EP4392492A1

EP4392492A1 - Rejuvenator for recycling of aged bituminous mixes

Info

Publication number: EP4392492A1
Application number: EP22787735.4A
Authority: EP
Inventors: Satish Pandey; Sangita Sharma; Prateek Tulsyan
Original assignee: Verma Industries; Council of Scientific and Industrial Research CSIR
Current assignee: Verma Industries; Council of Scientific and Industrial Research CSIR
Priority date: 2021-04-13
Filing date: 2022-04-13
Publication date: 2024-07-03
Also published as: WO2022219553A8; WO2022219553A1

Abstract

A rejuvenator for recycling asphalt is disclosed. The rejuvenator comprises a Bio-5 oil A, wherein the Bio-oil A is a non-hydrogenated plant oil comprising 10-16% Palmitic Acid, 40-50% Linoleic Acid, 8-16% Oleic Acid and 15-22% Stearic Acid of the total amount of fatty acid; and a Bio-oil B, wherein the bio-oil B is obtained from biomass pyrolysis and comprises 20% to 35% rosin acid; wherein the ratio of Bio Oil A to Bio-Oil B, is in the range of 1:100 to 100:1. A paving composition and 10 a process for preparing a paving composition that includes reclaimed asphalt pavement material is also disclosed.

Description

REJUVENATOR FOR RECYCLING OF AGED BITUMINOUS MIXES

FIELD OF THE INVENTION

The present disclosure relates to an asphalt rejuvenator, a paving composition, and a process for preparing a paving composition. Specifically, the disclosure relates to bio-oil based asphalt rejuvenator, a paving composition and a process for preparing a paving composition based on the asphalt rejuvenator.

BACKGROUND

Asphalt pavements or roads are prepared using a paving composition also known as asphalt that includes bitumen mixed along with coarse aggregates, such as stones, gravel, sand, and the like. Bitumen, is a dense, highly viscous, petroleum- based hydrocarbon that is found in deposits such as oil sands and pitch lakes (natural bitumen) or is obtained as a residue of the distillation of crude oil (petroleum residue). Generally, asphalt is prepared using the bitumen obtained from distillation of crude oil.

Asphalt pavements deteriorate over time due to the impact of traffic, water and sunlight. The deterioration in pavement quality can lead to permanent deformation or rutting, cracking or brittleness which leads to inferior riding quality and potholes. This deterioration in asphat pavements is a result of aging of bitumen which is majorly caused by ultraviolet radiation. The aging of bitumen results in a decrease in its penetration value and an increase in its softening point and viscosity.

In the last decade, rising prices of crude oil in the global market has made the cost of virgin bitumen high. Consequently, the use of recycled materials has grown as an alternative to keep the prices of asphalt down. Reclaimed asphalt pavements (RAP) material, obtained through milling of bituminous layers of asphalt pavement is the main source of recycled material, but their use has been limited to low proportions. A drawback in using a high content of recycled materials in asphalt (pavement composition) is that the resulting pavements become susceptible to distresses such as longitudinal and lateral cracking, map cracking, fatigue cracking etc., because of the high stiffness of aged bitumen. This higher potential for the occurrence of these distresses could ultimately result in higher pavement maintenance and rehabilitation costs. Higher stiffness of aged bitumen also limits the quantum of reclaimed material that can be utilized in recycled mix and limits the present utilization level of reclaimed asphalt pavement material to 20% to 30%. The recycling of aged bitumen is usually carried out by adding rejuvenating agents to restore the properties of aged bitumen in the asphalt to satisfy the requirement for use. However, a majority of rejuvenators currently used are based on petrochemicals and therefore result in increased cost of recycling as well as an environmental burden.

SUMMARY

The disclosure provides a rejuvenator for recycling asphalt. The rejuvenator includes a Bio-oil A, wherein the Bio-oil A is a non-hydrogenated plant oil comprising 10-16% Palmitic Acid, 40-50% Linoleic Acid, 8-16% Oleic Acid and 15-22% Stearic Acid of the total amount of fatty acid; and a Bio-oil B, wherein the bio-oil B is obtained from biomass pyrolysis and comprises 20% to 35% rosin acid. The ratio of Bio Oil A to Bio-Oil B, in the rejuvenator is in the range of 1:100 to 100:1.

