scholarly journals Adhesion between Asphalt and Recycled Concrete Aggregate and Its Impact on the Properties of Asphalt Mixture

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2528 ◽  
Author(s):  
Yueqin Hou ◽  
Xiaoping Ji ◽  
Jia Li ◽  
Xianghang Li
Keyword(s):  
Free Energy ◽  
Surface Energy ◽  
Asphalt Mixture ◽  
Recycled Concrete ◽  
Fatigue Performance ◽  
Concrete Aggregate ◽  
Water Stability ◽  
Recycled Concrete Aggregate ◽  
Adhesive Energy ◽  
Natural Aggregates

To study and evaluate the adhesion between recycled concrete aggregate and asphalt, the contact angles (CAs) between droplet (water and ethanol) and recycled concrete aggregate (RCA), natural aggregates, and solid bitumen (matrix asphalt, SBS modified asphalt) were tested via the sessile drop method with an optical microscope. The surface free energy was then calculated. The CAs between hot asphalt and RCA and natural aggregates were tested via the hanging slice method. The adhesive energy between asphalt and RCA and natural aggregates were calculated based on the test results of the surface free energy and CAs. Then, the influence of RCA on the water stability and fatigue performance of the asphalt mixture was analyzed by testing the water stability and fatigue properties of hot mix asphalts containing RCA (HMA-RCA) with different aggregates and RCA dosages. The surface energy of the various aggregates and the CAs between aggregates and asphalts were sorted as follows: Granite > RCA > serpentinite > limestone. The surface energy and CA of RCA were very close to that of serpentinite. The adhesive energy between various aggregates and asphalt were sorted as follows: Limestone > serpentinite > RCA > granite. The adhesive energy between RCA and asphalt was also very close to that of serpentinite. The residual Marshall stability, tensile strength ratio, and fatigue performance of the HMA-RCAs were gradually reduced along with the increasing RCA dosage. This effect may be attributed to the fact that the adhesive energy between the RCA and the asphalt was less than that of water and that the asphalt was easily stripped from the RCA surface. Excessive RCA content in the aggregate can lead to excessive porosity of the HMA-RCA. The CAs and adhesive energy between RCA and asphalt showed significant effects on the water stability and fatigue performance of HMA-RCA.

scholarly journals Physical, Deformation, and Stiffness Properties of Recycled Concrete Aggregate

2021 ◽  
Vol 13 (8) ◽  
pp. 4245
Author(s):  
Katarzyna Gabryś ◽  
Emil Soból ◽  
Wojciech Sas
Keyword(s):  
Recycled Concrete ◽  
Experimental Program ◽  
Concrete Aggregate ◽  
Test Results ◽  
Recycled Concrete Aggregate ◽  
Granulometric Analysis ◽  
Stiffness Properties ◽  
Grain Distribution ◽  
Natural Aggregates ◽  
Critical Reduction

The construction sector is currently struggling with the reuse of waste originating from the demolition and modernization of buildings and roads. Furthermore, old buildings are gradually being replaced by new structures. This brings a significant increase of concrete debris to waste landfills. To prevent this, many studies on the possibilities of recycling concrete, known as recycled concrete aggregate (RCA), have been done. To broaden the applicability of reused concrete, an understanding of its properties and engineering behavior is required. A difficulty in sustainable, proper management of RCA is the shortage of appropriate test results necessary to assess its utility. For this reason, in the present study, the physical, deformation, and stiffness properties of RCA with gravely grain distribution were analyzed carefully in the geotechnical laboratory. To examine the mentioned properties, an extensive experimental program was planned, which included the following studies: granulometric analysis, Proctor and oedometer tests, as well as resonant column tests. The obtained research results show that RCA has lower values of deformation and stiffness parameters than natural aggregates. However, after applying in oedometer apparatus repetitive cycles of loading/unloading/reloading, some significant improvement in the values of the parameters studied was noticed, most likely due to susceptibility to static compaction. Moreover, some critical reduction in the range of linear response of RCA to dynamic loading was observed.

