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International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064

Impact Factor (2012): 3.358

Volume 3 Issue 10, October 2014 www.ijsr.net

Licensed Under Creative Commons Attribution CC BY

Evaluation of Rutting Performances of Hot Mix Asphalt Containing Recycled Asphalt Mixes using

Flow Time Test

Darshita Tiwari1, Anoop Patel2

1Department of Civil Engineering, Shri G.S. Institute of Technology & Science Indore (M.P.) India, 452003

2Department of Civil Engineering, Shri G.S. Institute of Technology & Science Indore (M.P.) India, 452003 Abstract: Utilization of recycled asphalt pavement (RAP) has gained worldwide popularity in highway industry recently. Use of RAP in asphalt mixes can reduce cost of materials (aggregates and bitumen), conserve aggregates and asphalt, save environment, and help solve the problem of solid waste disposal. However, construction of highways with RAP is not as popular in India as it expected to be due to lack of laboratory facilities and field performance data. In this study, the objective was to conduct a laboratory investigation of rutting resistance of hot mix asphalt containing RAP. Two mixes, one without RAP and the other with up to 40% RAP (10%, 20%, 30% and 40%) were designed in the laboratory using Marshall mix design method. It can be comprehended that using RAP not only reduce the cost of construction but also increases the characteristics of mixes as it was seen that inclusion of RAP increases rutting performance of a mix. Overall, the present study would be helpful to characterize mixes containing RAP. Keyword: recycled asphalt pavement, hot mix asphalt, flow time, rutting resistance. 1. Introduction Reclaimed asphalt pavement (RAP) is a material collected from deteriorated and structurally deficient flexible pavements. The RAP contains aggregates coated with bitumen. Use of RAP in asphalt mixes can reduce cost of materials (aggregates and bitumen), conserve aggregates and asphalt which can help save the environment, and also help solve the problem of solid waste disposal. According to a survey conducted by National Asphalt Association (NAPA) in partnership with Federal highway Association (FHWA), about 86.7 million tons of recycled asphalt pavement (RAP) was utilized in construction of flexible pavements in US during 2012. However, due to the lack of laboratory facilities and field performance data, agencies and contractors are not trained enough to judge the quality of RAP materials and to design a mix containing RAP. Moreover, non-availability of standards and specification and variability of RAP, and past bitter experience with RAP have demotivated many industry and highway engineers to promote utilization of RAP. It is expected that aged binder in RAP may produce stiffer mixes, resulting in lower fatigue and brittle mixes. Many researchers have reported that addition of RAP results in better rutting resistance of mixes (Kanishak et al.,). However, limited studies have been done on evaluation of rutting performances of mixes containing RAP. 2. Objectives Study rutting performance of asphalt mixes with and without RAP (up to 40% RAP) using flow time test 3. Methodology In this study, a bituminous concrete (BC) Grade-1 was designed as per MoRTH specification with (0% RAP) and without (0 to 40%) RAP content. The flow chart of the

methodology is presented in Figure 1. The project started with materials collection, mix design, and performance evaluation of mixes in laboratory. The detail discussion on each of the task is presented below.

Figure 1: Flow Chart of Methodology

4. Materials Collection The aggregates of different sizes: 20 mm and 10 mm down and stone dust were collected from J.M. Mhatre Infra Private Limited. The aggregate was a basaltic rock with dark grey colour. The asphalt binder sample of viscosity grade (VG) was collected from Hindustan Colas Limited. The VG30 binder is generally used for construction of flexible pavements in India as per Indian Road Congress specification. RAP was collected from Indore. This road needed resurfacing due to potholes and other distresses, and hence top 40 mm of the pavement was removed by milling.

Paper ID: OCT14463 1660





4.1 Mix Design The Marshall mix design procedure was employed to design mixture. Materials meet the gradation specification of MoRTH and all the mixtures were adjusted to keep the similar aggregate structures after RAP was added, gradation curves of aggregates is shown in Figure 1and gradation curves of filler and stone dust is shown in Figure 2 . Table 3 presents the different asphalt contribution from RAP and virgin asphalt.

Table 1: Asphalt contribution from RAP and virgin

asphalt RAP (%)

OBC (%) Virgin Binder to be added (%)

Binder from RAP (%)

Binder Saving (%)

0 5.41 5.41 - - 10 4.89 4.89 0.49 9 20 4.25 4.25 1.12 20.7 30 3.92 3.92 1.61 29.76 40 2.83 2.83 2.26 41.77 OBC= Optimum Bitumen Content, RAP= Reclaimed

Asphalt Pavement 5. Laboratory Performance Tests Rutting Performance Using Flow Time

Rutting is one of the major distresses in a flexible pavement which can lead to early failure. The rutting is caused due to application of repeated loads which results in densification and lateral plastic flow under the wheel path. The flow time has been recognized as one of the important tests to evaluate rutting performance of asphalt mixes. In this test, a static load of selected magnitude is applied for 10,000 s to a cylindrical sample of 100 mm diameter and 150 mm height. The test is generally conducted a higher temperature to simulate rutting behavior of a pavement. The permanent deformation is measured with time. The plot of permanent deformation versus time has three different zones: primary zone (reflecting initial densification stage), secondary zone (indicate long time densification), and tertiary zone (shear

failure) which is shown in Figure 2. A flow time is defined as a time where zone shifts from secondary to tertiary. A flow time is an indication of rutting performance of a mix. A higher flow time value indicates stronger mix and vice versa. The rutting performance of asphalt mixes containing different percentages of RAP (i.e., 0%, 10%, 20%, 30%, and 40%) were evaluated in the laboratory.

