Performance Evaluation of Flexible Pavements with Modified Bitumen Binders

Abstract

In India majority of roads are being constructed by flexible pavements. But the performance of the pavement largely depends on quality and type of materials used, Construction methodology adopted, temperature, climatic conditions etc. Because of these variations in the mentioned parameters, pavements undergo distress/ failure. The different types of failure in flexible pavement are Rutting, Shovelling, Edge breaks, Cracks, Slippage etc. Rutting is a common phenomenon which occurs in flexible pavement surface due to overloading of vehicles and repeated application of wheel load. Rutting is defined as channelized depression in the pavement surface along wheel path due to heavy repetitive traffic load. Design of bituminous paving mixes greatly effects the performance of pavements. In the present laboratory research work, conventional bitumen is used in wearing/ surface course and Modified Bitumen is used in binder course of the layer. Pavement layers are constructed/casted in an Indigenously designed, developed and fabricated equipment called Roller Compactor cum Rut Analyzer (RCRA) and Rutting test was performed. The overall objective is to compare the Marshall properties of the conventional and Modified Bituminous mix and to study the rutting performance of these bituminous mixes. Results shows that bituminous mixes prepared with Modified Bitumen/Binders has a very high Marshall Strength and offers greater resistance to rutting

Introduction

I. INTRODUCTION

Bituminous pavement is extensively used in India for the construction of both rural and urban roads. Overloading of axles and increased traffic volume in excess of permissible limits and higher tyre pressure, have caused widespread problems with the performance of the pavement. The mix design is to produce a bituminous mix by proportioning various components so as to have sufficient bitumen to ensure a durable pavement, strength to resist shear deformation under traffic at higher temperature, sufficient air voids in compacted bitumen to avoid flushing and bleeding under traffic load and sufficient workability to provide easy placement without segregation. The Marshall Stability and flow test provides the performance prediction measure for the Bituminous mixes. It is related to the resistance of bituminous materials to distortion, displacement, rutting and shearing stresses. The stability is derived mainly from internal friction and cohesion. Cohesion is the binding force of binder material while internal friction is the interlocking and frictional resistance of aggregates. As bituminous pavement is subjected to severe traffic loads from time to time, it is necessary to adopt bituminous mix with good stability and flow. It is a common practice in India to use the Modified Bitumen in the wearing course and conventional bitumen in the binder course of pavement layers. But due repeated application of heavy wheel loads, temperature difference between the top and bottom of pavement layers, climatic conditions severely affects performance of pavement .So, in the present laboratory research work, an attempt is made to study the performance of bituminous mixes by using  Crumb Rubber Modified Bitumen (CRMB-55) as a Modified bitumen in the Binder course of pavement layers. The Rutting test is carried out on wearing course of bituminous layer (BC Gr-II with VG-30) and by adopting Binder course layer namely DBM Gr-II prepared with two different types of binders namely VG-30, CRMB-55.

II. OBJECTIVES OF THE RESEARCH WORK

A. To conduct the basic tests on Aggregates, Bitumen and Modified Bitumen (CRMB-55) in the laboratory as per the relevant IS/ MoRTH standards to ascertain its suitability for the use in research work.

B. Based on the obtained Job Mix Formula (JMF) for different bituminous mixes, conduct Marshall stability test on bituminous mixes with VG-30 and CRMB-55.

C. To Conduct the rutting test on casted specimens of bituminous mixes at different temperatures in the laboratory using Roller Compactor cum Rut analyser  (RCRA).

D. Comparison of results of  Marshall stability and rutting values for the bituminous mixes prepared with VG-30 and CRMB-55.

III. LITERATURE REVIEW

Prasad (1) Studied the importance to add the shredded waste plastic bottles to bituminous concrete (BC) mix and to evaluate the various mix properties like Marshall Stability, flow, bulk density, voids in the mix and VFB in 2012. Also the effect of soaking conditions of the mix was investigated. Indirect tensile strength was investigated for OBC and 8% plastic coated on aggregates which had yielded the highest marshal stability.

The optimum plastic content for 60/70 and 80/100 grade bitumen was 8%. For both 60/70 and 80/100 grade bitumen with plastic content 8%, the maximum stability was achieved in 80/100 grade bitumen. Hence there is an increase in stability with the addition of PET (polyethylene terephthalate) plastic in asphalt mix by incorporating dry process this can be used in highway construction for better stability for the appropriate traffic.

Sharma D K(2) Investigated the use of plastic/polymer as modifiers in 2009. The waste plastic/polymer was added on the aggregate before mixing Optimum Binder Content (OBC) in dry process at 150-1600C temperature. This type of mixing increases the bonding between aggregates coated with plastic/polymer which increases the strength of the bituminous concrete mixes. Stability values and indirect tensile strength values were observed to be more in polymer modified bitumen than in conventional bitumen. Rutting values were also higher in polymer modified bitumen mixes than in conventional mixes

Justo(3), Reported the possible use of the processed plastic bags as an additive in bituminous concrete mixes at the Centre for Transportation Engineering of Bangalore University in 2002.The properties of the modified bitumen were compared with ordinary bitumen. It was observed that the penetration and ductility values of the modified bitumen decreased with the increase in proportion of the plastic additive, up to 12 % by weight.

Therefore the life of the pavement surfacing course using the modified bitumen is also expected to increase substantially in comparison to the use of ordinary bitumen.

Sheeb(4)  Concluded that the modified mixture has a higher stability and VMA (Void in Mix Aggregate) percentage compared to the non-modified mixtures in 2007.

