Employment of Nanomaterial Treated Marginal Aggregates in Flexible Pavement: A VIKOR and TOPSIS Approach

Steel slag is a by-product of the steel industry. These waste materials create environmental pollution in the vicinity as they are imperishable and safe disposal of Industrial wastes is a major problem. This made engineers think about wastes that can be helpful for recycling. Based on intensive laboratory testing program, the characteristic properties of Steel Slag Aggregate (SSA) were assessed to determine its suitability to be used in Hot Mix Asphalt (HMA) and also as a potential material to be used as aggregate in flexible pavements. By utilizing this material in construction can minimize the depletion of natural resources around the world. Four different percentages (0%, 25%, 50% and 75%) of SSA were used and the proposed mix designs for HMA were conducted following the Marshall mix design. The experimental results indicate that the addition of SSA has significant improvement in the properties of HMA. An increase in density, stability and flow values and reduction in the per cent of air voids were observed in specimens prepared with above replacements. Keywords: Hot Mix Asphalt (HMA): Steel Slag Aggregate (SSA): Natural Aggregates (NA): Marshall Mix design:

Reclaimed Asphalt Pavement (RAP) has gained significant attention in recent years as a sustainable alternative to natural aggregate in road construction. This study presents a comparison of the physical attributes of RAP and natural aggregate, with a focus on their potential use as base and subbase materials in flexible pavements. The physical attributes of RAP and natural aggregate were evaluated using standard laboratory tests, including particle size distribution, specific gravity, water absorption, impact value test, Los Angles Abrasion test, flakiness and elongation test. The research concluded that RAP is comparable to natural aggregate in terms of particle size distribution and bulk density but has lower water absorption, impact, and abrasion values. The results shows that RAP is almost 53% more tougher that natural aggregate when tested for Aggregated Impact test and 30% more harder than natural aggregate when compared by Los Angeles abrasion test. Also, heatmap was used to analyse the relationship between physical attributes of natural aggregate and reclaimed asphalt pavement which depicted 93% similarity The findings suggest that RAP has the potential to replace natural aggregate in flexible pavements, further study is required to determine its long-term performance and durability.

The objectives of this study are to investigate and evaluate the benefits of inclusion of geogrids in two types of geosynthetic reinforced soil/aggregate structures—e.g. reinforced soil foundations (RSF) and reinforced base aggregate in flexible pavements, thus shedding the light on the design of these reinforced structures. Two different finite element models were developed using ABAQUS software. The first model was used to investigate the bearing capacity and settlement of RSF and to perform parametric study on the effect of different design parameters on the performance of RSF. The second model was used to analyze the performance of geogrid reinforced bases in flexible pavement in terms of surface rutting, which was also used to perform parametric study on the effect of different design parameters on the performance of reinforced pavements. Based on the results of finite element analyses, multiple regression models were developed to estimate the benefit of reinforced geomaterial structures under different combination of design parameters. The results of finite element analysis on RSF showed that the inclusion of reinforcement, in general, results in increasing the bearing capacity and reducing the settlement of the reinforced soil. The benefit increases with increasing the tensile modulus and/or number of reinforcement layers. The results also showed that the effective reinforcement depth is about 1.5 times the footing width, and there exists an optimum depth of first reinforcement layer where the highest bearing capacity can be achieved. The results of finite element analysis on geogrid reinforced bases in flexible pavements showed that the use of geogrid reinforcement reduces the lateral strains within the base and subgrade layers, reduces the vertical strains on top of subgrade layer, and hence significantly reduces the surface permanent deformation (or rutting) of pavements. In terms of traffic benefit ratio (TBR), the geogrid base reinforcement helps increasing the service life of pavements, with TRB values of up to 3.4 were obtained for pavement sections over weak subgrades. The finite element analysis clearly demonstrated that the geogrid improvement increases with increasing the geogrid tensile modulus and with decreasing of both the base course layer thickness and the subgrade strength.

