critical evaluation of journal papers

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a critical evaluation on the following proposed 3 PDF files+ one website is required + a summery

a journal critical evaluation sample is also provided to guide you on how to do the critical evaluation as per the college standards.

all references should be in Harvard style referencing.




website : http://journals.plos.org/plosone/article?id=10.137...

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International Research Journal of Engineering and Technology (IRJET) Volume: 03 Issue: 08 | Aug-2016 www.irjet.net e-ISSN: 2395 -0056 p-ISSN: 2395-0072 Partial replacement of natural aggregates and natural bitumen by construction demolition waste and recycled bitumen Vanishree S. Hadagali1, Arjun S. Virupakshi2, H G.Hunashikatti3 1 Research Scholar, Civil Engineering Department, KLE Dr.M.S.S.C.E.T, Belagavi, Karnataka, India 2 Assistant professor, Civil Engineering Department, KLE Dr.M.S.S.C.E.T, Belagavi, Karnataka, India 3 Assistant professor, Civil Engineering Department, KLE Dr.M.S.S.C.E.T, Belagavi, Karnataka, India ---------------------------------------------------------------------***--------------------------------------------------------------------- Abstract - Construction industry generates large amount of waste during the construction of new structure and demolition or reformation of old structures. In the present era even the healthy structures are many times reconstructed for creating more space to meet the present requirements. These activities generate a large amount of waste called construction demolition waste (CDW) giving rise to the problem of disposal in sustainable manner. Due to the mere development in construction industry, construction materials mainly aggregates are getting extinct as it is used in most of civil engineering works. In fact this has led to the use of different materials or recycled materials as a replacement to fresh aggregates. This study evaluates the possibility of designing hot mix asphalt road pavements using construction and demolition waste as coarse aggregates. The percentages of recycled aggregates used in mixtures were 0%, 5%, 10%, 15%, 20%, 25%. The mixtures made with coarse recycled aggregates were found to meet the requirement of stability, flow, VMA and VFA. Partial replacement of CDW for 10% found maximum stability, density and all the Marshall properties were found to be within the limit. In addition to this, attempt has been made to check the suitability of recycled bitumen as a replacement to virgin bitumen by keeping optimum percentage of building demolition waste i.e 10% as constant, and percentage of recycled bitumen was varied , from the tests we found that 15% replacement of recycled bitumen was optimum. enormous money related difficulties to builders, contractors, temporary workers, and regional authorities and then to the nation [1]. The creation of waste because of the destruction or demolition of structures is more than the wastage which occurs in the construction of new structures; the reason is being in-disciplinary and less focused regarding the issue. It has also given rise to Environmental issues like increase in the flood levels due to the illegal dumping of construction and demolition waste in the rivers, resource depletion, shortage of landfill and the illegal dumping on hill slopes. So there is need of management of construction and demolition waste (CDW). CDW can be defined as “waste which arises from construction, renovation and demolition activities which includes excavated materials, concrete, tiles, bricks, ceramics, asphalt, concrete, plaster, glass, metal and steel, plastics, wood, aggregates etc” [1]. Worldwide there is lot of response to reduce the waste with regulation and legislation. Civil construction generates large amounts of waste during the building of innovative structures and destruction or reformation of aged buildings. India is presently generating construction and demolition waste of 23.75 million tons and worldwide 30.15 billion tons per year [2]. Key Words: Construction demolition waste, bitumen, recycled aggregates, Marshal stability, recycled bitumen. 1.INTRODUCTION The construction industry has developed rapidly in the past few years due to increase in industrialization and urbanization because of which the interest for construction materials is immense for the development exercises which results in the era of tremendous measure of construction waste. Construction material wastage has brought about the © 2016, IRJET Due to on-going trend of reconstruction of even healthy structures, just for creating more space in order to meet the present requirement, such activities are generating large amount of waste called construction demolition waste (CDW), it also includes excavated materials such as rock, soil, waste asphalt, soil, concrete, bricks, timber, plasterboard, asbestos, and contaminated soil [3]. ISO 9001:2008 Certified Journal Page 519 International Research Journal of Engineering and Technology (IRJET) Volume: 