scholarly journals Cold Recycled Asphalt Mixture using 100% RAP with Emulsified Asphalt-Recycling Agent as a New Pavement Base Course

2020 ◽  
Vol 2020 ◽  
pp. 1-11 ◽  
Author(s):  
Wilson Unger Filho ◽  
Luis Miguel Gutiérrez Klinsky ◽  
Rosângela Motta ◽  
Liedi Légi Bariani Bernucci
Keyword(s):  
Tensile Strength ◽  
Heavy Traffic ◽  
Curing Time ◽  
Recycled Asphalt ◽  
Promising Alternative ◽  
Asphalt Mix ◽  
Recycling Agent ◽  
Base Course ◽  
Pavement Base ◽  
Emulsified Asphalt

The rehabilitation process of asphalt pavements using the technique of milling and filling can cause several environmental problems due to either the disposal of the milled asphalt mix or the exploration of natural resources. One alternative to mitigate these impacts is to reuse this milled material, known as reclaimed asphalt pavement (RAP), in the construction of new pavement layers. Within the several available techniques to reuse the RAP, cold recycling using an emulsified asphalt-recycling agent has shown great potential. The aim of this study is to evaluate the application of a cold recycled asphalt mix using 100% RAP with an emulsified asphalt-recycling agent as a new pavement base course. A trial section was built employing this material as a pavement base course in a heavy traffic highway in Brazil, and its structural behavior was monitored for 12 months using a Falling Weight Deflectometer (FWD) to assess its performance over time. Furthermore, a laboratory-testing program was performed to evaluate the recycled mixture stiffness and strength through resilient modulus and indirect tensile strength tests. These tests were used to investigate the influence of the storage interval (7, 14, and 28 days) considering the time between mixing and compaction of the mixture. The effect of the curing time after compaction (1, 3, 7, 26, and 56 days) was also assessed. It was verified in laboratory and in the trial section that the stiffness increases with curing time. Furthermore, the backcalculated elastic resilient moduli indicated values in the same order of magnitude to those obtained in the laboratory tests. In addition to the laboratory test findings, it was also observed that the longer the period of storage, the higher the values of stiffness and tensile strength for short periods of curing. This behavior was not verified when longer curing periods were used. In general, the use of cold recycled asphalt mixtures as base course of new pavements proved to be a promising alternative to reuse RAP.

scholarly journals Evaluation on Strength Properties of Lime–Slag Stabilized Loess as Pavement Base Material

2019 ◽  
Vol 11 (15) ◽  
pp. 4099 ◽  
Author(s):  
Liang Jia ◽  
Li Zhang ◽  
Jian Guo ◽  
Kai Yao ◽  
Sin Mei Lim ◽  
...  
Keyword(s):  
Base Material ◽  
Correlation Coefficients ◽  
Strength Properties ◽  
Binder Content ◽  
Curing Time ◽  
Test Results ◽  
Base Course Material ◽  
Course Material ◽  
Base Course ◽  
Pavement Base

This study aimed to investigate the feasibility of using lime–slag stabilized loess as base-course material by assessing its unconfined compressive strength (UCS). Loess stabilized with various mix ratios were compacted and cured to three, five, seven, and 28 days, respectively, for further strength tests. The effects of binder content, lime-to-slag (L/S) ratio, porosity, and curing time on the UCS of stabilized loess were addressed in detail. The test results show that UCS increases with the increase in binder content or curing time, and it gains strength rapidly within the first seven days of curing. At the same binder content, UCS decreases with the decrease in L/S ratio or porosity. Finally, the correlations of UCS with binder content, porosity, and curing time were derived, which exhibited reasonable correlation coefficients R2 (from 0.86 to 0.97).

scholarly journals Strength Mechanism and Influence Factors for Cold Recycled Asphalt Mixture

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Tao Ma ◽  
Hao Wang ◽  
Yongli Zhao ◽  
Xiaoming Huang ◽  
Yuhui Pi
Keyword(s):  
Tensile Strength ◽  
Asphalt Mixture ◽  
Influence Factors ◽  
High Viscosity ◽  
Asphalt Mixtures ◽  
Key Factors ◽  
Recycled Asphalt ◽  
Factors Affecting ◽  
Surface Areas ◽  
Emulsified Asphalt

