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The construction of pavements incorporating reclaimed asphalt pavement (RAP) is taking place around the world, implying the necessity to quantify their net environmental impacts. Life cycle assessment (LCA) is a popular method to analyze the environmental impacts of a product along the whole value chain, providing guidance to practices and technologies from environmental perspectives. However, the LCA research of RAP-modified pavement is seldom performed in Brazil. In addition, as an important source of uncertainties, there is also need of discussion regarding the geographical and technological characteristics in the LCA of pavements. For these motivations, this paper performs a cradle-to-gate LCA to compare the environmental performance of asphalt pavement in Brazil and Switzerland, using the practical rates of RAP use. The functional unit was defined based on the same traffic volume and service life of asphalt pavements, where the mix design and pavement structures follow the standards of the two countries. The results showed that RAP recycling can improve the environmental performance of hot asphalt mixtures in both countries. Binder amount has a high environmental burden and its reduced use by adding RAP has a positive environmental effect. Type of fuel also plays an important role in LCA. In Brazil, it is not recommended to use heavy oils as fuel during the mixing process if other options such as methane gas is available. The results show that the Swiss production of asphalt mixture had lower environmental impact. Nevertheless, a strategic location of material suppliers and mixing plants could lower the transportation distances, improving its environmental performance., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.) more...

Nobre, GG, de Almeida, MB, Nobre, IG, dos Santos, FK, Brinco, RA, Arruda-Lima, TR, de-Vasconcelos, KL, de-Lima, JG, Borba-Neto, ME, Damasceno-Rodrigues, EM, Santos-Silva, SM, Leandro, CG, and Moura-dos-Santos, MA. Twelve weeks of plyometric training improves motor performance of 7- to 9-year-old boys who were overweight/obese: a randomized controlled intervention. J Strength Cond Res 31(8): 2091-2099, 2017-The prevalence of childhood overweight/obesity has increased, and physical training at school may to be effective to combat this scenario. We analyzed the effects of a protocol of plyometric training on body composition and motor performance of boys who were overweight/obese aged 7-9 years. The sample was randomly assigned into 2 groups: plyometric training group (T, n = 40) and control group (C, n = 19). Training consisted of 20 min·d (twice a week, during 12 weeks) of lower extremity plyometric exercise. Health-related physical fitness was measured by handgrip strength, standing long jump (SLJ), curl-ups, sit and reach, square test, running speed, and mile run test. Gross motor coordination was evaluated by means of the Körperkoordinations-test für Kinder (KTK) tests. Baseline and postintervention differences were investigated, and effect size was estimated through Cohen's d coefficient. Both groups showed increased body weight, height, and sitting height after intervention with a negligible effect size. Only T group showed increased fat-free mass (p = 0.011) compared with baseline values with small effect size. Plyometric training improved handgrip strength (d = 0.23), sit and reach (d = 0.18), curl-ups (d = 0.39), SLJ (d = 0.80), agility (d = 0.48), and time in the mile run test (d = 0.38). For gross motor coordination results, T group showed better performance in all tests after plyometric training with moderate/large effect size. Thus, 12 weeks of PT improved health-related physical fitness components and motor coordination acquisition of 7- to 9-year-old boys who were overweight/obese. more...

Construction and demolition waste (CDW) worldwide generation accounts 10 billion tonnes yearly. The major fraction is landfilled requiring innovative recycling methods to reduce the associated environmental impacts and to increase its circularity. Our study demonstrated the feasibility of using different CDW fines to develop recycled cements and optimized the content of CDW recycled cements with well-graded crushed stone (WGCS) for use as pavement base layer. We scaled up the study obtaining CDW cement and aggregates from a local recycling plant, as well as pilot pavement sections designed, constructed and field deflections measured. As results, the CDW cement pastes exhibited accumulated heat values of up to 111 J g−1 and achieved a compressive strength of approximately 16 MPa. The unconfined compressive strength and resilient modulus (RM) achieved using CDW cement and WGCS were 2–3 and >3000 MPa, respectively. The sections constructed using CDW cement exhibited intermediate behaviour compared to those obtained using reference materials (6% Portland cement-WGCS and a conventional granular base made using WGCS). The deflection decreased over time owing to the pozzolanic reaction. [ABSTRACT FROM AUTHOR] more...

This study investigates the effect of storage temperature, storage time, base binder, polymer type, and poly-phosphoric acid (PPA) concentration on the properties of commercial-grade reactive elastomeric terpolymer-modified binders (RET-MBs). To mimic the practical storage conditions, RET-MBs were contained in sealed metal tubes and stored in a forced convection oven at temperatures 120, 135, 150, and 165 °C for up to 14 days. The results show that the deterioration in conventional and rheological properties of RET-MBs was noticeable even at a low storage temperature of 135 °C. At storage temperatures of 150 and 165 °C, significant property erosion was observed within the first three days of storage. After 7 days of storage at 150 °C, the softening point temperature, the PG upper temperature (Tu), and percent elastic recovery values decrease by 4 °C, 3.5 °C, and 45%, respectively. One PG-grade drop can occur after 3–7 days of storage at 150 and 165 °C, which can result in the RET-MB failing the required specification. FTIR analysis of the solution-cast films of RET polymer with PPA reveals the interaction of the epoxy ring with PPA molecules to form phosphate ester linkage during storage, due to which the interaction between RET polymer and binder molecules reduces, resulting in severe property erosion during storage. The result demonstrates that RET-MBs should be stored and transported at temperatures < 135 °C, and this specific storage requirement must be mentioned in the storage and handling guidelines for RET-MBs. [ABSTRACT FROM AUTHOR] more...