Figure 2: Different Zones of Rutting in Flow Time Test

The samples of 100 mm diameter and 150 mm in height were prepared in the laboratory using Marshall sample compactor with target air void in range of 5±1%. The number of blows was changed accordingly to achieve the target air voids in the compacted samples. This test was performed as uniaxial static creep test. Cylindrical samples were subjected to a constant compressive load of 500 kPa at a test temperature of 550C for 10,000 seconds. The samples were kept in water for 2 hours to achieve test temperature which is shown in Figure 3. The resulting axial strain was measured as a function of time and numerically differentiated to calculate the flow time which is defined as the time corresponding to the minimum rate of change of axial strain.

Figure 3: Flow time specimen testing






6. Results and Discussion The rutting performance of different types of HMA-RAP mixes is presented in Figure 4. A high value of flow time indicates a stronger mix, and better rut resistance. The results show the addition of RAP increases flow time. For example, addition of 10%, and 20% RAP resulted in an increase in flow time from 1925 seconds (0% RAP) to approximately 2250 seconds and 8750 seconds flow time, respectively. The addition to 30% and 40% RAP resulted in flow time greater than 10,000 seconds, indicating no sign of failure of a sample. The increase in rut resistance of a mix with addition of RAP can be due to the addition of aged and stiffer binders.

Figure 4: Comparison of Flow Time

7. Summary and Conclusions The construction of highways with RAP materials is not as popular in India as it expected to be, due to lack of laboratory and field performance data. The present study was undertaken to design and evaluate performance of bituminous mixes containing 0%, 10%, 20%, 30% and 30% RAP. The results show that RAP mix is better rut resistance than a mix without RAP. The results show the addition of RAP increases flow time. For example, addition of 10%, and 20% RAP resulted in increase in flow time from 1925 seconds (0% RAP) to approximately 2250 seconds and 8750 seconds flow time, respectively. The addition to 30% and 40% RAP resulted in flow time greater than 10,000 seconds, indicating no sign of failure of a sample. The increase in rut resistance of a mix with addition of RAP can be due to the addition of aged and stiffer binders. 8. Recommendations

1. The rutting performance of HMA and WMA mixes

should be evaluated based on the accelerated rutting test methods, such as Hamburg wheel tracking test

2. The effects of RAP on other laboratory performance parameters namely, dynamic modulus, creep compliance should be evaluated.

3. The effects of rejuvenators should be evaluated to use higher percentages of RAP in the laboratory

4. Overall, a field demonstration project should be carried out to validate laboratory performance of mixes containing RAP

References

[1] Ali, H. and Grzybowski, K. (2012). “Life Cycle of Hot In-Place Pavement Recycling”, Transportation Research Record 2292, Washington, D.C., pp. 29–35.

[2] Huang, B., Shu, X. and Tang, Y. (2005). “Comparison of semi-Circular Bending and Indirect Tensile Strength Tests for HMA Mixtures”, Advances in Pavement Engineering.

[3] Kanishak, C., Kumar, A., Mallick, R. and Veeraragavan, A., (2012). “Investigation on Laboratory Performance of Bituminous Mixes With Reclaimed Asphalt Pavement Materials- A Step Towords Sustainable Road Infrastructure In India”, Journal of the Indian Roads Congress Paper No. 584, India, Vol. 73-3.

[4] Mostafa A. Elseifi, Louay N. Mohammad, Hao Yang and Samuel cooper (2012). “Modeling and Evaluation of the Cracking Resistance of asphalt Mixtures Using the Semi-Circular Bending Test at Intermediate Temperature” Road Materials and Pavement Design, Vol. 13, No. S1, pp. 124-139.

[5] Zhao, S., Haung, B., Shu, X., Jia, X. and Woods, M. (2012). “Laboratory Performance Evaluation of Warm Mix Asphalt Containing High Percentage of RAP”, Transportation Research Board Annual Meeting.

[6] Mohammad, L.N., Saaadeh, S., Obulareddy, S. and Cooper, S. (2007). “Characterization of Louisiana Asphalt Mixtures Using Simple Performance Tests”, Transportation Research Board Annual Meeting, Washington, D.C.

[7] Mohammad, L.N., Cooper, S.B. and Mostafa, A.E. (2011). “Characterization of HMA Mixtures Containing High Reclaimed Asphalt Pavement Content with Crumb Rubber Additives”, Journal of Material in Civil Engineering, Vol. 23, pp. 1560-1568.

[8] Ying, H., Mostafa, A.E., Louay, N.M. and Heshmat A.A. (2013). “A Crack Propagation Model for Asphalt Mixtures Based on the Cyclic Semi-Circular Bending Test”, Transportation Research Board Annual Meeting, Washington, D.C.

[9] Mailick, R.B., Kandhal, P.S. and Bradbury, R.L. (2008). “Using-Warm Asphalt Technology to Incorporate High Percentage of Reclaimed Asphalt Pavement Material in Asphalt Mixture”, Transportation Research Record 2051, Washington, D.C., pp.


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