Mechanical Characterization of SRG Composites According to AC434

In the last decades, technologies and materials such as fiber reinforced polymer (FRP) have been used to strengthen different types of existing structures. More recently, composites have been developed consisting of reinforcement fabrics embedded in an inorganic mortar. These composites are known as fabric reinforced cementitious matrix (FRCM), when the fabric is made of aramid, glass, basalt, polyparaphenylene benzo-bisoxazole (PBO) or carbon fibers, and steel reinforced grout (SRG), when the fabric is made of twisted high-strength steel cords. In the United States, the characterization of FRCM/SRG systems is conducted in accordance to Acceptance Criteria AC434. According to AC434, the tensile properties of FRCM/SRG are obtained through a direct tensile test on coupons using clevis grips.The objective of this research is to discuss the applicability of the AC434 test method to determine the mechanical properties of SRG as a function of the length of the anchoring plates. SRG panels were cast and stored in a humidity chamber. After a 28-day curing period, they were cut to size and metal plates of different lengths adhered to their extremities. Results show that not all the assumptions currently made in AC434 are applicable to this type of composite. The experimental response was characterized by a trilinear stress-strain behavior. Furthermore, the cracked modulus calculated based on stress values between 60 and 90% of the ultimate stress does not accurately represent reality. Re-evaluation of this provision is of importance since the cracked modulus is used in design.

Download Full-text

Comparison of Tensile Strengths with Different Test Methods in Ultra High Strength Steel-Fiber Reinforced Concrete (UHS-SFRC)

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.417-418.649 ◽

2009 ◽

Vol 417-418 ◽

pp. 649-652 ◽

Cited By ~ 1

Author(s):

Su Tae Kang ◽

Jung Jun Park ◽

Gum Sung Ryu ◽

Gyung Taek Koh ◽

Sung Wook Kim

Keyword(s):

Tensile Strength ◽

Tensile Test ◽

High Strength ◽

Fiber Reinforced Concrete ◽

Steel Fiber Reinforced Concrete ◽

Flexural Tensile Strength ◽

Ultra High Strength Steel ◽

Direct Tensile ◽

Direct Tensile Test ◽

Direct Tensile Strength

Ultra High Strength Steel-Fiber Reinforced Concrete (UHS-SFRC) is characterized by very high compressive and tensile strength that is about 8 times of ordinary concrete, and high ductility owing to the addition of steel fibers. This paper investigates the relationship existing among the direct tensile strength, flexural tensile strength and splitting tensile strength of UHS-SFRC. Differently from ordinary concrete, it is found that the first cracking strengths in UHS-SFRC obtained through direct tensile test and splitting tensile test are similar, while the strength obtained from flexural tensile test is significantly larger than those from other tests. Based on the experimental results, relationships between the direct tensile strength and flexural tensile strength, between the first cracking strengths in direct tensile test and in flexural tensile test, and between the first cracking strength in direct tensile test and the flexural tensile strength are proposed.

Download Full-text

Interface Shear Strength of Carbon Fiber Mesh (CFM) Attached to RC Surface for External Reinforcing

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.324-325.799 ◽

2006 ◽

Vol 324-325 ◽

pp. 799-802

Author(s):

Soo Yeon Seo ◽

Hyun Do Yun ◽

Chang Sik Choi ◽

Ki Bong Choi

Keyword(s):

Carbon Fiber ◽

Bond Strength ◽

Drying Shrinkage ◽

Strengthening Effect ◽

Interface Shear ◽

Existing Structures ◽

Externally Bonded ◽

Direct Tensile ◽

Direct Tensile Test ◽

Fiber Mesh

The strengthening of concrete structures in situ with externally bonded carbon fiber is increasingly being used for repair and rehabilitation of existing structures since carbon fiber has good mechanical properties such as high tensile strength, good resistances to corrosion, and low self-weight, which are attractive for retrofitting of RC member. In using Carbon Fiber Mesh (CFM) as a retrofit material for RC member, most important structural property that should be developed is the bond strength between RC member and CFM. The additional strength increment by CFM can be developed if the bond strength is sufficient. If it is not, the strengthening effect can not be expected due to the bond failure between concrete and CFM. A direct tensile test was performed in order to find the variation of bond strength and load-displacement response of CFM attached to the concrete and the result is presented in this paper. The key parameters of the test are the location of clip for the installation of CFM, number of clips and thickness of cover mortar. Test results indicate that the bond strength is dependent on the number of clips and maximized at clip numbers of three per each rod. In specimens without clips, the highest strength was found in the specimen with cove mortar of 30mm and lowest one in specimen with largest mortar thickness. This means that in too much thick of cover mortar, it seems that the amount of drying shrinkage is increased and this reduces rather than improves the bond strength.

