectivamente. Se utilizaron cenizas en porcentajes de 5% y 10% y además una combinación binaria de 5% y 5% de ambas cenizas como reemplazo parcial de cemento. Las muestras fueron ensayadas luego de 28 días de curado a temperaturas de 24 °C (ambiente), 300 °C y 500 °C, con una duración de 2h de exposición y luego de 24 horas de enfriamiento al aire libre. Los resultados muestran un aumento de resistencia promedio a la compresión y flexión de hasta un 95% y 25%, respectivamente, luego de ser expuestos a temperaturas elevadas con respecto a las muestras de control. / This study article analyzed the fire resistance of concrete with the addition of rice hull ash (CCA) and sugarcane bagasse (CBCA). An experimental method was adopted as the research design, which produced seventy-two cylindrical specimens (72) and fifty-four beams (54), for compression and bending tests respectively. Ashes were used in percentages of 5% and 10% and a binary combination of 5% and 5% of both ashes as a partial replacement for cement. The samples were tested after 28 days of curing at temperatures of 25 ° C (ambient), 300 ° C and 500 ° C, with a duration of 2 hours of exposure and after 24 hours of cooling in the open air. The results show an increase in average resistance to compression and flexion of up to 95% and 25%, respectively, after being exposed to high temperatures compared to the control samples. / Trabajo de investigación

En los últimos años existe una demanda cada vez más creciente de infraestructura; actualmente en el Perú el sector construcción ha ido en constante crecimiento; sin embargo, es uno de los más contaminantes debido a la fabricación del concreto y sus componentes, ya que la industria concretera es responsable de la extracción de recursos no renovables; siendo el concreto el material fundamental para los diferentes tipos de proyectos en vías de desarrollo. Frente a este entorno, se propone como alternativa sostenible el uso de residuos de demolición, es decir agregado grueso de concreto reciclado en reemplazo del agregado grueso natural; sin embargo, en investigaciones anteriores el reemplazo de este, presenta una disminución en la resistencia a la compresión y flexión de 10% - 25% y 23.7% respectivamente. Por esta razón, se seleccionó el vidrio triturado proveniente del reciclado de botellas incoloras, este es un material eco amigable y de características que contribuyen en la resistencia del concreto. En consecuencia, se propone el uso de estos agregados reciclados en reemplazo total y parcial del agregado grueso y fino respectivamente. Los resultados de estos ensayos indicaron un aumento en las propiedades mecanicas del concreto y el porcentaje óptimo de reemplazo de vidrio triturado es 20%, en donde se obtuvo un incremento de 12.33% en la Resistencia a la compresión, 17.19% en la Resistencia a la flexion y 1.98% en la Resistencia a la tracción. / In recent years there is an increasingly growing demand for infrastructure; Currently in Peru the construction sector has been in constant growth; However, it is one of the most polluting due to the manufacture of concrete and its components, since the concrete industry is responsible for the extraction of non-renewable resources; concrete being the fundamental material for the different types of projects under development. Faced with this environment, the use of demolition waste is proposed as a sustainable alternative, that is, coarse aggregate of recycled concrete to replace the natural coarse aggregate; However, in previous research, its replacement shows a decrease in compressive and flexural strength of 10% -25% and 23.7%, respectively. For this reason, the crushed glass from the recycling of colorless bottles was selected since it is an eco-friendly material and features that contribute to the strength of the concrete. Consequently, the use of these recycled aggregates is proposed in total and partial replacement of the coarse and fine aggregate respectively. The results of these tests indicated an increase in the mechanical properties of the concrete and the optimum percentage of replacement of crushed glass is 20%, where an increase of 12.33% in Compressive Strength, 17.19% in Resistance to Compression was obtained. flexion and 1.98% in tensile strength. / Tesis