03 Issue: 08 | Aug-2016 www.irjet.net 1.1 Bitumen e-ISSN: 2395 -0056 p-ISSN: 2395-0072 3. EXPERIMENTAL RESULTS Bitumen is a one of the most complex material used in the construction. It is relatively low cost material, it is used for laying of roads to bind aggregates, it is also used as water proofing agent in the road construction. The relationship between temperature and viscoelastic behavior of bitumen is sometimes unsatisfactory as it shows lack of stiffness or elastic response at elevated road temperature, it exhibits sufficient stiffness at road temperature but lacks ductility and is therefore susceptible to brittle behavior at low temperature and resistance to permanent deformation [4]. Currently the continuous concern of saving natural resources and reduction of waste generation is promoting an increase in the recycling of used materials. Continuous study are being done for the extraction and recycling of bitumen from the scrapped pavements. 2. OBJECTIVES AND METHODOLOGY This study presents a laboratory investigation aimed to view the properties of hot mix asphalt and the effects of recycled bitumen and construction demolition waste on Marshall Parameters [5]. The trials conducted includes, (1) Recycled aggregate content in the mixtures: tests are made at (5%, 10%, 15%, 20%, 25% and 100%). (2) Natural bitumen content: the mixtures are designed by adding (4%, 4.5%, 5%, 5.5%, 6%). (3) Recycled bitumen content in the mixture: tests are made with (5%, 10%, 15%, 20%, 25% and 30%). 3.1 Marshal stability results for natural aggregates Table-1: Marshal design results conducted for natural aggregates 1. To study the effect of varying percentage of 2. 3. demolition waste as a replacement to natural aggregates on the performance of HMA. To study the improvement in the properties of hot mix asphalt by additions of varying percentage of recycled bitumen. To assess the economics of adding recycled aggregates and bitumen to work out the feasibility. The collected construction and demolition waste were crushed, sieved and according to gradation it was separated with a required quantity for the analysis. Natural aggregates according to gradation with the percentages of 4%, 4.5%, 5%, 5.5%, 6% of 60/70 penetration grade bitumen was used, and casted moulds. The mixture having 100% natural aggregates is labeled as control mix. By the results we found the optimum percentage of bitumen. By keeping that as ideal then the partial replacement of natural aggregates by recycled construction demolition waste according to gradation was done with optimum bitumen content , 5%, 10%, 15%, 20% & 25% of CDW. From the results found the optimum percentage of CDW, keeping that as constant instead of natural bitumen recycled bitumen was incorporated. In this study aged scrapped pavement is crushed and then by adding benzene with 500gm for each trial, bitumen is extracted by centrifuge the same will be used as a replacement to fresh bitumen in small proportions like 5%, 10%, 15%, 20%, 25%. The specific gravity of mixtures are found. The aggregates more than 4.75 mm size are conducted by wire basket method, and the sizes below 4.75 mm are conducted by pycnometer method. Table 1 shows the results of the Marshall Parameters conducted for natural aggregates and percentage bitumen content. Also given are the core density (Gb), theoretical density,% air voids of Aggregates Fig – 1 Graph Showing % bitumen versus stability The stability has increased from 1326.6 kg at 4% bitumen content to 2326.5 kg at 5.5% bitumen content. © 2016, IRJET ISO 9001:2008 Certified Journal Page 520 International Research Journal of Engineering and Technology (IRJET) Volume: 03 Issue: 08 | Aug-2016 www.irjet.net e-ISSN: 2395 -0056 p-ISSN: 2395-0072 Table – 2 Marshall design results for construction demolition waste replacement Fig – 2 Graph Showing % bitumen versus bulk density Fig – 3 Graph Showing % bitumen versus percentage air voids With the increase in the percentage of bitumen the percentage air voids decreased as the air voids were occupied with bitumen after compaction. From the graphs obtained bitumen content 5.5% as ideal. 3.2 Marshal results for CDW After obtaining the optimum bitumen content as mentioned above, the natural aggregates were replaced with CDW in varying percentages of 5, 10, 15, 20, 25 and complete replacement was done. The effect of varying percentage of demolition waste on the properties of the mix are shown in table. © 2016, IRJET Fig – 4 Graph showing % CDW versus density for optimum bitumen content Construction demolition waste was replaced with the natural aggregates in varying percentages of 5, 10, 15, 20, 25 and 100% replacement respectively. The addition of demolition waste as replacement to natural aggregates did show an increase in the stability of the mix till 10% replacement after which it started reducing constantly till 100% replacement. The reason for the downward trend after 10% is probably because of the fact that natural aggregates will be much stronger than that of CDW, and the initial increase in stability may be because of the