scholarly journals Development of a Correlation between the Resilient Modulus and CBR Value for Granular Blends Containing Natural Aggregates and RAP/RCA Materials

2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
Muhammad Arshad
Keyword(s):  
Statistical Analysis ◽  
Resilient Modulus ◽  
Recycled Concrete ◽  
Experimental Results ◽  
Triaxial Tests ◽  
Concrete Aggregate ◽  
Reclaimed Asphalt ◽  
Serviceable Life ◽  
Natural Aggregates ◽  
Repeated Load Triaxial

Limited supplies of natural aggregates for highway construction, in addition to increasing processing costs, time, and environmental concerns, have led to the use of various reclaimed/recycled materials. Reclaimed asphalt pavement (RAP) and recycled concrete aggregate (RCA) have prospective uses in substantial amounts in base and subbase layers of flexible pavement in order to overcome the increasing issue of a shortage of natural aggregates. This research presents the development of an empirical model for the estimation of resilient modulus value (MR) on the basis of CBR values using experimental results obtained for 52 remoulded granular samples containing natural aggregates, RCA, and RAP samples. Statistical analysis of the suggested model shows promising results in terms of its strength and significance when t-test was applied. Additionally, experimental results also show that MR value increases in conjunction with an increase in RAP contents, while the trend for the CBR value is the opposite. Statistical analysis of simulation results using PerRoad and KenPave demonstrates that addition of RAP contents in the subbase layer of flexible pavements significantly improves its performance when considering resistance against rutting and fatigue. However, results of repeated load triaxial tests show that residual accumulative strain under a certain range of loading conditions increases substantially due to the addition of RAP materials, which may be disadvantageous to the serviceable life of the whole pavement structure.

Geotechnical characteristics of recycled crushed brick blends for pavement sub-base applications

2012 ◽  
Vol 49 (7) ◽  
pp. 796-811 ◽  
Author(s):  
A. Arulrajah ◽  
J. Piratheepan ◽  
M.W. Bo ◽  
N. Sivakugan
Keyword(s):  
Recycled Concrete ◽  
Engineering Properties ◽  
Triaxial Tests ◽  
Crushed Rock ◽  
Dry Density ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Crushed Brick ◽  
Repeated Load ◽  
Repeated Load Triaxial

This paper presents the findings of a laboratory investigation on the characterization of recycled crushed brick when blended with recycled concrete aggregate and crushed rock for pavement sub-base applications. The engineering properties of the crushed brick blends were compared with typical state road authority specifications in Australia for pavement sub-base systems to ascertain the potential use of crushed brick blends in these applications. The experimental programme included particle-size distribution, modified Proctor compaction, particle density, water absorption, California bearing ratio (CBR), Los Angeles abrasion, pH, organic content, and repeated load triaxial tests. Laboratory tests were undertaken on mixtures of 10%, 15%, 20%, 25%, 30%, 40%, and 50% crushed brick blended with recycled concrete aggregate or crushed rock. The research indicates that up to 25% crushed brick could be safely added to recycled concrete aggregate and crushed rock blends in pavement sub-base applications. The repeated load triaxial test results on the blends indicate that the effects of crushed brick content on the mechanical properties in terms of permanent deformation and resilient modulus of both the recycled concrete aggregate and crushed rock blends were marginal compared to the effects on dry density and moisture content.

scholarly journals Desempenho de misturas asfálticas recicladas mornas e sua influência no dimensionamento do revestimento asfáltico

2020 ◽  
Vol 41 (2) ◽  
pp. 157
Author(s):  
Fernanda Gadler ◽  
Leonardo Fagundes Rosemback Miranda ◽  
Joe Villena
Keyword(s):  
Resilient Modulus ◽  
Asphalt Pavement ◽  
Asphalt Binder ◽  
Binder Content ◽  
Asphalt Mixtures ◽  
Recycled Concrete ◽  
Concrete Aggregate ◽  
Reclaimed Asphalt Pavement ◽  
Recycled Concrete Aggregate ◽  
Reclaimed Asphalt

The main purpose is to evaluate the performance of asphalt regarding resilient modulus and fatigue curve.The asphalt was produced with two wastes, reclaimed asphalt pavement (RAP) and recycled concrete aggregate (RCA), using the technique of warm mixtures. The evaluation includes, based on these parameters, the thickness differences in the design of asphalt layer for each mixture. Five asphalt mixtures were produced with incorporation of RAP and RCA, in different gradation fractions (fine and/or course), without adding any natural aggregate. In view of the aim of the article, the mixtures were evaluated through tests of resilient modulus and fatigue life, in order to support the design, establishing the necessary thickness to meet traffic demands of each mixture. The design was performed using MeDiNa software. Among all results, it is highlighted that asphalt binder content is the component that exerts the greatest influence on the resilient modulus of the mixtures. As for fatigue, in addition to the binder content, the possible anchoring of the asphalt binder in the pores of the RCA may have favored the performance of the GARC_MRAP mixture. Still, all mixtures with RAP, both in fine or course fraction, resulted in lower coating thicknesses compared to the REF, for the same load request, with better performance of the GARC_MRAP mixture produced with 100 % waste material and incorporation of only 3.1 % neat binder.

