scholarly journals Engineering Reactive Clay Systems by Ground Rubber Replacement and Polyacrylamide Treatment

Polymers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1675 ◽  
Author(s):  
Amin Soltani ◽  
An Deng ◽  
Abbas Taheri ◽  
Brendan C. O’Kelly
Keyword(s):  
Soil Aggregate ◽  
Experimental Program ◽  
Second Phase ◽  
Expansive Clay ◽  
Stress Strain ◽  
Sediment Volume ◽  
Ground Rubber ◽  
Resistance To Sliding ◽  
Volume Properties ◽  
Overall Resistance

This study investigates the combined performance of ground rubber (GR), the additive, and polyacrylamide (PAM), the binder, as a sustainable solution towards ameliorating the inferior geotechnical attributes of an expansive clay. The first phase of the experimental program examined the effects of PAM concentration on the soil’s mechanical properties—consistency, sediment volume attributes, compactability, unconfined compressive strength (UCS), reactivity and microstructure features. The second phase investigated the effects of GR content, with and without the optimum PAM concentration. An increase in PAM beyond 0.2 g/L, the identified optimum concentration, caused the excess PAM to act as a lubricant rather than a flocculant. This feature facilitated reduced overall resistance to sliding of soil particles relative to each other, thereby adversely influencing the improvement in stress–strain–strength response achieved for ≤0.2 g/L PAM. This transitional mechanism was further verified by the consistency limits and sediment volume properties, both of which exhibited only minor variations beyond 0.2 g/L PAM. The greater the GR content, the higher the mobilized UCS up to 10% GR, beyond which the dominant GR-to-GR interaction (i.e., rubber-clustering) adversely influenced the stress–strain–strength response. Reduction in the soil’s swell–shrink capacity, however, was consistently in favor of higher GR contents. Addition of PAM to the GR-blended samples amended the soil aggregate–GR connection interface, thereby achieving further improvements in the soil’s UCS and volume change behaviors. A maximum GR content of 20%, paired with 0.2 g/L PAM, managed to satisfy a major decrease in the swell–shrink capacity while improving the strength-related features, and thus was deemed as the optimum choice.

Mechanical Characterization of Assemblies Bonded With Pressure-Sensitive Adhesives (PSAs)

2015 ◽  
Author(s):  
Hao Huang ◽  
Abhijit Dasgupta ◽  
Ehsan Mirbagheri ◽  
Srini Boddapati
Keyword(s):  
Mechanical Behavior ◽  
Failure Modes ◽  
Mechanical Characterization ◽  
Bonding Temperature ◽  
Process Conditions ◽  
Second Phase ◽  
Loading Conditions ◽  
Stress Strain ◽  
Strain Behavior ◽  
Pressure Sensitive

The focus of this paper is on the stress-strain behavior and creep response of a pressure-sensitive adhesive (PSA) with and without carrier layers. This study consists of two phases. The first phase focuses on understanding of the effects of fabrication profiles, including bonding pressure, bonding temperature, bonding time, and aging time, on the PSA joint strength. This part of the study is used to identify an acceptable bonding and aging conditions for manufacturing a robust PSA bonded assembly. Specimens fabricated with this selected set of bonding process conditions are then used for mechanical characterization. The second phase focuses on the assembly’s mechanical behavior (stress-strain behavior and the creep curves) under different loading conditions, including loading stress, loading rate, and loading temperature. The mechanical behavior of PSA bonded assemblies is affected not only by the loading conditions, but also by the assembly architecture. The mechanical behaviors and failure modes of PSAs with and without carrier layers are compared. The reasons for these differences are also discussed.

Macroscopic and Microscopic Properties of High Performance Concrete with Partial Replacement of Cement by Fly Ash

2019 ◽  
Vol 292 ◽  
pp. 108-113 ◽  
Author(s):  
Josef Fládr ◽  
Petr Bílý ◽  
Roman Chylík ◽  
Zdeněk Prošek
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
Fly Ash ◽  
High Performance ◽  
High Performance Concrete ◽  
Partial Replacement ◽  
Experimental Program ◽  
Second Phase ◽  
Depth Of Penetration ◽  
Cement Replacement

