Experimental Investigation of Adhesive Bonding for Post‐installed Rebars into Concrete at High Temperatures

2019 ◽  
Author(s):  
Thanyawat Pothisiri ◽  
Pitcha Jongvivatsakul ◽  
Vanichapoom Nantavong
Keyword(s):  
Experimental Investigation ◽  
High Temperatures ◽  
Mechanical Behaviour ◽  
Epoxy Resins ◽  
Adhesive Bonding ◽  
Elevated Temperatures ◽  
Adhesive Bond ◽  
Steel Rebar ◽  
Pull Out ◽  
Embedment Length

<p>The use of post‐installed rebars into existing reinforced concrete structures bonded with epoxy resins was constantly increasing due to the advantage of equivalent or even higher bearing capacities at service temperature, compared with conventional cast‐in‐place rebars. Previous studies have examined the effects of different parameters on the mechanical properties of bonded post‐installed rebars at normal temperature. These studies showed that, for rebar diameter equal to 10 mm, the load bearing capacity increases linearly with the embedment length up to 75 mm. However, upon exposure to high temperatures, the glass transition of epoxy resins may occur and affect the mechanical behaviour of the adhesive bond. Studying the mechanical behaviour of an adhesive anchor at high temperatures is therefore necessary. An experimental investigation is conducted herein to examine the characteristics of the adhesive bonding stress between steel rebar and concrete interface at elevated temperatures using a series of pull‐out tests with varying rebar diameters and embedment lengths.</p>

Parametric study of fully grouted cable bolts subjected to axial loading

2019 ◽  
Vol 56 (10) ◽  
pp. 1514-1525 ◽  
Author(s):  
Danqi Li ◽  
Hossein Masoumi ◽  
Serkan Saydam ◽  
Paul C. Hagan ◽  
Mostafa Asadizadeh
Keyword(s):  
Mechanical Behaviour ◽  
Peak Load ◽  
Axial Loading ◽  
Borehole Diameter ◽  
Initial Stiffness ◽  
Pull Out ◽  
Cable Bolts ◽  
Embedment Length ◽  
Improved Design ◽  
Cable Bolt

The laboratory short encapsulation pull-out test (LSEPT) has been widely accepted as the most efficient method to characterize the mechanical behaviour of cable bolts under axial loading. In this study, a number of LSEPTs was performed on conventional (Plain SuperStrand) and modified (MW9S) cable bolts using the improved pull-out test design. The effects of several parameters including the uniaxial compressive strength (UCS) of the confining medium and grout and the borehole diameter on the mechanical behaviour of MW9S and Plain SuperStrand cable bolts were investigated. Response surface methodology (RSM) was employed to quantify the contribution of these parameters on the responses including peak and residual loads and initial stiffness. RSM revealed that the UCS of the confining medium is a key contributing factor to the mechanical behaviour of both cable bolts. Also, it was demonstrated that the borehole diameter had a negligible impact on the overall behaviour of the MW9S cable bolt while the peak load of the SuperStrand cable bolt was increased due to an increase in the diameter of the borehole. Finally, from a comparative analysis, it was confirmed that the improved design can better represent the field mechanical behaviour of cable bolts through maintenance of the embedment length during large deformation.

EASTERN STAINLESS TYPE 310S

Alloy Digest ◽  
1984 ◽  
Vol 33 (8) ◽  
Keyword(s):  
High Temperatures ◽  
Elevated Temperatures ◽  
High Strength ◽  
Heat Treating ◽  
Oil Refining ◽  
Steel Company ◽  
Plant Equipment ◽  
The Many ◽  
Corrosion And Oxidation ◽  
Refining Equipment

Abstract EASTERN STAINLESS TYPE 310S has high resistance to corrosion and oxidation at high temperatures. It also has high strength at elevated temperatures. Thus it is especially suitable for service at high temperatures. It is very ductile and can be welded readily. Among the many applications for Type 310S, a few typical uses include annealing boxes, chemical plant equipment, fire box sheets, furnace linings, heat exchangers, oil-refining equipment, kiln linings and tube hangers. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as creep. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SS-450. Producer or source: Eastern Stainless Steel Company.

scholarly journals Pull-out and Critical Embedment Length of Grouted Rebar Rock Bolts-Mechanisms When Approaching and Reaching the Ultimate Load

2021 ◽  
Author(s):  
Are Håvard Høien ◽  
Charlie C. Li ◽  
Ning Zhang
Keyword(s):  
Ultimate Load ◽  
Failure Mechanisms ◽  
Concrete Block ◽  
Rock Bolts ◽  
Rock Stratum ◽  
Pull Out ◽  
Deformation Length ◽  
Embedment Length ◽  
Pull Tests ◽  
Grouted Bolts

