Papers by Keyword: Modulus of Rupture

Abstract: Panel wall systems are increasingly preferred in modern construction due to their efficiency and sustainability. However, conventional cement-based materials are brittle, have limited tensile strength, and are prone to cracking, necessitating reinforced alternatives. This study investigates using palm kernel fiber (PKF) and bamboo leaf ash (BLA) in cement-based composite panels to improve mechanical properties and durability. A water-to-binder ratio of 0.55 and a cement-to-BLA ratio of 3:1 were used, with PKF added in varying proportions from 0% to 4% by binder weight. 165 specimens were cast and tested for density, water absorption, modulus of rupture (MOR), modulus of elasticity (MOE), and compressive strength at 7, 14, and 28 days of curing. The results showed water absorption between 2.5% and 7.5% and densities from 1375 to 1497 kg/m³. The compressive strength was found within the range of 7.6 -16.54N/mm² and generally decreases with the increasing percentage of fiber contents but increases with curing age. The bending strength (MOR) ranges from 3.03 to 7.24 N/mm², while the modulus of elasticity (MOE) ranges from 6.03 to 10.49 N/mm². Both MOE and MOR increased with curing age and showed a slight increase with fiber content. All results complied with American Concrete Institute (ACI) standards. The study concludes that PKF-reinforced, BLA-blended composite panels exhibit suitable strength and durability for wall construction, offering a sustainable alternative to conventional materials.

Abstract: This article shows the results of the modulus of rupture test for concrete specimens added with PET fibers and also with polypropylene, with the objective of giving a second use to this waste through recycling, and its incorporation into concrete to improve its mechanical properties. The samples were tested with different fiber contents, and the results showed an increase in the modulus of rupture at 90 days with respect to a normal sample (1-3%). Specimens with PET and polypropylene fibers had a poor performance (<18%).

Abstract: Kenaf fiber-reinforced beech plywood was evaluated with 5variantmanufacturing adhesive methods in order to increase its acceptance in the wider industrial use. We aimed in enhancing the mechanical characteristics of beech wood kenaf fiber-reinforced using epoxy resin, Urea-formaldehyde, Melamine urea-formaldehyde, isocyanate MDI prepolymer and polyurethane and exhibited diverse effects. Tensile strength, Modulus of Elasticity, Modulus of Rupture, Shear Strength and Screw withdrawal resistance were enhanced by urea formaldehyde, while tensile strength was decreased by Urea Formaldehyde, Melamine Urea-Formaldehyde and isocyanate prepolymer. Epoxy resin, on the other hand, is well suited for kenaf fibre reinforcing. For example, polyurethane reduced the mechanical characteristics of kenaf fibre reinforced beech wood. Shear strength, Modulus of Elasticity and Modulus of Rupture were all superior than glass fibre reinforced epoxy resin bound beech wood.

Abstract: This research aims to investigate the mechanical properties of engineered cementitious composites including compressive strength, splitting tensile strength, modulus of rupture, and load-deflection behavior. In addition, the abrasion test of concrete under water, which is recommended by ASTM C1138, was carried out and its results were compared with the splitting and modulus of rupture test results. Untreated low-cost polyvinyl fibers were used with different volume fractions of 0.5, 1.0, 1.5, and 2.0%. All tests were carried out at the standard age of 28 days. The experimental results showed that the use of 2% of low cost polyvinyl fibers with the engineered cementitious composites led to the increase of the splitting tensile strength and the modulus of rupture by 134% and 287%, respectively, compared to specimens incorporating no fibers. The results showed also that the deflection and the ultimate failure load increases as the fiber content increase.

Abstract: The purpose of this work was to study the microstructure and the mechanical properties of the fiber-reinforced cement composites that used the nucleating-agent activated coal-fired power plant bottom ash as a raw material in the mixture for producing the composites. The raw materials for producing the fiber reinforced cement composites were the ordinary Portland cement (OPC), natural gypsum, cellulose fiber, and bottom ash. The bottom ash was chemically treated by the nucleating agent, a chemical that was prepared by the precipitation process from the aqueous solutions of sodium silicate (Na₂SiO₃) and calcium nitrate (Ca (NO₃)₂). To prepare the samples, the mixture consisting of 34.75 wt% OPC, 34.75 wt% bottom ash, 25 wt% natural gypsum, and 5.5 wt% cellulose fiber was mixed with the nucleating agent at the amount of 0 to 4.5 % of OPC weight in the mixture, and water to form the slurry. Then, the samples were produced by filter pressing process and cured in the autoclave for 16 hrs at 180 °C, and 10 bars. The mechanical properties of the samples including modulus of rupture (MOR), modulus of elasticity (MOE), and toughness were characterized by the universal testing machine (UTM). The microstructures of the samples were observed by scanning electron microscope (SEM). The results showed that the utilization of nucleating agent affect the microstructure of the sample leading to the improvement in the mechanical properties of samples.

