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Performance of Recycled Asphalt Pavement as Coarse Aggregate in Concrete  [PDF]
Fidelis O. OKAFOR
Leonardo Electronic Journal of Practices and Technologies , 2010,
Abstract: Recycled asphalt pavement (RAP) is the reclaimed and reprocessed pavement material containing asphalt and aggregate. Most RAP is recycled back into pavements, and as a result there is a general lack of data pertaining to the mechanical properties for RAP in other possible applications such as Portland cement concrete. In the present study, some mechanical properties of Portland cement concrete containing RAP as coarse aggregate were investigated in the laboratory. Six concrete mixes of widely differing water/cement ratios and mix proportions were made using RAP as coarse aggregate. The properties tested include the physical properties of the RAP aggregate, the compressive and flexural strengths of the concrete. These properties were compared with those of similar concretes made with natural gravel aggregate. Results of the tests suggest that the strength of concrete made from RAP is dependent on the bond strength of the asphalt-mortar (asphalt binder-sand-filler matrix) coatings on the aggregates and may not produce concrete with compressive strength above 25 MPa. However, for middle and low strength concrete, the material was found to compare favorably with natural gravel aggregate.
Sintered Calcined Clay as an Alternative Coarse Aggregate for Asphalt Pavement Construction  [PDF]
Cleudinei Lopes da Silva, Hidembergue Ordozgoith da Frota, Consuelo Alves da Frota
Open Journal of Civil Engineering (OJCE) , 2015, DOI: 10.4236/ojce.2015.53028
Abstract: The aim of this study is to search for a substitute for the natural coarse aggregate in various regions of the world, such as Amazon-Brazil, where this type of material is lacking. The asphalt binder AC 50/70 is mixed with an aggregate obtained from the sinterization of a calcined clay (SACC) as a possible alternative to coarse aggregate material for the construction of asphalt pavements in tropical zones. The dynamic modulus |E*| of this mixture was measured under strain control mode and in tension control mode. The results are compared with those obtained from AC 50/70 mixed with pebbles, which is currently used as the coarse aggregate in this region. For pavements that work at high temperatures, such as 40, and low frequencies, the mixture with SACC appears to be a viable alternative to coarse aggregate material for the construction of asphalt pavements in tropical zones.
Characterising the ductility and fatigue crack resistance potential of asphalt mixes based on the laboratory direct tensile strength test  [cached]
L F Walubita,G S Simate,J H Oh
Journal of the South African Institution of Civil Engineering , 2010,
Abstract: As a means to investigate the applicability of the direct tensile strength (DT) test as a surrogate fatigue crack test, the ductility and fatigue crack resistance potential of various asphalt (HMA) mixes were evaluated in the laboratory using the DT test, at ambient temperature (20oC) and a displacement loading rate of 1,27 mm/min. Various HMA mixes were included in the DT test program and the results were compared with those of the Overlay Tester, also conducted at ambient temperature. Up to 23 commonly used Texas HMA mixes with different mix design characteristics were evaluated and are discussed in this paper. The results indicated that the mix design volumetrics, such as the asphalt binder content and aggregate gradation, play a significant role in the ductility and fatigue crack resistance potential of HMA mixes. The dense-to fine-graded HMA mixes with high asphalt binder content exhibited better ductility potential and laboratory fatigue crack resistance than the coarse- and open-graded mixes. Overall, the DT test was found to be a promising surrogate fatigue crack test for mix design and HMA mix screening for fatigue crack resistance in the laboratory. Recommendations to improve the test protocol are included in the paper. However, sample fabrication and test set-up were the two critical issues found to be associated with the DT test.
Hot Mix Asphalt Using Light Weight Aggregate Concrete  [PDF]
Mohammad T. Awwad
Journal of Applied Sciences , 2007,
Abstract: Hot mix asphalt concrete is produced by properly blending asphalt, coarse and fine aggregates in addition to filler at temperatures ranging from 80 to 165 C. This research is directed to study the effect of replacing the conventional aggregates by the recycled Light Weight Aggregate Concrete (LWAC) on the properties of the produced asphalt mix. The research studied the optimum asphalt content and the effect of some parameters on the properties of the recycled LWAC. The research included studying thirty-six Marshal Specimens lie in four main groups. Each group was made from crushed LWAC in addition to a comparison group used the pumice instead of the crushed LWAC. The LWAC mixes contained (0, 10, 15 and 20%) of silica powder content. The density, stability, flow, percentages of the air Voids in the Compacted Mixture (VTM), compacted mineral aggregate (VMA) and the Voids Filled by Asphalt (VFA) were investigated for all the studied specimens. The main conclusions drawn from the current research implies that the optimum percent of asphalt was 7.5% for the different percentages of silica powder ratios. The presence of voids in the light weight aggregates and the porosity of the obtained concrete affected largely the behavior of the obtained mix.