The disclosure also provides a paving composition. The paving composition comprises 30 % to 80 % w/w reclaimed asphalt pavement (RAP) material, 70 % to 20 % w/w freshly crushed natural aggregate, 2% to 4 w/w % virgin bitumen and 2% to 6% w/w % rejuvenator by weight of residual bitumen content in the reclaimed asphalt pavement (RAP) material wherein the rejuvenator, comprises a Bio-oil A, wherein the Bio-oil A is a non-hydrogenated plant oil comprising 10-16% Palmitic Acid, 40-50% Linoleic Acid, 8-16% Oleic Acid and 15-22% Stearic Acid of the total amount of fatty acid; and a Bio-oil B, wherein the bio-oil B is obtained from biomass pyrolysis and comprises 20% to 35% rosin acid; and wherein the ratio of Bio Oil A to Bio-Oil B, is in the range of 1:100 to 100:1. The disclosure also provides a process of preparing a recycled paving composition, the process comprising mixing reclaimed asphalt pavement material having nominal aggregate size equal to or less than 37.5mm; virgin aggregates, bitumen, rejuvenator and filler.

BRIEF DESCRIPTION OF DRAWINGS

The present disclosure is further described in terms of exemplary embodiments. These exemplary embodiments are described in detail with reference to the drawings. These embodiments are non-limiting exemplary embodiments, wherein:

Figure 1 illustrates the effect of 5% rejuvenator on penetration of aged binder in accordance with an embodiment of the disclosure.

Figure 2 illustrates the effect of rejuvenator content on penetration of aged binder in accordance with an embodiment of the disclosure.

Figure 3 illustrates the effect of 5% rejuvenator on softening point of aged binder in accordance with an embodiment of the disclosure.

Figure 4 illustrates the effect of rejuvenator content on softening point of aged binder in accordance with an embodiment of the disclosure.

Figure 5 illustrates the effect of rejuvenator content on viscosity of aged binder in accordance with an embodiment of the disclosure.

Figure 6 illustrates the effect of rejuvenator content on rutting behaviour of aged binder at 1.59 Hz frequency at different temperatures in accordance with an embodiment of the disclosure.

Figure 7 illustrates the effect of rejuvenator content on fatigue behaviour of aged binder at 1.59 Hz frequency at different temperatures in accordance with an embodiment of the disclosure. Figure 8 shows the Multiple Stress Creep Recovery Test curve at 0.1 kPa of Virgin Binder, aged binder, and rejuvenated binder with 2%, 4%, 6%, and 8% by weight rejuvenator content in accordance with an embodiment of the disclosure.

Figure 9 shows the Multiple Stress Creep Recovery Test curve at 3.2 kPa of Virgin Binder, aged binder, and rejuvenated binder with 2%, 4%, 6%, and 8% by weight rejuvenator content in accordance with an embodiment of the disclosure.

Figure 10 shows the Creep compliance value at 0.1 KPa of Virgin Binder, aged binder, and rejuvenated binder with 2%, 4%, 6%, and 8% by weight of the rejuvenator in accordance with an embodiment of the disclosure.

Figure 11 shows the viscosity curves of virgin, aged and rejuvenated binder with 2%, 4%, 6%, and 8% by weight of the rejuvenator, at variable shear rate at 60°C in accordance with an embodiment of the disclosure.

DETAILED DESCRIPTION

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs. In this regard, unless otherwise indicated, concentrations of ingredients given in this document refer to the concentrations of these ingredients in the master batch, in keeping with customary practice.

The term “ aggregate ” as used herein , refers to particulate material suitable for use in asphalt. It generally comprises sand, gravel and crushed stone. Any conventional type of aggregates suitable for use in asphalt can be used. Examples of suitable aggregates include granite, lime stone, basalt, quartzite, gravel, and mixtures thereof.

The term “Bitumen” as used herein, refers to a hydrocarbon based substance and includes both the naturally occurring bitumen and bitumen that is obtained from crude refining process. The term “Asphalt” as used herein, refers to the coarse aggregates, such as stones, gravel, sand, and the like mixed with bitumen.

