scholarly journals Influence of the addition of carbon fibers on the properties of hydraulic lime mortars: comparison with glass and basalt fibers

2020 ◽  
Vol 70 (340) ◽  
pp. 229
Author(s):  
A. Bustos ◽  
E. Moreno ◽  
F. González ◽  
A. Cobo
Keyword(s):  
Carbon Fibers ◽  
Negative Impact ◽  
Void Content ◽  
Historic Buildings ◽  
Basalt Fibers ◽  
Architectural Heritage ◽  
Hydraulic Lime ◽  
Lime Mortars ◽  
Air Void ◽  
Mechanical Strengths

In recent years, the use of hydraulic lime in conservation and restoration of historic buildings has increased due to the pathological processes involved in the use of Portland cement. This investigation deter­mines the properties of hydraulic lime mortars with added carbon fibers for their possible use in restoration of architectural heritage. The results obtained are compared with mortars to which glass and basalt fibers have been added. The results show that the fibers affect significantly the behaviour of the mortar. Although the fibers have a negative impact in the workability and increase the air void content, they improve significantly the mechanical strengths. Although no relevant differences have been found in the pre-cracking behaviour, it has been proven that the fibers avoid a fragile behaviour of the mortar, showing a better post-cracking behaviour. Mortars with carbon fibers are the ones that show the best performance, increasing the toughness up to 12080% over the reference mortars.

scholarly journals Brick Debris Dust as an Ecological Filler and Its Effect on the Durability of Asphalt Mix

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5023
Author(s):  
Agnieszka Woszuk ◽  
Michał Wróbel ◽  
Lidia Bandura ◽  
Wojciech Franus
Keyword(s):  
Asphalt Concrete ◽  
Negative Impact ◽  
Void Content ◽  
Bonding Layer ◽  
Recycling Process ◽  
Stiffness Modulus ◽  
Asphalt Mix ◽  
Resistance Decrease ◽  
Air Void ◽  
Brick Dust

Brick debris is one of the main construction wastes obtained from demolition of buildings. However, this material can be successfully used in the recycling process. The purpose of the study was to determine the brick dust addition effect on asphalt surface service life. An asphalt concrete reference mix was designed for bonding layer and prepared using a Marshall compacting device. In addition, three mixes with combined lime-brick filler were prepared as well as one mix containing only brick filler. The samples were tested for their volumetric properties—density, bulk density, air void content, resistance to water and frost and stiffness modulus with varying test temperatures. It was found that 25% of brick dust addition to the filler did not considerably change the properties of the tested samples, while in the case of 50% filler the replacement stiffness and frost resistance decrease; however, the minimum required value is maintained. It can be concluded that the lime filler can be replaced with up to 50% of brick dust without a negative impact on the properties of asphalt mix. The proposed solution fits into the idea of sustainable development indicating a way of brick debris management.

scholarly journals Estimation of the Age of Architectural Heritage Objects by Microstructural Changes of Calcite in Lime Mortars of Ancient Brickwork and Masonry

Buildings ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 240
Author(s):  
Vladimir Kotlyar ◽  
Victoria Pishchulina ◽  
Alexey N. Beskopylny ◽  
Besarion Meskhi ◽  
Yury Popov ◽  
...  
Keyword(s):  
18Th Century ◽  
Degree Of Crystallinity ◽  
Architectural Heritage ◽  
Natural Conditions ◽  
Relative Age ◽  
Lime Mortars ◽  
Powder Samples ◽  
Diffraction Patterns ◽  
Cultural Monuments ◽  
The Degree Of Crystallinity

