DESIGN AND PERFORMANCE EVALUATION OF RECYCLED ASPHALT PAVEMENT(RAP) USING WARM MIX ASPHALT MIXES PROJECT REFERENCE NO.: 38S1219

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1 DESIGN AND PERFORMANCE EVALUATION OF RECYCLED ASPHALT PAVEMENT(RAP) USING WARM MIX ASPHALT MIXES PROJECT REFERENCE NO.: 38S1219 COLLEGE : BASAVESHWARA ENGINEERING COLLEGE BAGALKOT BRANCH : DEPARTMENT OF CIVIL ENGINEERING GUIDE : MR. SRINIVAS. F. CHITRAGAR STUDENTS : MS. SOUMYA YADAHALLI MR. REDDY MANOHAR MR. TALEK GAPAK. MR. BASALINGAYYA KASHIMATH Key words: BC HMA IRC ITS IS MORTH RAP SCB TSR WMA Bituminous Concrete Hot Mix Asphalt Indian Road Congress Indirect Tensile Strength Indian Standard Ministry Of Road Transport and Highways Reclaimed Asphalt Pavement Semi-circular Bending Tensile Strength Ratio Warm Mix Asphalt Introduction: Recycling of flexible pavement materials result in considerable savings in terms of material, money, energy and solve disposal problems. The recycling of pavement is good approach of rehabilitation of deteriorated road surface. It could be undertaken through the reutilization of the existing pavement materials with an improvement of their characteristics. Pavement recycling is

2 becoming more and more important alternative worldwide for the maintenance of highways, due to sustainability and environmental issues have continued to receive more attention. Recycling is the process which implies that of considering the use of road materials in a closed cycle, in which natural material, previously used in road construction, should not be rejected in the following life cycle. The old material can be used to renewal the deteriorated road to improve its quality in the same application that it was initially used for, or as part of a new material in different percentages.rap is an old asphalt pavement that is milled up from the raodway.rap contains both aggregates and bitumen, it can be combined with virgin aggregates, new binder, or recycling agents to produce a recycled mix, which is the most frequent use of RAP. RAP use not only good for economical and environment but also preserve the natural resources without compromising structural performance of pavement. Now a day s warm mix asphalt is giving worldwide popularity due to reduced in mixing and compaction temperature and hence saving in the energy. In this study WMA mixes performances are evaluated by following tests namely Moisture damage by ITS and Fracture resistance by SCB. Objectives : The overall objective of the present study was to design and evaluate laboratory performance of bituminous mixes containing different percentages of RAP. Specifically, the objectives of the present study were to: 1. Design of bituminous concrete (BC) with different percentage of RAP (i.e., 0%, 20% and 40%) using Marshall mix design method. 2. Evaluate moisture damage potential of WMA mixes containing RAP using retained tensile strength ratio (TSR) test. 3. Evaluate fracture resistance of WMA mixes containing RAP using semi-circular bending (SCB) test. Study methodology : 1. All the mechanical tests on aggregates. 2. Characterization of RAP. 3. Preliminary tests on bitumen such as ductility, specific gravity, penetration, softening point and elastic recovery. 4. Marshall mix design using 0%,20% and 40% RAP.

3 5. Performance evaluation of WMA mixes for fracture resistance by SCB and moisture damage by ITS. Marshall mix design: This test procedure is used in designing and evaluating bituminous paving mixes. There are two major features of the Marshall method of designing mixes namely, (1) Density-Void analysis (2) Stability-Flow test. The Marshall stability of the mix is defined as a maximum load carried by a compacted specimen at a standard test temperature at 60 0 C. The flow value is the deformation the Marshall Test specimen undergoes during the loading up to the maximum load, in 0.25 mm units. In this test an attempt is made to obtain optimum binder content for the type of aggregate mix and traffic intensity. Indirect Tensile Strength Ratio Test: The moisture damage potential of WMA mixes with different percentages of RAP (0%, 20%and 40%) were evaluated using retained tensile strength (TSR) test. This test is conducted by applying a compressive load at a rate of 50.8 mm/min on a cylindrical sample as shown in Figure Two different types of samples (i) conditioned (ii) unconditioned, were prepared. The conditioned samples were placed in water bath maintained at a temperature of 60 C for 24 hour prior to testing. Similarly, unconditioned sample were kept in water at 60 C for 30-40min prior to testing. The ratio of failure load of conditioned and unconditioned samples is reported as a TSR value. A high TSR value indicates a good water resistance mix and vice versa. The MORTH recommends a minimum TSR value of 0.80 for a mix to ensure moisture resistant mix. Semi Circular Bending Test: The fracture resistance of asphalt mixes can be evaluated using SCB test on the basis of fracture mechanism principals. Mull et al. (2002) reported that SCB test can be a good predictor of the cracking performance of asphalt mixes. The critical energy release rate, also called the critical value of J-Integral or J c are estimated from this test which is an indication of fracture resistance. Higher J c values are desirable for a fracture resistant mix (Wu et al., 2005). Results and conclusion: Test results of ITS. WMA mixes % of RAP Unconditi oned samples(k pa) Conditioned samples(kpa) TSR( %) 0% % % TSR % % 20% 40% RAP % ITS results for WMA mix Min TSR as per MORTH

4 Test results for SCB y = x R² = y = x R² = y = x R² = %RAP 20% RAP jc value jc integral for WMA mixes 0% 20% 40% jc integral for WMA mixes Change of strain energy with notch depth for WMA mixes change in rate of strain energy with RAP% Conclusion: 1. Moisture Damage Potential: WMA-RAP Mix a. For WMA-RAP mix, comparison with 0% RAP, the TSR value increases with an increase in RAP for up to 30%, and then after it started decreasing. For example, addition of 0%, 20%, and 40% RAP resulted in 84.57%, 95.08%, and 85.51% TSR values respectively, compared to 84.57%, TSR value for 0% RAP. It should be noted that addition of different percentages of RAP satisfies the minimum requirement of 80% as per MORTH specification. 2. Fracture Resistance of WMA-RAP Mix a. Load at failure decreases with an increase in the notch depth for all types of WMA mixes. The load at failure increases with an increase in amount of RAP. For example, at 20 mm notch depth, addition of 40% RAP, resulted in increase in load at failure from 0.32kN (0% RAP) to 0.96kN (40% RAP). A similar trend was observed for other notch depths. The significant improvement is seen in load at failure at for all notch depths for a mix with 40% RAP. The results show that addition of RAP enhances strength of a mix, hence load at failure increases. This can be due to the fact that RAP material has aged and stiff binder which resulted in a stiffer mix.

5 Scope for future work: 1. In the future work the study can be carried out for 10,30, 50 and other percentage of RAP. 2. Modification of asphalt can be made by using a additive such as evotherm, diseal etc., 3. Cost savings can be identified by the comparison of HMA and WMA. 4. Varying bitumen grade may show different results for the addition of RAP.