Download Full-text

Experimental Characterization of the Elastic-Plastic Strain Fields at the Crack Tip Due to Cyclic Loading

Journal of Engineering Materials and Technology ◽

10.1115/1.2904271 ◽

1994 ◽

Vol 116 (2) ◽

pp. 187-192 ◽

Cited By ~ 6

Author(s):

N. Ranganathan ◽

K. Jendoubi ◽

N. Merah

Keyword(s):

Cyclic Loading ◽

Plastic Strain ◽

Crack Tip ◽

High Strength ◽

Elastic Plastic ◽

Strain Behavior ◽

Linear Elastic ◽

Elastic Fracture ◽

Aluminum Alloy 2024

Some mechanical components cease to function satisfactorily, failing either under excessive elastic deformation or extensive plastic yielding. In the case of constrained plastification, the researcher is faced with some difficulties in evaluating plastic and elastic-plastic strain behavior near the crack tip. In the present study local strains are measured by microstrain gages, mounted near the crack tip on CT specimens made from the high strength aluminum alloy 2024-T351 under cyclic loading at constant ΔK. The behavior and the evolution of the elastic-plastic zone are studied as a function of the stress ratio R, the thickness of the specimen and the level of ΔK. The experimental results are compared with those given by numerical and theoretical analyses based on the concepts of linear elastic fracture mechanics (LEFM).

Download Full-text

Utilization of Local Ingredients for the Production of High-Early-Strength Engineered Cementitious Composites

Advances in Materials Science and Engineering ◽

10.1155/2018/8159869 ◽

2018 ◽

Vol 2018 ◽

pp. 1-15 ◽

Cited By ~ 5

Author(s):

Hanwen Deng

Keyword(s):

High Performance ◽

High Strength ◽

Bending Test ◽

Cementitious Composites ◽

Chinese Market ◽

The Matrix ◽

High Performance Fiber ◽

Early Strength ◽

Direct Tensile ◽

Direct Tensile Test

The rapid repair and retrofitting of existing transportation infrastructure requires dimensional stability and ductile repair material that can obtain sufficiently high strength in a few hours to accommodate the large loading and deformation at an early age. Engineering cementitious composites (ECCs) is a class representative of the new generation of high-performance fiber-reinforced cement-based composites (HPFRCC) with medium fiber content. The unique properties of tremendous ductility and tight multiple crack behavior indicate that ECC can be used as an effective retrofit material. The wide application of this material in China will require the use of all local ingredients. In this study, based on Chinese domestic ingredients, including matrix materials and all fibers, high-early-strength ECC (HES-ECC) was designed under the guidance of strain-hardening criterion of ECC. The matrix properties and fiber/matrix interfacial micromechanics properties were obtained from three-point-bending test and single-fiber pullout test. The mechanical properties of HES-ECC were achieved by direct tensile test. The experimental results show that HES-ECC was successfully developed by using all Chinese materials. When using the domestic PVA fiber at 2%, the strength requirement can be achieved but only a low ductility. When using the domestic PE fiber at 0.8%, the strength and deformation requirement both can be obtained. The HES-ECC developed in this study exhibited compressive strength of more than 25 MPa within 6 hours, and an ultimate tensile strength of 5-6 MPa and tensile strain capacity of 3-4% after 60 days. Moreover, the cost of using domestic fiber can be largely reduced compared with using imported fiber, up to 70%; it is beneficial to the promotion of these high-early-strength ECCs in the Chinese market.

