Numerıcal Modelıng And Experımental Evaluatıon Of Shrınkage Of Concretes Incorporatıng Fly Ash And Sılıca Fume

Rötre genellikle sertleşmiş betonun önemli bir özelliği olarak ele alınır. Kuruma sürecinde boşluk yapısında bulunan serbest ve emilmiş su kaybedilir. Betonun rötresi kısıtlandığı zaman betonda olşan gerilmelere bağlı olarak çatlak oluşumu gözlenir. Bu çatlaklardan zararlı maddelerin geçmesiyle betonun dayanım ve dayanıklılıgında azalma olur. Bu çalışman ilk aşamasinda genetik programlama ve yapay sinir ağları yöntemleri kullanılarak rötre tahmin modelleri geliştirilmiştir. Modellerin eğitimi ve test edilmesi için literatürden veri toplanmıştır. Çalışmanın ikinci aşamasında ise uçucu kül ve silis dumanı içeren betonlar hazırlanarak kırk günlük kuruma sürecinde rötreleri ölçülmüştür. En yüksek rötre değerleri en çok mineral katkı içeren betonlarda gözlenmiştir. Bunların yanı sıra deneysel çalışmada elde edilen sonuçlar tahmin modellerinin verdikleriyle karşılaştırılmışlardır. YSA ile elde edilen değerlerin GP ile elde edilenlere göre gerçeğe daha yakın oldukları görülmüştür

Stability risk assessment of slopes using logistic model tree based on updated case histories

A new logistic model tree (LMT) model is developed to predict slope stability status based on an updated database including 627 slope stability cases with input parameters of unit weight, cohesion, angle of internal friction, slope angle, slope height and pore pressure ratio. The performance of the LMT model was assessed using statistical metrics, including accuracy (Acc), Matthews correlation coefficient (Mcc), area under the receiver operating characteristic curve (AUC) and F-score. The analysis of the Acc together with Mcc, AUC and F-score values for the slope stability suggests that the proposed LMT achieved better prediction results (Acc = 85.6%, Mcc = 0.713, AUC = 0.907, F-score for stable state = 0.967 and F-score for failed state = 0.923) as compared to other methods previously employed in the literature. Two case studies with ten slope stability events were used to verify the proposed LMT. It was found that the prediction results are completely consistent with the actual situation at the site. Finally, risk analysis was carried out, and the result also agrees with the actual conditions. Such probability results can be incorporated into risk analysis with the corresponding failure cost assessment later

Explicit formulation of drying and autogenous shrinkage of concretes with binary and ternary blends of silica fume and fly ash

Shrinkage is generally considered as an important durability property of hardened concrete. During the drying process, free and absorbed water is lost from the concrete. When the drying shrinkage is restrained, cracks can occur depending on the internal stresses in the concrete. The ingress of deleterious materials through these cracks can cause decrease in the compressive strength and the durability of concrete. In the first stage of the study, a prediction model through the most popular soft computing method called neural network (NN) was derived. The data set used for training and testing of the prediction model covers the experimental data presented in the literature. In the second stage of the study, the findings of an experimental study on drying shrinkage behavior of concretes incorporated with silica fume (SF) and fly ash (FA) were reported. Free shrinkage strain measurements as well as corresponding weight loss were measured over 40 days of drying. The obtained experimental results were also used for the validation of the proposed prediction models. The highest amount of mineral admixture resulted in high shrinkage strain development. Moreover, the proposed NN model also accurately predicted the values obtained from experimental study. (C) 2015 Elsevier Ltd. All rights reserved

Effect of slag on engineering properties of contamination soil

In this study investigates utilizing of slag as an additional material to improve engineering properties of contaminated soil by crude oil to changing the engineering characteristics to be satisfying and compatible, this is due to its pozzolanic reactivity. The aim of this study the impact of slag material in geotechnical engineering and to stabilize properties of contaminated soils. Two percentages of slag were utilized in this study, which is 0% and 6%. Compaction and direct shear strength tests had been conducted on the artificial contaminated prepared soil samples. In the results, showed that the increasing of slag leads to a decrease in the optimum water contents while the maximum dry density values increase. Furthermore, the shear strength is improved by utilizing slag so that slag can be considered as a stabilizing material to improve the properties of contamination soil. © 2020 Trans Tech Publications Ltd, Switzerland

Concrete made with partially substitution corn cob ash: A review

The idea of using agricultural and industrial waste materials in concrete helps to develop alternatives for protecting the environment, compensating for the shortage of environmental sources, and resolving the waste dumping issue. Environmental awareness about possible adverse effects has substantially expanded, and, consequently, recycling or utilizing agricultural and industrial waste by-products has become an increasingly desirable option for waste disposal. A review of corn cob ash (CCA) use in the construction industry is provided, and emerging trends in fresh properties, strength properties, durability characteristics, and microstructural properties are evaluated. The results show that adding CCA to concrete is advantageous for waste reduction and sustainable development. Furthermore, the optimum substitution of CCA is important. Although different researcher recommends different optimum substitution of CCA due to different source. However, the typical range of optimum substitution of CCA varies by 5–10% by weight of the binder. Therefore, the review recommends that CCA can be utilized in concrete for up to 10% without any harmful impact on concrete qualities. To close the possible research gap, a thorough investigation of the chemical composition of CCA from a different source and durability factors including alkali-silica reaction, shrinkage, and creep properties must be performed

