scholarly journals Influence of curing temperature and stress conditions on mechanical properties of cementing paste backfill

2016 ◽  
Vol 53 (1) ◽  
pp. 148-161 ◽  
Author(s):  
Megan L. Walske ◽  
Heather McWilliam ◽  
James Doherty ◽  
Andy Fourie
Keyword(s):  
Mechanical Properties ◽  
Effective Stress ◽  
Elevated Temperatures ◽  
Small Strain ◽  
Curing Temperature ◽  
Temperature Conditions ◽  
In Situ Conditions ◽  
Paste Backfill ◽  
Temperature Controlled

Cemented paste backfill (CPB) has been observed to achieve greater cemented strength when cured in situ compared with equivalent mixes cured and tested in a laboratory environment. This is in part due to the development of effective stress and generation of elevated temperatures by exothermic cement hydration reactions occurring during curing in a typical underground stope environment. This differs from curing in typical laboratory environments, where little or no effective stresses are generated and curing occurs under constant-temperature conditions. This paper outlines the development, calibration, and testing of a temperature-controlled hydration cell that provides closer representation of in situ conditions by controlling the rate and final amount of specimen temperature increase, in addition to curing under effective stress. The temperature-controlled hydration cell was used to examine the effect of curing under combined effective stress and temperature conditions on the development of small-strain stiffness over a 7 day curing period and the unconfined compressive strength at the end of this period. Curing with both elevated temperature and effective stress was found to significantly increase the mechanical properties of CPB compared with curing at elevated effective stress or ambient temperatures alone.

Full-Scale Elevated Temperature Testing of Composite Repairs in Bending and Compression

2016 ◽  
Author(s):  
Colton Sheets ◽  
Robert Rettew ◽  
Chris Alexander ◽  
Tanya Axenova
Keyword(s):  
Elevated Temperature ◽  
Elevated Temperatures ◽  
Water Immersion ◽  
Full Scale ◽  
Composite Repair ◽  
In Situ Conditions ◽  
Depth Analysis ◽  
Repair Systems ◽  
Full Scale Testing

The increasing use of composite repair systems in critical and complex applications has brought greater scrutiny to their design and performance. This has been especially true in high-temperature, immersed environment applications where ambient temperature test results with industry standard de-rating factors are all that is available for design. Since this approach does not always adequately capture environmental effects or the performance of composite systems at elevated temperatures, it is beneficial to perform full-scale testing which accurately replicates the in-situ application. In order to accomplish this, a full-scale testing program was developed that subjected multiple composite repair systems to internal and external loads at temperatures up to 120 °C with and without water immersion. This program involved the reinforcement of 12.75-inch × 0.375-inch pipe samples that had simulated corrosion defects. Full-scale load and pressure testing was conducted to simulate the long-term performance of the composite repair systems in the environmental conditions of the application. A strain based performance threshold of 0.4% strain at 120 °C and 100% SMYS was used to develop a competitive program that ranked the participating systems and reduced the number of acceptable repairs from six down to three. This approach increased the efficiency of the full-scale testing and allowed for more in-depth analysis of the top-performing systems. The results of the full-scale testing of six composite repair systems at elevated temperature allowed for a quantitative measure of their effectiveness under in-situ conditions. Several of the systems were shown to provide inadequate reinforcement under these conditions; however, it was also observed that appropriately designed and installed systems are capable of meeting the intense demands of elevated temperature, harsh-service conditions.

Fabrication of Aluminum/Aluminum Nitride Composites by Reactive Mechanical Alloying

2007 ◽  
Vol 534-536 ◽  
pp. 181-184
Author(s):  
Seung Hoon Yu ◽  
Kwang Seon Shin
Keyword(s):  
Mechanical Properties ◽  
Mechanical Alloying ◽  
Elevated Temperatures ◽  
Hot Extrusion ◽  
Extrusion Process ◽  
Processing Technique ◽  
Compression Tests ◽  
Composite Powders ◽  
Al Matrix Composites

Various reactions and the in-situ formation of new phases can occur during the mechanical alloying process. In the present study, Al powders were strengthened by AlN, using the in-situ processing technique during mechanical alloying. Differential thermal analysis and X-ray diffraction studies were carried out in order to examine the formation behavior of AlN. It was found that the precursors of AlN were formed in the Al powders and transformed to AlN at temperatures above 600oC. The hot extrusion process was utilized to consolidate the composite powders. The composite powders were canned in an Al can and then extruded at elevated temperatures. The microstructure of the extrusions was examined by SEM and TEM. In order to investigate the mechanical properties of the extrusions, compression tests and hardness measurements were carried out. It was found that the mechanical properties and the thermal stability of the Al/AlN composites were significantly greater than those of conventional Al matrix composites.

