Recycled Asphalt Pavement Aggregates Research Articles

Bond Strength between Steel and Recycled Asphalt Pavement Aggregate and Recycled Concrete Aggregate

Bond Strength between Steel and Recycled Asphalt Pavement Aggregate and Recycled Concrete Aggregate

Economical Assessment of Recycled Asphalt Pavement (RAP) Aggregate for Structural Concrete Production in Italy

Structural concrete aggregate can be substituted with sustainable alternatives from construction and demolition waste, such as reclaimed asphalt pavement (RAP). This contribution assesses the RAP aggregate production chain and aims to investigate the economic aspect of RAP aggregate, evaluating the costs associated with its production and comparing them with the ones necessary to produce NA and recycled concrete aggregate (RCA). This analysis aims to provide additional information on the possible advantages of RAP aggregate use in order to promote sustainable construction. The evaluation was developed using a four-step methodology consisting of (i) determining the RAP aggregate production procedure; (ii) selecting a case study; (iii) defining the mix design; and (iv) performing a cost evaluation and comparing it to the cost of NA and RCA production. The results of the cost analysis of three concretes containing different RAP percentages (0%, 30%, and 45%) demonstrated that RAP’s presence led to more expensive admixtures, with the RAP unit cost being higher than NA (+155.39%). Some strategies were proposed to diminish RAP’s cost, resulting in a reduction of −39.64% with respect to NA’s cost and ranging from 45.13% to 67.30% when compared to RCA’s cost.

Effect of waste brick powder rich in SiO2 on the physical and mechanical properties of Portland cement concrete containing coarse recycled asphalt pavement aggregates (RAP)

Promoting sustainable development involves minimizing the consumption of natural resources, including aggregates, without compromising the performance of concrete. In Algeria, the rapid expansion of road projects results in substantial quantities of Recycled Asphalt Pavement (RAP) generated through milling and excavation of existing bituminous roads. To enhance the reuse of RAP aggregates in concrete, it is well-established that incorporating cement with silica-rich mineral additives can reduce energy consumption and enhance concrete efficiency and performance. This study focuses on investigating the potential use of waste brick powder (WBP) as supplementary cementitious materials (SCMs) to enhance the physical and mechanical properties of concrete containing coarse RAP aggregates. The substitution levels of WBP were set at 0%, 5%, and 15%, respectively, in blends comprising 0%, 25%, 50%, 75%, and 100% RAP aggregates. Various tests were conducted, including slump tests, compression strength analysis, ultrasonic velocity measurements, dynamic elastic modulus assessments, water permeability evaluations, and examination through Scanning Electron Microscope (SEM). The results indicate that blends containing 5% WBP demonstrate improved mechanical and physical properties compared to other blends. However, microstructural and elemental analyses reveal that the enhancement in Interfacial Transition Zone (ITZ) properties is not significant. It was also observed that water absorption decreased with increasing RAP content. Generally, a coarse RAP content of up to 50% proves to be suitable for achieving satisfactory performance in concrete.

An overview of fresh and mechanical properties of recycled coarse aggregate self- compacting concrete

To make sure of balance growth between socio-economic and environmental concerns, most of the endless changes are faced by the present generation to handle distinct types of wastes obtained by industrial sectors. The manufacturing industries throw a lot of challenging tasks to develop the products as eco-friendly by enhancing the usage of construction wastes incorporating various recycling methods. Due to urbanization, there is an increasing demand for the manufacturing of self-compacting concrete (SCC) in the construction industry over conventional concrete. Stating the above scenario, the need for alternative natural aggregates is crucial to support possible environment in the construction sector. One such alternative material is recycled coarse aggregate (RCA) as it poses a substantial number of benefits like preserving ecological balance, generating cost-effective constructions, decreasing excessive natural resources consumption, and manufacturing concrete for sustainable development. In this paper, the most relevant literature study of various fresh and hardened properties of SCC with RCA, various industrial wastes like fly ash (FA), silica fume (SF), recycled asphalt pavement aggregates (RAPA), rubber granules (RG), Slag and fibers are discussed to create the importance of the structural performance of SCC with RCA in the construction sector.