AbstractRock bolts are one of the main measures used to reinforce unstable blocks in a rock mass. The embedment length of fully grouted bolts in the stable and competent rock stratum behind the unstable rock blocks is an important parameter in determining overall bolt length. It is required that the bolt section in the stable stratum must be longer than the critical embedment length to ensure the bolt will not slip when loaded. Several series of pull tests were carried out on fully grouted rebar bolts to evaluate the pull-out mechanics of the bolts. Bolt specimens with different embedment lengths and water/cement ratios were installed in either a concrete block of one cubic meter or in steel cylinders. Load displacement was recorded during testing. For some of the bolts loaded beyond the yield load, permanent plastic steel deformation was also recorded. Based on the test results, three types of failure mechanisms were identified, corresponding to three loading conditions: (1) pull-out below the yield strength of the bolt steel; (2) pull-out between the yield and ultimate loads, that is, during strain hardening of the steel; and (3) steel failure at the ultimate load. For failure mechanisms 2 and 3, it was found that the critical embedment length of the bolt included three components: an elastic deformation length, a plastic deformation length and a completely debonded length due to the formation of a failure cone at the borehole collar.

scholarly journals Strengthening epoxy adhesives at elevated temperatures based on dynamic disulfide bonds

2020 ◽  
Vol 1 (9) ◽  
pp. 3182-3188
Author(s):  
Hsing-Ying Tsai ◽  
Yasuyuki Nakamura ◽  
Takehiro Fujita ◽  
Masanobu Naito
Keyword(s):  
Glass Transition ◽  
Disulfide Bonds ◽  
Epoxy Resins ◽  
Elevated Temperatures ◽  
Adhesive Properties ◽  
Epoxy Adhesives ◽  
Transition Points ◽  
Increasing Temperature

Epoxy resins incorporating aromatic disulfide bonds demonstrated improved adhesive properties with increasing temperature below their glass transition points.

scholarly journals Deformation of Ordered Mesoporous Silica Structures on Exposure to High Temperatures

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
John B. Lowe ◽  
Richard T. Baker
Keyword(s):  
Mesoporous Silica ◽  
Pore Structure ◽  
High Temperatures ◽  
Elevated Temperatures ◽  
Ordered Mesoporous Silica ◽  
Large Cage ◽  
Pore Structures ◽  
Ordered Mesoporous ◽  
Pore Size Distributions ◽  
Wide Range

Ordered mesoporous silica materials are of interest for a wide range of applications. In many of these, elevated temperatures are used either in the preparation of the material or during its use. Therefore, an understanding of the effect of high temperature treatments on these materials is desirable. In this work, a detailed structural study is performed on silicas with three representative pore structures: a 2-D hexagonal pore arrangement (SBA-15), a continuous 3D cubic bimodal pore structure (KIT-6), and a 3D large cage pore structure (FDU-12). Each silica is studied as prepared and after treatment at a series of temperatures between 300 and 900°C. Pore structures are imaged using Transmission Electron Microscopy. This technique is used in conjunction with Small-Angle X-ray Diffraction, gas physisorption, and29Si solid state Nuclear Magnetic Resonance. Using these techniques, the pore size distributions, the unit cell dimensions of the mesoporous structures, and the relative occupancy of the distinct chemical environments of Si within them are cross correlated for the three silicas and their evolution with treatment temperature is elucidated. The physical and chemical properties before, during, and after collapse of these structures at high temperatures are described as are the differences in behavior between the three silica structures.

Structural Performance of Pultruded Composites under Elevated Temperatures

2009 ◽  
Vol 79-82 ◽  
pp. 2223-2226
Author(s):  
Ayman S. Mosallam
Keyword(s):  
Elevated Temperature ◽  
High Temperatures ◽  
Elevated Temperatures ◽  
Oxidative Degradation ◽  
Viscoelastic Behavior ◽  
Structural Performance ◽  
Crystalline Polymers ◽  
Damage To The Material ◽  
Continuous Working ◽  
Pultruded Composites

One of the major limitations for wider use of pultruded fiber reinforced polymeric (PFRP) composites in the civil engineering sector has been their behavior under elevated temperature and ultimately fire. This limitation arises not only due to the reduction in mechanical properties at high temperatures, including increased propensity to creep, but also due to limitations on the continuous working temperature causing permanent damage to the material as a result of thermal and oxidative degradation. Significant gains in property retention at high temperatures with crystalline polymers have been derived from the incorporation of fibrous reinforcement, but the development of new polymer matrices is the key for further elevation of the useful temperature range. This paper presents summary results of a research project focused on characterizing the viscoelastic behavior of commercially-produced, off-the-shelf unidirectional PFRP materials subjected to elevated temperature environments.