scholarly journals Experimental investigation of the mechanical behaviour of soft carbonate rock/grout interfaces for the design of offshore wind turbines

2019 ◽  
Vol 92 ◽  
pp. 13006
Author(s):  
Eleni Stavropoulou ◽  
Christophe Dano ◽  
Marc Boulon
Keyword(s):  
Mechanical Properties ◽  
Wind Turbines ◽  
Mechanical Behaviour ◽  
Carbonate Rock ◽  
Offshore Wind ◽  
Normal Stiffness ◽  
Cyclic Shear ◽  
Shear Response ◽  
In Situ Conditions

Since a few years, in France, the development and construction of offshore wind farms in different sites of the country is investigated. The wind turbines will be installed in soft carbonate rock formations (calcarenite, limestone), the mechanical properties of which can vary in a significant way according to the location of the site. Once installed, the bored piles will be sealed with grout in the hosting rock. It is well known that the mechanical behaviour of piles is mainly governed by the behaviour of the interface at the contact between the structure and the hosting rock. The study of the mechanical behaviour of these interfaces, being the weakest points in terms of mechanical resistance, is of great importance for the improvement of the design methods of such infrastructures. The shear response of the rock/grout interface is studied with laboratory experiments in the 3SR lab (Grenoble). The interface's mechanical properties are characterised by a series of shear tests under Constant Normal Stiffness (CNS), these conditions being the most representative of the in-situ conditions. Interface samples of a roughness representative of the in-situ drilling traces, are tested under different levels of applied normal stiffness. The shear response is studied for both monotonic and cyclic shear paths, while all tests are performed under wet conditions. The failure mechanisms are explored, taking into account the contrasting mechanical properties of the two materials composing the interface, as well as, the evolution of the geometrical profile of the interface. The correlation between roughness and the mechanical response of the interface is investigated and the importance of an existing roughness is discussed.

Two-Dimensional Mapping of the Mechanical Properties of Pb-Free Solders for Reliability Optimization

2009 ◽  
Vol 6 (3) ◽  
pp. 182-185
Author(s):  
V. Marques ◽  
C. Johnston ◽  
P.S. Grant
Keyword(s):  
Mechanical Properties ◽  
Solder Joint ◽  
Elevated Temperatures ◽  
Constitutive Models ◽  
Processing Temperature ◽  
Reliability Optimization ◽  
Two Dimensional ◽  
Free Solder ◽  
Dimensional Mapping

The development of thermomechanical models of Pb-free solders is more complex than for Pb-Sn solders as a result of their higher reactivity and processing temperature that leads to the continuous evolution of stiff and angular intermetallics in the microstructure. In this paper, nanoindentation has been explored for its potential to characterize mechanically the complex microstructure of Pb-free solder joints. Hardness and Young's modulus of the various microphases in a Sn-Ag-Cu/Cu solder joint were characterized at 25°C and averages were obtained from nanoindentation maps composed of 100–200 indentations. The possibility to map mechanical property gradients across the various solder joint interfaces and to differentiate between different presentations of the same phase, including in situ at elevated temperatures, has been suggested to be useful in extending the available data for constitutive models used in reliability simulations of Pb-free solders.

An Artificial Material for Simulating Champlain Clays

1973 ◽  
Vol 10 (3) ◽  
pp. 489-503 ◽  
Author(s):  
F. A. Tavenas ◽  
M. Roy ◽  
P. La Rochelle
Keyword(s):  
Mechanical Properties ◽  
Effective Stress ◽  
Sampling Technique ◽  
Model Material ◽  
Compression Tests ◽  
Unconfined Compression ◽  
Failure Envelope ◽  
Synthetic Material ◽  
Strain Behavior

As part of an investigation on the behavior of Champlain clays, full scale penetrometer and vane tests had to be performed in the laboratory to observe the behavior of the soil during such tests. Since it was impossible to obtain samples of the necessary size, it was decided to develop a synthetic material which would model the mechanical properties of the Champlain clays.Such a model material has been defined. It consists of a mixture of kaolinite, bentonite, cement, and water. It is first shown to have a stress–strain behavior identical to that of the clay in unconfined compression tests, provided it is aged for 16 days. It is also shown to simulate very well all other mechanical properties of the Champlain clays, and more particularly the peculiar shape of the failure envelope in effective stress as well as the preconsolidation pressure.This material has been used successfully for laboratory penetrometer tests. It can also be used for the installation of instruments in situ or for the analysis of any testing or sampling technique.