Strength characteristics of recycled asphalt pavement aggregate based geopolymer concrete

Strength characteristics of recycled asphalt pavement aggregate based geopolymer concrete

THE COMPARATIVE EXPERIMENTAL STUDIES ON THE SUITABILITY OF CERAMIC WASTE AGGREGATE AND RECYCLED ASPHALT PAVEMENT AGGREGATE AS AN ALTERNATIVE FOR BASE COURSE MATERIAL

The study aimed to assess the suitability of ceramic waste aggregate and recycled asphalt pavement aggregate as an alternative for base course material. An experimental research design method and Non-Probability sampling techniques were used. The comparative analysis of ceramic waste aggregate and recycled asphalt pavement aggregate were blended with crushed stone aggregate at different proportions by weight and their laboratory result was compared with standard specifications. The study results shown that the aggregate crushing value (ACV) for neat Crushed stone aggregate (CSA) and Recycle asphalt pavement (RAP) are 19.20% and 8.20% respectively and the blended CSA with 10%, 20%, 30%, 40% and 50% of RAP were 18.20%, 16.4%, 15.90%, 14.40%, and 13.10% respectively. Similarly, a 24.32% - 12.06% for Los Angeles abrasion (LAA) and 18.50% - 12.60% for aggregate impact value (AIV) were found to the lower and higher value in the range of the test result. The CBR test for a different proportion of RAP (10% - 50%) blended with CSA was also conducted and an economically acceptable result of 104.20% was found at 30% RAP mix at 98% maximum dry density (MDD). Additionally, the California Bearing Ratio (CBR) test result for 100%RAP at 98%MDD was 49.10%. On the other hand, the experimental tests were conducted on different proportions of Ceramic West aggregate (CWA) (10%, 20%, 30%, 40%, and 50%) which satisfy the principal mechanical properties of aggregate materials. The ACV result for neat CWA is 26.70% while the blended CWA- CSA aggregate was tested with 10%, 20%, 30%, 40%, and 50% of CWA with its complement of CSA as indicated and at 20% CWA replacement of CSA test results were (21.60%, for ACV), (26.31% for LAA), (106.9 for CBR) and (20.60 for AIV). For this investigation an economically acceptable results were achieved by satisfying the Ethiopian road authority (ERA) standard specification limit at 20% CWA and 30% RAP blended with CSA for base course construction material.

Modeling and Optimization of Concrete Compressive Strength Produced by Replacing Natural Aggregate with Recycled Coarse and Recycled Asphalt Pavement Aggregates

The modeling and optimization of concrete compressive strength produced by replacing natural aggregate (NA) with recycled coarse aggregate (RCA) and recycled asphalt pavement (RAP) aggregates was investigated. The materials used were cement, water, fine aggregate, and coarse aggregate (NA, RCA, and RAP). The RCA and RAP replaced NA at 20, 40, 60, 80, and 100% separately, and in combination, with a total of two hundred and forty (240) cubes cast, while the concrete compressive strength was determined after curing by complete immersion in water at 3, 7, 14, 21, and 28 days. The modeling and optimization was done with the aid of design expert (version 13) software, while the Analysis of Variance (ANOVA) was done using SPSS (Statistical Package for Social Sciences) version 23 and adopting the Least Square Difference (LSD) method. Results from the findings showed that the optimum 28 days concrete compressive strength are concrete produced with 20%RAP, 40%(20%RAP +20%RCA), 60%(30%RAP + 30%RCA), and 80%(40%RAP + 40%RCA) replacements which are not significantly different from the control concrete, however, 40%(20%RAP +20%RCA) and 80%(40%RAP + 40%RCA) concrete had compressive strength higher than the control concrete. Also, the 3, 7, 21, and 28 days compressive strength can be predicted with quadratic model, while the 14 days strength can be predicted with 2-Factor Interaction (2FI) model. The optimization result showed that by replacing natural aggregate with 10.0% RAP and 50.0% RCA, the 28 days compressive strength of the concrete was 33.74N/mm2.

