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This document is a compilation of research articles that focus on sustainable construction materials and techniques. The articles cover a range of topics, including the use of blast furnace slag in geopolymer concrete, the effects of nanosilica on the strength and durability of fly ash aggregate concrete, and the durability of alkali-activated slag concrete in a hydrochloric acid environment. Other articles explore plant-based cementitious composites, the potential use of water treatment sludge in fired clay bricks, and the use of waste tires in concrete columns. The document also includes research on the impact of fracture-seepage-stress coupling on the sustainability and durability of concrete, the relationship between concrete strength and resistance against carbonation-induced corrosion, and the numerical modeling and design of reinforced Polyvinyl-Alcohol-engineered cementitious composite beams. These articles provide valuable insights into the development of environmentally friendly construction materials and techniques. [Extracted from the article]

The traditional production process of clay bricks involves the extraction of significant amounts of raw materials and consumes considerable energy, leading to anthropogenic greenhouse gas emissions and environmental degradation. Using environmentally friendly materials in the construction industry has become an attractive alternative for mitigating sustainability issues. One such alternative is incorporating waste materials, such as water treatment sludge (WTS), into clay brick production. This research aims to assess the viability of using WTS as a replacement for conventional clay in fired clay brick production, thereby mitigating environmental pollution. Five distinct mixtures were created, with WTS replacing clay at 0, 20, 40, 60, and 80% ratios. The mechanical properties and durability of the produced bricks were analyzed through various tests, such as Atterberg limits, optimum water content, unconfined compression, apparent porosity, compressive strength, flexural strength, density, water absorption, and efflorescence. The results demonstrated that as WTS content increased, Atterberg limits and apparent porosity increased. The bulk density, compressive strength, and bending capacity of the specimens were found to decrease as the WTS replacement ratio increased. Additionally, moderate efflorescence was observed in samples with higher sludge ratios. [ABSTRACT FROM AUTHOR]

Rebar corrosion and its consequences are one of the most common damages to reinforced concrete (RC) structures. In structures with greater sensitivity, such as prestressed reinforced concrete (PRC) structures, where steel elements, including prestressed tendons, play a more significant role in supporting the structure, the importance of this issue increases. Methods for repairing and reinforcing such structures have been developed, including incorporating fibers into the concrete mixture to improve its mechanical properties, particularly its bending resistance. This paper presents the results of an experiment that studied the influence of steel fibers on the flexural behavior of PRC beams subjected to accelerated corrosion. Twelve beams with a rectangular cross-section of 150 mm × 300 mm and a length of 2000 mm were fabricated. The steel fibers used in the experiment were corrugated and hooked-end types, with volume fractions of 0.5% and 1.0% in the concrete. Nine beams were subjected to accelerated corrosion testing, with three of them being without fibers and the remaining six being reinforced with steel fibers at volume fractions of 0.5% and 1.0%. Each group of three beams was exposed to three different levels of corrosion, namely 5%, 10%, and 15%. The specimens were tested after exposure to corrosion through a four-point bending load. The accelerated corrosion was induced using an electric current on the prestressing tendons. The results indicated that different levels of corrosion reduced the final bearing capacity and other behavioral characteristics of the specimen, including the amount of energy absorption, effective hardness, and midspan displacement. Adding fibers to the concrete mixture positively affects the compensation of these reduced capacities. Moreover, the amount of this compensation was directly correlated with the volume fraction of used fibers. [ABSTRACT FROM AUTHOR]

Using recycled aggregate in concrete is one of the best ways to reduce construction pollution and prevent the exploitation of natural resources to provide the needed aggregate. However, recycled aggregates affect the mechanical properties of concrete, but the existing information on the subject is less than what the industry needs. Compressive strength, on the other hand, is the most important mechanical property of concrete. Therefore, having predictive models to provide the required information can be helpful to convince the industry to increase the use of recycled aggregate in concrete. In this research, three different optimization algorithms including genetic algorithm (GA), salp swarm algorithm (SSA), and grasshopper optimization algorithm (GOA) are employed to be hybridized with artificial neural network (ANN) separately to predict the compressive strength of concrete containing recycled aggregate, and a M5P tree model is used to test the efficiency of the ANNs. The results of this study show the superior efficiency of the modified ANN with SSA when compared to other models. However, the statistical indicators of the hybrid ANNs with SSA, GA, and GOA are so close to each other. [ABSTRACT FROM AUTHOR]

Today, architectural application and economic constraints require that vertical-irregular structures be constructed in urban areas. Proposing methods to minimize damage to these structures during earthquakes is therefore crucial. Strict regulations have been enforced for the design and analysis of irregular structures given their higher vulnerability to damage compared to that of regular structures. The present study aimed to evaluate eight regular and irregular 10-story and 15-story steel structures with buckling-restrained braces frames (BRBFs) and concentric braced frames (CBFs) in terms of their responses to twelve far-field earthquakes. According to the obtained results, the mean value of maximum drift, top floor displacement and floor acceleration were higher in both regular and irregular structures with BRBFs than in those with CBFs. [ABSTRACT FROM AUTHOR]