Destructive Strength Properties of Recycled Coarse Aggregate  [PDF]
Chetna M Vyas,,Darshana R Bhatt
International Journal of Innovative Technology and Exploring Engineering , 2013,
Abstract: Due to a critical shortage of natural aggregate, the availability of demolished concrete for use as recycled coarse aggregate (RCA) is increasing. Use of waste concrete as RCA conserves natural aggregate, reduces the impact on landfills, save energy and can provide cost benefit. Recycled aggregates are the materials for the future. The application of recycled aggregate has been started in many Asian & Western countries for construction projects. Research Paper reports the basic strength properties of recycled coarse aggregate. It also compares these properties with natural aggregates. Basic changes in all aggregate properties were determined. Basic concrete properties like compressive strength, pull out strength are explained here for different combinations of recycled coarse aggregate with natural aggregate. The compressive strength, pull out strength is used to determine the maximum resistance of a concrete to axial loading of the concrete specimens that having different percentage of recycled coarse aggregate replacement. The testing is just carried out after 28 days of casting. The resting specimen was 100mm diameter and 200 mm height for M25 grade concrete. There were total of six batches of concrete mixes, consists of every 20% increment of recycled aggregate replacement from 0% to 100%.
Performance of Palm Kernel Shells as a Partial replacement for Coarse Aggregate in Asphalt Concrete
Peter Ndoke NDOKE
Leonardo Electronic Journal of Practices and Technologies , 2006,
Abstract: This paper looks at the potentials of palm kernel shells as coarse aggregates in road binder courses with emphasis on strength of the asphalt concrete as given by the Marshal Stability and flow values. It was observed that palm kernel shells can be used to replace coarse aggregate up to 30% before drastic reductions become noticeable. It is therefore recommended that for heavily trafficked roads, palm kernel shells up to 10% can be used for the replacement while even 100% replacement is possible for lightly trafficked roads in the rural settings.
Steel Slag as an Aggregate Replacement in Malaysian Hot Mix Asphalt  [PDF]
Mohd Rosli Hainin,Nur Izzi Md. Yusoff,Mohd Fahmi Mohammad Sabri,Mohd Azizi Abdul Aziz,Mohd Anwar Sahul Hameed,Wasid Farooq Reshi
ISRN Civil Engineering , 2012, DOI: 10.5402/2012/459016
Abstract: As natural aggregate sources are becoming depleted due to high demand in road construction and the amount of disposed waste material keeps increasing, researchers are exploring the use of alternative materials which could preserve natural sources and save the environment. In this study, steel slag was used as an aggregate replacement in conventional dense graded asphalt mixes (ACW14 and ACB28). 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. The same gradations of mixtures were produced using normal crushed aggregate as control samples. The Marshall mix design system was used for sample preparation in accordance with Malaysian specifications. Samples of asphaltic concrete were subjected to the resilient modulus test, creep test and rutting test. Samples made from steel slag show significantly better results than conventional aggregate. Therefore, utilization of steel slag will reduce land fill, save natural resources and improve the strength of pavement to sustain a higher volume of vehicles. This will shift the gear in sustainable pavement construction, which is most desirable in today’s energy deficient world. 1. Introduction The development of the highway construction industry is increasing rapidly. Consequently, the aggregate resources in Malaysia are becoming depleted, and the land is being sacrificed to obtain raw materials. Thus, it is necessary to find a recycled material that can replace aggregates in highway construction. Much research has been done to improve and upgrade the materials used for preparing hot-mix asphalt (HMA). The utilization of waste material as a replacement for aggregates in the production of HMA could have many benefits to mankind. Waste materials can be categorized broadly as follows: industrial waste (e.g., cellulose waste, wood lignins, slags, bottom ash, and fly ash), municipal or domestic waste (e.g., incinerator residue, scrap rubber, waste glass, and roofing shingles) and mining waste (e.g., coal mine refuse) [1]. Steel-slag is a byproduct of the steel industry, and is reported to exhibit great potential as a replacement for natural aggregates in road construction. Steel-slag is a waste material that can be recycled as a road construction material. Steel-slag aggregates have been reported to retain heat considerably longer than natural aggregates. The heat retention characteristics of steel-slag aggregates can be advantageous for HMA construction, as less gas (energy) is used
Effect of Mix Parameters on the Strength Performance of Waste Plastics Incorporated Concrete Mixes  [PDF]
Santhosh M. Malkapur,Ashish Anand,Amit Prakash Pandey,Alok Ojha,Nimesh Mani,Narasimhan Chandrashekara Mattur
Journal of Structures , 2014, DOI: 10.1155/2014/389014
