Effect of Ageing Period on Properties of Mechanically Activated Portland Cement

2018 ◽  
Vol 760 ◽  
pp. 37-42
Author(s):  
Karel Dvořák ◽  
Matěj Švéda
Keyword(s):  
Mechanical Properties ◽  
Portland Cement ◽  
Mechanical Activation ◽  
Aging Time ◽  
Ball Mill ◽  
High Speed ◽  
Aging Period ◽  
High Speed Grinding ◽  
Ageing Period ◽  
The Moment

This experiment describes the effects of the aging time since the moment of milling to Portland cements physico-mechanical properties. Possible mechanical activation effects to Portland cement particles has been found. For this experiment two kind of milling technology were used, the conventional milling in a ball mill and high-speed grinding technology in high speed disintegrator and influence of these technologies was also described. The aging period of the cement influences in particular physico-mechanical properties in the early stages of hydration but the final properties after 28 days were not influenced.

scholarly journals Effect of mechanical activation on the properties of Portland cement

2021 ◽  
Vol 1205 (1) ◽  
pp. 012003
Author(s):  
S Ravaszová ◽  
K Dvořák
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Mechanical Activation ◽  
Ball Mill ◽  
High Speed ◽  
Activation Effect ◽  
Cement Production ◽  
Grinding Method ◽  
Ground Material ◽  
Mechanical Activation Effect

Abstract The paper deals with the mechanical activation of cement by grinding in a high-speed mill, and compares the parameters found with the commonly used grinding method in cement production, which uses grinding of cement by means of a ball mill. The aim is to verify the influence of the aging time of the ground material on the preservation of the mechanical activation effect and on the properties of the final product at different stages of hydration. It evaluates the physical-mechanical properties, the compressive and tensile strength after 1, 2, 7, 14 and 28 days, as well as the course of the hydration process. The evaluated results suggest the existence of mechanical activation, but this effect is very difficult to achieve and depends on many other factors.

scholarly journals Investigation of the Impact of Aging Upon the Mechanical Properties of Cocoa Pod Husk

2021 ◽  
Vol 37 (2) ◽  
pp. 146-165
Author(s):  
Renique Murray ◽  
Sanjay Bachu ◽  
Cilla Pemberton ◽  
Robert Birch
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Cutting Force ◽  
Aging Time ◽  
Correlation Coefficients ◽  
Raw Material ◽  
Aging Period ◽  
Cocoa Pod Husk ◽  
New Research ◽  
The Impact

The husk of fresh cocoa pods has traditionally been considered a waste by-product in the production of chocolate and other related confectionaries. However, in recent times new research has shed light on an  increasing number of uses for this material. Of particular interest are applications that utilize the cocoa pod husk (CPH) for its mechanical properties. In most instances, the CPH raw material is allowed to age for several days before pre-processing or utilization in the intended application. Despite this, the impact of aging on its mechanical properties is an area that has not been well investigated. Consequently, this work seeksto determine the impact of aging upon the mechanical properties of CPH. To investigate this, several CPH properties were identified and selected for evaluation. These included CPH tensile strength, CPH compressive strength, cocoa pod transverse compressive strength, cocoa pod longitudinal compressive strength, CPH cutting force, cocoa pod cutting force, CPH hardness, and CPH colour. These properties were subsequently assessed over an aging period of seven days. The results obtained indicated that most CPH mechanical properties vary significantly with aging time. Moreover, CPH colour was found to bestrongly related to the mechanical properties of pod longitudinal compressive strength and CPH hardness, with correlation coefficients of -0.71 and 0.86 respectively. Further, these relationships were found to be strongly linear in nature and regression analyses indicated that up to 83% of the variation in longitudinal compressive  strength can be accounted for by changes in colour, hardness and aging time. These results provide the basis for the potential development of image analysis and computer vision approaches to CPH sorting and grading.