Mechanical Properties of SS400 Steel Plate at Elevated Temperatures

2019 ◽  
Vol 889 ◽  
pp. 51-57
Author(s):  
Gia Hai Vuong ◽  
Nguyen Thi Hong Minh ◽  
Nguyen Duc Toan
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperatures ◽  
Steel Plate ◽  
Testing Machine ◽  
Heating System ◽  
Steel Plates ◽  
Test Results ◽  
Temperature Relation ◽  
Tensile Testing Machine ◽  
Temperature Conditions

This paper presents the experimental test results on mechanical properties of steel plate grade SS400 at elevated temperatures. The steel is often used as structural steel due to its weldability and machinability. The steel plates were heated by a high frequency heating system to reach specific temperatures before being tested on a tensile testing machine. Five different temperature conditions were used, namely room temperature, 100°C, 300°C, 500°C and 600°C. The data of mechanical properties measured for SS400 steel plates at various temperature conditions were recorded and analysed. The research showed that when the temperature is increased, the force in tensile test is decreased while the strain is increased. The observation and the data were then used to setup the stress – strain – temperature relation for formability study of SS400 steel plates. The same method can be used to establish the mechanical properties at elevated temperatures.

Microstructures and Mechanical Properties of NiAl+Mo In-Situ Eutectic Composites

1990 ◽  
Vol 194 ◽  
Author(s):  
P. R. Subramanian ◽  
M. G. Mendiratta ◽  
D. B. Miracle ◽  
D. M. Dimiduk
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
Room Temperature ◽  
Composite System ◽  
Elevated Temperatures ◽  
Two Phase ◽  
Structural Applications ◽  
Temperature Fracture

AbstractThe quasibinary NiAI-Mo system exhibits a large two-phase field between NiAl and the terminal (Mo) solid solution, and offers the potential for producing in-situ eutectic composites for high-temperature structural applications. The phase stability of this composite system was experimentally evaluated, following long-term exposures at elevated temperatures. Bend strengths as a function of temperature and room-temperature fracture toughness data are presented for selected NiA1-Mo alloys, together with results from fractography observations.

scholarly journals In Situ Formation of TiB2 in Fe-B System with Titanium Addition and Its Influence on Phase Composition, Sintering Process and Mechanical Properties

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4188
Author(s):  
Mateusz Skałoń ◽  
Marek Hebda ◽  
Benedikt Schrode ◽  
Roland Resel ◽  
Jan Kazior ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Phase Composition ◽  
Elevated Temperatures ◽  
Thermodynamic Calculations ◽  
X Ray Diffraction ◽  
Titanium Addition ◽  
Titanium Borides ◽  
Hard And Brittle Material ◽  
In Situ Formation

Interaction of iron and boron at elevated temperatures results in the formation of an E (Fe + Fe2B) eutectic phase that plays a great role in enhancing mass transport phenomena during thermal annealing and therefore in the densification of sintered compacts. When cooled down, this phase solidifies as interconnected hard and brittle material consisting of a continuous network of Fe2B borides formed at the grain boundaries. To increase ductile behaviour, a change in precipitates’ stoichiometry was investigated by partially replacing iron borides by titanium borides. The powder of elemental titanium was introduced to blend of iron and boron powders in order to induce TiB2 in situ formation. Titanium addition influence on microstructure, phase composition, density and mechanical properties was investigated. The observations were supported with thermodynamic calculations. The change in phase composition was analysed by means of dilatometry and X-ray diffraction (XRD) coupled with thermodynamic calculations.

Mechanical properties and strengthening effects of in situ (TiB+TiC)/Ti-1100 composite at elevated temperatures

2016 ◽  
Vol 654 ◽  
pp. 352-358 ◽  
Author(s):  
Fengcang Ma ◽  
Tianran Wang ◽  
Ping Liu ◽  
Wei Li ◽  
Xinkuan Liu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperatures
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