In pavement engineering, cold recycled material (CRM) mixtures allow implementing circular economy concepts by maximizing the reuse of reclaimed asphalt without heating. Along with bitumen emulsion and foamed bitumen, Portland cement is often added to CRM mixtures to improve the field performance. However, the role of cement on the fatigue failure is not sufficiently investigated. The objective of this research is to provide new insights into the fatigue failure of CRM mixtures produced with bitumen emulsion and cement. To this aim, two CRM mixtures prepared with different dosages of cement (1 and 2%) were subjected to uniaxial cyclic tension fatigue tests. Empirical and energy-based failure criteria, originally developed for asphalt concrete mixtures, were used to define the fatigue failure. The results showed that the fatigue failure mechanism of CRM mixtures was of a composite type, affected by both cementitious and bituminous bonds. A new criterion was proposed to identify the failure of the cementitious bonds. [ABSTRACT FROM AUTHOR] more...

Illegal dumping of construction and demolition waste continues to be a problem hindering circular economy efforts. Controlling illegal dumping necessitates establishing an effective surveillance scheme and investigating the proper penalty value. This problem has previously been described as a game theory problem, with the government and construction contractors as the players. Taking into account illegal dumping hotspots, which can often be identified through topographical and geographical characteristics, is also important when establishing supervision strategies. This study develops an evolutionary game-theoretic model that can assist in devising effective supervision strategies to control the spread of illegal dumping, while taking into consideration hotspots. In specific, this study investigates the suitability of two alternative strategies: police patrols and hybrid monitoring through both patrols and the installation of closed-circuit television cameras in hotspots. The model was applied to two case studies, using parameters informed by real-world contexts, to demonstrate its potential for selecting suitable strategies according to local situations. The results suggest that nine possible scenarios govern the stable evolutionary strategies of game players, with five scenarios in which contractors converge to adopt legal dumping. Accordingly, based on the parameters of the region (hotspot areas, cost of supervision, efficiency of patrols, penalties, etc.), governments would be able to assess which of the strategies would lead to long-term compliance of contractors while also increasing their payoffs. Further analysis allowed to determine the minimum efficiency required, and simulations were performed to demonstrate the influence of different supervision efficiencies and penalties on the evolutionary strategies. [ABSTRACT FROM AUTHOR] more...

Traffic paints hold paramount importance in road markings and ensuring efficient traffic flow. Self-cleaning marking traffic paints are a type of paint which recently developed to keep traffic lines clean with high visibility. Several paints were formulated with acrylic resin and self-cleaning agents, titanium dioxide (TiO2), silicon dioxide (SiO2), and zinc oxide (ZnO) individually and or in combination. All agents were treated in a furnace at 800°C for 2 hours before incorporating into the paint formulation. The effect of untreated and treated agents on several crucial properties of the formulated paints was assessed and compared. It revealed that heat treatment was effective on the crystallinity and impurity content of the agents evidenced by traditional characteristic techniques. The SEM-EDX analysis confirmed the presence and distribution of self-cleaning agents in the paint matrix. Water contact angles ranged from 68° to 97° for paints with self-cleaning agents, indicating improved hydrophilicity. Oil contact angles ranged from 27° to 42° for most paints with self-cleaning agents, showing some improvement in hydrophobicity. The qualitative assessment confirmed superior self-cleaning performance for paints with self-cleaning agents compared to the reference paint, especially for treated agents. Overall, the type and amount of self-cleaning agents significantly affect the hydrophilicity, hydrophobicity, and self-cleaning performance of paints. [ABSTRACT FROM AUTHOR] more...

A great complexity limits its use as the degree of aging of the asphalt binder of the RAP is a determinant for the interaction with the new binder and recycling agents to design asphalt mixtures with reclaimed asphalt pavement (RAP). One of the ways to analyze the level of interaction between the aged binder and the recycling agent is through the analysis of the performance of the mixtures after the accelerated aging of the samples in the laboratory. Thus, this paper evaluated the mechanical performance of asphalt mixtures with high contents of RAP (50%, 75%, and 100%) and organic type recycling agents (residual engine oil) and surfactant (ADCAP WM), submitted to aging protocols short and long term. The data obtained verified the feasibility of adding up to 75% of RAP in the recycled mixtures. However, detailed monitoring of its execution and performance throughout its useful life is necessary. Fatigue and flexural fracture data were highly altered by aging conditioning, evidencing the reduction in the performance of the compositions of the recycled mixtures. The statistical test showed significance for the parameters RAP content and type/content of the recycling agent used. In addition, there was an increase in the deformation capacity and better resistance to aging and cracking with the incorporation of the surfactant recycling agent. [ABSTRACT FROM AUTHOR] more...