This study focused on the key factors affecting the tensile strength of cold recycled asphalt mixture with cement and emulsified asphalt. The specific surface areas and strength of RAP were analyzed. The interaction between the emulsified asphalt and cement was observed. Comprehensive laboratory testing was conducted to evaluate the influences of RAP, emulsified asphalt, and cement on the tensile strength of cold recycled asphalt mixture. It is found that although RAP is used as aggregates, its inner structure and strength are much different from real aggregates. The strength of RAP has decisive effect on the strength of cold recycled asphalt mixture. New aggregates and fine gradation design can help improve the bonding between RAP and binder. For emulsified asphalt, slow setting of asphalt can give sufficient time for cement to hydrate which is helpful for strength formation in the cold recycled asphalt mixture. The high viscosity of asphalt can improve the early strength of cold recycled asphalt mixture that is important for traffic opening in the field. Cement is an efficient additive to improve the strength of cold recycled asphalt mixtures by promoting demulsification of emulsified asphalt and producing cement hydrates. However, the cement content is limited by RAP.

scholarly journals Effects of Cement and Emulsified Asphalt on Properties of Mastics and 100% Cold Recycled Asphalt Mixtures

Materials ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 754 ◽  
Author(s):  
Yanan Li ◽  
Yuchao Lyv ◽  
Liang Fan ◽  
Yuzhen Zhang
Keyword(s):  
Tensile Strength ◽  
Rheological Properties ◽  
Subsurface Layer ◽  
Temperature Stability ◽  
Asphalt Mixtures ◽  
Mineral Filler ◽  
High Temperature Stability ◽  
Recycled Asphalt ◽  
Technical Specifications ◽  
Emulsified Asphalt

Cold recycled asphalt mixtures (CRAM) are a cost-effective and environmentally-friendly way to reuse reclaimed asphalt pavement (RAP). This paper evaluates the rheological properties and microstructure of mineral filler-asphalt mastic, mineral filler-residue mastic, and cement-residue mastic. Then, based on the premise of using 100% RAP with a gradation that was determined experimentally, the effects of emulsified asphalt and cement on the porosity, indirect tensile strength, tensile strength ratio, dynamic stability, and mechanical properties of CRAM were evaluated. It was found that the rheological properties and cohesive coefficient of the cement-residue mastic varied differently to those of the first two types of mastic and the results show that the addition of cement can greatly improve the interfacial bonding between binders and fillers in the mastic, thereby improving the water damage resistance and high-temperature stability of CRAM. The relationships between cement content and the dynamic modulus and phase angle of CRAM are different to that for emulsified asphalt obviously. In addition, under certain conditions, the properties of CRAM can meet the requirements of relevant technical specifications for its application to subsurface layer of pavement. Hence, the use of 100% RAP in CRAM may be feasible.

Mitigation of permanent deformation in base layer containing recycled asphalt aggregates

2013 ◽  
Vol 40 (2) ◽  
pp. 181-187 ◽  
Author(s):  
Jean-Pascal Bilodeau ◽  
Guy Doré ◽  
Jonas Depatie
Keyword(s):  
Asphalt Concrete ◽  
Deformation Behaviour ◽  
Permanent Deformation ◽  
Design Procedure ◽  
Base Layer ◽  
Repeated Loading ◽  
Recycled Asphalt ◽  
Thickness Increase ◽  
Permanent Strain ◽  
Pavement Base

The use of recycled asphalt pavement (RAP) aggregates as replacement for new materials in the pavement base weakens the layer in regards to the resistance to permanent deformation under repeated loading. A mechanistic based design procedure is proposed to ensure that base layers containing RAP particles have a similar rutting behaviour to base layers made of virgin aggregates. The design procedure allows calculating an asphalt concrete thickness increase that is based on permanent deformation behaviour of base materials. The calculation approach is based on multistage triaxial permanent deformation tests performed on granular material samples with varied RAP content. The tests allowed proposing an equation that relates permanent strain rate, RAP content, and deviatoric stress, which is the basis of the design procedure. Design charts are proposed to select adequate thickness increase for the asphalt concrete layer according to the expected RAP content in the base layer and asphalt concrete modulus.