Modified recycled concrete aggregates for asphalt mixture using microbial calcite precipitation

RSC Advances ◽  
2015 ◽  
Vol 5 (44) ◽  
pp. 34854-34863 ◽  
Author(s):  
Zhong-Yao Pan ◽  
Gengying Li ◽  
Cheng-Yu Hong ◽  
Hui-Ling Kuang ◽  
Yu Yu ◽  
...  
Keyword(s):  
Bonding Strength ◽  
Asphalt Binder ◽  
Asphalt Mixture ◽  
Recycled Concrete ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Calcite Precipitation ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Porosity And Permeability

Recycled concrete aggregate (RCA) was pretreated by microbial calcite precipitation. The surface treatment reduced the porosity and permeability of RCA by 32% and 86.5%, respectively. The treatment improved the bonding strength of RCA–asphalt binder by 55%.

scholarly journals Suitability of recycled concrete aggregate for transportation infrastructure embankments and improved subgrade

2018 ◽  
Vol 2018 (11) ◽  
pp. 72-84
Author(s):  
Bartłomiej Krawczyk ◽  
Elżbieta Stigler-Szydło
Keyword(s):  
Recycled Concrete ◽  
Transportation Infrastructure ◽  
Concrete Aggregate ◽  
Concrete Pavements ◽  
Recycled Concrete Aggregate ◽  
Alternative Source ◽  
Suitable Material ◽  
Crushed Concrete ◽  
Natural Aggregates

The paper presents research in the field of utilizing materials recycled from concrete pavements through crushing and re-incorporating them in road embankments and improved subgrade layers. Crushed concrete rubble is an alternative source of aggregates, replacing natural aggregates. Recycled concrete aggregate was tested with regard to the current national requirements. It was proven that recycled concrete aggregate is a suitable material for incorporation into new unbound and cement-bound layers of the improved subgrade. The problem of utilization recycled concrete aggregate in road embankments is also addressed in the paper. Limitations in the use of recycled concrete aggregate are also shown in the paper.

scholarly journals Bricks and Concrete Wastes as Coarse and Fine Aggregates in Sustainable Mortars

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Alessandra Mobili ◽  
Chiara Giosuè ◽  
Valeria Corinaldesi ◽  
Francesca Tittarelli
Keyword(s):  
Crack Formation ◽  
Recycled Concrete ◽  
Recycled Aggregates ◽  
Concrete Aggregate ◽  
Capillary Absorption ◽  
Recycled Concrete Aggregate ◽  
Environment Friendly ◽  
Fine Aggregates ◽  
Natural Aggregates ◽  
Coarse Recycled Concrete Aggregate

The total substitution by volume of natural coarse calcareous aggregate by coarse recycled brick aggregate (RBA) and coarse recycled concrete aggregate (RCA) has been investigated to produce more sustainable and environment-friendly mortars. Aggregates were also partially substituted by their fines at 12.5% by volume. Mortars have been tested in terms of mechanical, microstructural, and durability properties. Results show that it is feasible to replace a natural calcareous aggregate entirely by recycled aggregates. In particular, the obtained mortars, even if more porous and more prone to the water capillary absorption than that manufactured with natural aggregates, result in less stiffness and thus are less subjected to crack formation, more permeable to water vapour, and less susceptible to sulphate attack.

scholarly journals Studies on the fresh properties an durability of unshrinkable fill containing recycled concrete aggregate or natural aggregates of marginal quality

2021 ◽  
Author(s):  
Maryam Kolahdoozan
Keyword(s):  
Calcium Content ◽  
Recycled Concrete ◽  
Expansion Rate ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Sulphate Attack ◽  
Fresh Properties ◽  
Severe Damage ◽  
Sulphate Content ◽  
Natural Aggregates

The intention of this research is to explore the feasibility of incorporating aggregates of low or marginal quality, such as Recycled Concrete Aggregate (RCA) and aggregate with high sulphate content, in U-fill mixtures. It has been determined that where RCA is used, water dissipation may be hindered due to the increase in fines caused by abrasion, hence causing an increase in hardening time. To reduce this effect, addition of natural aggregates may be necessary. Moreover, through a series of investigation it has been found that high percentages of sulphate may cause severe damage due to Ettringite and Thaumasite formation; however by incorporation of supplementary materials such as slag the deleterious effects of internal sulphate attack can be reduced. The effects of using Na2SO4 and gypsum in the presence of slag have also been investigated. Results indicated that due to the lower available calcium content within bars containing Na2SO4 expansion rate is low.

scholarly journals VERIFICATION OF THE BASIC PROPERTIES OF RECYCLED AND NATURAL AGGREGATES

2019 ◽  
Vol 22 ◽  
pp. 67-71
Author(s):  
Karel Mikulica ◽  
Iveta Hájková
Keyword(s):  
Recycled Concrete ◽  
Construction And Demolition Waste ◽  
Recycled Aggregates ◽  
Concrete Aggregate ◽  
Building Structures ◽  
Recycled Concrete Aggregate ◽  
Apartment Building ◽  
Demolition Waste ◽  
Concrete Mixtures ◽  
Natural Aggregates