filling up of larger voids by the CDW fines. So from the trials conducted it was found that 10% replacement of fines was found to be ideal. ISO 9001:2008 Certified Journal Page 521 International Research Journal of Engineering and Technology (IRJET) Volume: 03 Issue: 08 | Aug-2016 www.irjet.net e-ISSN: 2395 -0056 p-ISSN: 2395-0072 Table – 3 Marshal design results for recycled bitumen replacement Fig – 5 Graph showing % CDW versus bulk density for optimum bitumen content Similar to marshall stability, density has also shown an increase till 10% replacement and later is continues to decrease till complete replacement. The density is varying from 1.97 gm/cc to 2.25 gm/cc. Fig – 7 Graph showing % recycled bitumen versus stability for optimum CDW content Fig – 6 Graph showing % CDW versus percentage air voids for optimum bitumen content For the same mixture the air voids have shown constant increase from 3% at 6% for CWD replacement varying from 5% at 100%. The graph shows an increase in stability varies from 1347 kg at 5% recycled bitumen to 1681.3 kg at 15% recycled bitumen content after which stability decreased to 1320 at 25% replacement. Based on the graph below, 15% replacement if found to be ideal with the stability of 1681 kg.. From the discussion made above it is evident that 10% replacement of demolition waste is giving good results for most of the Marshall properties. Hence by keeping 10% CDW as constant further trials were carried out by replacing virgin bitumen with recycled bitumen. 3.2 Marshal results for recycled bitumen After obtaining the optimum CDW as mentioned above, the natural bitumen were replaced with recycled bitumen in varying percentages of 5, 10, 15, 20, 25 replacement was done. The effect of varying percentage of recycled bitumen on the properties of the mix is shown in table 3. Fig – 8 Graph showing % recycled bitumen versus bulk density for optimum CDW content © 2016, IRJET ISO 9001:2008 Certified Journal Page 522 International Research Journal of Engineering and Technology (IRJET) Volume: 03 Issue: 08 | Aug-2016 www.irjet.net e-ISSN: 2395 -0056 p-ISSN: 2395-0072 REFERENCES [1] Harish. P. Gayakwad, Neha. B. Sasane, “Construction and Demolition Waste Management in India” International Research Journal of Engineering and Technology (IRJET), vol 2,p-ISSN: 2395-0072,issue 03, june 2015. [2]Johnny Bolden, Taher Abu-Lebdeh and Ellie Fini, “Utilization of recycled and waste materials in various construction applications”, American Journal of Environmental Science, vol 9, pp 14-24, 2013. Fig – 9 Graph showing % recycled bitumen versus % air voids for optimum CDW content Percentage air voids have shown constant decline with the increase in the percentage replacement of recycled bitumen [6]. 4. CONCLUSIONS The objective of the study was to evaluate the effects of recycled aggregates compare to natural aggregates in hotmix asphalt. Thus, various laboratory tests were conducted to evaluate the characteristics of hot mix asphalt containing recycled aggregates and also this work was conducted for the surface course of the pavement, based on the results of the laboratory tests, the following conclusions were made:” 1. 2. 3. 4. [3] Tomas U. GanironJr,“ Recycling Concrete Debris from Construction and Demolition Waste”, International Journal of Advanced Science and Technology, Vol 77 , pp.7-24, 2015. [4] Tom V. Mathew, K V Krishna Rao, Chapter 23. Pavement Materials: Bitumen, introduction to Transportation Engineering, NPTEL May 8, 2007. [5] Pérez A.R. Pasandín, L. Medina, “Hot mix asphalt using C&D waste as coarse aggregates”, materials and design, vol 36, pg no. 840-846, 2012. [6] Ministery Of Road Transport & Highways (MORTH), specification for road and bridge works. Based on the trials conducted on the replacement of natural aggregates with construction demolition waste, a replacement of 10% was found to be ideal, as all the marshall properties such as marshall stability, Density, Air voids, VMA, VFA etc are found to be within the permissible limit as specified by IRC. By keeping 10% construction demolition waste constant, the trails for recycled bitumen demonstrated optimum results at 15% replacement of recycled bitumen with virgin bitumen. And all the marshall properties such as marshall stability, Density, Air voids, VMA, VFA etc are found to be within the permissible limit as specified by IRC. . By using construction demolition waste as recycled aggregates cost can reduce by 10% in natural aggregats for surface course. The marshall quotient value is increased from 474.79 to 851.9 with 10% replacement of Construction demolition waste, which will result in reduced susceptibility to permanent deformation. © 2016, IRJET ISO 9001:2008 Certified Journal Page 523 Author’s version Effects of the use of construction and demolition waste aggregates in cold asphalt mixtures B. GÓMEZ-MEIJIDE and I. PÉREZ Published in CONSTRUCTION AND BUILDING MATERIALS as: B. Gómez-Meijide, I. Pérez. Effects of the use of construction and demolition waste aggregates in cold asphalt mixtures. Construction and Building Materials 