Effect of Shortened Light-Curing Modes on Bulk-Fill Resin Composites

2020 ◽  
Vol 45 (5) ◽  
pp. 496-505
Author(s):  
CS Sampaio ◽  
PG Pizarro ◽  
PJ Atria ◽  
R Hirata ◽  
M Giannini ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Bond Strength ◽  
Shear Bond Strength ◽  
Light Output ◽  
High Mode ◽  
Resin Composites ◽  
Curing Time ◽  
Micro Computed Tomography ◽  
Polymerization Shrinkage ◽  
Light Curing

Clinical Relevance Shortened light curing does not affect volumetric polymerization shrinkage or cohesive tensile strength but negatively affects the shear bond strength of some bulk-fill resin composites. When performing shortened light curing, clinicians should be aware of the light output of their light-curing units. SUMMARY Purpose: To evaluate volumetric polymerization shrinkage (VPS), shear bond strength (SBS) to dentin, and cohesive tensile strength (CTS) of bulk-fill resin composites (BFRCs) light activated by different modes. Methods and Materials: Six groups were evaluated: Tetric EvoCeram bulk fill + high mode (10 seconds; TEC H10), Tetric EvoFlow bulk fill + high mode (TEF H10), experimental bulk fill + high mode (TEE H10), Tetric EvoCeram bulk fill + turbo mode (five seconds; TEC T5), Tetric EvoFlow bulk fill + turbo mode (TEF T5), and experimental bulk fill + turbo mode (TEE T5). Bluephase Style 20i and Adhese Universal Vivapen were used for all groups. All BFRC samples were built up on human molar bur-prepared occlusal cavities. VPS% and location were evaluated through micro–computed tomography. SBS and CTS tests were performed 24 hours after storage or after 5000 thermal cycles; fracture mode was analyzed for SBS. Results: Both TEC H10 and TEE H10 presented lower VPS% than TEF H10. However, no significant differences were observed with the turbo-curing mode. No differences were observed for the same BFRC within curing modes. Occlusal shrinkage was mostly observed. Regarding SBS, thermal cycling (TC) affected all groups. Without TC, all groups showed higher SBS values for high mode than turbo mode, while with TC, only TEC showed decreased SBS from high mode to turbo modes; modes of fracture were predominantly adhesive. For CTS, TC affected all groups except TEE H10. In general, no differences were observed between groups when comparing the curing modes. Conclusions: Increased light output with a shortened curing time did not jeopardize the VPS and SBS properties of the BFRCs, although a decreased SBS was observed in some groups. TEE generally showed similar or improved values for the tested properties in a shortened light-curing time. The VPS was mostly affected by the materials tested, whereas the SBS was affected by the materials, curing modes, and TC. The CTS was not affected by the curing modes.

scholarly journals Long-Term Performance of Pavement Structures with Cold In-Place Recycled Base Course

2021 ◽  
Vol 16 (2) ◽  
pp. 48-65
Author(s):  
Audrius Vaitkus ◽  
Judita Gražulytė ◽  
Andrius Baltrušaitis ◽  
Jurgita Židanavičiūtė ◽  
Donatas Čygas
Keyword(s):  
Asphalt Pavement ◽  
Asphalt Mixture ◽  
Asphalt Pavements ◽  
Recycled Asphalt ◽  
Binding Agents ◽  
Pavement Structure ◽  
Pavement Structures ◽  
Base Course ◽  
Surface Distress ◽  
Foamed Bitumen

Properly designed and maintained asphalt pavements operate for ten to twenty-five years and have to be rehabilitated after that period. Cold in-place recycling has priority over all other rehabilitation methods since it is done without preheating and transportation of reclaimed asphalt pavement. Multiple researches on the performance of cold recycled mixtures have been done; however, it is unclear how the entire pavement structure (cold recycled asphalt pavement overlaid with asphalt mixture) performs depending on binding agents. The main objective of this research was to evaluate the performance of cold in-place recycled asphalt pavements considering binding agents (foamed bitumen in combination with cement or only cement) and figure out which binder leads to the best pavement performance. Three road sections rehabilitated in 2000, 2003, and 2005 were analysed. The performance of the entire pavement structure was evaluated in terms of the International Roughness Index, rut depth, and pavement surface distress in 2013 and 2017.