Abstract: Repair materials have been produced using an unsaturated polyester resin (UPR) as a matrix of a binder. Other ingredients are sand, cement and fly ash. No water is added to the mixture, so both the cement and fly ash only act as fillers. The UPR content is in the range of 50-60% by weight of total filler (cement plus fly ash). Their flexural performance has been characterized in term of the load-deflection behaviour, modulus of rupture, flexural modulus and stiffness. The results show that the flexural capacity of these materials at early age is at least 20 MPa, but they tend to have a lower elastic modulus. At early age, the higher amount of UPR content tends to gain a higher flexural characteristic. However, at later age there is a little influence of UPR content.

Abstract: This article discusses the use of artificial neural networks for solving industrial non-trivial problem, which is undoubtedly modulus of rupture optimization in case of sintered ceramics based on amorphous SiO₂. Melting crucibles made from high purity silica are commonly used for production of high purity silicon ingots that are used in photovoltaic industry. Optimal modulus of rupture is very important variable that is related to the reliability and crucible usage value.

Abstract: Ultra-High Performance Fibre Reinforced Concrete (UHPFRC) is a fine-gained composite material achieving both high compressive and tensile strengths. Values of compressive strength, tensile strength and bending strength depend not only on a composition of the mixture itself, but also on the border conditions of the setting of the test, it means the support type, the loading rate etc. UHPFRC is used not only in European countries (Germany, France, Holland), but in distant countries (USA, Japan, Australia), too. In the Czech Republic is UHPFRC produced mainly in laboratories. The first using of UHPFRC for the real construction in the Czech Republic was a production of lost shuttering slabs that were used at the reconstruction of the raod-bridge across R10 highway. These results of the lost shuttering slabs became the base of a more detailed research of the homogeneity of the steel fibre distribution and its impact on load bearing capacity of the UHPFRC elements. Experimental beams with a different volume fraction of steel fibres were made and tested on the basis of the determined results of a nonhomogeneous fibre distribution at the cross section of lost shuttering slabs. Then the layered beams with a controlled steel fibre distribution at the cross section were made and tested too. The test results together with a description and characterization of the behaviour of tested homogeneous beams with different volume fraction of the steel fibres and functionally layered beams are published in this paper.

Abstract: The paper discusses strength-time relation of unfired soil-lime bricks in presence of different water content of soil as one of principal materials for the brick making. Two batches of soil-lime bricks were made with a mixture of lime, soil and water with a mass proportion of 1: 5.7: 1. Water contents of the first and second batch of soil are 30% and 40.581% respectively. Both batches of brick underwent compression and three point bending test. Absorption and physical change of bricks were also evaluated. Experimental investigation reveals that for both batches of bricks, up to 90 days compressive strength decreases a little but modulus of rupture rapidly decreases with time. The study shows that unfired soil-lime bricks with lower soil water content resulted in better strength performances compared to those with higher soil water content.

Abstract: This study was examined about the relationship between the fillers added to the grain layer of a resinoid bond diamond wheel and mechanical properties, the grade, the grinding performance. In the abrasion test using a constant pressure grinding, it was shown clearly that the critical grain holding power changed by kinds of fillers. On the other hand, in the constant cut surface grinding, the grinding interval was evaluated based on the grinding force. And, it was confirmed that the grinding interval changed by kinds of filler. Also, it was found that the characteristics of truing and dressing changed by kinds of filler. In addition, Young's modulus and bending strength of the grain layer of a resinoid bond diamond wheel was measured by three point bending test and ultrasonic pulse method. In the results, it checked that the mechanical properties such as bending strength and Young's modulus of a grain layer changed by kinds of filler. And, the modulus of rupture was calculated from the Young's modulus and bending strength.The result of having compared the modulus of rupture with the critical grain holding power, it was found that the modulus of rupture and the critical grain holding power have good correlation. Namely, the critical grain holding power of a resinoid bond diamond wheel can be evaluated by the modulus of rupture. Furthermore, it was shown that the grinding performance may be able to be predicted by the modulus of rupture of a grain layer of a resinoid bond diamond wheel.