TECHNICAL SOLUTIONS TO IMPROVE PERFORMANCE OF THE RECYCLED CEMENT CONCRETE AGGREGATES FOR DURABLE ROAD PAVEMENTS

2013 ◽  
Vol 12 (3) ◽  
pp. 595-602 ◽  
Author(s):  
Nicolae Taranu ◽  
Marius Muscalu ◽  
Radu Andrei ◽  
Irina Lungu ◽  
Mihai Budescu ◽  
...  
Keyword(s):  
Cement Concrete ◽  
Improve Performance ◽  
Concrete Aggregates ◽  
Technical Solutions

scholarly journals Long-term performance of sustainable pavements using ternary blended concrete with recycled aggregates

2021 ◽  
Author(s):  
Gilson Lomboy ◽  
Douglas Cleary ◽  
Seth Wagner ◽  
Yusef Mehta ◽  
Danielle Kennedy ◽  
...  
Keyword(s):  
Portland Cement ◽  
Cementitious Materials ◽  
Recycled Concrete ◽  
Supplementary Cementitious Materials ◽  
Recycled Aggregates ◽  
Concrete Aggregate ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Concrete Aggregates ◽  
Concrete Mixtures

Dwindling supplies of natural concrete aggregates, the cost of landfilling construction waste, and interest in sustainable design have increased the demand for recycled concrete aggregates (RCA) in new portland cement concrete mixtures. RCA repurposes waste material to provide useful ingredients for new construction applications. However, RCA can reduce the performance of the concrete. This study investigated the effectiveness of ternary blended binders, mixtures containing portland cement and two different supplementary cementitious materials, at mitigating performance losses of concrete mixtures with RCA materials. Concrete mixtures with different ternary binder combinations were batched with four recycled concrete aggregate materials. For the materials used, the study found that a blend of portland cement, Class C fly ash, and blast furnace slag produced the highest strength of ternary binder. At 50% replacement of virgin aggregates and ternary blended binder, some specimens showed comparable mechanical performance to a control mix of only portland cement as a binder and no RCA substitution. This study demonstrates that even at 50% RCA replacement, using the appropriate ternary binder can create a concrete mixture that performs similarly to a plain portland cement concrete without RCA, with the added benefit of being environmentally beneficial.

Recycled Concrete Mixes for Slip-Form Paving of Roads and Airports

2016 ◽  
Vol 711 ◽  
pp. 730-736
Author(s):  
Maurizio Crispino ◽  
Emanuele Toraldo ◽  
Filippo Giustozzi ◽  
Edoardo Mariani
Keyword(s):  
Mechanical Performance ◽  
Recycled Concrete ◽  
Concrete Slabs ◽  
Cement Concrete ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Plastic Concrete ◽  
Fresh State ◽  
Concrete Mix ◽  
High Production

Slip-form paving is gaining consensus in road and airport construction due to high production rates and automation of the process. Concrete slabs are extruded by pulling the forms continuously through and surrounding the plastic concrete mass. The technology uses low-slump cement concrete mixes so that the fresh mass is able to hold its shape once the slip-form paver has passed; besides low-slump, several other parameters should be considered for a proper slip-form concrete mix, especially at the fresh state. To date, recycling is being commonly adopted in concrete mixes to address sustainability in construction of transport infrastructures. Recycled Concrete Aggregates (RCA) are used to reduce the consumption of virgin materials although their increased porosity leads to higher absorption and generally lower mechanical performance. The present study aimed at evaluating the compatibility of 100% recycled concrete mixes with slip-form paving; recycled concrete was tested to evaluate the fresh-state properties as well as the hardened strength. Results showed that slip-form effective and high-resistance mixes could be prepared by using high content of RCA.

scholarly journals Innovative Technologies and Logistical Solutions for the Reuse of Demolished Concrete in the Construction of Cement Concrete Pavements

2013 ◽  
Vol 8-9 ◽  
pp. 259-268
Author(s):  
Marius Teodor Muscalu ◽  
Andrei Radu ◽  
Nicolae Taranu ◽  
Mihai Budescu ◽  
Irina Lungu
Keyword(s):  
Recycled Aggregates ◽  
Concrete Pavements ◽  
Original Performance ◽  
Cement Concrete ◽  
Roller Compacted Concrete ◽  
Rigid Pavements ◽  
Concrete Mixtures ◽  
Negative Effect ◽  
Natural Aggregates ◽  
Technical Solutions

The paper presents the results and conclusions of investigations aiming to encourage the use of recycled materials, namely recycled aggregates (RA) and recycled steel fibers (RSF), in the construction of durable, economic and environmental friendly rigid pavements. To minimize and limit the negative effect of RA on the mechanical properties of cement concrete pavements, the research program considered both, development of technical solutions to improve the performance characteristics of RA particle, and RSF disperse reinforcement of concrete mixtures. Roller compacted concrete (RCC) cylindrical and prismatic test specimens manufactured with natural aggregates (NA) and original/performance improved RA have been subjected to flexure and compressive testes to evaluate the influence and contribution of developed technologies. Finally, guidelines and considerations for the use of RA in RCC and plain cement concrete (PCC) pavements are drawn.