Influence of Different Grinding Types on Granulometry of Cement Grains

2014 ◽  
Vol 897 ◽  
pp. 34-38 ◽  
Author(s):  
Karel Dvořák
Keyword(s):  
Portland Cement ◽  
Ball Mill ◽  
High Speed ◽  
Cement Grinding ◽  
Shape And Size

This work is opening study in issue of potential utilization of high-speed shredder for portland cement grinding. The article deals with comparison the influence of traditional ball mill with high-speed shredder on shape and size of grains.

Influence of Recycled Materials on Resulting Mechanical Properties of Cement Composites

2016 ◽  
Vol 825 ◽  
pp. 53-56
Author(s):  
Zdeněk Prošek ◽  
Jaroslav Topič ◽  
Jan Trejbal ◽  
Karel Šeps ◽  
Pavel Tesárek
Keyword(s):  
Mechanical Properties ◽  
High Speed ◽  
Resonance Method ◽  
Recycled Concrete ◽  
Silica Sand ◽  
Destructive Testing ◽  
Recycled Materials ◽  
High Speed Grinding ◽  
Marble Powder ◽  
Non Destructive

This article presents the mechanical properties of composite materials based on recycled materials which differ in their composition – type of recycled materials. Dynamic modulus of elasticity was monitored during the first 28 days since manufacture by use of non-destructive testing (resonance method). Flexural strength and compressive strength were determined for the 28 days old specimens. The aim of this article was to determine the influence of type and amount of recycled material on the resulting mechanical properties. Mixtures with 3 different microground materials (recycled concrete, marble powder and silica sand) were tested. Microground materials were produced in the company Lavaris (Czech Republic) by use of high speed grinding. The results obtained from these materials were compared with reference material – cement mortar.

Influence of ageing treatment on microstructure, mechanical properties and adhesive wear behaviour of 6063 aluminium alloy

2014 ◽  
Vol 66 (4) ◽  
pp. 520-524 ◽  
Author(s):  
Serkan Büyükdoğan ◽  
Süleyman Gündüz ◽  
Mustafa Türkmen
Keyword(s):  
Mechanical Properties ◽  
Wear Resistance ◽  
High Speed ◽  
Al Alloys ◽  
Wear Behaviour ◽  
Al Alloy ◽  
Strain Ageing ◽  
Content Type ◽  
Static Strain ◽  
Structural Applications

Purpose – The paper aims to provide new observations about static strain ageing in aluminium (Al) alloys which are widely used in structural applications. Design/methodology/approach – The present work aims to provide theoretical and practical information to industries or researchers who may be interested in the effect of static strain ageing on mechanical properties of Al alloys. The data are sorted into the following sections: introduction, materials and experimental procedure, results and discussion and conclusions. Findings – Tensile strength, proof strength (0.2 per cent) and percentage elongation measurement were used to investigate the effect of strain ageing on the mechanical properties. Wear tests were performed by sliding the pin specimens, which were prepared from as-received, solution heat-treated, deformed and undeformed specimens after ageing, on high-speed tool steel (64 HRC). It is concluded that the variations in ageing time improved the strength and wear resistance of the 6063 Al alloy; however, a plastically deformed solution-treated alloy has higher strength and wear resistance than undeformed specimens for different ageing times at 180°C. Practical implications – A very useful source of information for industries using or planning to produce Al alloys. Originality/value – This paper fulfils an identified resource need and offers practical help to the industries.

scholarly journals Fiber Formation and Structural Development of HBA/HNA Thermotropic Liquid Crystalline Polymer in High-Speed Melt Spinning

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1134
Author(s):  
Bo Seok Song ◽  
Jun Young Lee ◽  
Sun Hwa Jang ◽  
Wan-Gyu Hahm
Keyword(s):  
Mechanical Properties ◽  
Shear Rate ◽  
High Speed ◽  
Melt Spinning ◽  
Liquid Crystalline Polymer ◽  
Liquid Crystalline ◽  
Crystalline Polymer ◽  
Fiber Formation ◽  
Structural Development ◽  
Thermotropic Liquid Crystalline Polymer