The use of warm mix asphalt (WMA) and reclaimed asphalt pavement (RAP) technologies presents challenges in optimizing binder activation and mechanical performance in asphalt mixtures. This study aimed to evaluate the effects of three WMA additives (sunflower oil, WarmGrip®, and natural zeolite) and different RAP contents (30% and 70%) on the rheological and mechanical properties of recycled asphalt mixtures. The research focused on assessing the degree of RAP binder activation, determining the extent of partial activation, and analyzing the impact on tensile strength, moisture resistance, modulus, fatigue life, and deformation resistance. The methodology included chemical and rheological analysis of RAP and modified binders, as well as mechanical testing of recycled mixtures. Results indicated partial RAP binder activation, with 96.16% activation in mixtures containing 30% RAP and 80.77% in those with 70% RAP. Sunflower oil acted as a rejuvenator, reducing binder stiffness and decreasing the maximum PG temperature by 6 °C. The use of natural zeolite improved moisture resistance, resulting in TSR values 20% higher than those of conventional hot mixtures with the same RAP content (70%). Warm recycled mixtures demonstrated enhanced fatigue life and moisture resistance, particularly with WarmGrip®. Overall, the incorporation of WMA additives allowed for enhanced fatigue life and deformation resistance in recycled mixtures, enabling the use of up to 70% RAP without compromising mechanical performance. The findings support the potential of WMA and RAP additives to improve sustainability, cost-effectiveness, and durability in asphalt pavement construction., Competing Interests: Declarations. Ethics approval: I certify that this manuscript is original and has not been published and will not be submitted elsewhere for publication while being considered by Environmental Science and Pollution Research. And the study is not split up into several parts to increase the number of submissions and submitted to various journals or to one journal over time. No data have been fabricated or manipulated (including images) to support your conclusions. No data, text, or theories by others are presented as if they were our own. The submission has been received explicitly from all co-authors. And authors whose names appear on the submission have contributed sufficiently to the scientific work and therefore share collective responsibility and accountability for the results. Human and animal rights and informed consent This article does not contain any studies with human participants or animals performed by any of the authors. Consent to participate: We, the authors, are giving our consent for this paper to be published in your journal if found publishable. Consent for publication: We, the authors, are giving our consent for this paper to be published in your journal if found publishable. Competing interests: The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.) more...

In this study, the low temperature creep properties of multiphase bituminous materials (binder, mastic, Fine Aggregate Matrix—FAM, and mixture) were experimentally evaluated, and the impact of size effect on FAM and mixture specimen was also assessed. First, the mix design of mastic and FAM was performed based on the reference mixture Asphalt Concrete (AC) 22 TS. The mathematical adaptation to the boundary sieve method was applied to calculate FAM gradation and binder content. Next, a preparation method was proposed to produce Fine Aggregate Matrix (FAM) in a laboratory environment, and scale-up slab samples were also fabricated for FAM and mixture specimens to evaluate the size effect phenomenon. Finally, three-point bending (3 PB) creep tests were conducted on the multiphase bituminous specimens with different dimensions at -6 °C, -12 °C, and -18 °C with a modified Bending Beam Rheometer (BBR) device and a dynamic loading machine, depending on the sample size. Results indicate that the creep stiffness of the FAM was close to mixtures and much higher than the one observed in binder and mastic. The proposed fabrication approach provides a satisfactory method for preparing a representative FAM phase in the mixture, while the air voids can be easily adjusted during the slab compaction procedure. This study supports the idea of using FAM to discriminate asphalt mixtures for cold regions. The correlation between up-scaled FAM and mixture specimens should be further investigated, including different mixture types and corresponding FAM. [ABSTRACT FROM AUTHOR] more...

An enormous amount of construction and demolition waste is generated globally every year, and it increases disposal costs in landfills. The advantage of adopting crushed concrete aggregate as an alternative cushioning material provides a novel approach for reusing and recycling waste materials. However, a lack of understanding of the dynamic responses of recycled concrete aggregate (RCA) inhibits their potential use. In this study, large-scale field tests are carried out to replicate dynamic impact loading on an instrumented concrete shed that is shielded by a 1 m-thick RCA cushioning layer. Six successive large-scale field boulder impact tests with energy levels reaching 70 kJ are conducted. Two different RCA particle sizes—RS (100–150 mm) and RL (200–250 mm)—are investigated. The results show that up to 82% maximum transmitted load can be reduced if the RL cushioning layer is replaced with RS cushioning layer. This phenomenon is attributed to the force chains composed of small particles that are more susceptible to collapse than large particles. To optimize the load-reduction performance of the RCA cushioning layer, practitioners should adopt a small particle size when considering a single boulder impact. In contrast, after six impacts, the maximum transmitted load for Rs is approximately 4.2 times larger than that for RL. This increased load is caused by the relative particle breakage index (Br) for RL being at least 1.3 times larger than that for Rs. This finding indicates that the amount of crushing RCA particles increases with increasing particle size. This phenomenon induces force chains to collapse more easily, and the transmitted load decreases. An RCA cushioning layer with a large particle size can effectively reduce the transmitted load under the consideration of successive impacts. This implies that the combined effects of particle size and number of successive impacts strongly influence the load distributions exerted on structures shielded by an RCA cushioning layer. Highlights: Six successive large-scale field boulder impact tests with energy levels reaching 70 kJ are conducted. [ABSTRACT FROM AUTHOR] more...

The curing process in bituminous mixes plays a vital role during the early-stage strength development of cold in-place recycling technology. Curing temperature and curing period (collectively termed as curing regime) are the critical factors governing the curing process. Inadequate curing of cold recycled (CR) bituminous mixes can result in distresses as well as premature failure. The present study evaluated the influence of the curing regime on the mechanical characteristics of CR-Bituminous mixes stabilized with foam and emulsion bitumen (CR-Foam and CR-Emulsion) respectively. The moisture loss pattern in both CR-Foam and CR-Emulsion mixes was monitored over a curing period of 14 days and at three temperatures of 25, 40 and 60 °C. Results of the research showed that moisture loss was rapid during the 24 h and then the rate of moisture loss decreased eventually becoming constant approximately after 7 to 10 days. An increase in curing temperature accelerated the moisture loss in the initial days of curing resulting in better mechanical characteristics whereas the increase in humidity delayed the strength development process even after a prolonged curing period of 7 days. Both the CR-Mixes were found to have similar resilient modulus values for the same residual moisture content indicating the impact of curing temperature. In terms of performance, CR-Emulsion mixes showed superior cracking resistance than CR-Foam mixes as indicated by the Cracking Tolerance Index. [ABSTRACT FROM AUTHOR] more...