The paper describes an experimental program focused on the research of high performance concrete with partial replacement of cement by fly ash. Four mixtures were investigated: reference mixture and mixtures with 10 %, 20 % and 30 % cement weight replaced by fly ash. In the first stage, the effect of cement replacement was observed. The second phase aimed at the influence of homogenization process for the selected 30% replacement on concrete properties. The analysis of macroscopic properties followed compressive strength, elastic modulus and depth of penetration of water under pressure. Microscopic analysis concentrated on the study of elastic modulus, porosity and mineralogical composition of cement matrix using scanning electron microscopy, spectral analysis and nanoindentation. The macroscopic results showed that the replacement of cement by fly ash notably improved compressive strength of concrete and significantly decreased the depth of penetration of water under pressure, while the improvement rate increased with increasing cement replacement (strength improved by 18 %, depth of penetration by 95 % at 30% replacement). Static elastic modulus was practically unaffected. Microscopic investigation showed impact of fly ash on both structure and phase mechanical performance of the material.

Comparisons of Monotonic, Low-Cycle and Ultra-Low-Cycle Fatigue Behaviours of X52, X60 and X65 Piping Steel Grades

2014 ◽  
Author(s):  
J. C. R. Pereira ◽  
A. M. P. de Jesus ◽  
A. A. Fernandes ◽  
J. Xavier ◽  
B. Martins
Keyword(s):  
Low Cycle Fatigue ◽  
High Amplitude ◽  
Optical Methods ◽  
Experimental Program ◽  
Cycle Fatigue ◽  
Stress Strain ◽  
Deformation Localization ◽  
Damage Models ◽  
Steel Grades ◽  
Cyclic Plastic Strain

Seismic actions, settlements and landslides, accidental loads, fluctuations in the layers of permafrost and pipelines reeling induce large plastic deformations, with widespread yielding in the pipelines which may lead to failure, either due to monotonic loading or due to cyclic plastic strain fluctuations with high amplitude and short duration (Nf<∼100 cycles). The damage mechanisms from the high intensity cyclic loading show distinct mechanisms from the monotonic and low-cycle fatigue (LCF) (∼100<Nf<∼10000cycles). This fatigue domain is often called ultra-low-cycle fatigue (ULCF) or extreme-low-cycle fatigue (ELCF), in order to distinguish it from LCF. Despite of monotonic ductile fracture and LCF have been subjected to significant research efforts and a satisfactory understanding of these damaging phenomena has been already established, ULCF regime is not sufficiently investigated nor understood. Consequently, further advances should be done since the data available in literature is scarce for this fatigue regime. In addition, the performance of ULCF tests is very challenging and there is no specific help from standards available in literature. In this work, the performance of X52, X60 and X65 API steel grades under monotonic, LCF and ULCF loading conditions are investigated. An experimental program was carried out to derive monotonic, LCF and ULCF data for three piping steel grades. Typical smooth geometries are susceptive to instability under ULCF tests. To overcome or minimize this shortcoming anti-buckling devices may be used in the ULCF tests. The use of notched specimens facilitates the deformation localization and therefore contributes to overcome the instability problems. However, the non-uniform stress/strain states raise difficulties concerning the analysis of the experimental data, requiring the use of multiaxial stress/strain parameters. Optical methods and non-linear finite element models were used to assess the strain and stress histories at critical locations, which are used to assess some damage models.

Flexural Behavior of Prestressed UHPC Beams

2011 ◽  
Vol 243-249 ◽  
pp. 1145-1155
Author(s):  
Jian Yang ◽  
Zhi Fang ◽  
Gong Lian Dai
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Strain Curve ◽  
Flexural Behavior ◽  
Experimental Program ◽  
Ultra High Performance Concrete ◽  
Stress Strain ◽  
Flexural Response ◽  
Strain Relationship ◽  
Relationship Of

Ultra High Performance Concrete (UHPC), which has very special properties that are remarkably different to the properties of normal and high performance concrete, is being increasingly used for the construction of structure. In this paper, an experimental program was formulated to investigate the characteristics of complete stress-strain curve of UHPC in uniaxial compression and flexural behaviors of prestressed UHPC beams. The particular focus was the influence of the partial prestress ratio and jacking stress on the flexural response of UHPC beams. The results show that UHPC is of good deformability, and a general form of the serpentine curve is proposed to represent the complete stress-strain relationship of UHPC in compression. The tests of beams demonstrated that the UHPC beams have an excellent behavior in load carrying capacity, crack distribution and deformability, their ultimate deflection can reach 1/34～1/70 of the span. Based on this investigation, theoretical correlations for the prediction structure response of UHPC beam are proposed.