<p>Developing a reliable in-situ non-destructive testing method to determine the strength of in-place concrete is critical because a fast-paced construction schedule exposes concrete pavement and/or structures undergoing substantial loading conditions, even at their early ages. Conventional destructive testing methods, such as compressive and flexural tests, are very time-consuming, which may cause construction delays or cost overruns. Moreover, the curing conditions of the tested cylindrical samples and the in-place concrete pavement/structures are quite different, which may result in different strength values. An NDT method that could directly correlate the mechanical properties of cementitious materials with the sensing results, regardless of the curing conditions, mix design, and size effect is needed for the in-situ application.</p><p>The piezoelectric sensor-based electromechanical impedance (EMI) technique has shown promise in addressing this challenge as it has been used to both monitor properties and detect damages on the concrete structure. Due to the direct and inverse effects of piezoelectric, this material can act as a sensor, actuator, and transducer. This research serves as a comprehensive study to investigate the feasibility and efficiency of using piezoelectric sensor-based EMI to evaluate the strength of newly poured concrete. To understand the fundamentals of this method and enhance the durability of the sensor for in-situ monitoring, this work started with sensor fabrication. It has studied two types of polymer coating on the effect of the durability of the sensor to make it practical to be used in the field.</p><p>The mortar and concrete samples with various mix designs were prepared to ascertain whether the results of the proposed sensing technique were affected by the different mixtures. The EMI measurement and compressive strength testing methods (ASTM C39, ASTM C109) were conducted in the laboratory. The experimental results of mortar samples with different water-to-cement ratios (W/C) and two types of cement (I and III) showed that the correlation coefficient (R²) is higher than 0.93 for all mixes. In the concrete experiments, the correlation coefficient between the EMI sensing index and compressive strength of all mixes is higher than 0.90. The empirical estimation function was established through a concrete slab experiment. Moreover, several trial implementations on highway construction projects (I-70, I-74, and I-465) were conducted to monitor the real-time strength development of concrete. The data processing method and the reliable index of EMI sensing were developed to establish the regression model to correlate the sensing results with the compressive strength of concrete. It has been found that the EMI sensing method and its related statistical index can effectively reflect the compressive strength gain of in-place concrete at different ages.</p><p>To further investigate the in-situ compressive strength of concrete for large-scale structures, we conducted a series of large concrete slabs with the dimension of 8 feet × 12 feet × 8 inches in depth was conducted at outdoor experiments field to simulate real-world conditions. Different types of compressive strength samples, including cast-in-place (CIP) cylinder (4” × 6”) – (ASTM C873), field molded cylinder (4” × 8”) – (ASTM C39), and core drilled sample (4” × 8”) – (ASTM C42) were prepared to compare the compressive strength of concrete. The environmental conditions, such as ambient temperatures and relative humidity, were also recorded. The in-situ EMI monitoring of concrete strength was also conducted. The testing ages in this study were started from 6 hours after the concrete cast was put in place to investigate the early age results and continued up to 365 days (one year) later for long-term monitoring. The results indicate that the strength of the CIP sample is higher than the 4” x 8” molded cylinder , and that core drilled concrete is weaker than the two aforementioned. The EMI results obtained from the slab are close to those obtained from CIP due to similar curing conditions. The EMI results collected from 4 × 8-inch cylinder samples are lower than slab and CIP, which aligns with the mechanical testing results and indicates that EMI could capture the strength gain of concrete over time.</p><p>The consequent database collected from the large slab tests was used to build a prediction model for concrete strength. The Artificial Neuron Network (ANN) was investigated and experimented with to optimize the prediction of performances. Then, a sensitivity analysis was conducted to discuss and understand the critical parameters to predict the mechanical properties of concrete using the ML model. A framework using Generative Adversarial Network (GAN) based on algorithms was then proposed to overcome real data usage restrictions. Two types of GAN algorithms were selected for the data synthesis in the research: Tabular Generative Adversarial Networks (TGAN) and Conditional Tabular Generative Adversarial Networks (CTGAN). The testing results suggested that the CTGAN-NN model shows improved testing performances and higher computational efficiency than the TGAN model. In conclusion, the AI-guided concrete strength sensing and prediction approaches developed in this dissertation will be a steppingstone towards accomplishing the reliable and intelligent assessment of in-situ concrete structures.</p><br>

This thesis deals with measurement of hardness and microhardness in relation to structure of homogeneous and heterogeneous materials. In the introduction basic theoretical background is commented, i.e. definitions, terminology, principles of measuring techniques for estimation of hardness, microhardness, tensile strength, compressive strength and bending strength. Follows a brief review of present research results focused on use of described principles in materials engineering. Then the experimental equipment and sample preparation is described. The crucial part of the thesis is summary of achieved results of original measurement and discussion of their relations to each other. Finally, the groundbreaking estimation is described, showing the correlation of chemical composition gradient and mechanical properties in interfacial zone of geopolymeric material.

A building industry is expanding branch all the time and it intervenes in the life of everyone. Aeroconcrete is very attractive and actual subject nowadays because economy is important point of view of production. This material finds a wide-spread use thanks to its specific properties. The good manipulation and great thermal insulating properties are secured by its porous structure. Furthermore, proper material selection provides a saving of power of house for every customer demands. Due to aeroconcrete's sufficient compressive strength it is useful for both constructions and internal walls. Fundamental and very important for final material properties is raw material composition of aeroconcrete. A relationship between composition of filler (quartz sand) and resultant properties of aeroconcrete is an objective of the thesis.

This thesis is focused on the study of the influence of crystalline ingredients XYPEX, on the rheology of fresh concrete and durability of hardened concrete. It examines the influence of crystalline additives on the rheology of cement pastes with different types of cement with different temperatures, increasing water tightness and gas tightness and compressive strength. Also assesses pore structure with different bridging cracks.