Geri Dönüştürülmüş Asfalt Kaplama Malzemesinin Betonda Kullanımı Üzerine Bir Araştırma

Doğal kaynaklarımızın giderek yok olması, agrega temini için yeni kaynakların araştırılması ve bitüm malzemesi konusunda dışa bağımlı olunması, yıpranmış asfalt kaplamaların yeniden kullanımı konusunda teşvik edici olmaktadır. Ayrıca asfalt kaplamaların ekonomik açıdan yüksek değere sahip olması da kaplamaların yeniden kullanılabilirliği üzerinde çalışılması gerektiği düşüncesini doğurmaktadır.
 Bu çalışmada; yol inşasında kullanılan asfalt kaplamanın geri dönüştürülmesi ve geri dönüşüm yöntemlerinin incelenmesi amaçlanmıştır. Ayrıca geri kazanılmış asfalt kaplama malzemesi üzerine yapılan bilimsel çalışmalar incelenmiştir. Çalışma sonucunda; geri dönüştürülmüş asfalt kaplama agregalarının betonun basınç dayanımı ve akışkanlık değerlerinde azalma, tuza ve dona karşı dayanımlarında ise artış meydana geldiği görülmüştür. Bunun yanı sıra atık asfalt kaplamaların ekonomiklik, sürdürülebilirlik ve enerji tasarrufu yönünden oldukça değerli bir atık olduğu tespit edilmiştir. Ayrıca yıpranmış, bozulmuş eski asfalt kaplamaların yeniden kullanımı çevre korunumu açısından oldukça önem arz ettiği anlaşılmıştır.

Compressive behavior of light–gauge steel tubes filled with concrete containing recycled aggregates

Abstract The axial capacity of light–gauge steel tube columns filled with concrete including recycled asphalt pavement (RAP) aggregates and recycled concrete aggregates (RCA) was investigated. A total of 51 specimens, including 6 bare steel tubes, 30 composite columns and 15 concrete-only columns were tested under uniaxial load. Fifteen concrete mixes were considered by replacing the weight of natural coarse aggregates (NA) with RCA and RAP at replacement levels of 0, 20, 40, 60, 80, and 100%. In addition, RAP and RCA were combined in the same mixes with replacement levels of (1) 20% RAP and 80% RCA; (2) 40% RAP and 60% RCA; (3) 60% RAP and 40% RCA; and (4) 80% RAP and 20% RCA. Experimental results were analyzed by reporting the ultimate capacities and the patterns of failure. Moreover, the predictions of EUROCODE 4 (EC4) and American Institute of Steel Construction (AISC) codes were checked. ABAQUS software was used to perform a finite element analysis (FEA) of the tested composite specimens. The results showed that using recycled aggregates decreased the carrying capacity of columns. Carrying capacity of light–gauge steel tubes filled with concrete including different combinations of RCA, NA and RAP aggregates can be conservatively predicted by the AISC and EC4 recommendations. Results of FEA showed a good agreement with the experimental results.

Influence of mobilized RAP content on the effective binder quality and performance of 100% hot in-place recycled asphalt mixtures

Hot in-place recycling (HIR) is a promising technique to consume 100% recycled asphalt pavement (RAP) for pavement surface rehabilitation. When RAP aggregates are incorporated in asphalt mixtures, a proportion of the RAP binder can be mobilized by the virgin binder or additive and achieve a homogenous binder blend, named “the effective binder blend.” There exist two major concerns of using 100% RAP in HIR mixes: 1. How much of the RAP binder can be mobilized to coat aggregates? 2. What are the contributions of the mobilized RAP binder to the performance of HIR mixes? This study firstly developed an approach to quantify the mobilized RAP content in HIR mixes. Afterward, the effective binder blends were prepared in the laboratory, based on the mobilized RAP and virgin asphalt percentage. Finally, the dynamic shear rheometer test and sessile drop method were adopted to characterize the effective binder qualities, while AMPT and Ideal-CT tests were utilized for mixture performance evaluation. Results showed that the mobilized RAP binder altered the binder qualities of the effective binder blends and also the effective asphalt content in HIR mixes. The binder qualities, including rheological properties and surface free energy, contributed to the different stiffness and cohesion of the effective binder blends in HIR mixes. However, the effective asphalt content proved to dominate the cracking resistance of HIR mixes.