Download Full-text

Experimental and Numerical Characterization of Self-Compacting Concrete «Using Construction Waste»

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.749.353 ◽

2015 ◽

Vol 749 ◽

pp. 353-357 ◽

Cited By ~ 1

Author(s):

Hassiba Hermime ◽

Youcef Bouafia ◽

Sarah Benakli

Keyword(s):

Shear Force ◽

Mechanical Tests ◽

Test Results ◽

Numerical Characterization ◽

Fresh State ◽

Hardened State ◽

Mechanical Performances ◽

Direct Tensile ◽

Direct Tensile Test

This work carries an experimental study on the composition and the characterization of the self-compacting concretes made starting from waste of construction with comparisons which were made by contribution with the vibrated concrete. Studies on the workability and the compactness of material were made and this in a fresh state and a hardened state. Five different mechanical tests were performed: compression, direct tensile, splitting tensile, 3 points binding and failure to the shear force. Confrontations of the test results compared to formulas for calculating the shear force were realized. All the test results showed an increase in terms of resistance for SCC contribution to the VC, except the direct tensile test which gave values slightly lower. The SCC improves the failure load notably and gives better mechanical performances.

Download Full-text

Characterization of hydrogen in a high strength aluminum alloy

Materials Testing ◽

10.1515/mt-2020-620916 ◽

2020 ◽

Vol 62 (9) ◽

pp. 962-964

Author(s):

Xiao Yang ◽

Xianfu Luo ◽

Xianfeng Zhang ◽

Jieming Chen ◽

Lingqing Gao

Keyword(s):

Aluminum Alloy ◽

Aluminum Alloys ◽

Secondary Ion Mass Spectrometry ◽

High Strength ◽

Test Method ◽

Face Centered Cubic ◽

Tof Sims ◽

Face Centered ◽

High Strength Aluminum Alloys

Abstract High strength aluminum alloys have a face-centered cubic structure and it is not easy to form hydrides due to the extremely low solubility of hydrogen. Therefore, it is very difficult to test and characterize hydrogen in the high-strength aluminum alloys. In this work, the penetration of hydrogen and the distribution of hydrogen near the crack tip in the highstrength aluminum alloy were analyzed by time of flight secondary ion mass spectrometry (TOF-SIMS). Meanwhile, the test method of trace H in highstrength aluminum alloy was investigated by using TOF-SIMS technology.

Download Full-text

Footwear. Test method for the characterization of elastic materials. Tensile performance

10.3403/30181876 ◽

2010 ◽

Keyword(s):

Test Method ◽

Elastic Materials ◽

Tensile Performance

Download Full-text

Characterization of Antibacterial-Producing Endophytic Fungi of Syzygiumpolyanthum Leaves

Infectious Disorders - Drug Targets ◽

10.2174/1871526519666181226123541 ◽

2020 ◽

Vol 20 (4) ◽

pp. 448-454

Author(s):

Rahmita Burhamzah ◽

Gemini Alam ◽

Herlina Rante

Keyword(s):

Molecular Characterization ◽

Endophytic Fungi ◽

Morphological Characterization ◽

Test Method ◽

Analysis Method ◽

Nitrogen Base ◽

Rdna Genes ◽

Antibacterial Screening ◽

Planting Method

Background: Endophytic fungi live in plants’ tissue and can produce the same bioactive compounds as its host plant produces. Syzygiumpolyanthum leaves have known to be one of the antibacterial compound producers. Aim and Objective: This study aimed to characterize morphologically, microscopically, and molecularly the antibacterial-producing endophytic fungi of Syzygiumpolyanthum leaves. Methods: The isolation of endophytic fungi was done by fragment planting method on PDA medium. The antibacterial screening was performed using the antagonistic test as the first screening followed by the disc diffusion test method. The morphological characterization was based on isolate’s mycelia color, growth pattern, margin, and surface texture of the colony, while the microscopic characterization was based on its hyphae characteristics. The molecular characterization of the isolate was done by nitrogen base sequence analysis method on nucleotide constituent of ITS rDNA genes of the isolate. Results: The results found that isolate DF1 has antibacterial activity against E.coli, S.aureus, P.acne, and P.aeruginosa, with the greatest inhibition at 10% concentration of broth fermentation extract on S.aureus with a diameter of inhibition of 13.77 mm. Conclusion: Based on macroscopic, microscopic, and molecular characterization, DF1 isolate is similar to Ceriporialacerate.

Download Full-text