Marginal Aggregates in Flexible Pavements: Field Evaluation

Can flexible pavements’ waste (RAP) be utilized in cement concrete pavements? – A critical review

A strong road system is essential for a nation's economy to develop quickly since it connects outlying locations to the rest of the country for use in many types of transportation. Reclaimed asphalt pavement (RAP) is a suitable substitute for virgin material since it lessens the requirement for virgin material. In this investigation, sample of recovered asphalt pavement was gathered and examined to determine whether it would work well as flexible pavement. In this experimental study, bituminous concrete mixtures containing 10%, 20%, 30%, 40%, 50%, and 60% RAP material were the focus. These mixtures were made by scarifying bitumen like VG-30, fresh surface aggregate, and damaged existing asphalt paving without the addition of any additives. In this research, the RAP to new aggregate rates were 10:90, 20:80, 30:70, 40:60, 50:50, and 60:40 . RAP mix was the subject of several laboratory tests, including the Marshall Mix design and many other Physical Properties tests, this paper presents a comprehensive investigation into the behavior of asphalt mixtures with varying proportions of RAP. Ultimately, guidelines derived from reference samples are proposed to facilitate the use of higher RAP proportions and determine the optimum value for modified samples.

The broad production of building and destruction waste and its illegal deposition is dangerous present phenomena. This investigation suggests assessing the utility of using recycled building rubble (RBR) in pavement implementing. An experimental plan was achieved on various compositions of RBR by geotechnical characterization, bearing capacity and repeated plate loading tests. Relationship between the vertical applied stress and the corresponding vertical deformation as well as the deformation along the horizontal distance from the load center was studied experimentally and theoretically using Mechanistic- Empirical methods. Non linear relationships between measured and predicted values were achieved for each mixture. The results illustrate that the structure and the compaction effort affect on the natural and mechanical features of the RBR aggregate. The compaction operation has confirmed a fractional squashing and fracturing of RBR particles, altering the gradation and raising the percentage of cubic grains contributing to a best intensification of the RBR grains and consequently a refinement in strength, resilient modulus and resistance to rutting. Based on the statistical process achieved in this paper, the developed equation can be used to calculate the measured deformation for any collection of the parameters included in the regression model. Generally, the use of RBR aggregates in pavement is totally feasible and that the advantages related to these aggregates spread beyond the environmental notions of their use.

Security is considered as a fundamental right and a critical necessity for social livings. Women are among one of the most vulnerable groups to insecure conditions. Therefore researches about the amount of social damages imposed on this category of the society have found a crucial position. The objective of this study is to assess the amount of women's social security status in rushing sidewalks in Mashhad metropolis as the second city from the view point of importance and area in Iran based on multiple criteria decision making (MCDM) approach. Sample size was selected 172 individuals for each sidewalk. This study was conducted based on a descriptive- analytical approach. First of all, the deterministic criteria of women social security in sidewalks were listed and weighted according to analytical hierarchy approach (AHP). In order to rank the highest secure sidewalks VIKOR and TOPSIS approaches were used.

The development of a reviewer selection method: a multi-level hesitant fuzzy VIKOR and TOPSIS approaches

Multirepon optimization in the Taguchi method can be done by using the VIKOR and TOPSIS approach, which are based on the concept that the best chosen alternative not only has the shortest distance from a positive ideal solution, but also has the longest distance from the negative ideal solution. The basic concept of these two methods is to determine the ranking of existing samples by looking at the results of the utility (S), regrets (R) and solution distances as the best alternatives for each sample. This study aims to obtain significant process variables on the brightness and soreness response variables in the envelope making process by using VIKOR and TOPSIS method approaches, and comparing the results of VIKOR and TOPSIS optimization. The results showed that the two methods produced process optimization in setting variables that were not the same. The VIKOR method produced a setting variable namely A3B2C1D1 while the TOPSIS method produced a setting variable A1B1C3D3. Looking at the value of the two methods, the VIKOR method produced a better estimated value of the brightness parameters and TOPSIS produced a better estimate value for the silence parameter.