Thermo-Mechanical Fatigue of the Nickel Base Superalloy IN738LC for Gas Turbine Blades

2006 ◽  
Vol 321-323 ◽  
pp. 509-512 ◽  
Author(s):  
Jung Seob Hyun ◽  
Gee Wook Song ◽  
Young Shin Lee
Keyword(s):  
Gas Turbine ◽  
Turbine Blades ◽  
Material Behavior ◽  
Experimental Program ◽  
Nickel Base Superalloy ◽  
Strain History ◽  
Stress Strain ◽  
Mechanical Fatigue ◽  
Nickel Base ◽  
Base Superalloy

A more accurate life prediction for gas turbine blade takes into account the material behavior under the complex thermo-mechanical fatigue (TMF) cycles normally encountered in turbine operation. An experimental program has been carried out to address the thermo-mechanical fatigue life of the IN738LC nickel-base superalloy. High temperature out-of-phase and in-phase TMF experiments in strain control were performed on superalloy materials. Temperature interval of 450-850 was applied to thermo-mechanical fatigue tests. The stress-strain response and the life cycle of the material were measured during the test. The mechanisms of TMF damage is discussed based on the microstructural evolution during TMF. The plastic strain energy based life pediction models were applied to the stress-strain history effect on the thermo-mechanical fatigue lives.

Monotonic, Low-Cycle Fatigue, and Ultralow-Cycle Fatigue Behaviors of the X52, X60, and X65 Piping Steel Grades

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
J. C. R. Pereira ◽  
A. M. P. de Jesus ◽  
A. A. Fernandes ◽  
G. Varelis
Keyword(s):  
Low Cycle Fatigue ◽  
High Amplitude ◽  
Optical Methods ◽  
Cyclic Plasticity ◽  
Experimental Program ◽  
Cycle Fatigue ◽  
Stress Strain ◽  
Deformation Localization ◽  
Damage Models ◽  
Steel Grades

Seismic actions, soil settlements and landslides, fluctuations in permafrost layers, accidental loads, and reeling are responsible for large plastic deformations and widespread yielding of pipelines, which may lead to damage or failure, either due to monotonic loading or cyclic plastic strain fluctuations of high amplitude and short duration (e.g., Ni < ∼100 cycles). The damage associated to high intensity cyclic plasticity shows a combination of distinct mechanisms typical of both monotonic and low-cycle fatigue (LCF) (∼102 < Ni < ∼104 cycles) damage regimes. This fatigue domain is often called ultralow-cycle fatigue (ULCF) or extreme-low-cycle fatigue, in order to distinguish it from LCF. Despite monotonic ductile fracture and LCF have been subjected to significant research efforts and a satisfactory level of understanding of these phenomena has been already established, ULCF is neither sufficiently investigated nor understood. Consequently, further advances should be done since the data available in literature is scarce for this fatigue regime. In addition, ULCF tests are very challenging and there are no specific standards available in literature providing guidance. In this work, the performances of the X52, X60, and X65 API steel grades under monotonic, LCF, and ULCF loading conditions are investigated by means of an experimental program. Smooth specimens are susceptive to instability under ULCF tests. To overcome or minimize this shortcoming, antibuckling devices may be used in the ULCF tests. The use of notched specimens facilitates the deformation localization and therefore contributes to overcome the instability problems. However, the nonuniform stress/strain states raise difficulties concerning the analysis of the experimental data, requiring the use of multiaxial stress/strain parameters. Optical methods and nonlinear finite-element models were used to assess the strain and stress histories at critical locations, which were used to assess some existing damage models.

scholarly journals Volume Changes and Mechanical Properties of Expansive Mudstone below Canals under Wet-Dry/Wet-Dry-Freeze-Thaw Cycles

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Rui Zhu ◽  
Ying-hao Huang ◽  
Zhu Song ◽  
Feng Zhou
Keyword(s):  
Volume Change ◽  
Northern China ◽  
Volume Measurement ◽  
Experimental Program ◽  
Failure Strength ◽  
Test Results ◽  
Compression Tests ◽  
Volume Changes ◽  
Stress Strain ◽  
Freeze Thaw