Determining the age of ancient architectural and cultural monuments is a significant scientific problem. An approach based on the transformation of portlandite into calcite and subsequent recrystallization of calcite is considered, which allows for estimating the relative age of ancient brickworks for local groups of historic buildings based on the results of diffraction studies of powder samples of carbonate mortars and measurements of samples with a known age. This article presents the results of the study of lime mortars of ancient brickwork. Under natural conditions, the process of transformation of portlandite into calcite takes from 100 to 200 years. The rate of this process is influenced by temperature, humidity, peculiarities of interaction with carbon dioxide contained in the air, etc. Examples show that portlandite is completely transformed into calcite in masonry mortars of the 18th century and that portlandite is not found in older mortars. It was determined that after the transformation of portlandite into calcite, an increase in the degree of recrystallization of calcite is observed, which manifests itself in powder diffraction patterns in the relative broadening of the diffraction peak of calcite hkl 104. In a detailed study, an estimate of the peak width at half maximum (FWHM) associated with the degree of crystallinity is effective. The actual data are given, which show that in older lime mortars the degree of recrystallization of calcite is higher than in younger ones. This fact makes it possible to indirectly determine the relative age of brickwork and masonry of various buildings of architectural heritage, which is especially relevant for the objects with the use of lime mortars of the northern provinces of the Byzantine Oecumene and other periods of various cultures.

scholarly journals A GPR-Based Pavement Density Profiler: Operating Principles and Applications

2021 ◽  
Vol 13 (13) ◽  
pp. 2613
Author(s):  
Nectaria Diamanti ◽  
A. Peter Annan ◽  
Steven R. Jackson ◽  
Dylan Klazinga
Keyword(s):  
Asphalt Pavement ◽  
Wave Impedance ◽  
Asphalt Mixtures ◽  
Void Content ◽  
Air Voids ◽  
New Instrument ◽  
Pavement Engineering ◽  
And Performance ◽  
Air Void ◽  
Air Void Content

Density is one of the most important parameters in the construction of asphalt mixtures and pavement engineering. When a mixture is properly designed and compacted, it will contain enough air voids to prevent plastic deformation but will have low enough air void content to prevent water ingress and moisture damage. By mapping asphalt pavement density, areas with air void content outside of the acceptable range can be identified to predict its future life and performance. We describe a new instrument, the pavement density profiler (PDP) that has evolved from many years of making measurements of asphalt pavement properties. This instrument measures the electromagnetic (EM) wave impedance to infer the asphalt pavement density (or air void content) locally and over profiles.

scholarly journals Study of High-Temperature Properties of Asphalt Mixtures Used for Bridge Pavement with Concrete Deck

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4238
Author(s):  
Piotr Pokorski ◽  
Piotr Radziszewski ◽  
Michał Sarnowski
Keyword(s):  
Permanent Deformation ◽  
Asphalt Mixture ◽  
Binder Content ◽  
Void Content ◽  
Concrete Bridge ◽  
Asphalt Mixes ◽  
Protective Layers ◽  
Concrete Bridge Decks ◽  
Air Void ◽  
Air Void Content

The paper presents the issue of resistance to permanent deformations of bridge pavements placed upon concrete bridge decks. In Europe, bridge asphalt pavement usually consists of a wearing course and a protective layer, which are placed over the insulation (waterproofing). Protective layers of bridge pavement are commonly constructed using low air void content asphalt mixes as this provides the suitable tightness of such layers. Due to increased binder content, asphalt mixes for bridge pavement may have reduced resistance to permanent deformations. The article presents test results of resistance to permanent deformations of asphalt mixes for the protective layers. In order to determine the composition of mixtures with low air void content and resistance to permanent deformation, an experimental design was applied using a new concept of asphalt mix composition. Twenty-seven different asphalt mixture compositions were analyzed. The mixtures varied in terms of binder content, sand content and grit ratio. Resistance to permanent deformation was tested using the laboratory uniaxial cyclic compression method (dynamic load creep). On the basis of experimental results and statistical analysis, the functions of asphalt mixture permanent deformation resistance were established. This enabled a determination of suitable mixture compositions for protective layers for concrete bridge decks.