Construction and demolition wastes (CDW) are a concern in urban areas, in addition, it is well understood that soft soils are inappropriate for paving designs. Therefore, this paper presents an alternative solution combining CDW and a soft silty soil, aiming to overcome the soft soil drawbacks by repeated loadings. For this purpose, a laboratory study was developed, comprising both resilient modulus (MR) and unconfined compressive strength (UCS) tests over soil and soil-CDW compacted blends, to evaluate the mechanical properties of the proposed stabilization. Also, three compaction efforts (standard, intermediate, and modified) and a curing time of up to 90 days were used. The UCS of blends was also measured with the identical specimens with which the resilience tests were carried out. The results indicated that incorporating CDW (size sand and gravel materials) into the soil improves the qu and MR for all compaction energies, and the Resilient Modulus test affects the UCS of all blends, increasing its effect with the decrease in compaction effort. Repeated loads caused a decrease in the specimen's voids whereby the density increased and, therefore, qu. Finally, the results conclude that the compacted mixtures in the intermediate effort and 40–60% CDW by weight are potentially applicable in pavements compared to the traditional soil–cement base/subbase. [ABSTRACT FROM AUTHOR] more...

Autoclaved aerated concrete powder (AACP) is a kind of solid waste, which is characterized by strong water absorption ability and low compressive strength. In this work, it is used as the admixture to enhance the engineering performance of wet filter cakes. The compaction behaviors and shear strength characteristics of the filter cakes stabilized with different AACP content were studied. Test results were further compared to those of brick-concrete demolition waste (BCDW)/filter cake mixtures. Changes in permeability coefficient, CBR value and pore structure of compacted samples before and after AACP amendment were also tested. The test results indicated that with the addition of AACP, the permeability coefficient, CBR value and the optimum water content of the compacted samples increased, while their maximum dry density decreased. The AACP/filter cake mixtures exhibited comparable shear strength to those of BCDW/filter cake mixtures under the same compaction degree. From the perspective of compaction effect, the suitable content of AACP in the mixture ranged from 37.2 to 55.3%. Changes in the soil fabric, as determined from MIP test and SEM analysis, agreed well with the changes in their geotechnical properties. These experimental results provide technical references for utilization of AACP and filter cakes in road embankment. [ABSTRACT FROM AUTHOR] more...

The depletion of natural aggregate sources has increased exponentially due to the enormous demand for concrete. Therefore, the recycled aggregate (RA) extracted from old concrete structures may reduce the demand for natural aggregate (NA). This paper introduced a new double processing technique that combines mechanical grinding in the Los Angeles Abrasion Machine (LAAM) followed by silica fume (SF) impregnation technique to produce high-quality double-processed recycled aggregate (DPRA). To examine the effect of DPRA, five different types of DPRAs [viz: DPRA (0RVS), DPRA (200RVS), DPRA (300RVS), DPRA (400), and DRA (500RVS)] were utilized to replace NA in an M30 grade control mix. In this investigation, different DPRAs were employed to replace NA in each concrete mix (e.g., 0%, 25%, 50%, 75%, and 100%). In addition, experiments were carried out to examine the workability, strength, and durability of concrete made with DPRAs. The compressive strength has decreased by 7.58% compared to the control mix at a 75% replacement level of NA. Similarly, the Rapid Chloride Penetration Test (RCPT) value within the lower permeability zone is up to a 75% replacement level of NA with DPRA (400RVS). Further mechanical crushing in an LAAM with 400 revolutions followed by SF impregnation of 10% concentration is the optimum processing to produce superior quality double-processed recycled aggregate (DPRA). Based on the experimental investigations, a 75% substitution level of DPRA (400RVS) in place of NA is finally suggested for structural concrete. [ABSTRACT FROM AUTHOR] more...

The present study was conducted to recycle waste tire rubber and steel slag (SS) in asphalt pavement and investigates the moisture stability of asphalt mixtures incorporating these solid wastes. To this end, two types of aggregates (SS and diabase), three kinds of SS content and multiple freeze–thaw cycles were considered and three kinds of adhesion assessment methods: pull-out test and surface free energy (SFE) method, and freeze–thaw splitting test were performed. Three corresponding adhesion evaluation indicators like adhesion strength, SFE characteristics, and tensile strength ratio were obtained and six energy parameters were introduced to characterize moisture susceptibility of asphalt mixture. To explore the relations between the SFE parameters and the adhesion evaluation indicators, a grey correlation analysis method was adopted. Asphalt mixtures with high consumption of SS obtained a better moisture resistance because SS has a superior adhesion strength and higher SFE components than diabase aggregate. Stripping energy increase was found to be the main failure mode of the asphalt rubber-SS aggregate system. SFE method provides a comprehensive and accurate evaluation of adhesion property of loose asphalt rubber–SS aggregate system and moisture stability of compacted asphalt mixtures. [ABSTRACT FROM AUTHOR] more...