51 (2014) 267–277 http://dx.doi.org/10.1016/j.conbuildmat.2013.10.096 Effects of the use of construction and demolition waste aggregates in cold asphalt mixtures B. Gómez-Meijide a,* and I. Pérez a a E.T.S.I. Caminos, Canales y Puertos, Universidade da Coruña. Campus de Elviña s/n, 15071. A Coruña, Spain *Corresponding autor. Tel.: +34-981167000. Fax: +34-981167170 E-mail addresses: breixo.gomez.meijide@udc.es (B. Gómez Meijide), iperez@udc.es (I. Pérez) Abstract: Cold asphalt mixtures (CAM) with 100% recycled aggregates from construction and demolition waste (CDW) were researched to ecologically and economically improve cold asphalt mixtures. The present study indicates that the UCS, ITS, ITSM and moisture susceptibility were very satisfactory not only compared with a control mix with 100% natural aggregates (NA) but also with values given by different standards and recommendations. A new global approach to design these aggregates has also been explored because conventional methods are inaccurate in this case. Keywords: Construction and Demolition Waste; cold asphalt mixture; sustainable pavement engineering; Indirect Tensile Strength; Indirect Tensile Stiffness Modulus 1. Introduction Cold asphalt mixes (CAM) have been considered inferior to hot-mix asphalt (HMA) in the last several decades, mainly due the high air-void content of the compacted mixtures, their weak early life strength and the long curing times required to achieve an optimal performance [1]. After lay-down, these mixtures need to pass through a number of stages in which the binder and mastic cohesion, binder-aggregate adhesion and mixture shear strength develop. During these stages, cold asphalt does not lend itself to studies of the influence of material and/or process variables, e.g., moisture condition, on its mechanical properties [2]. This drawback is due to the associated peculiarities of cold asphalt, which include the presence of water, 1 emulsion-aggregate reactivity, evolving characteristics with time and an undeveloped internal structure [3]. Many studies have been conducted to minimise these considerations and approximate hot asphalt mixtures, such as incorporating a certain amount of cement, as well as modified asphalt emulsions in the mixture [4-6]. In addition, cold mixes have features that make them preferable to hot mixes, such as a lower energy consumption, ecological impact, economic costs or occupational hazards for operators. Moreover, cold mixes are storable at room temperature until lay-down, non-polluting and show a lower tendency for cracking, due to their flexibility when the subgrade is not of great quality. Thus, cold mixes are especially suitable for low/medium traffic local roads, which are normally placed far away from the manufacturing plants. Cold asphalt mixtures are currently regaining their importance within the asphalt world market, reaching annual production levels of 1.5 million tonnes in France or 2 million tonnes in Turkey in recent years [7]. Nevertheless, researchers and producers continue to improve these mixtures in an attempt to increase their competitiveness. As such, and to improve the ecological and economic properties of CAM, CAM containing 100% recycled aggregates from construction and demolition waste (CDW) were studied. An extensive, growing and successful body of research on hot asphalt mixes with recycled aggregates from waste materials [8-16] reinforces this new approach in pavement engineering. This research was focused on the mechanical properties of CAMcontaining 100% construction and demolition waste aggregates (CDWA) once they have already reached a high curing degree. The results obtained were satisfactory not only compared with a control mix containing 100% natural aggregates (NA) but also with values given by different standards and recommendations. An ANOVA statistical analysis was performed to test and support the experimental results. Because the interaction between water and bitumen is unclear, one 2-way ANOVA and two 1- 2 way ANOVA (one for each fixed variable water/bitumen) were performed for each studied property. As explained, both analyses served to confirm the results because the conclusions drawn from both follow the same direction and did not contradict in any of the cases. 2. Materials Used Two different aggregates were used: a hornfels, a metamorphic siliceous aggregate from a natural quarry used to produce the control mixes (hereafter, natural aggregate or NA) and a 100% recycled aggregate from construction and demolition waste (hereafter CDWA), whose composition is given in Table 1 for the received coarse and medium fractions. This composition was used to analyse the potential behaviour of this material in CAM. Most of this aggregate was concrete and natural stone but also contained other materials (Figure 1) that required the use of an X-Ray diffractogram to truly define their source in some cases. In this way, materials such as asphalt materials, plaster, aerated concrete or l ...
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nkostas
School: UT Austin