Crack Resistance of the Old Cement Concrete Pavement Treatment

2012 ◽  
Vol 190-191 ◽  
pp. 440-443
Author(s):  
Hong Jiang ◽  
Jian Bo Yuan ◽  
Hua Yang
Keyword(s):  
Crack Resistance ◽  
Concrete Pavement ◽  
Cement Concrete ◽  
Cement Concrete Pavement ◽  
Technical Solutions

Overlay new cement concrete pavement on the old cement concrete pavement following different treatment schemes, survey pavement cracking phenomenon after the opening of the new pavement , analysis the crack resistance of the various programs, accumulate experience for the cement concrete pavement repair technical solutions.

Study on the Practicability of PVA Porous Cement Concrete Pavement

2012 ◽  
Vol 450-451 ◽  
pp. 513-517
Author(s):  
Du La Man ◽  
Xiao Yu Hu
Keyword(s):  
Flexural Strength ◽  
Effective Porosity ◽  
Concrete Pavement ◽  
Cement Concrete ◽  
Porous Concrete ◽  
Concrete Aggregates ◽  
Bonding Performance ◽  
Cement Based Materials ◽  
Cement Concrete Pavement ◽  
Pva Fiber

In this study, Through the research of the porous concrete which have special structure,without sand and added PVA fibers form a fiber cement-based materials as the bonding materials of porous concrete. The results show that after mixed with quantitative PVA fibers, the bonding performance of the porous concrete aggregates can be enhanced, the flexural strength obviously improved, obtained the effective porosity and the best PVA fiber contents.

On-line image readout in CTEM

1994 ◽  
Vol 52 ◽  
pp. 400-401
Author(s):  
K.-H. Herrmann ◽  
W. D. Rau ◽  
R. Sikeler
Keyword(s):  
Primary Electron ◽  
Digital Information ◽  
Electron Hole ◽  
Detection Technology ◽  
Long Time ◽  
On Line ◽  
Electron Image ◽  
Optical Transfer ◽  
Detection Quantum Efficiency ◽  
Technical Solutions

Quantitative recording of electron patterns and their rapid conversion into digital information is an outstanding goal which the photoplate fails to solve satisfactorily. For a long time, LLL-TV cameras have been used for EM adjustment but due to their inferior pixel number they were never a real alternative to the photoplate. This situation has changed with the availability of scientific grade slow-scan charged coupled devices (CCD) with pixel numbers exceeding 106, photometric accuracy and, by Peltier cooling, both excellent storage and noise figures previously inaccessible in image detection technology. Again the electron image is converted into a photon image fed to the CCD by some light optical transfer link. Subsequently, some technical solutions are discussed using the detection quantum efficiency (DQE), resolution, pixel number and exposure range as figures of merit.A key quantity is the number of electron-hole pairs released in the CCD sensor by a single primary electron (PE) which can be estimated from the energy deposit ΔE in the scintillator,

Replication of the Superstition and Performance Study by

2014 ◽  
Vol 45 (3) ◽  
pp. 239-245 ◽  
Author(s):  
Robert J. Calin-Jageman ◽  
Tracy L. Caldwell
Keyword(s):  
Task Difficulty ◽  
Statistical Power ◽  
Meta Analysis ◽  
A Priori ◽  
Significant Heterogeneity ◽  
Performance Study ◽  
Improve Performance ◽  
Research Designs ◽  
Series Of Experiments ◽  
And Performance

A recent series of experiments suggests that fostering superstitions can substantially improve performance on a variety of motor and cognitive tasks ( Damisch, Stoberock, & Mussweiler, 2010 ). We conducted two high-powered and precise replications of one of these experiments, examining if telling participants they had a lucky golf ball could improve their performance on a 10-shot golf task relative to controls. We found that the effect of superstition on performance is elusive: Participants told they had a lucky ball performed almost identically to controls. Our failure to replicate the target study was not due to lack of impact, lack of statistical power, differences in task difficulty, nor differences in participant belief in luck. A meta-analysis indicates significant heterogeneity in the effect of superstition on performance. This could be due to an unknown moderator, but no effect was observed among the studies with the strongest research designs (e.g., high power, a priori sampling plan).

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