The adhesion between asphalt and aggregate directly affects the water damage resistance of asphalt mixtures. Water vapor is a prominent cause of water damage to asphalt mixtures, but the influence of water vapor on the adhesion performance of asphalt and aggregates is still unclear. To clarify the effect of moisture on adhesion, the surface energy parameters of three asphalt types and four aggregates under six relative humidity (RH) conditions from 0–100% were measured. Then, the adhesion energy between asphalt and aggregate under different RH conditions is calculated according to the surface energy theory. The results first show that both aged and virgin asphalt surface energy parameters do not change significantly with RH and curing time. Second, the surface energy parameters of aggregates decreasing relationship with RH. After RH increased from 0–100%, the total surface energy parameters of the four aggregates reduced by more than 60%, and the aggregate material showed high sensitivity to RH. Finally, when RH is greater than 80%, the rate of decrease in adhesion caused by water vapor was approximately equal to half of that of liquid water. This study shows that water vapor significantly influences the adhesion between asphalt and aggregate. [ABSTRACT FROM AUTHOR] more...

The application of construction and demolition (C&D) waste and used tires in geotechnical engineering contributes to the demand of the sustainable development. This study mainly compared the mechanical behavior of pure sand embankment (PSE), C&D material embankment (CDME), sand-tire shreds mixture embankment (STSME) through a scale model test. Effects of tire shreds content, the first layer geocell reinforcement burial depth, geocell reinforcement depth and compaction degree on the bearing capacity of embankments were investigated. Moreover, embankment load-settlement ratio, the reinforced bearing capacity ratio, the bearing capacity improvement factor (IF), the embankment surface deformation, and the vertical earth pressure distribution inside the embankment were discussed. Results indicate that both C&D material fillers and sand-tire shreds mixture can improve the bearing capacity and stability of embankment slopes. However, C&D material is better than sand-tire shreds mixture in the improvement. The optimum value of tire shreds content is 5%. The reinforcement effect of geocell decreases with the increase of reinforcement depth. With the increase of the buried depth of the first layer, it first increases and then decreases. With the increase of compaction degree increases. The minimum earth pressure appears near the slope. The bearing capacity of CDME is greater than STSME. The ultimate bearing capacity of CDME under the action of the geocell is twice that of the unreinforced embankment. [ABSTRACT FROM AUTHOR] more...

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While the construction industry has brought substantial economic benefits to society, it has also generated substantial construction and demolition waste (CDW). Illegal dumping, which refers to dumping CDW in an unauthorized non-filling location, has become widespread in many countries and regions. Illegally dumping CDW destroys the environment, causing groundwater pollution and forest fires and causing significant economic impacts. However, there is a lack of research on the decision-making behaviours and logical rules of the main participants, construction contractors and the government in the illegal CDW dumping process. This paper constructs an evolutionary game model on a small-world network considering government supervision to portray the decision-making behaviours of illegal dumping participants and conducts a numerical simulation based on empirical equations to propose an effective supervision strategy for the government to manage illegal CDW dumping efficiently. It is found that the illegal dumping behaviours of contractors are mainly affected by the intensity of government supervision, the cost of fines and the income of illegal dumping; while for government, a supervision strategy is found to be necessary, and a supervision intensity of approximately 0.7 is the optimal supervision probability given supervision efficiency. Notably, under a low-level supervision probability, increasing the penalty alone does not curb illegal dumping, and a certain degree of supervision must be maintained. The results show that in addition to setting fines for illegal dumping, the government must enforce a certain level of supervision and purify the market environment to steadily reduce illegal dumping. [ABSTRACT FROM AUTHOR] more...

The utilization of recycled aggregate (RA) extracted from construction and demolition (C&D) waste contributes to reducing the usage of natural aggregate (NA) to produce new concrete. The authors used immersion of RA in mild acetic acid (3%concentration), with subsequent rotation in Los Angeles (LA) abrasion machine (mechanical grinding) treatment to produce high-quality RA in the current work. To study the influence of treated recycled aggregates (TRAs), various types of TRAs [viz: TRA (0 min), TRA (3 min), TRA (5 min), TRA (7 min), TRA (10 min), TRA (12 min)] were replaced with NA in a control mix of M40 grade concrete. In this work, different replacement levels (viz: 0%, 25%, 50%, 75%, and 100%) were used to substitute NA in each different type of TRAs. The properties viz: slump, compressive, tensile strength, flexural strength, density, modulus of elasticity, ultrasonic pulse velocity, drying shrinkage, and Scanning electron microscope of RA were reported. Based on the test results, 72 h of soaking in mild acetic acid (3% concentration) followed by 7 min of mechanical grinding in the LA abrasion machine was observed as the optimal treatment duration to generate high-quality RA. The compressive and split tensile strength were reduced by 17.11%, 14.33%, respectively, in concrete with RA compared to natural aggregate concrete (NAC). [ABSTRACT FROM AUTHOR] more...

Asphalt fine aggregate matrix (FAM) consists of a binder, fine aggregate, filler, and air voids. Studies on FAM, which is one scale smaller than asphalt concrete (AC), have been gaining attention among researchers because of its considerable similarities with AC and increased testing efficiency it provides. FAM tests are mostly performed to evaluate relative material performance in case of damage. This review presents recent studies regarding mix design, fabrication methods, material incorporation, and experimental design to evaluate the performance of FAM mixtures. This study also summarizes the recent research findings on using micromechanical computational modeling and the correlation between the FAM and AC properties. It is the general consensus that microstructure of the FAM has a substantial effect on the mechanical properties and evolution of damage in AC. The main issue in the available literature is the detailed understanding of how FAM exists in the AC and how to replicate this for experimental purposes. This lack of understanding makes it to view the literature as disorganized information because each researcher employs his own method to study FAM materials. Therefore, there is a need to establish comprehensive fabrication and testing protocols as a specification to precisely resemble the FAM that exists within AC and hence accurately predict the performance characteristics of AC. [ABSTRACT FROM AUTHOR] more...

