scholarly journals Mechanical Performance Evaluation of Self-Compacting Concrete with Fine and Coarse Recycled Aggregates from the Precast Industry

Materials ◽  
2017 ◽  
Vol 10 (8) ◽  
pp. 904 ◽  
Author(s):  
Sara Santos ◽  
Pedro da Silva ◽  
Jorge de Brito
Keyword(s):  
Performance Evaluation ◽  
Mechanical Performance ◽  
Recycled Aggregates ◽  
Self Compacting Concrete

scholarly journals Preparation and Performance Evaluation of Duotone 3D-Printed Polyetheretherketone as Oral Prosthetic Materials: A Proof-of-Concept Study

Polymers ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1949
Author(s):  
Ling Ding ◽  
Wei Lu ◽  
Jiaqi Zhang ◽  
Chuncheng Yang ◽  
Guofeng Wu
Keyword(s):  
Titanium Dioxide ◽  
Performance Evaluation ◽  
Mechanical Performance ◽  
Mechanical Tests ◽  
Flexural Properties ◽  
Proof Of Concept ◽  
Tooth Color ◽  
Dental Application ◽  
3D Printed ◽  
And Performance

Literature has reported the successful use of 3D printed polyetheretherketone (PEEK) to fabricate human body implants and oral prostheses. However, the current 3D printed PEEK (brown color) cannot mimic the vivid color of oral tissues and thus cannot meet the esthetical need for dental application. Therefore, titanium dioxide (TiO2) and ferric oxide (Fe2O3) were incorporated into PEEK to prepare a series of tooth-color and gingival-color PEEK composites in this study. Through color measurements and mechanical tests, the color value and mechanical performance of the 3D printed PEEK composites were evaluated. In addition, duotone PEEK specimens were printed by a double nozzle with an interface between tooth-color and gingival-color parts. The mechanical performance of duotone PEEK with two different interfaces (horizontal and vertical) was investigated. With the addition of TiO2 and Fe2O3, the colors of 3D printed PEEK composites become closer to that of dental shade guides. 3D printed PEEK composites generally demonstrated superior tensile and flexural properties and hence have great potential in the dental application. In addition, duotone 3D printed PEEK with a horizontal interfacial orientation presented better mechanical performance than that with a vertical one.

The Mechanical Performance Evaluation of a Mechanism with Curved Edge Driving Component

2013 ◽  
Vol 834-836 ◽  
pp. 1290-1294
Author(s):  
Xin Qin Liu
Keyword(s):  
Performance Evaluation ◽  
Fast Moving ◽  
Mechanical Performance ◽  
Gain Coefficient ◽  
The Other ◽  
Force Transmission ◽  
Transmission Performance ◽  
Connecting Rod ◽  
Numerical Examples ◽  
Straight Line

Mechanicalmethods were employed to study the motion and force transmission performance ofa kind of connecting rod slider mechanism with a curved edge driving component.The deduction methods and the computation formulae of the slider displacement,velocity, acceleration and the executive force gain coefficient were given.Considering two cases of the driving components with straight line edge andexponential function edge, the numerical examples was computed respectively,the results show that the former one is suitable for the force transmission andcan be used in the grip design and the other one is suitable for the motiontransmission which can be used in the fast moving mechanism

Mechanical Performance of Steam-Cured Self-Compacting Concrete Incorporating Silica Fume and Limestone Powder

2021 ◽  
Vol 56 ◽  
pp. 111-122
Author(s):  
Youcef Ghernouti ◽  
Bahia Rabehi ◽  
Sabria Malika Mansour
Keyword(s):  
Heat Treatment ◽  
Silica Fume ◽  
Mechanical Performance ◽  
Limestone Powder ◽  
Maximum Temperature ◽  
Self Compacting Concrete ◽  
Curing Period ◽  
Heat Treated ◽  
Binder Ratio ◽  
Mechanical Strengths

In this paper, influence of heat treatment on evolution of mechanical strengths at early age, less than 24hours of self-compacting concretes containing limestone powder and silica fume as fine materials was investigated experimentally. Two compositions of self-compacting concrete have been studied; the first is elaborated with silica fume addition and the second with limestone powder, each mixture were prepared with a constant water/binder ratio of 0.39. Concrete samples were either cured in water at (23±1°C), or steam cured at 65°C maximum temperature over six hours (6h) curing period. Tests of mechanical strengths were performed on specimens cooled down slowly to room temperature after heating.The obtained results show that all self-compacting mixtures exhibited satisfying fresh properties and check EFNARC specifications of self-compacting concrete (slump flow diameter higher than 650mm, L-box ratio higher than 80% and sieve stability less than 17%).Mechanical strengths of concrete containing limestone addition are slightly lower than those of concrete based on silica fume at all ages. Moreover, heat treatment generates an improvement of compressive and flexural strength. Interesting compressive strengths are obtained. At 24 hours, after heat treatment, the strengths are already greater than 35 MPa. The values ​​are 37 MPa and 40 MPa for self-compacting concrete containing limestone powder and silica fume respectively compared to 40 MPa and 46 MPa obtained at 7 days for the corresponding non-heat treated concretes. Compressive strength gain of SCCs mixtures with limestone powder and with silica fume, undergoing heat treatment at the age of 24hours is 85% and 75% respectively compared to SCCs mixtures cured in water.