High-speed melt spinning of thermotropic liquid crystalline polymer (TLCP) resin composed of 4-hydroxybenzoic acid (HBA) and 2-hydroxy-6-napthoic acid (HNA) monomers in a molar ratio of 73/27 was conducted to investigate the characteristic structure development of the fibers under industrial spinning conditions, and the obtained as-spun TLCP fibers were analyzed in detail. The tensile strength and modulus of the fibers increased with shear rate in nozzle hole, draft in spin-line and spinning temperature and exhibited the high values of approximately 1.1 and 63 GPa, respectively, comparable to those of industrial as-spun TLCP fibers, at a shear rate of 70,000 s−1 and a draft of 25. X-ray diffraction demonstrated that the mechanical properties of the fibers increased with the crystalline orientation factor (fc) and the fractions of highly oriented crystalline and non-crystalline anisotropic phases. The results of structure analysis indicated that a characteristic skin–core structure developed at high drafts (i.e., spinning velocity) and low spinning temperatures, which contributed to weakening the mechanical properties of the TLCP fibers. It is supposed that this heterogeneous structure in the cross-section of the fibers was induced by differences in the cooling rates of the skin and core of the fiber in the spin-line.

scholarly journals Enhanced electrical conductivity and mechanical properties in thermally stable fine-grained copper wire

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Qingzhong Mao ◽  
Yusheng Zhang ◽  
Yazhou Guo ◽  
Yonghao Zhao
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Electrical Conductivity ◽  
Yield Strength ◽  
High Speed ◽  
Copper Wire ◽  
Rapid Development ◽  
Dislocation Slip ◽  
Ultrafine Grains ◽  
The Wire

AbstractThe rapid development of high-speed rail requires copper contact wire that simultaneously possesses excellent electrical conductivity, thermal stability and mechanical properties. Unfortunately, these are generally mutually exclusive properties. Here, we demonstrate directional optimization of microstructure and overcome the strength-conductivity tradeoff in copper wire. We use rotary swaging to prepare copper wire with a fiber texture and long ultrafine grains aligned along the wire axis. The wire exhibits a high electrical conductivity of 97% of the international annealed copper standard (IACS), a yield strength of over 450 MPa, high impact and wear resistances, and thermal stability of up to 573 K for 1 h. Subsequent annealing enhances the conductivity to 103 % of IACS while maintaining a yield strength above 380 MPa. The long grains provide a channel for free electrons, while the low-angle grain boundaries between ultrafine grains block dislocation slip and crack propagation, and lower the ability for boundary migration.

Simulation and Experiment on the Residual Stress in Super-High Speed Grinding

2010 ◽  
Vol 135 ◽  
pp. 238-242
Author(s):  
Yue Ming Liu ◽  
Ya Dong Gong ◽  
Wei Ding ◽  
Ting Chao Han
Keyword(s):  
Residual Stress ◽  
High Speed ◽  
Element Model ◽  
Residual Stress Distribution ◽  
X Ray Diffraction ◽  
Machined Surface ◽  
X Ray ◽  
High Speed Grinding ◽  
Simulation And Experiment ◽  
Cylindrical Workpiece

In this paper, effective finite element model have been developed to simulation the plastic deformation cutting in the process for a single particle via the software of ABAQUS, observing the residual stress distribution in the machined surface, the experiment of grinding cylindrical workpiece has been brought in the test of super-high speed grinding, researching the residual stress under the machined surface by the method of X-ray diffraction, which can explore the different stresses from different super-high speed in actual, and help to analyze the means of reducing the residual stresses in theory.

scholarly journals Texture and mechanical properties of Cu alloy by cryogenic high-speed rolling

2021 ◽  
Vol 1121 (1) ◽  
pp. 012009
Author(s):  
S Lee ◽  
R Muchime ◽  
R Matsumoto ◽  
H Utsunomiya
Keyword(s):  
Mechanical Properties ◽  
High Speed ◽  
Cu Alloy
Sign in / Sign up

Export Citation Format

Share Document