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.

Possibilities of Recycled Concrete Aggregate in Cement-Based Flowscreed

2014 ◽  
Vol 897 ◽  
pp. 247-251
Author(s):  
Adam Hubáček ◽  
Luc Boehme ◽  
Iveta Nováková
Keyword(s):  
Mechanical Properties ◽  
Recycled Concrete ◽  
Experimental Results ◽  
Recycled Aggregates ◽  
Partial Replacement ◽  
Concrete Aggregate ◽  
Rheological Characteristics ◽  
Test Results ◽  
Recycled Concrete Aggregate ◽  
Natural Aggregates

This paper presents some test-results of using fine recycled concrete as a partial replacement of natural aggregates in cement-based flowscreed. Special attention is given to describing and studying rheological characteristics and mechanical properties of cement-based flowscreed. Experimental results indicate that it is possible to prepare flowscreed with partial replacement of natural aggregates by recycled aggregates and obtain a quality that meets the requirements. This study was partially connected to the research-project RecyFlowscreed [1].

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.

scholarly journals Compacted Anthropogenic Materials as Backfill for Buried Pipes

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 717
Author(s):  
Andrzej Głuchowski ◽  
Raimondas Šadzevičius ◽  
Rytis Skominas ◽  
Wojciech Sas
Keyword(s):  
Recycled Concrete ◽  
Special Treatment ◽  
Soil Reaction ◽  
Concrete Aggregate ◽  
Buried Pipe ◽  
Recycled Asphalt ◽  
Empirical Parameter ◽  
Backfill Material ◽  
Constrained Modulus ◽  
Natural Aggregates

Buried pipe design requires knowledge about the fill to design the backfill structure. The interaction between the backfill envelope and the pipe impacts the structural performance of the buried pipe. The backfill material and compaction level respond to the backfill’s overall strength and, therefore, for pipe-soil interaction. The strength of backfill material is described in terms of modulus of soil reaction E’ and constrained modulus Eode. As the E’ is an empirical parameter, the Eode can be measured in the laboratory by performing the oedometer tests. In this study, we have performed extensive oedometric tests on five types of anthropogenic materials (AM). Three of them are construction and demolition materials (C–D materials) namely, recycled concrete aggregate (RCA), crushed brick (CB), and recycled asphalt pavement (RAP). Two of them are industrial solid wastes (ISW) namely, fly ash and bottom slag mix (FA + BS) and blast furnace slag (BFS). The results of the tests revealed that AM behaves differently from natural aggregates (NA). In general, the Eode value for AM is lower than for NA with the same gradation. Despite that, some of AM may be used as NA substitute directly (RCA or BFS), some with special treatment like CB and some with extra compaction efforts like RAP or FA + BS.

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.

Review of Studies concerning Effects of Unbound Crushed Concrete Bases on PCC Pavement Drainage

1996 ◽  
Vol 1519 (1) ◽  
pp. 51-58 ◽  
Author(s):  
Mark B. Snyder ◽  
James E. Bruinsma
Keyword(s):  
Drainage System ◽  
Field Studies ◽  
Recycled Concrete ◽  
Concrete Aggregate ◽  
Drainage Systems ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Crushed Concrete ◽  
Pavement Structures ◽  
Natural Aggregates

Recycled concrete aggregate (RCA) products are sometimes used as replacements for virgin aggregate products in concrete pavement structures. Recent concerns have centered on the deposit of RCA-associated fines and precipitate suspected of reducing the drainage capacity of RCA base layers and associated drainage systems. Environmental concerns have focused on the relatively high pH of the effluent produced by untreated RCA base layers. Several studies have examined these concerns and others; the results of some of these studies have not been published or publicized. The most relevant of these studies are summarized herein. These research efforts demonstrate that calcium-based compounds are present in most recycled concrete aggregates in quantities sufficient to be leached and precipitated in the presence of carbon dioxide. Precipitate potential appears to be related to the amount of freshly exposed cement paste surface. Thus, selective grading or blending with natural aggregates can reduce, but not eliminate, precipitate problems. It was also noted that insoluble, noncarbonate residue makes up a major portion of the materials found in and around pavement drainage systems. Washing the RCA products before using them in foundation layers appears to reduce the potential for accumulation of dust and other fines in the drainage system, but probably has little effect on precipitate potential. Field studies have shown that precipitate and insoluble materials can significantly reduce the permittivity of typical drainage fabrics but that attention to drainage design details can minimize the effects of these materials on pavement drainage.

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