Maturation process and characterization of a novel thermostable and halotolerant subtilisin-like protease with high collagenolytic but low gelatinolytic activity

2021 ◽  
Author(s):  
Kui Zhang ◽  
Qianqian Huang ◽  
Yu Li ◽  
Lanhua Liu ◽  
Xiao-Feng Tang ◽  
...  
Keyword(s):  
High Temperatures ◽  
Type I Collagen ◽  
Elevated Temperatures ◽  
Catalytic Domain ◽  
Ion Pairs ◽  
Gelatinolytic Activity ◽  
Type I ◽  
Fish Scale ◽  
Collagenolytic Proteases ◽  
Collagenolytic Protease

Enzymatic degradation of collagen is of great industrial and environmental significance; however, little is known about thermophile-derived collagenolytic proteases. Here, we report a novel collagenolytic protease (TSS) from thermophilic Brevibacillus sp. WF146. The TSS precursor comprises a signal peptide, an N-terminal propeptide, a subtilisin-like catalytic domain, a β-jelly roll (βJR) domain, and a prepeptidase C-terminal (PPC) domain. The maturation of TSS involves a stepwise autoprocessing of the N-terminal propeptide and the PPC domain, and the βJR rather than the PPC domain is necessary for correct folding of the enzyme. Purified mature TSS displayed optimal activity at 70°C and pH 9.0, a half-life of 1.5 h at 75°C, and an increased thermostability with rising salinity up to 4 M. TSS possesses an increased number of surface acidic residues and ion pairs, as well as four Ca 2+ -binding sites, which contribute to its high thermostability and halotolerance. At high temperatures, TSS exhibited high activity toward insoluble type I collagen and azocoll, but showed a low gelatinolytic activity, with a strong preference for Arg and Gly at the P1 and P1’ positions, respectively. Both the βJR and PPC domains could bind but not swell collagen, and thus facilitate TSS-mediated collagenolysis via improving the accessibility of the enzyme to the substrate. Additionally, TSS has the ability to efficiently degrade fish scale collagen at high temperatures. IMPORTANCE Proteolytic degradation of collagen at high temperatures has the advantages of increasing degradation efficiency and minimizing the risk of microbial contamination. Reports on thermostable collagenolytic proteases are limited, and their maturation and catalytic mechanisms remain to be elucidated. Our results demonstrate that the thermophile-derived TSS matures in an autocatalytic manner, and represents one of the most thermostable collagenolytic proteases reported so far. At elevated temperatures, TSS prefers hydrolyzing insoluble heat-denatured collagen rather than gelatin, providing new insight into the mechanism of collagen degradation by thermostable collagenolytic proteases. Moreover, TSS has the potential to be used in recycling collagen-rich wastes such as fish scales.

Adhesive bond strength between orthodontic resin and acrylic surfaces

2020 ◽  
pp. 1-5
Author(s):  
Evelyn Guadalupe Torres-Capetillo ◽  
Guadalupe Rosalía Capetillo-Hernández ◽  
Laura Roesch-Ramos ◽  
Flora Moreno-Marín
Keyword(s):  
Bond Strength ◽  
Adhesive Bonding ◽  
Statistical Processing ◽  
Adhesive Bond ◽  
Diamond Bur ◽  
Fine Diamond ◽  
Adhesive Bond Strength ◽  
Application Protocols ◽  
Made In

The use of orthodontic treatments in patients with temporary prostheses has been increasing, the purpose of this in vitro research is to measure the adhesive bond strength between orthodontic resin and acrylic surfaces by applying different procedures. Objective. To compare the adhesive bonding strength between orthodontic resin and acrylic surfaces under different application protocols. Methodology. Transversal, experimental, prospective study. In vitro with acrylic provisions, was carried out in the laboratory of the Faculty of Dentistry of the Universidad Veracruzana region of Veracruz. In the period of February-June of the year 2019. The sample was conformed by two control groups of specimens and four experimental ones, each group conformed by 20 specimens, in total 120 provisional ones were made in acrylic Nic Tone of quick self-cure. The tests performed by the ULTRATESTER machine were expressed in MPa. Later, the data obtained were processed in Excel tables (version) for statistical processing in SPSS version 24. Contribution. When comparing the pre-cutting protocol of acrylic surfaces with fine diamond bur and the protocol without pre-cutting, no statistically significant differences were found, therefore, this step could be omitted in clinical practice.

Working in elevated temperatures: risks and consequences

2020 ◽  
pp. 10-16
Author(s):  
Anatoly Zernov
Keyword(s):  
Risk Assessment ◽  
Surface Temperature ◽  
High Temperatures ◽  
Elevated Temperatures ◽  
Industrial Safety ◽  
Labor Protection ◽  
Technological Processes ◽  
Occupational Risks

A number of technological processes are accompanied by an increase in surface temperature and the release of heat into the working area. The speaker of the conference “Assessment of occupational risks. Working in high temperatures" Anatoly Zernov, expert in the field of professional risk assessment and expertise in the field of labor protection and industrial safety, head of the methodological department RiskProf

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