Numerical investigation of RC deep beams containing recycled aggregates

In this study, the behavior of reinforced concrete deep beams containing natural coarse aggregates (NCA), recycled concrete aggregates (RCA), and recycled asphalt pavement aggregates (RAP) was numerically investigated. The required parameters for use in the nonlinear finite element analysis were discussed in detail. To examine the accuracy of the nonlinear analysis, the numerical analysis results for deep beams containing NCA, RCA, and RAP were validated with experimental results. The most important parameters that could affect the behavior of concrete deep beams were proposed. The numerical analysis results for 63 concrete deep beam specimens indicated that the deep beams containing NCA and RCA exhibited nearly similar behavior for any a/h and L/h ratios, whereas RAP deep beams behaved differently from the two corresponding specimens. The deep beams made with RCA and NCA had brittle behavior for any value of the a/h and L/h ratios, while those containing RAP showed more ductility. The energy absorption was far greater for RAP deep beams compared with the NCA and RCA specimens. The absorbed energy in NCA and RCA deep beams was nearly the same. The size effect phenomenon was almost similar in the deep beams made with NCA and RCA, whereas in the RAP deep beams, the intensity of this effect was less severe.

Characteristics and optimization of cement concrete mixes with recycled asphalt pavement aggregates

Characteristics and optimization of cement concrete mixes with recycled asphalt pavement aggregates

Restriction of RAP% in HMA Based on Aggregate Gradation and Binder Properties

The use of recycled asphalt pavement (RAP) in pavement construction reduces the project cost and helps in conserving the naturally occurring aggregates. To incorporate RAP in hot mix asphalt, it is vital to know the amount and quality of the reclaimed binder. Three new asphalt binders were selected for this investigation. RAP material from one source was blended in different proportions with VG-10 and VG-30. Penetration, softening point, G */sin δ, G * sin δ and binder fatigue life Nf (from Linear Amplitude Sweep test) values of different blends were compared. The milled RAP aggregate gradation varied from source to source due to factors such as the gradation of the mix used in the existing layer, milling method and processing of RAP material. This variability controls the use of higher proportions of RAP in new mixes. To investigate the effect of RAP gradation on the proportion of RAP that can be used in the new mix, RAP sources with different gradation (three dense and two gap gradations) were selected. The proportion of RAP that can be used for preparing mixes with these gradations varied significantly with the source of RAP, and the target gradation. In most cases, it was found that allowable RAP percentages are smaller for the gap gradations compared to those permitted for dense gradations. The proportion of RAP in a mix can be increased by selecting an appropriate gradation for a RAP source or by using a suitable RAP source for a given gradation.

Mechanical Behavior Investigation of Reclaimed Asphalt Aggregate Concrete in a Cold Region.

Recycled construction and demolition (C&D) waste can reduce the rebuild cost, and is environmentally friendly when recycled asphalt pavement (RAP) aggregate constitutes the main part. This paper investigated the mechanical performance of RAP concrete, and the applicability of RAP in road base layers also was discussed. Several mechanical laboratory tests were selected, including the unconfined compressive-strength, splitting-strength, and compressive-resilience modulus tests. The RAP concrete had a good road performance in a cold region, which was proved by the temperature-shrinkage test, dry-shrinkage test, freeze–thaw-cycle test, and water-stability test. Based on various cement dosages from 3.5% to 5.5% in RAP concrete mix design, three RAP aggregate replacement ratios (30%, 40%, and 50%) were selected to study the variation of mechanical properties with increasing curing time, and the optimal aggregate substitute ratio was determined. A scanning electron microscope (SEM) was used to observe the inner-structure interface between the asphalt binder and cement stone. A numerical model is presented to simulate the RAP compressive strength with respect to the effect of multiple parameters. The research results can provide a technical reference for RAP use in the reconstruction and expansion of low-grade highway projects.

Production of Roller Compacted Concrete Made of Recycled Asphalt Pavement Aggregate and Recycled Concrete Aggregate and Silica Fume

Production of Roller Compacted Concrete Made of Recycled Asphalt Pavement Aggregate and Recycled Concrete Aggregate and Silica Fume

Experimental study on bond behavior between heat-damaged recycled asphalt pavement concrete and NSM-CFRP strips

