Tensile strength of concrete is the basic property when estimating the cracking resistance of the structure and when analysing fracture processes in concrete. The most common way of testing tensile strength is the Brazilian method. It has been noticed that the shape and size of specimens influence the tensile splitting strength. The experiments were performed to investigate the impact of cylinder’s length on tensile concrete strength received in the Brazilian method. During the experiment the tensile concrete strength was tested on two different sizes cylindrical specimens: 150 mm × 150 mm and 150 mm × 300 mm. Experiments were performed in two stages, with two types of maximum aggregate size: 16 mm and 22 mm. The software “Statistica” was used to perform the broad scale statistical analysis. When comparing test results for shorter and longer specimens, the increase of tensile splitting strength tested on shorter cylinders was observed (approximately 5%). However, when performing deeper statistical analysis, it has been found that the length effect was not sensitive to the strength of the cement matrix and the type of aggregate but was influenced by the aggregate size. Further experiments are needed in order to perform a multi-parameter statistical analysis of scale effect when testing the splitting tensile strength of concrete.
Fracture mechanics of concrete is a complex matter still thoroughly researched from different angles. It is not an easy task to describe fracture process in concrete, as there are many factors affecting crack development and propagation. Practical applications of fracture mechanics could allow engineers to design concrete structures more effectively and safely. At the minimum, it could help estimate the “safe” period of time left before the unstable, dangerous crack propagation. This utilitarian goal was the reason for many researchers to invent numerous theoretical models in order to describe the crack occurrence better. However, dealing with various analytical problems was not a simple matter and thus existing models of fracture mechanics for concrete have different limitations. Over the years first fracture theories for concrete were reviewed repeatedly. All of these investigations lead to modifications of older models in order to overcome found drawbacks, which proved not to be an easy task. Recently, new approaches to fracture analyses seemed to produce promising results, like universal size effect law (USEL) or modified two parameter fracture model (MTPM) with alternative ways for evaluating fracture parameters. In the paper some of them will be discussed together with other fracture models, starting from some of the very first ones introduced for concrete, like fictitious crack model (FCM) and crack band model (CBM).
Hybrid fiber composites are widely used composites in engineering applications, especially for the frame and wall structure of Acehnese traditional boat Jalo Kayoh. The purpose of this study is to obtain a hybrid material which is a blend of natural jute fiber reinforced with the synthetic fibers E-glass and polyester as a matrix. The materials potential to become a material for the structure and walls in the traditional Acehnese boat Jalo Kayoh. The fabrication of the hybrid composites is carried out manually using an engineered press at a pressure of 25 kg/cm2 for 24 hours. The ratio of jute fiber and E-glass in the composites at each layer are (1:0), (1:1) and (2:1). Tensile testing of the hybrid composites refers to ASTM D 3039 - 00. The results show that the tensile strength of the hybrid composites tends to increase with the increase in the volume of the fiber, with the maximum tensile strength of 4.8 MPa. The increasing number of layers in the jute and E-glass is adding strength to the composites. This will be good to use in the initial material of the structure and walls in the traditional Acehnese boat Jalo Kayoh.
Fiber composites are very commonly used for engineering applications nowadays. The product has begun to enter the field of boat and ship manufacturing. An Acehnese traditional boat known as thep-thep, which has a capacity of 3 GT, is a means of transportation used in Aceh waters. This study focuses on the mechanical properties of the material used for the structure and walls of the thep-thep. Specimens are made from materials with E-glass fiber reinforced polyester resin. The hand lay-up method is used in the process of making the specimens, applied with a pressure of 25 kg/cm2 for 24 hours. This study aimed to obtain higher mechanical properties using composites of layers of chopped strand mat (CSM) fibers and woven roving mat (WRM) fibers with a ratio of 1:0, 1:1, and 2:1, respectively. Tensile testing is done using the ASTM D3039-00 standard. From the tensile test data obtained from several different composite ratios, the highest composite is found at around 49.2 MPa. An increase in the number of fiber layers makes the fiber composites more reliable to be the raw material in the making of the Acehnese boat thep-thep.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.