The waste generated from the agriculture and construction sector is a serious threat to the environment due to its disposal problems. This study is an attempt to utilize agriculture and construction waste to stabilize the geotechnical properties of clayey soil to use the composite as sub-grade material. For this purpose, rice husk ash (agriculture waste) and construction demolition waste (used construction waste) are mixed in varying amounts in clayey soil alone and along with lime to obtain the best sub-grade material. The results of the experimental testing reveal that the geotechnical properties of clayey soil are improved by stabilizing it with various waste materials thereby solving their disposal problem thus sustaining a healthy environment. The use of wastes and lime in combination improves the unconfined compressive strength, California bearing ratio, and resilient modulus of the composite. The mix obtained on the addition of rice husk ash and construction demolition waste along with lime can be used as a sub-grade material thus achieving higher economic benefits. [ABSTRACT FROM AUTHOR] more...

It is increasingly important to find solutions for the problem of construction waste (CW) which is generated in high quantities and is often disposed of irregularly. The reuse of this material in large scale projects, such as base and sub-base layers for road pavements, can lead to long term environmental benefits. This paper describes the novel use of CW to partially replace a lateritic natural soil in fiber-reinforced cement mixtures. In addition to the CW, Portland cement and polypropylene fibers were added to the natural soil as a percentage of its dry mass. The geotechnical characterization, unconfined compressive strength, tensile strength, direct shear strength, permanent strain and resilient modulus were used to the evaluate the effect of polypropylene fiber and Portland cement on the behavior of the soil–CW mixtures. Laboratory test results indicate that the partial replacement of soil with CW and the addition of 0.1% of 50 mm long polypropylene fiber to soil–CW mixtures produces a viable alternative material for geotechnical applications, with better performance than natural soil alone. [ABSTRACT FROM AUTHOR] more...

The creep deformation characteristics of recycled construction and demolition waste (CDW) filler are important factors affecting its road performance. In this paper, a series of laboratory tests are carried out on CDW filler, including gradation test, compaction test, California bearing ratio (CBR) test, and creep test, and the road performance of different ratios of recycled CDW filler is systematically studied. The mechanical properties of different ratios of CDW materials can meet the requirements of subgrade filler in the specification. Through the creep test, it can be seen that the elastic-plastic deformation speed of CDW material is fast and the duration is short. The creep deformation stage is opposite. Combined with the theoretical analysis, it is found that the t/ε-t curve under each stress level has a good linear relationship. The relationship between strain and time is hyperbolic, and the relationship between parameters A, B, and load is a power function. The creep process belongs to attenuation creep, which conforms to the Kelvin model. [ABSTRACT FROM AUTHOR] more...

Recycled aggregate (RA) acknowledge with its inferior quality due to high water absorption and lower strength which is mainly due to presence of attached adherent mortar. Concrete made with RA have lower strength and durability properties when compared with natural aggregate concrete (NAC), recorded by many previous researches in past. In order to overcome these difficulties, two‐stage mixing approach (TSMA) is a good tool to improve the properties of recycled aggregate concrete when compared with normal mixing approach (NMA). The main objective of present research work is to study the influence of mixing approaches on concrete made with treated recycled aggregate (TRA). Basically the workability, mechanical and durability properties of concrete have been studied at fresh and hardened state. In this work, four different types of mixing approaches (viz. NMA, TSMA, TSMA1, and TSMA2) were used. In all types of mixing approaches, the natural aggregate was replaced with TRA at different replacement levels viz.: 0, 25, 50, 75, and 100% in a control mix of M40 grade. Based on the experimental results the workability, strength, and durability properties of concrete made with TRA were improved in TSMA2 when compared with all other mixing approaches. [ABSTRACT FROM AUTHOR] more...

This paper presents a laboratory investigation on the use of construction demolition waste in poor clayey soil to improve its strength and drainage characteristics. Various laboratory tests such as differential free swell, Atterberg's limits, compaction, unconfined compressive strength (UCS), California bearing ratio (CBR), and permeability have been conducted on un-stabilized and Construction Demolition Waste (CDW) stabilized clayey soil. The outcomes revealed that the addition of CDW in poor soil reduced both maximum dry density and optimum moisture content. The UCS, CBR, and permeability got improved on adding optimum content of CDW in poor clayey soil. The secant modulus also increased on addition of the CDW in virgin soil. The regression analysis performed for different tests showed good agreement of laboratory results with predicted values. Thus, it can be revealed that using CDW in stabilization of poor clayey soil will not only solve the problem of its disposal but will also be cost effective and protect the environment. [ABSTRACT FROM AUTHOR] more...