This, in returns, would positively influence the rutting resistance of these mixtures. The air void contents of the modified mixtures are not far from that of the non-modified one. Air void proportion around 4% is not enough to room for the expansion of asphalt binder to prevent bleeding or flushing that would reduce the skid resistance of the pavement and increase rutting susceptibility. In summary, using the poly-ethylene in asphalt mixtures reduces pavement deformation; increase fatigue resistance and provide better adhesion between the asphalt and the aggregates

Tayde(5) Intended to find the effective ways to reutilize the hard plastic waste particles as bitumen modifier for flexible pavements. The use of recycled waste plastic in pavement asphalt represents a valuable reuse for such materials. The use of modified bitumen with the addition of processed waste plastic of about 5-10% by weight of bitumen helps in substantially improving the Marshall stability, strength, fatigue life and other desirable properties of bituminous concrete mix, resulting which improves the longevity and pavement performance with marginal saving in bitumen usage. The process is environment friendly. The use of waste plastics in the construction of roads and laminated roofing also help to consume large quantity of waste plastics.

Darshna B Joshi (6) conducted tests on finding out of Optimum binder content by Marshall mix design for DBM. Bituminous mix design is done to find out the properties of coarse aggregate, filler and binder materials and also mix should be workable, strong, durable and economical. Aggregate gradation and mix design requirements are primary concern in a asphalt mix. Various volumetric parameter and Marshall Stability is different for different mixes. Material tests should be done to make sure that all material satisfies the Indian Standards /MoRTH.

IV. METHODOLOGY

The following methodology is adopted in the present research work:

1. The methodology includes conducting the Basic tests on the materials used in the research work such as aggregate, bitumen, modified bitumen binders as per the relevant IS/MoRTH Codal standards
2. Preparing the Marshall specimens and conducting Marshall Stability test
3. Preparing the specimens for Rutting and conducting rutting test by Roller Compactor cum Rut analyser (RCRA) at different temperatures with VG-30 and Modified Bitumen (CRMB-55).

V. LABORATORY TEST RESULTS

The laboratory investigation/tests were carried out on different materials used in the research work and the obtained results are as follows:

Table 1

Tests on Aggregates

Table 2

Tests on Bitumen and Modified Bitumen

TABLE 3

Obtained job Mix Formula (JMF) and Optimum Binder Content (OBC)

TABLE 4

OBTAINED RESULTS OF MARSHALL STABILITY TEST

TABLE 5

RUTTING TEST RESULTS FOR PAVEMENT LAYERS, USING BC GR-II WITH VG-30 AS WEARING COURSE AND

DBM GR-II AS BINDER COURSE WITH VG-30 AND CRMB -55 AT DIFFERENT TEMPERATURES.

VI. DISCUSSIONS

A. The basic properties on aggregates, bitumen and modified binders are carried out in the laboratory and the materials satisfies the requirements as per the relevant IS / MoRTH standards.

B. The optimum binder Content (OBC) for BC Gr-II with VG-30 is found to be 5.6%, DBM Gr-II with VG-30 is 5.1% and DBM Gr-II with CRMB-55 is 5.1% respectively.

C. The stability value of Binder course (DBM Gr-II) with CRMB-55 shows 55% higher value than with VG-30.

D. mThe Wearing course (BC Gr-II ) with VG-30 at 300 C shows, 14%  and  48% higher resistance to rutting at 500 C and 700C respectively.

E. The Modified Bitumen (CRMB-55) shows 25%, 25%, 32% higher resistance to rutting at 300C, 500C, and 700C respectively, when compared at same temperatures with VG 30.

VII. ACKNOWLEDGEMENT

The Author/ Researcher sincerely want to thank Dr B V Kiran Kumar, who is also the Co-author of this research paper in design, development,  and fabricating the Roller Compactor cum Rut Analyzer (RCRA) Equipment. Also, want to thank The office of Bruhat Bangalore Mahanagara Palike (BBMP) for sponsoring the materials required for the research work.

Conclusion

From the present research work, it can be concluded that: 1) The modified binders shows a higher Marshall stability value when compared with VG-30 bitumen. 2) The use of modified binders (CRMB-55) in the binder course layer of pavement shows a high resistance to rutting when compared with VG-30. The percentage of higher resistance is upto 48%. 3) Modified Binders can also be used in Binder course of pavement. The use of modified bitumen makes the structural layer of pavement to have more stability and greater resistance to rutting. 4) The temperature significantly affects the rutting in pavement. The pavement undergoes higher rutting with increase in temperature.

References

[1] Prasad, “Importance of adding the shredded waste plastic bottles to bituminous concrete mix-a literature review” (2012 ) [2] Sharma D K, “Use of plastic/polymer as modifiers-a literature”(2009) [3] Justo, “Use of the processed plastic bags as an additive in bituminous concrete mixes - a literature review”- a literature review” (2002) [4] Sheeb,” Comparing the stability and VMA of conventional and non-conventional mixtures – a literature review “(2007) [5] Tayde, “The effective ways to reutilize the hard plastic waste particles as bitumen modifier for flexible pavements – a literature review” [6] Darshna B joshi and Prof. A K Patel, “Optimum binder content by Marshall mix design for DBM?”Journal of information, knowledge and research in civil engineering, volume-2, November 12 to October 13, ISSN: 0975- 6744 (2012). [7] S.K. Khanna, C.E.G. Justo and A. Veeraragavan, “Highway Materials and Pavement Testing.”

Copyright

Copyright © 2022 Praveen Kumar P, Dr. Kiran Kumar B V . This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.