As a lateral load-bearing system, the steel plate shear wall (SPSW) is utilized in different structural systems that are susceptible to seismic risk and because of functional reasons SPSWs may need openings. In this research, the effects of rectangular openings on the lateral load-bearing behavior of the steel shear walls by the finite element method (FEM) is investigated. The results of the FEM are used for the prediction of SPSW behavior using the artificial neural network (ANN). The radial basis function (RBF) network is used to model the effects of the rectangular opening in the SPSW with different plate thicknesses. The results showed that the opening leads to reduced load-bearing capacity, stiffness and absorbed energy, which can be precisely predicted by employing RBF network model. Besides, the suitable relative area of the opening is determined. [ABSTRACT FROM AUTHOR]

Recent studies highlight the potential impact of earthquakes on cultural heritage sites and monuments, which in turn yield significant adverse impacts on economies, politics, and societies. Several aspects such as building materials, structural responses, and restoration strategies must be considered in the conservation of heritage structures. Timber is an old organic construction material. Most of the historic timber structures were not designed to withstand seismic forces; therefore, the seismic vulnerability assessment of heritage timber structures in areas with high seismic hazard is essential for their conservation. For this purpose, different strategies for the numerical modeling of heritage timber buildings have been developed and validated against tests results. After performing seismic analysis using detailed analytical methods and predicting the susceptible structural components, strengthening techniques should be utilized to mitigate the risk level. To this aim, various methods using wooden components, composite material, steel components, SMA etc., have been utilized and tested and are reviewed in this study. There are still some gaps, such as full-scale numerical modeling of strengthened buildings and investigating the soil–structure interaction effects on the seismic behavior of buildings that should be investigated. [ABSTRACT FROM AUTHOR]

Infrastructures and industrial buildings are commonly exposed to aggressive environments and damaged by corrosion. In prestressed reinforced concrete structures, the potential risks of corrosion could be severe since reinforcements are already subjected to high amounts of stress and, consequently, their load-bearing capacity could abruptly decrease. In recent years, some experimental studies have been conducted to explore the flexural behavior of corroded pretensioned reinforced concrete (PRC) beams, investigating several aspects of residual structural performance. Although many studies have been done in this area, there is no concise paper reviewing the state-of-the-art research. Accordingly, the main objective of this paper is to provide a review of the available experimental tests for residual capacity assessment of corroded PRC beams. Based on the state-of-the-art review, a degradation law for the flexural strength of corroded PRC beams is suggested. [ABSTRACT FROM AUTHOR]

Improvements in the science of health monitoring and maintenance have facilitated the observation of damage and defects in existing structures and infrastructures, such as bridges and railways. The need to extend sensing technology through the use of wireless sensors as well as the lack of description tools for understanding, visualizing, and documenting sensor outputs has encouraged researchers to use powerful tools such as Building Information Modelling (BIM) systems. BIM has become important because of conducting tools widely used in the Architecture, Engineering, and Construction (AEC) industry to present and manage information on structural systems and situations. Since combining health monitoring and maintenance results with BIM models is a new field of study, and most projects utilize various aspects of it, we have conducted a review of important work related to this subject published from 2010 to November of 2020. After reviewing 278 journal articles, research trends, approaches, methods, gaps, and future agenda related to BIM in monitoring and maintenance were highlighted. This paper, through a bibliometric and content analysis, concludes that besides main improvements, some limitations now exist which affect the modeling and maintenance process. These limitations are related to extending the IFC schema, optimizing sensor data, interoperability among various BIM platforms, optimization of various sensing technologies for fault detection and management of huge amounts of data, besides consideration of environmental effects on monitoring hazards and underground objects. Finally, this paper aims to help to solve the mentioned limitation through a comprehensive review of existing research. [ABSTRACT FROM AUTHOR]

The reduction of the moisture content of concrete during the drying process reduces the concrete's volume and causes it to shrink. In general, concrete shrinkage is a phenomenon that causes concrete volume to dwindle and can lead to durability problems. There are different types of this phenomenon, among them chemical shrinkage, autogenous shrinkage, drying shrinkage including free shrinkage and restrained shrinkage, and thermal contraction. Shrinkage-reducing admixtures are commercially available in different forms. The present study investigates the effect of liquid propylene glycol ether on mechanical properties and free shrinkage induced by drying at different water-cement (w/c) ratios. Furthermore, the effect of shrinkage-reducing admixtures on the properties of hardened concrete such as compressive and tensile strength, electrical resistivity, modulus of elasticity, free drying shrinkage, water absorption, and depth of water penetration was investigated. The results indicated that shrinkage reducing agents performed better in a low w/c ratio and resulted in up to 50% shrinkage reduction, which was due to the surface reduction of capillary pores. The prediction of free shrinkage due to drying was also performed using an artificial neural network. [ABSTRACT FROM AUTHOR]

Worldwide, steel corrosion is one of the greatest deterioration problems for reinforced concrete structures. Comparing some experimental results from literature with a complex FEM model, the present paper points out the principal aspects that characterize the static behavior of reinforced concrete (RC) elements damaged by corrosion. Moreover, the nondimensional abaci defined for some specific case studies finalized to the evaluation of the residual flexural strength of corroded elements highlight the dangerousness of the corrosion degradation if the failure of the element is governed by the steel. [ABSTRACT FROM AUTHOR]