The moisture stability of an asphalt mixture was enhanced with cement, hydrated lime, and an anti-stripping agent (called AMR II) to improve the adhesive bond of asphalt with the aggregate. A total of eight asphalt binders and three aggregates (crushed gravel, limestone, and granite) were used for the preparation of different asphalt mixtures. Indirect tensile strength and residual stability tests were carried out to determine the moisture stability. The surface free energy (SFE) of the asphalt binder and aggregates were measured using the sessile drop method and universal sorption device method, respectively. Based on the SFE method, the cohesive, adhesive, and stripping energies of the asphalt and asphalt mixtures were studied. Moreover, the SFE parameters were introduced while analyzing the correlation of the cohesive, adhesive, and stripping energies of the asphalt with the moisture stability. The results show that the incorporation of a single or compound anti-stripping agent can improve the moisture stability of the asphalt mixture, and the improvement effect of compound agents is greater. Furthermore, the SFE components improved after the addition of the anti-stripping agent. The addition of the anti-stripping agent influenced the cohesive and adhesive energy remarkably, whereas the aggregate type, especially its silica content and specific surface area, has a significant effect on the adhesive and stripping energy of the asphalt mixture. A linear regression analysis suggested that the SFE parameters have a good correlation with the moisture damage properties. The SFE parameters can be used to determine the moisture damage performance, and the SFE method can be used to verify the moisture stability of asphalt mixtures. [ABSTRACT FROM AUTHOR] more...

Nowadays, one of the main challenges to a wider application of cold recycling techniques is the lack of reliable information on the mechanical behavior of cold recycled materials (CRM). In this context, measurement and modelling of the complex modulus of CRM mixtures may give an important contribution to the design and analysis of pavements including cold recycled layers. In this study, we analyzed the rheological behavior of CRM mixtures produced using bitumen emulsion and cement through the study of their fine aggregate matrix (FAM). Starting from a fixed CRM mixture composition, we compared different FAM mortars, focusing on the effect of water and air content. Then, we selected a composition as representative of the FAM in the mixture and investigated the evolution of both materials during a fixed curing period. Next, we measured the complex modulus of the CRM mixture and FAM at two curing stages and applied a rheological model to simulate and compare their behavior. Results showed that the properties of CRM mixtures are comparable to those of FAM mortars produced using all the binding agents (bitumen emulsion and cement) and a fraction of the voids contained in the mixture. Despite the huge difference in volumetric compositions, the FAM mortar controlled the curing and the thermo-rheological behavior of the CRM mixture, while the coarse reclaimed asphalt aggregate fraction and the voids mainly affected the asymptotic properties (equilibrium and glassy moduli) and the non-viscous dissipation component. [ABSTRACT FROM AUTHOR] more...

Soil improvement has become an important issue on which further investigations should have to be performed in depth as a result of an increasing demand rate on land use in order to compensate increasing population. The main reasons for soil improvement are to decrease plasticity, reduce permeability and compressibility and increase soil strength. Wastes can be used along with some other additive materials such as cement, lime, fly ash, and bitumen in the improvement of soils which are inadequate in terms of engineering properties. In recent years, as a result of increasing rates of earthquakes along with the numbers of constructions which are to be demolished as the updated regulations point out, a great amount of wastes have been accumulating. These wastes are generally referred to as construction demolition wastes (CDW). There exist some methods which are considered for the elimination of these wastes. One of the mentioned methods is to use construction demolition wastes in soil improvement procedures. Within the context of this study, effects of construction demolition wastes (CDW) and cement (CMT) on soil stabilization and engineering properties of sandy soils (SS) were investigated. Parameters such as optimum ratios of CDW and CMT, bearing capacity and settlement values, soil improvement depths, and time factor were analyzed. Consequently, an equation with high-degree correlations was obtained in order to use CDW and CMT efficiently at optimum ratios. It was determined that by using CDW, increments of up to 3.09 times were attained in the values of bearing capacities. The optimum value of improvement depth for sandy soil was obtained as H/D = 0.75 (H: soil improvement depth, D: diameter of the model footing) up to a pressure value of 520 kPa. It was also found that the highest bearing capacity with respect to time was reached at the end of 28 days and a significant increment did not take place in the values of bearing capacities after exceeding the mentioned time period. Therefore, it is proposed that at least 28 days should pass after the completion of any soil improvement procedure before any further construction work is initiated. [ABSTRACT FROM AUTHOR] more...

Numerous distresses in pavement structures on chemically stabilized expansive soils have raised considerable debate regarding the long-term performance of lime-stabilized subgrades. Therefore, this paper examines the effects of continuous leaching on the durability of lime- and waste ceramic dust (WCD)-stabilized expansive subgrades. The tests were performed with different percentages of quicklime (3.5, 4.5, 5 and 10%), while the combined effects of lime and WCD were evaluated by adding 1.5% of WCD to the mixtures containing 3.5 and 4.5% lime. Geotechnical tests such as Atterberg limits, compaction and California bearing ratio (CBR), in addition to microstructural and leachate analyses, were used to evaluate the engineering properties of the stabilized soils. The CBR result shows that early strength development occurred in the soils mixed with lime and WCD. However, at longer curing periods, the beneficial effect of lime on the engineering properties of the soil increased with an increase in lime content. Results of the leaching tests show considerable changes in the physicochemical properties of the soil mixtures, while the estimated service life of the stabilized soils increased from 3.4 to 9.2 years, as lime content increased from 3.5 to 10%. Microstructural analysis results reveal that the flocculated nature of the soil fabric and the density of the fibrous cementitious compounds increased with an increase in lime content. This study clearly indicates that electrical conductivity, pH and pore-water cation concentrations can be used in combination with geotechnical tests, to correctly evaluate the durability of lime- and lime-WCD-stabilized expansive soils. [ABSTRACT FROM AUTHOR] more...