Design and Construction Analysis of Cement-Stabilized Macadam Foundation

2013 ◽  
Vol 340 ◽  
pp. 80-84
Author(s):  
Deng Lin
Keyword(s):  
Mechanical Property ◽  
Frost Resistance ◽  
Water Stability ◽  
Good Mechanical Property ◽  
Control Methods ◽  
Mechanical Theory ◽  
Cement Stabilization ◽  
Base Course ◽  
Pavement Base ◽  
Design And Construction

Cement-stabilized macadam has good mechanical property, but also has the advantages of plate nature, water stability and frost resistance, and it is widely used in the pavement base or sub-base course of expressway. Based on the fundamental mechanical theory of the strength and the global stability of cement stabilization macadam, this article discusses how to design the grading of the cement stabilization macadam and the influencing factors, besides, it also presents the construction control methods of the cement stabilization macadam, which is of guiding significance to the design and construction of the cement stabilization macadam.

Experimental Study in Gangue Base-Course Mixture Materials for Pavement

2013 ◽  
Vol 860-863 ◽  
pp. 1270-1273 ◽  
Author(s):  
Fu Jun Wang ◽  
Jing Luo ◽  
Hui Rong Zhu
Keyword(s):  
Industrial Waste ◽  
Road Construction ◽  
Drying Shrinkage ◽  
Pozzolanic Reaction ◽  
Water Stability ◽  
Solid Skeleton ◽  
Grass Roots ◽  
Base Materials ◽  
Base Course ◽  
Pavement Base

Coal gangue, acting as the solid skeleton of pavement base materials, can efficiently reduce the drying shrinkage. Additionally, similar to fly ash in mixture material, gangue can react with lime (so called pozzolanic reaction), resulting in the formation of pavement base with a certain strength, good water stability and frost resistance, are good overall at the grass-roots level. Many cities in our country has gradually tried to use different kinds of industrial waste residue instead of sand to prepare the pavement base materials. This way, not only the waste residue is recycled, the lack of sand aggregates in road construction can also be overcome, which facilitate technical and economic growths.

scholarly journals Strength and Micro-Mechanism Analysis of Cement-Emulsified Asphalt Cold Recycled Mixture

Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 128 ◽  
Author(s):  
Yuhui Pi ◽  
Yan Li ◽  
Yingxing Pi ◽  
Zhe Huang ◽  
Zhe Li
Keyword(s):  
Raw Materials ◽  
Asphalt Binder ◽  
Microscopic Analysis ◽  
Hydration Product ◽  
Mechanism Analysis ◽  
Recycled Asphalt ◽  
Aggregate Gradation ◽  
Asphalt Cement ◽  
Emulsified Asphalt ◽  
Cementing Material

The strength of EACRM (emulsified asphalt cold recycled mixture) is closely related to the properties and proportion of raw materials. In this paper, the strength formation mechanism of EACRM was first studied through microscopic analysis, and the influence regular of aggregate gradation, emulsified asphalt, water consumption, cement consumption, and other factors on its strength was analyzed through a series of laboratory tests. The analysis results show that the asphalt binder plays the role of cementing material in cement emulsified asphalt mortar. The combination of cement and emulsified asphalt is a physical combination. The hydration product not only increases the viscosity of asphalt cement, but also makes the surface of asphalt cement become uneven, which increases the adhesion area with the aggregate. Therefore, the microstructure of the interface between mortar and aggregate is improved. The bonding force of the interface and the mechanical properties of concrete are improved. Due to the influence of recycled asphalt pavement (RAP) materials, the excessive amount of emulsified asphalt and cement are not conducive to improve the strength of cold recycled mixture. Through experiments, the optimal amount of emulsified asphalt and cement is determined as 2.9% and 1.5%, respectively, for the RAP materials. At the same time, improving the performance of emulsified asphalt and adding quicklime and organic activator are also helpful to improve the strength of a cold recycled mixture.

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