The complex environment in northern China is the main reason for degradation of expansive mudstone below the canals, which resulted in instability and damage of canal slopes. In this study, a serial of laboratory tests was conducted to explore the volume changes and mechanical behaviors of expansive mudstone below the canals in Xinjiang. The experimental program includes wet-dry (WD) and wet-dry-freeze-thaw (WDFT) tests, volume measurement, and unconfined compression tests. The test results show that during the WD cycles, the volume changes of expansive mudstones with a higher dry range would be more significant. The freeze-thaw process in the WDFT cycles resulted in a decrease of volume change ranges when the expansive mudstones had a relatively smaller dry range and a slight increase of volume change ranges when the expansive mudstones had a relatively larger dry range. In the meantime, the stress-strain relationships of expansive mudstones with different dry ranges all presented strain softening under the cycles of WD or WDFT. The first cycle resulted in a significant decrease of failure strength. After seven WD/WDFT cycles, the failure strength of expansive mudstones with different dry ranges decreased by 37.2%∼59.1%. In addition, the freeze-thaw process in the WDFT cycles promoted the softening of the stress-strain relationships and aggravated the failure strength attenuation of expansive mudstones. Through this study, we expect to provide a preliminary basis for the construction and maintenance of expansive mudstone canals in Xinjiang.

Properties of self-compacting concrete containing granite dust particles

2019 ◽  
Vol 10 (2) ◽  
pp. 34
Author(s):  
Joseph Abah Apeh
Keyword(s):  
Carbon Dioxide Emission ◽  
Tensile Tests ◽  
Dust Particles ◽  
Partial Replacement ◽  
Experimental Program ◽  
Second Phase ◽  
Self Compacting Concrete ◽  
Suitable Material ◽  
Hardened Properties ◽  
Quarry Dust

In the course of production in the Granite Industry, a lot of quarry dust wastes is generated which is either heaped at sites causing environmental and health hazards or dumped in landfills causing ecological problems. It is imperative to evolve a viable option for disposal so to rid the environment of this menace. This study investigated the use of quarry dust particles (QDP) generated from the granite industry as a cement replacement in self-compacting concrete (SCC). The experimental program was carried out in two phases: the first phase optimized the amount of QDP as replacement of Portland cement (PC) with acceptable flow-ability. The second phase evaluated the fresh and hardened properties of SCC which include tests on slump flow, J-ring and L-box to determine filling, passing abilities of SCC while compression and splitting tensile tests were conducted to determine the compressive and splitting tensile strengths, respectively. Test results show that at 20% replacement of cement with QDP, the SCC-QDP mixes has a slump ranged from 642 to 730 mm compared with 578 mm for SCC mix, a compressive strength of 37 N/mm2 compared with 30 N/mm2 for SCC. This was enhanced by QDP which filled the voids between the coarse grains of cement and water molecules which facilitated the flow ability of the mixes and then at later ages reacted with liberated calcium hydroxide from cement hydration to enhance the strength of the mixes. The results then indicated that QDP can be used to replace PC up to 20% by mass of PC in the production of SCC without adverse effect on both fresh and hardened properties. This results also show that QDP, a suitable material for partial replacement of PC in SCC production, can be used to reduce demand for cement thus reducing carbon dioxide emission and also solve other environmental problems.

Comparison of Stress-Strain Diagrams in Different Age of the Cement Matrix for Textile Reinforced Concrete

2015 ◽  
Vol 824 ◽  
pp. 155-159 ◽  
Author(s):  
Filip Vogel ◽  
Ondřej Holčapek ◽  
Petr Konvalinka
Keyword(s):  
Reinforced Concrete ◽  
Load Force ◽  
Experimental Program ◽  
Cement Matrix ◽  
Textile Reinforced Concrete ◽  
Stress Strain ◽  
Ordinary Concrete ◽  
Deformation Speed ◽  
Reinforced Cement ◽  
C 30

This article deals with cement matrix for the textile reinforced concrete. It is necessary to know maximum of the mechanical properties of cement matrix for using textile reinforced concrete. The main topic of this article is to determine stress-strain diagrams at various age of the cement matrix. The compressive strength of the cement matrix was determined by using cube specimens (100 x 100 x 100 mm). The cement matrix, steel fibre reinforced cement matrix and ordinary concrete C 30/37 were tested at age 12 and 18 hours and 1, 7, 28 and 45 days. Cubes were tested in one-axial press. Loading of cubes was controlled by increase of deformation. Speed of loading was 0.008 mm/s. Time, load force and deformation were recorded for determination stress strain diagrams. The results of the experimental program and stress-strain diagrams were compared with each other in conclusion of this article.

Sign in / Sign up

Export Citation Format

Share Document