Depletion of natural resources has created a problem to the construction industry. Owing to which engineers are now looking for alternative non-conventional materials that can be used in infrastructure development. This need has made scientists and engineers to think about wastes that can be used for benefit of mankind. In present scenario safe disposal of Industrial wastes is a great problem. These waste materials create environmental pollution in the vicinity because many of them are non-biodegradable. Studies reveal that industrial wastes can be used in road construction. Keeping this in mind, industrial waste materials which have been used till now were looked for and steel slag was selected finally. An extensive research has been made on utilization of steel slag for partial replacement of aggregates in flexible and rigid pavements. Steel slag was selected due to its characteristics which are almost similar to conventional aggregates and the fact that it is easily obtainable as a by-product of the steel industry. Steel slag has been considered for replacement of coarse aggregate in binder layer i.e. below surface layer of flexible pavements. Physical and mechanical properties were tested according to Indian Standard codes. Gradation was done as per trial and error method for conventional mixes and same was used for consecutive replacements using steel slag for the coarser portion. Marshall Tests were conducted to obtain optimum binder content and maximum possible replacement corresponding to optimum stability. The stability and flow values of conventional and replaced mixes were compared. The stability values of mix prepared with steel slag increased by 15% with respect to mix prepared with Natural aggregate. There is decrease of percentage air voids and increase in flow values for modified mix with different replacement when compared with conventional mix.

An experimental program was undertaken for determining the feasibility of demolition concrete waste for utilization in subbase, base, and binder course of flexible pavement. Marshall mix design and retained stability test were conducted for predicting the performance of recycled concrete aggregates (RCA)and thermally treated recycled concrete aggregates (TRCA) in binder course as dense bituminous macadam (DBM) in comparison to natural aggregates (NA).DBM mixes containing RCA and TRCA observed satisfactory results, though the optimum bitumen content (OBC) was more as compared to mixes containing NA. OBC for mixes containing NA, RCA, and TRCA was observed as 5.15%, 5.95%, and 5.83%, respectively. Thermal treatment of RCA had a positive impact on its properties resulting in improved results in the context of optimum bitumen content and retained stability but had a negative impact on Marshall stability. Compaction and California Bearing Ratio test results concluded that RCA was meeting the required specifications for utilization in the subbase/base course.

This study aims at investigating the feasibility of the partial replacement of aggregates of asphaltic concrete by recycled aggregates from construction and demolition waste (CDW). It was adopted as parameter a project design mixture of an asphalt concrete used in the construction of Itaueira-Canto do Buriti state highway (Piaui). Two project mixtures were used: in the first 38% of the natural aggregate were replaced by the recycled aggregate and in the second, 70%. We carried out the characterization of the aggregates through physical, chemical and mechanical testing analyzing them based on specific reference standards of paving. We performed assays related to the asphaltic mixture with CDW determining the apparent specific mass, the volume of voids, the relationship bitumen/voids and mechanical testing of traction resistance by diametric compression and Marshall Stability. The results indicate that the recycled aggregate, in a defined proportion, can partially replace natural aggregate in flexible pavements.

Assessment of treatment methods of recycled aggregates for utilization in flexible pavements

Every year, there is a considerable increase in the exploitation of deposits to supply the market for aggregates. On the other hand, so does the production of solid waste from construction and demolition waste (CDW). In 2010 Brazil approved the PNRS (National Policy on Solid Waste), which sets out how the country should have their waste, encouraging recycling and sustainability. As an alternative to the above problem, this paper aims to investigate the feasibility of partial and total replacement of the asphalt concrete aggregates by recycled aggregates from CDW in order to reduce the environmental impacts caused by the operation of quarries and give an adequate final destination the residue produced by man in construction. Were carried out five (05) projects mixture of: the first (parameter of our research) used only natural aggregates (0% CDW) in the second, third and fourth replaced 25%, 50% and 75% respectively of natural aggregate by the recycled aggregate and the fifth and last, used only recycled aggregates (100% CDW). They carried out the characterization of the aggregates by means of physico-chemical and mechanical, analyzing them with reference based on specific standards paving. For mixtures, they calculated the volumetric parameters and performed mechanical tests of tensile strength and stability. The results indicate that the recycled aggregate, in a defined proportion, can replace the natural aggregate in the flexible pavements