Concrete Made with Iron Ore Tailings as a Fine Aggregate: A Step towards Sustainable Concrete

The need for low-cost raw materials is driven by the fact that iron ore tailings, a prevalent kind of hazardous solid waste, have created major environmental issues. Although many studies have focused on using iron ore tailing (IOT) in concrete and have reported positive results, readers may find it difficult to accurately assess the behaviors of IOT in concrete due to the scattered nature of the information. Therefore, a comprehensive assessment of IOT in concrete is necessary. This paper thoroughly reviews the characteristics of concrete that contains IOT such as fresh properties, mechanical properties and durability at different age of curing. The outcome of this review indicates that by using IOT, concrete’s mechanical properties and durability improved, but its flowability decreased. Compressive strength of concrete with 20% substitution of IOT is 14% more than reference concrete. Furthermore, up to 40% substitution of IOT produces concrete that has sufficient flowability and compactability. Scan electronic microscopy results indicate a weak interfacial transition zone (ITZ). The optimum IOT dosage is important since a greater dose may decrease the strength properties and durability owing to a lack of fluidity. Depending on the physical and chemical composition of IOT, the average value of optimum percentages ranges from 30 to 40%. The assessment also recommends areas of unsolved research for future investigations

Mechanical, Durability and Microstructure Analysis Overview of Concrete Made with Metakaolin (MTK)

Metakaolin (MTK) has received a lot of interest in the past two decades as a supplemental cementitious ingredient. MTK is actively being utilized in concrete and there is a large body of literature on the characteristics of concrete containing MTK. A rigorous evaluation of the use of MTK in concrete, however, is lacking, which is required to better know its (MTK) benefits, mechanisms, past and current progress. As a result, the objective of this study is to deliver an overview of MTK utilized in concrete. The physical and chemical characteristics of MTK, as well as the hydration, workability, mechanical qualities, hydration durability, and microstructure analysis of MTK-based concrete, are discussed. A comparison of the findings of diverse literature is presented, as well as some key recommendations. The findings suggest that adding MTK to concrete enhances certain characteristics, particularly mechanical capabilities, but decreases concrete flowability. Improvement in the durability of concrete with MTK was also observed but, for this, less information is available. For optimal performance, the right dosage is crucial. The typical ideal range is between 10 to 20% by weight of the binder. Further research gaps into the characteristics of concrete containing MTK are also recommended

Sustainable concrete with partial substitution of paper pulp ash: A review

The paper industry is one of the biggest sources of trash and stands out for its effects on both human health and ecological harmony. However, these waste could also help the building sector become more ecologically friendly. Beyond ecological considerations, modern construction often requires materials to make concrete durable, resisting heavy loads and less harmful environmental influences. This creates opportunities for waste management and practical application. This review provides a detail overview of eco-friendly construction ideas that deal with the practical use of materials that are often discarded (paper pulp ash). The impact they had on the characteristics of the construction material, the best mixture composition, and a discussion of the benefits and drawbacks of the “green” addition received the majority of the attention (paper pulp ash). The essential concrete properties such as consistency, setting time, flowability, compressive strength, flexural strength, tensile strength, and impact strength are reviewed. Furthermore, the cost benefits and environmental benefits of paper pulp ash as construction materials are also discussed. The study concludes by suggesting a line of inquiry for the creation of an environmentally friendly structural material for a sustainable future

A Review on Sustainable Concrete with the Partially Substitutions of Silica Fume as a Cementitious Material

Self-compacting concrete (SCC) uses a lot of natural resources, much like regular concrete, which results in unsustainable construction. Even though silica fume (SF) and other secondary cementitious materials are the subjects of a lot of studies, to determine the past, present, and future direction of research, information must first be reviewed. This paper compiles data on SSC with SF substations. Slump flow, slump T50, L-box, and V-funnel tests were used to investigate fresh SCC properties, such as filling and passing capabilities. Mechanical properties were examined using compressive, tensile, and flexure strength, while the durability characteristics of SCC were examined through water absorption, porosity, sorptivity, and chloride resistance. The internal structure of SCC, with and without SF, is reviewed through scan electronic microscopy (SEM). The results indicate that SF lacked the filling and passing ability of SCC, but is still within the limit defined by the technical specification for SCC. However, the study suggests a larger dosage of plasticizer for a higher dose of SF. Improvements in SCC’s strength and durability were also seen; however, greater doses had a negative impact on these attributes due to an absence of flowability. Researchers recommended the ideal SF dosage ranges from 10 to 15% by volume of cement. The assessment also reveals research gaps that need to be addressed