Numerous Experiment on Impact Compression of the Mixture of Graphite with Water

2017 ◽  
Keyword(s):  
Impact Compression ◽  
Numerous Experiment

Numerous experiment on impact compression of a mixture of graphite and water

2017 ◽  
Vol 53 (4) ◽  
pp. 471-478
Author(s):  
L. V. Shurshalov ◽  
A. A. Charakhch’yan ◽  
K. V. Khishchenko
Keyword(s):  
Impact Compression ◽  
Numerous Experiment

scholarly journals Lightweight Cement Conglomerates Based on End-of-Life Tire Rubber: Effect of the Grain Size, Dosage and Addition of Perlite on the Physical and Mechanical Properties

Materials ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 225
Author(s):  
Andrea Petrella ◽  
Michele Notarnicola
Keyword(s):  
Grain Size ◽  
End Of Life ◽  
Compression Tests ◽  
Tire Rubber ◽  
Impact Compression ◽  
Weight Percentage ◽  
Deep Groove ◽  
Mechanical Strengths ◽  
The Impact ◽  
Thermal Conductivities

Lightweight cement mortars containing end-of-life tire rubber (TR) as aggregate were prepared and characterized by rheological, thermal, mechanical, microstructural, and wetting tests. The mixtures were obtained after total replacement of the conventional sand aggregate with untreated TR with different grain sizes (0–2 mm and 2–4 mm) and distributions (25%, 32%, and 40% by weight). The mortars showed lower thermal conductivities (≈90%) with respect to the sand reference due to the differences in the conductivities of the two phases associated with the low density of the aggregates and, to a minor extent, to the lack of adhesion of tire to the cement paste (evidenced by microstructural detection). In this respect, a decrease of the thermal conductivities was observed with the increase of the TR weight percentage together with a decrease of fluidity of the fresh mixture and a decrease of the mechanical strengths. The addition of expanded perlite (P, 0–1 mm grain size) to the mixture allowed us to obtain mortars with an improvement of the mechanical strengths and negligible modification of the thermal properties. Moreover, in this case, a decrease of the thermal conductivities was observed with the increase of the P/TR dosage together with a decrease of fluidity and of the mechanical strengths. TR mortars showed discrete cracks after failure without separation of the two parts of the specimens, and similar results were observed in the case of the perlite/TR samples thanks to the rubber particles bridging the crack faces. The super-elastic properties of the specimens were also observed in the impact compression tests in which the best performances of the tire and P/TR composites were evidenced by a deep groove before complete failure. Moreover, these mortars showed very low water penetration through the surface and also through the bulk of the samples thanks to the hydrophobic nature of the end-of-life aggregate, which makes these environmentally sustainable materials suitable for indoor and outdoor elements.

P071 Osteoid osteoma in children: About 15 cases

Rheumatology ◽  
2021 ◽  
Vol 60 (Supplement_5) ◽  
Author(s):  
N Khernane ◽  
S Fortas ◽  
M M Makhloufi ◽  
T Boussaha
Keyword(s):  
Femoral Neck ◽  
Ct Scan ◽  
Vertebral Body ◽  
Osteoid Osteoma ◽  
Lower Limbs ◽  
Bone Tumours ◽  
Lumbar Pain ◽  
Surgical Removal ◽  
Posterior Arch ◽  
Impact Compression

Abstract Background Osteoid osteoma (OO)also called osteoblastoma, if the localization is in the spine, is a benign osteoblastic tumor of variable clinical expression, depending on the location of the lesion. It represents 2% to 3% of bone tumours and 15% of benign bone tumours in children. It affects mainly older children and adolescents and most often occurs in the lower limb, especially the femur. The diagnosis is radio-clinical. The aim of this study is to demonstrate the effectiveness of surgical removal of the tumor, the therapeutic difficulty in certain osteoarticular localizations and finally the radio-clinical evolution after surgery. Material & methods We report the radio-clinical outcomes of a series of 15 children (4 girls/11 boys; aged of 03–14 years) with OO operated in our department, over a period of 08 years (2011–2019). Results The OO is located in most of cases of the lower limbs: acetabulum (1 case); femoral neck (3 cases); femoral diaphysis (2 cases); tibial diaphysis (4 cases); distal metaphysis of the tibia (1 case); talus (1 case) and in the spine (3 cases: vertebral body of T3, the posterior arch of T12 and the sacrum S3). Nocturnal pain yielding to aspirin, was the main symptom. It was associated with lameness when walking in patients with location of OO in the lower limbs. Diagnosis was delayed in patients with localization of OO in the spine (after 3 years) and in the talus (after 2 years). Imaging (standard Rx, CT scan and MRI) allowed the diagnosis of OO in all cases (nidus and cocarde image) and assessed the loco-regional impact (compression of the spinal canal in the sacral location; eccentricity of the femoral epiphysis, in the acetabular location, scoliosis in the spinal location). Thirteen children received surgical treatment under fluoroscopic guidance, which consisted of: A surgical abstention was decided in 2 cases: an inaccessible location at the bottom of the acetabulum and the T3 thoracic vertebral body localization in a 6-year-old girl. 12 operated children have good outcomes. However, 03 children experienced post-therapy problems: lumbar pain radiating towards the left thigh in the girl with sacral location (S3) despite the large laminectomy; a relapse 7 months later in the child with the femoral neck localization; A valgus misalignment of the right knee after removal of the OO of the proximal metaphysis of the tibia with a relapse 3 months later. Conclusion OO is a rare, benign tumor. However, certain locations can lead to diagnostic difficulties, loco-regional, organic and functional repercussions and certain constraints on their therapeutic management. Modern imaging helps to improve the care of these patients, both in terms of early diagnosis (scintigraphy, CT scan and MRI) and therapeutic precision (photo-coagulation, radiofrequency ablation).

scholarly journals Blasting-Induced Permeability Enhancement of Ore Deposits Associated with Low-Permeability Weakly Weathered Granites Based on the Split Hopkinson Pressure Bar

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Lei Yan ◽  
Wenhua Yi ◽  
Liansheng Liu ◽  
Jiangchao Liu ◽  
Shenghui Zhang
Keyword(s):  
Split Hopkinson Pressure Bar ◽  
Deformation Modulus ◽  
Constant Speed ◽  
Initial Porosity ◽  
Peak Strain ◽  
Variable Speed ◽  
Hopkinson Pressure Bar ◽  
Impact Compression ◽  
Split Hopkinson ◽  
Pressure Bar

By utilizing the improved split Hopkinson pressure bar (SHPB) test device, uniaxial, constant-speed cyclic, and variable-speed cyclic impact compression tests were conducted on weakly weathered granite samples. By combining nuclear magnetic resonance (NMR) and triaxial seepage tests, this study investigated the change laws in the mechanical properties, porosity evolution, and permeability coefficients of the samples under cyclic impacts. The results showed that in constant-speed cyclic impacts with increasing impact times, deformation modulus decreased, whilst porosity firstly decreased and then increased. Furthermore, dynamic peak strength firstly increased and then decreased whereas peak strain constantly increased before failure of the samples. In the variable-speed cyclic impacts, as impact times increased, deformation modulus firstly increased and then declined with damage occurring after four impact times. The compaction process weakened and even disappeared with increasing initial porosity. Three types of pores were found in the samples that changed in multiscale under cyclic loading. In general, small pores extended to medium- and large-sized pores. After three variable-speed cyclic impacts, the porosity of the samples was larger than the initial porosity and the permeability coefficient was greater than its initial value. The results demonstrate that the purpose of enhancing permeability and keeping the ore body stable can be achieved by conducting three variable-speed cyclic impacts on the samples.

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