Attached.

ASPHALT AND NATURAL AGGREGATES

Asphalt and Natural Aggregates

By:

Course Title:

Professor:

Name of the University:

Date:

1

ASPHALT AND NATURAL AGGREGATES

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A). Utilization of recycled asphalt concrete with warm mix asphalt and cost-benefit
analysis.
In this study Oner, J & Sengoz, B. 2015, (pg. 3) investigates the problems
surrounding the asphalt paving industries. In their research, it's pointed out that the challenges
being experienced are brought up by an elevation in demand of the paving mixtures which
are environment-friendly and the issue of a rapid increase in the raw materials. Reclaimed
asphalt pavement (RAP) is a vital element which can salvage precious and valuable
aggregates through a reduction in utilization of expensive bitumen.
The use of Warm Mix Asphalt (WMA) technology encourages the use of RAP and
also provides recycling of asphalt pavement at low temperatures than the maintained
temperatures in hot mixes, which saves money and energy. Their study is based on feasibility
of using WMA additives which are different (Organic, water and chemical) at required
composition in different percentages of RAP.
The materials that are being used in this research include base bitumen which has a
penetration ability of 50/70. To characterize base bitumen properties, conventional tests were
performed, and they include, thin film oven experiment (TFOT), softening experiment,
penetration experiment (ASTM D5-06), softening and penetration level after TFOT. These
experiments were carried out following the necessary standard experimental methods.
Figure 1: Base bitumen properties

ASPHALT AND NATURAL AGGREGATES

3

To find the course and exceptional limestone aggregates properties, various tests like specific
gravity (ASTM 127), sieve analysis (ASTM C136) among others were conducted.
Figure two: Limestone Aggregate properties.

The Sasobit is a WMA which is organically composed of Sasol Wax that ranges with a
dosage of 1%- 4% weight of bitumen. According to Oner, J & Sengoz, B. 2015, (pg.6),
Sasobit has to be added at a 3.0% by bitumen mass.
Moreover, the cost-benefit analysis and the mechanical properties of WMA has RAP
in comparison to WMA without RAP was carried out. The results showed that 20%, 30%,
and 10% could be the necessary maximum RAP additive component as water, organic and
chemical components respectively, containing additives with a 30% RAP organic additive
content that has got a significant rise in the tensile strength over the control mix.
On cost benefit analysis, Oner, J & Sengoz, B. 2015, (pg. 5) says that various
techniques of WMA production give a Promise on multiple energy-saving outputs. This is
basically depended on the lowered quantity of output and the kin...

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Top quality work from this guy! I'll be back!

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