In recent years several studies have been carried out using waste from various industries to partially replace cement in concrete. In addition to improving concrete durability, the use of these waste materials also contributes to reducing emissions, mainly carbon dioxide, and to saving resources. In this study, the applicability of finely ground construction and demolition waste (CDWg) in concrete as a partial substitute for Portland cement was evaluated and the effects on durability were assessed. Mortars and pastes with cement replacements of 0%, 5% (CDWg5) and 10% (CDWg10) were produced. The different mortar types were tested to ascertain their 7, 28 and 90 d strengths and durability-related properties, including capillary absorption, chloride diffusion, accelerated carbonation, resistance to alkali–silica reaction (ASR) and sulfate attack. Mortar containing CDWg performed better than the control only with regard to expansion due to ASR. In the other tests, mortar containing CDWg did not attain the performance of the control specimens. However, for the CDWg5 mortar, performance losses were not significant, indicating that this particular waste at this dosage may be used to partially replace Portland cement. A replacement of 10% could be considered in concretes with lower levels of performance requirements. [ABSTRACT FROM AUTHOR] more...

Cold recycling techniques emerged in road construction to recycle deteriorated pavements as bases and surfaces. A detailed review is carried out in the current study on the design, evaluation, performance, and advances in the emulsified asphalt-treated bases (EATB). The mix-design of EATB is a complex procedure in which the performance is based on optimizing water, additives, and emulsified asphalt contents. This paper covers the design methods, compaction characteristics, curing periods, additive contents, strength development, strength parameters, determination of the optimum emulsified asphalt content, and finally, the performance evaluation of EATB. From the detailed review, indirect tensile strength (ITS) is the most influencing parameter considered in the mix design of the EATB. Maximum dry density, Marshall Stability, and ITS are considered as primary performance indicators of the EATB. Modulus, rutting, and fatigue being consider secondary performance indicators. Overall, the recycled bases using emulsified asphalt proved sustainable and economical compared with the natural aggregates (NA)., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.) more...

Copyright of Brazilian Journal of Surgery & Clinical Research is the property of Master Editora and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) more...

Copyright of Algerian Journal of Environmental Science & Technology is the property of Algerian Journal of Environmental Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) more...

Copyright of Journal of Nursing UFPE / Revista de Enfermagem UFPE is the property of Revista de Enfermagem UFPE and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) more...

The present work establishes a reliable model to describe the influence due to the interfacial transition zone (ITZ) between cement paste and aggregates on the mechanical, thermal and diffusion properties of concrete. The mesostructure of concrete consists of aggregates with a random distribution embedded in the cement paste as well as the interface elements with zero-thickness representing the ITZ. In this work, the cohesive zone model (CZM) is used to model the debonding at the ITZ between cement paste and aggregates. Furthermore, a traction-separation law in CZM combined with micromechanically motivated thermal flux-separation relation and diffusion flux-separation relation is developed, thus enabling to describe the temperature jump and humidity jump across the cohesive crack. [ABSTRACT FROM AUTHOR] more...

The objective of this study was to investigate certain aspects of asphalt mastic moisture diffusion characteristics in order to better understand the moisture damage phenomenon in asphalt mixtures. Moisture sorption experiments were conducted on four asphalt mastics using an environmental chamber capable of automatically controlling both relative humidity (85 %) and temperature (23 °C). The four mastics tested were identical in terms of bitumen type (40/60 pen), bitumen amount (25 % by of wt% total mix), mineral filler amount (25 % by wt%) and fine aggregate amount (50 % by wt%). The materials differed in terms of mineral filler type (granite or limestone) and fine aggregate type (granite or limestone). Preliminary data obtained during the early part of the study showed certain anomalous behavior of the materials including geometry (thickness)-dependent diffusion coefficient. It was therefore decided to investigate some aspects related to moisture diffusion in mastics by applying the Fickian and two non-Fickian (anomalous) diffusion models to the moisture sorption data. The two non-Fickian models included a two-phase Langmuir-type model and a two-parameter time-variable model. All three models predicted moisture diffusion in mastics extremely well ( R > 0.95). The observed variation of diffusion coefficient with thickness was attributed in part to microstructural changes (settlement of the denser fine aggregates near the bottom of the material) during the rather long-duration diffusion testing. This assertion was supported by X-ray computed tomography imaging of the mastic that showed significant accumulation of aggregate particles near the bottom of the sample with time. The results from the Langmuir-type model support a two-phase (free and bound) model for moisture absorbed by asphalt mastic and suggests about 80 % of absorbed water in the free phase remain bound within the mastic. The results also suggest that moisture diffusion in asphalt mastic may be time-dependent with diffusion decreasing by about four times during a typical diffusion test lasting up to 500 h. The study concludes that both geometry and time-dependent physical characteristics of mastic are important factors to consider with respect to moisture diffusion in asphalt mastics. [ABSTRACT FROM AUTHOR] more...

In this paper, the effects of aggregates temperature reduction in asphalt mix manufacturing process have been analyzed in terms of complex modulus, fatigue and stripping resistance according to standard tests. The limits of these conventional standardized tests have been analyzed and a new method has been developed to estimate the bitumen-aggregate bonding quality when aggregate temperature is reduced. This method is based on the thermal contact resistance (TCR) assessment at the bitumen-substrate interface which reflects the contact imperfection at the microscopic scale. The study has shown that the TCR decreases when the aggregate temperature increases. Consequently, the TCR could be used as a bonding quality criterion in asphalt manufacturing condition when aggregates temperature is reduced. The results have been well correlated with a modified mechanical stripping test developed. It has been proved that when aggregates temperature decreases, the TCR increases and the stripping resistance decreases due to the poor bitumen-aggregates bonding. [ABSTRACT FROM AUTHOR] more...