In this work, the effect of high temperature on the bond behavior between Recycled Asphalt Pavement (RAP) concrete and Fiber Reinforced Polymer (FRP) was studied. The use of RAP in concrete construction has been developed and utilized recently due to its various economic and environmental features. Nevertheless, very few studies have examined the bonding performance and failure mode between RAP concrete and FRP. A total of 46 asphalt pavement concrete specimens with three different concrete compressive strength were cast and tested under pullout test. The specimens were prepared using different RAP aggregate content and were subjected to elevated temperatures within a range from 23 °C to 600 °C. The heat damaged specimens were repaired using two Near-Surface Mounted Carbon Fiber Reinforced Polymer (NSM-CFRP) strips spaced at 50 mm with three different bonded lengths. According to the experimental results of the pullout test, RAP concrete specimens showed lower bonding strength and slippage than Natural Aggregate (NA) concrete specimens. Furthermore, specimens exposed to elevated temperatures showed a significant decrease in bonding strength and a significant increase in slippage. Results also indicated that as the temperature increased, specimens with high RAP aggregate content failed at higher slippage compared to specimens with low RAP aggregate content with the same compressive strength. Moreover, the relationships between bond load and strain of (CFRP) strips were established and discussed in the results. The failure mode in all specimens was concrete separation.

Influence of using two types of recycled aggregates on shear behavior of concrete beams

This paper investigates experimentally and theoretically the shear behavior of thirteen reinforced concrete (RC) beams made of Recycled Asphalt Pavement (RAP) and Recycled Coarse Aggregate (RCA). The span length of the beams was 2240 mm, and the width and depth of the beams were 200 and 400 mm, respectively. Three groups of beams were used in this study: The first group was five beams made of RAP and natural aggregate (NA), where the NA was substituted by RAP with replacement levels of 20%, 40%, 60%, 80%, and 100% by the total weight of NA. The second group was four beams made entirely of RAP and RCA. The third group was four RC beams made of RCA and NA, where NA was replaced by RCA with replacement levels of 20%, 40%, 60%, and 80%. The beams were tested under four-point loading setup. The maximum shear forces, deflections, and cracking patterns were studied. The experimental results were compared with theoretical results determined from the equations of selected international codes and fracture mechanics approaches available in the literature. The results showed that the experimental shear capacity increased as the RAP and RCA replacement levels decreased for the beams in group one and three, and decreased for group two beams when the RCA replacement levels increased. The theoretical shear strength capacities were more conservative when compared to the experimental results. Therefore, the theoretical shear equations can be applicable to the beams constructed with recycled aggregates. In general, using RAP and RCA in RC beams can be considered as an effective approach.

Influence of temperature on mechanical properties of recycled asphalt pavement aggregate and recycled coarse aggregate concrete

The effect of fire on reinforced concrete (RC) structures is very important because it is threatening the human life and property safety. Using Recycled Asphalt Pavement (RAP) and Recycled Coarse Aggregate (RCA) in concrete mixtures can be considered economically and environmentally friendly because it saves our natural resources. This paper investigates experimentally the influence of incorporating RAP and RCA on the mechanical properties of concrete mixes after exposure to different temperatures: 20 °C, 200 °C, 400 °C, and 500 °C. The Natural Coarse Aggregate (NCA) was replaced by RAP aggregates at three replacement ratios (10%, 20% and 30%), and the NCA was replaced by RCA at four replacement ratios (20%, 40%, 60%, and 100%). As well as using three mixes of 90%RCA-10%RAP, 80%RCA-20%RAP, and 70%RCA-30%RAP. Compressive, splitting tensile and flexural strengths, compressive stress-strain curves, and modulus of elasticity were studied on two hundred sixty four cylinders and one hundred thirty two prisms. The results showed that the mechanical properties decreased as the replacement ratios of RAP and RCA increased for the same temperature. And the mechanical properties decreased for the same replacement ratio of recycled aggregates when the temperature increased. The decrease in mechanical properties at elevated temperatures for RAP-RCA mixes can be comparable with NCA, RAP and RCA only mixes. Therefore, the RAP and RCA have the potential to be incorporated in the concrete mixes on high temperatures since the decrease in the mechanical properties is not that significant relative to the efforts in reduction the negative impacts of recycled aggregates on the environment and human health.