Impact of Specimen Configuration and Characteristics on Illinois Flexibility Index

2018 ◽  
Vol 2672 (28) ◽  
pp. 383-393 ◽  
Author(s):  
Jose Rivera-Perez ◽  
Hasan Ozer ◽  
Imad L. Al-Qadi
Keyword(s):  
Correction Factor ◽  
Loading Rate ◽  
Void Content ◽  
Displacement Curve ◽  
Specimen Thickness ◽  
Index Test ◽  
Notch Length ◽  
Air Void ◽  
Flexibility Index ◽  
Air Void Content

The Illinois Department of Transportation adopted the Illinois Flexibility Index Test (I-FIT) to evaluate the cracking vulnerability of asphalt concrete (AC) mixtures that was often shown to increase with the addition of recycled materials such as reclaimed asphalt pavement and recycled asphalt shingles. The test consists of a semi-circular AC sample that has a notch, loaded along the symmetric axis. Fracture energy (FE), post-peak slope, and the flexibility index (FI) are computed from the load displacement curve. These results can be influenced by specimen geometry and test parameters such as loading rate, AC voids content, and so forth. Therefore, this study investigated the effect of notch length, specimen thickness, loading rate, and AC air void content on the I-FIT results. It was found that an increase in the specimen thickness or loading rate resulted in a steeper post-peak slope without affecting the FE. As a result, the FI decreased. An increase in the notch length or AC air void content resulted in a flatter post-peak slope, thus, increasing the FI. From the results, it was concluded that existing correction factors to address the variations caused by specimen thickness and air void content are appropriate. A correction factor to address notch length variations is proposed. A unique correction factor for loading rate could not be developed because of the varying rate dependency of each AC mixture.

scholarly journals Hotel design and adaptive reuse: From historic palaces to the city’s dilapidated structures

2014 ◽  
Vol 12 (1) ◽  
pp. 97-112 ◽  
Author(s):  
Marko Nikolic ◽  
Nadja Kurtovic-Folic ◽  
Aleksandar Milojkovic
Keyword(s):  
Historic Buildings ◽  
Historical Buildings ◽  
Architectural Heritage ◽  
Popular Approach ◽  
Alternative Models ◽  
Hotel Design ◽  
Historic Structures ◽  
Relationship Of ◽  
The Relationship ◽  
The City

At the time of changing economic circumstances, adaptation and conversion of historic structures is an increasingly popular approach. Some historical buildings are very suitable for the revitalization into the modern hotels. The paper analyzes the relationship of the hotel, the city and its architectural heritage, as well as some of the factors that led to the eruption of alternative models of hotels, shown through a series of successful solutions. Many challenges of hotel design in historic buildings are listed and corresponding solutions are offered. Some methodological directions are indicated, and certain guidelines and principles for further activities in this field are formulated. In conclusion their applicability in practice is discussed, and certain disadvantages and limitations are listed.

scholarly journals Development of thermoplastic composite materials based on modified polypropylene

2021 ◽  
pp. 145-149
Author(s):  
D.O. Chervakov ◽  
◽  
O.S. Sverdlikovska ◽  
O.V. Chervakov ◽  
◽  
...  
Keyword(s):  
Tensile Strength ◽  
Composite Materials ◽  
Carbon Fibers ◽  
Thermophysical Properties ◽  
Reactive Extrusion ◽  
Substantial Improvement ◽  
Thermoplastic Composite ◽  
Basalt Fibers ◽  
Reinforcing Fillers ◽  
Reinforcing Fibers

To improve the physical-mechanical and thermophysical properties of polypropylene-based thermoplastic composite materials, we performed modification of a polymer matrix by reactive extrusion of polypropylene in the presence of benzoyl peroxide and polysiloxane polyols. Modified polypropylene was compounded with basalt, carbon, and para-aramide reinforcing fillers in a screw-disc extruder. It was established that the reinforcement of modified polypropylene by basalt fibers ensured a 110% increase in tensile strength. The reinforcement of modified polypropylene by carbon fibers allowed fabricating thermoplastic composite materials with tensile strength increased by 14%. The maximum reinforcing effect was observed by using para-aramide fibers as reinforcing fibers for modified polypropylene with tensile strength increased by 30% as compared with initial polypropylene. It was determined that the obtained thermoplastic composite materials based on modified polypropylene can be processed into products by the most productive methods (extrusion and injection molding). The developed materials exhibited improved thermal stability. The proposed ways of modification methods provide substantial improvement in physical-mechanical and thermophysical properties of modified polypropylene-based thermoplastic composite materials as compared with initial polypropylene. In addition, they ensure a significant increase in service properties of the products prepared from thermoplastic composite materials based on modified polypropylene.

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