In the future, it is planned to use up to 50% of construction and demolition waste (C&DW) for the production of new building structures. This leads us to think about how we can use recycled concrete aggregate (RCA) as a substitute for natural aggregate (NA) in concrete mixtures. This is why we compare the two typical representatives of recycled aggregates with a representative of natural aggregates. As a representative of recycled aggregates, we chose pure concrete recycled from the cutting of concrete and mixed recyclate from the demolition of the apartment building. As a representative of natural stone, we chose the extracted aggregate.

scholarly journals Mechanical Performance of Gilsonite Modified Asphalt Mixture Containing Recycled Concrete Aggregate

2021 ◽  
Vol 11 (10) ◽  
pp. 4409
Author(s):  
Daniel Alberto Zuluaga-Astudillo ◽  
Hugo Alexander Rondón-Quintana ◽  
Carlos Alfonso Zafra-Mejía
Keyword(s):  
Mechanical Performance ◽  
Permanent Deformation ◽  
Asphalt Binder ◽  
Asphalt Mixture ◽  
Coarse Fraction ◽  
Recycled Concrete ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates

Hot-mix asphalts exposed to hot weather and high traffic volumes can display rutting distress. A material that can be used to increase the stiffness of asphalt binders is gilsonite. On the other hand, from an environmental point of view, the virgin natural aggregates of asphalt mixtures can be replaced with recycled concrete aggregates. For these reasons, this study modified the asphalt binder with gilsonite by wet-process to improve rutting resistance, and replaced (by mass and volume) part of the coarse fraction of the aggregate with recycled concrete aggregate in two hot-mix asphalts with different gradations. Unlike other studies, a larger experimental phase was used here. Marshall, indirect tensile strength, resilient modulus, permanent deformation, fatigue resistance, and Cantabro tests were performed. An ANOVA test was carried out. If the replacement of the virgin aggregate by recycled concrete aggregates was made by volume, both materials (gilsonite and recycled concrete aggregate) could be used in hot-mix asphalts for thick-asphalt layers in high temperature climates and any level of traffic. The use of both materials in hot-mix asphalts is not recommended for thin-asphalt layers in low temperatures climates. It is not advisable to replace the aggregates by mass.

scholarly journals The Influence of Fly Ash on the Compressive Strength of Recycled Concrete Utilizing Coarse Aggregates from Demolition Works

2021 ◽  
Vol 11 (3) ◽  
pp. 7107-7110
Author(s):  
V. T. Phan ◽  
T. H. Nguyen
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Recycled Concrete ◽  
Experimental Results ◽  
Strength Development ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Coarse Aggregates ◽  
Natural Aggregates

The compressive strength of recycled concrete with coarse aggregates with and without fly ash was studied in this paper. The recycled concrete was designed to have a compressive strength of Rn=15Mpa. The ratio of conventional aggregates and recycled coarse aggregates was 50-50. Fifteen samples for each recycled concrete aggregate had been cast and were tested 7, 14, and 28 days after curing. The experimental results indicate that the strength development of the two recycled concrete mixes is relatively uniform. Fly ash increased the compressive strength of recycled concrete by 11% for 7-day aged samples. The recycled concrete with fly ash had 7% less compressive strength than the concrete consisting of natural aggregates.

scholarly journals Studies on the fresh properties an durability of unshrinkable fill containing recycled concrete aggregate or natural aggregates of marginal quality

2021 ◽  
Author(s):  
Maryam Kolahdoozan
Keyword(s):  
Calcium Content ◽  
Recycled Concrete ◽  
Expansion Rate ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Sulphate Attack ◽  
Fresh Properties ◽  
Severe Damage ◽  
Sulphate Content ◽  
Natural Aggregates

The intention of this research is to explore the feasibility of incorporating aggregates of low or marginal quality, such as Recycled Concrete Aggregate (RCA) and aggregate with high sulphate content, in U-fill mixtures. It has been determined that where RCA is used, water dissipation may be hindered due to the increase in fines caused by abrasion, hence causing an increase in hardening time. To reduce this effect, addition of natural aggregates may be necessary. Moreover, through a series of investigation it has been found that high percentages of sulphate may cause severe damage due to Ettringite and Thaumasite formation; however by incorporation of supplementary materials such as slag the deleterious effects of internal sulphate attack can be reduced. The effects of using Na2SO4 and gypsum in the presence of slag have also been investigated. Results indicated that due to the lower available calcium content within bars containing Na2SO4 expansion rate is low.

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