Feasibility of Using Recycled Asphalt Pavement Aggregates in Concrete Pavement

The feasibility of using concrete containing recycled asphalt pavement (RAP) in concrete pavement applications was evaluated. Recycled asphalt pavement (RAP) is the removed pavement material containing asphalt and aggregate. However, limited researches have been done to examine the potential of incorporating RAP into concrete. Since RAP contains asphalt, it is very likely that the toughness of concrete made with RAP could be improved. An alternative use of RAP is to use it as an aggregate in Portland cement concrete (PCC). Concrete containing 0%, 15% and 30% of RAP replacement by weight of natural coarse aggregates with different cement content with (250, 300 and 350 kg/m3) were produced in the laboratory and evaluated for their properties that are relevant to performance of concrete pavements. Mechanical properties of the concrete mainly compressive strength, modulus of elasticity and Poisson’s ratio after 28 days were recorded. The test results indicated that, the modulus of elasticity was found to decrease as the RAP content of the concrete increased, due to a decrease in the compressive strength of the concrete. However, these results as RAP were incorporated in the concrete, the resulting of compressive strength to modulus of elasticity and Poisson’s ratio for the concrete was reduced as compared with mixes that of a reference concrete without RAP. This indicates that, using a concrete containing RAP could possibly result in improvement in the performance of concrete pavements. Moreover, RAP could be used into Portland cement concrete without any modification to the conventional equipment or procedures.

Evaluation of Mixture Performance Recycled Asphalt Pavement Materials as Base Layer with or without Rejuvenator into the Asphalt

The binder properties were determined in accordance with Chinese standard such as ductility test, which allowed to measure the distance in centimeters that a standard briquette of asphalt had been stretched before breaking. Then, penetration test was carried out in order to know some properties of the asphalt, which are the hardness and the softness. Finally, softening point test was carried out in order to determine the temperature at which the bitumen attains a particular degree of softening under the specification of the test. According to Chinese standard for performance tests, firstly, Marshall test was carried out in order to measure the theoretical density, air voids, voids filled with asphalt, stability, flow, and voids in mineral aggregate of asphalt specimens. Secondly, Freeze-thaw splitting test was carried out in order to determine Splitting strength ratio. Finally, dynamic stability (rutting) test was carried out to determine average dynamic stability. Beside the tests carried out, the gradation of the extracted aggregate in accordance with American Association of State Highway and Transportation Officials was carried out to determine the dimensions of the particles weight distribution. Furthermore, both the percentage of recycled asphalt pavement materials and binder in mixture were determined to know how much of the new material during the mixture was needed. However, two specimens were used to evaluate the performance of recycled asphalt pavement materials. One specimen of recycled asphalt pavement materials was ten years old, and another one of recycled asphalt pavement materials was five years old. The results show that the conditions of the environment such as moisture, temperature, and age, decrease the ductility and penetration properties of binder when increase the softening point property of binder. Then the gradation of recycled asphalt pavement aggregate is of the required values to reuse in the mixture, while the flow ratio, the splitting strength ratio, and the dynamic stability ratio, are less than the required value test. With regard to the properties of mixture of recycled asphalt pavement material binder with rejuvenator, the results show that when the penetration and ductility versus percentage of rejuvenator increase, softening point versus percentage of rejuvenator decreases. Also, when the bitumen and rejuvenator percentage increase, the air voids decrease. Consequently, voids filled with asphalt and voids in the mineral aggregate increase. Moreover, the theoretical density and stability values decrease in a mixture containing four-point fifty percent to six percent of bitumen and rejuvenator, whereas the flow values increase. More interestingly, with four percent to four-point fifty percent mixture ratio of bitumen and rejuvenator, density, stability, and flow values increase. The splitting strength ratio values of mixtures and the dynamic stability test (rutting test) values of mixtures with forty percent of specimen one and specimen two respectively are greater than the required value of the standard test. In addition, the high percentage of rejuvenator increases the rut of pavement, in the same manner, the low percentage of rejuvenator induces low rut. In conclusion, the binder content from recycled materials without rejuvenator seems not be sufficient to be reused on the new pavement while the aged recycled material seems to be performed better than no aged recycled material with rejuvenator into bitumen. Then, the rejuvenator can influence the bitumen properties and performance of the pavement. Finally, the pavement made by only recycled pavement materials as a base layer appears to be more economical but cannot be more effective than the pavement made by mixture of new and recycled pavement materials as a base layer.