Thesis describes properties of HPC compared to concretes of normal and high strength. It further describes the input materials and the procedure for designing the composition of the mixture. It gives examples of already completed structures made of HPC. The experimental part describes the optimization of concrete mix and production of specimens. In the end results of testing the properties of the developed mixes from tests of dynamic and static modulus of elasticity, compressive strength and tensile strength by bending are described.

Compressive strength is one of the most monitored parameter of hardened concrete and it is usually determinated by destructive testing. Non-destructive testing applied on existing constructions uses regression analysis to estimate compressive strength. High variability of outputs and eventually failure of necessary requirements for using regression analysis complicate these methods. The aim of this thesis is to show posibility of using fuzzy clustering in this topic and to compare outputs with classic methods.

Byggbranschen utvecklas konstant, strävan efter att utveckla nya och effektivare material ärstor. Några av de viktigaste egenskaperna som byggsektorn eftersöker är hög hållfasthet, lågvärmekonduktivitet och låg miljöpåverkan.Isobetong är ett nyligen framtaget material. Det är en typ av skumbetong med egenskaper ochfunktioner som skiljer sig från traditionell skumbetong ur hänseende på hållfasthet,värmekonduktivitet och miljöpåverkan.Syftet med denna undersökning är att identifiera Isobetongens karakteristiska egenskaper ochjämföra de med egenskaper av konkurrerande material. Resultatet föreslås tydliggöramaterialets styrkor och vidare utgöra en grund för fortsatt undersökning samt främja enutökad användning. De frågor vilket undersökningen formas kring är ’Vad har materialet förmiljöpåverkan?’ och ’Hur jämför sig materialet mot mineralull och cellplast gällande funktionoch miljöpåverkan?’.Resultatet visar att miljöpåverkan av materialet Isobetong varierar från 65,5 kg CO2-ekvivalenter per kubikmeter för dess produkt med lägst densitet, upp till 230,7 kg CO2-ekvivalenter per kubikmeter för produkten med högst densitet. Beräkningarna som utförts ijämförande syfte tyder på att Isobetong i genomsnitt inte är likställd med cellplast ellermineralull inom områdena för densitet, värmekonduktivitet och miljöpåverkan. Resultatet förtryckhållfastheten av Isobetong ger ett betydligt högre värde än de övriga materialen.Slutsatsen är att relativt mot de jämförda materialen kan inte Isobetong konkurrera med varesig cellplast- eller mineralullsisoleringar då högre krav ställs på densitet, värmekonduktivitetoch miljöpåverkan. I projekt där en god tryckhållfasthet krävs har Isobetong en klar fördel. / The construction industry is continuously developing, the strive to develop new and moreefficient materials is great. In the industry, some of the most sought for properties of theimproved materials are high strength, low thermal conductivity, and low environmentalimpact.Isobetong is a recently developed material. It is a variety of foam concrete with properties thatdiffer from traditional foam concrete regarding strength, thermal conductivity, andenvironmental impact.The purpose of this analysis is to identify characteristic properties of Isobetong and tocompare them to the properties of competitive materials. The results are proposed to clarifythe material’s strengths and to furthermore act as a foundation for continued research as wellas encouraging an increased usage. The questions the analysis is based on are ‘What is theenvironmental impact of the material?’ and ‘How does the material compare to mineral wooland polystyrene?’.The result displays an environmental impact of the material Isobetong to vary between 65,5kg CO2-equivalents per cubic meter for the product with the lowest density, up to 230,7 kgCO2-equivalents per cubic meter for the product with the highest density. The computationsthat have been completed for comparative purposes indicates that Isobetong on average is notequal to polystyrene or mineral wool in areas of density, thermal conductivity, orenvironmental impact. The result for the compressive strength of Isobetong yield aconsiderably higher value than the other materials.The conclusion is that relative to the compared materials is Isobetong unable to compete withneither polystyrene or mineral wool insulations when higher requirements are set for density,thermal conductivity, and environmental impact. For projects that require a notablecompressive strength does Isobetong show a clear advantage.

In dieser Arbeit wurden das feldaktivierte Sinterverhalten sowie das geschwindigkeitsabhängige Druckfestigkeitsverhalten von WC-Co-Hartstoffen mit variierenden Bindergehalten untersucht. Dazu wurde eine Herstellungsroute für kornwachstumshemmerfreie near-nanokristalline WC-Co-Hartstoffe mit der Field Assisted Sintering Technique (FAST) entwickelt und genutzt, um Materialien mit Co-Gehalten von 2 bis 12 Ma.-% zu erzeugen. Gezielte Werkstoffzustände und Probengeometrien sind durch Anpassung des Sinterprozesses herstellbar. Ausgewählte WC-Co-Materialien mit Co-Anteilen von 6 bis 12 Ma.-% wurden unter Einfluss von Beanspruchungsgeschwindigkeit, Spannungszustand und Beanspruchungshäufigkeit hinsichtlich der Druckfestigkeit und des Versagensverhaltens charakterisiert.