scholarly journals Mortars with CDW Recycled Aggregates Submitted to High Levels of CO2

2021 ◽  
Vol 6 (11) ◽  
pp. 159
Author(s):  
Ricardo Infante Gomes ◽  
David Bastos ◽  
Catarina Brazão Farinha ◽  
Cinthia Maia Pederneiras ◽  
Rosário Veiga ◽  
...  
Keyword(s):  
Large Scale ◽  
Mechanical Performance ◽  
Construction Materials ◽  
Environmental Benefits ◽  
Recycled Aggregates ◽  
Construction And Demolition Wastes ◽  
Short Period ◽  
Natural Aggregates ◽  
Cement Factories ◽  
Made In

Construction and demolition wastes (CDW) are generated at a large scale and have a diversified potential in the construction sector. The replacement of natural aggregates (NA) with CDW recycled aggregates (RA) in construction materials, such as mortars, has several environmental benefits, such as the reduction in the natural resources used in these products and simultaneous prevention of waste landfill. Complementarily, CDW have the potential to capture CO2 since some of their components may carbonate, which also contributes to a decrease in global warming potential. The main objective of this research is to evaluate the influence of the exposure of CDW RA to CO2 produced in cement factories and its effect on mortars. Several mortars were developed with a volumetric ratio of 1:4 (cement: aggregate), with NA (reference mortar), CDW RA and CDW RA exposed to high levels of CO2 (CRA). The two types of waste aggregate were incorporated, replacing NA at 50% and 100% (in volume). The mortars with NA and non-carbonated RA and CRA from CDW were analysed, accounting for their performance in the fresh and hardened states in terms of workability, mechanical behaviour and water absorption by capillarity. It was concluded that mortars with CDW (both CRA and non-carbonated RA) generally present a good performance for non-structural purposes, although they suffer a moderate decrease in mechanical performance when NA is replaced with RA. Additionally, small improvements were found in the performance of the aggregates and mortars with CRA subjected to a CO2 curing for a short period (5 h), while a long carbonation period (5 d) led to a decrease in performance, contrary to the results obtained in the literature that indicate a significant increase in such characteristics. This difference could be because the literature focused on made-in-laboratory CDW aggregates, while, in this research, the wastes came from real demolition activities, and were thus older and more heterogeneous.

Durability and Mechanical Properties of Self-Compacting Concrete Incorporating Recovered Filler from Hot Mix Asphalt Plants and Recycled Fine Aggregate

2021 ◽  
Vol 894 ◽  
pp. 95-101
Author(s):  
Sepehr Ghafari ◽  
Fereidoon Moghadas Nejad ◽  
Ofelia Corbu
Keyword(s):  
Compressive Strength ◽  
Hot Mix Asphalt ◽  
Mechanical Performance ◽  
Fine Fraction ◽  
Production Plant ◽  
Fine Aggregate ◽  
Self Compacting Concrete ◽  
Limestone Filler ◽  
Recycled Fine Aggregate ◽  
Maximum Particle

In this research, a sustainable approach is followed to develop efficient mixtures incorporating recycled fine aggregate (RFA) remained from structure demolition as well as limestone filler (LF) from production of hot mix asphalt (HMA). The LF is a byproduct of the drying process in HMA production plant which is not entirely consumed in the production of the HMA and must be hauled and disposed in landfills. The maximum particle size of the LF is approximately 40 µm. Self-Compacting Concrete (SCC) mixtures were designed replacing 5% and 10% of the cement with LF. Incorporation of 50%, and 100% RFA with the fines in the mixtures were considered with and without addition of the LF. Due to the formwork and prefabrication restrictions, the paste volume and the high range water reducer content were tuned in such a way that the slump flow of the mixtures remained between 660 mm to 700 mm without segregation. Durability and mechanical performance of the mixtures were evaluated by resistance against freeze-thaw scaling exposed to deicing agents and compressive strength. It was observed that the SCC mixtures containing 10% LF outperformed those without the use of LF while 5% SCC mixtures did not exhibit tangible superiority. Incorporation of RFA as the fine fraction degraded the durability of all the mixtures. While replacing all the fine fraction with RFA significantly impaired durability and compressive strength, 50% RF mixtures could be designed containing 10% LF that remained in the allowable limits.

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