Abstract: Disposal of solid wastes has been a major problem all over the world. Out of all the different types of solid wastes, the major challenge of disposal is posed by the ever increasing volumes of plastic wastes. While several methods are in practice, producing newer useful materials by recycling of such plastic wastes is, by far, the best method of their disposal. One such possible method is to use the waste plastics as an ingredient in the production of the concrete mixes in the construction industry. The present study aims to investigate the relative contributions of the various mix parameters to the mechanical properties of concrete mixes produced with waste plastics as partial replacement (10–30% by volume) to coarse aggregates. Initially, strength test results of a set of trial mixes, selected based on Taguchi’s design of experiments (DOE) method are obtained. A detailed analysis of the experimental results is carried out to study the effect of using waste plastics as a partial replacement to coarse aggregates on the strength parameters of these concrete mixes. It is found that all these trial mixes have performed satisfactorily in terms of workability in the fresh state and strength properties in their hardened state. 1. Introduction In the urge of making a cleaner and sustainable environment, one important concern has been on disposing of the solid wastes. There have been many attempts to use different solid wastes as possible construction materials. The present study explores the use of waste plastics as a possible replacement to coarse aggregates in concrete mixes. The study aims at investigating the mechanical properties of concrete mixes with waste plastic aggregates incorporated in them as a partial replacement to their coarse aggregate fraction. This work is focused on developing mixes with as maximum replacement of waste plastic as possible but retaining a minimum compressive strength of grade M20. In general, the inclusion of waste plastics into concrete has been found to decrease the strength performance characteristics of concrete. This decrease in performance is expected both in fresh and hardened properties. In fresh state, the workability of the concrete mixes produced with recycled plastic aggregates was found to be smaller as compared to the control mixes [1–5]. The hardened properties of concrete such as the compressive strength, tensile strength, flexural strength, and modulus of elasticity reduce with increased percentage of waste plastics [1, 2, 5–10]. Though many works have been reported on the strength performance
Reduction of optimum bitumen content in bituminous mixes using plastic coated aggregates  [PDF]
International Journal of Innovative Research in Science, Engineering and Technology , 2013,
Abstract: Use of plastic in road construction is gaining importance these days because plastic roads perform better than ordinary roads and the plastic waste, otherwise considered to be a pollution menace can find its use. This paper deals with the investigations of the use of waste plastic for coating of aggregates in the bituminous mix. Optimum bituminous mixes are designed using ordinary aggregate and plastic coated aggregate. The comparative study of the mixes is also presented.
Utilization of Industrial Waste Slag as Aggregate in Concrete Applications by Adopting Taguchi’s Approach for Optimization  [PDF]
Mohammed Nadeem, Arun D. Pofale
Open Journal of Civil Engineering (OJCE) , 2012, DOI: 10.4236/ojce.2012.23015
Abstract: This paper presents result of an experimental investigation carried out to evaluate effects of replacing aggregates (coarse & fine) with that of Slag (Crystallized & Granular) which is an industrial waste by-product on concrete strength properties by using Taguchi’s approach of optimization. Whole study was done in three phases, in the first phase natural coarse aggregate was replaced by crystallized slag coarse aggregate keeping fine aggregate (natural sand) common in all the mixes, in the second phase fine aggregate (natural sand) was replaced by granular slag keeping natural coarse aggregate common in all the mixes and in the third phase both the aggregates were replaced by crystallized & granular aggregates. The study concluded that compressive strength of concrete improved almost all the % replacements of normal crushed coarse aggregate with crystallized slag by 5% to 7%. In case of replacements of fine aggregate and both type of aggregates, the strength improvements were notably noticed at 30% to 50% replacement level. It could also be said that full substitution of slag aggregate with normal crushed coarse aggregate improved the flexure and split tensile strength by 6% to 8% at all replacements and in case of replacing fine aggregate & both the aggregates( Fine & coarse) with slag, the strength improvement was at 30% to 50% replacements. It is evident from the investigation that Taguchi approach for optimization helped in indentifying the factors affecting the final outcomes. Based on the overall observations, it could be recommended that Slag could be effectively utilized as coarse & fine aggregates in all concrete applications.
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