The term “Reclaimed Asphalt” as used herein, refers to removed and/or milled, reprocessed pavement materials obtained from asphalt/bituminous mix layers, containing oxidized bitumen and aggregates.

The present disclosure provides a rejuvenator for recycling asphalt. The rejuvenator comprises of two bio-oils - Bio-Oil A and Bio-Oil B.

The Bio-Oil A comprises of non-hydrogenated plant oil that includes a mixture of fatty acids. Specifically, the Bio-oil A is a non-hyrogenated plant oil comprising of 10-16% Palmitic Acid, 40-50% Linoleic Acid, 8-16% Oleic Acid and 15-22% Stearic Acid. The percentage of each of the fatty acids is as per the total amount of fatty acid that is present in the bio-oil A. Bio-Oil A has physio- chemical properties such as low water content in a range from 5% to 15 %, high density at 20°C in a range from 1000 kg m³ tol300 kg m³ and a pH value in a range from 3 to 6. The viscosity of Bio-Oil A is low in a range from 5.5 to 8.5 x 10⁶ m²/s. The flashpoint of Bio-Oil A is in a range from 180°C to 210°C to ensure transportation and storage at high temperature. The specific gravity of Bio-Oil A is in a range from 0.92 to 1.1. The saponification value of Bio-Oil A is in a range from 190 to 200. The acid value of Bio-Oil A is in a range from 5 to 17. In accordance with an aspect, Bio-oil A is essentially obtained from the oil-bearing seeds/plants and includes but is not limited to rapeseed oil, jatropha curcas oil, pongamia oil or castor oil. In accordance with an aspect the Bio-oil A is jatropha curcas oil.

The Bio-Oil B is a by product of kraft process of the wood paper pulp industry and is obtained from biomass pyrolysis and comprises between 20% to 35% of rosin acid. In addition 20% to 35% of rosin acid Bio-oil B it also comprises one or more fatty acids. The Bio- Oil B has a specific gravity in a range from 0.95 to 0.99 and acid value in a range from 180 to 210. The saponification value of Bio-Oil B is in a range from 190 to 200. The value of unsaponifiables which includes all the fractions of a fatty substance which are barely soluble in aqueous solutions but are soluble in organic solvent is within a range from 190 to 220. In accordance with an embodiment, Bio-Oil B is distilled tall oil. In accordance with an embodiment, Bio oil B is distilled tall oil obtained from soft wood including but not limited to wood from pine or spruce tree having an acid value in a range of 185 to 205. In accordance with an aspect, the ratio of Bio Oil A and Bio-Oil B in the rejuvenator is in a range of 1:100 to 100:1 vol/vol. In an embodiment, the ratio of Bio-oil A to Bio-oil B in the rejuvenator is is the range of 80:20vol/vol to 60:40 vol/vol. In a specific embodiment the ratio of Bio-oil A to Bio-oil B is in a range of 70:30 vol/vol In accordance with an embodiment, rejuvenator has a specific gravity in a range from 0.91 to 0.98, moisture content in a range from 5% to 10 %, initial boiling point (5% mass) in a range from 200 to 210°C. The kinematic viscosity of the rejuvenator at 135 °C is in a range from 4 x 10⁶m²/s to 6 x 10⁶m²/s. The flash point of the rejuvenator is in a range from 185 °C to 220°C. The density (g/cc at 15°C) is in a range from 0.91 gm/cc to 0.94 gm/cc.

In accordance with an embodiment, the rejuvenator may further include additives. The additive compises of a mixtures of aromatic C9-C15 component of hydrocarbons originating from high temperature cracking of petroleum fraction and are separated by distillation and are rich in indene, methylidenes and naphthalene. The rejuvenator of the present disclosure is capable of modifying the properties of the aged/oxidized bitumen in the reclaimed asphalt pavement composition, such that the recycled/rejuvenated bitumen binder has the properties that closely resemble those of virgin/original bituminous binder.

Bitumen mainly includes two major components, the asphaltene component and the maltenes component. With ageing caused by UV radiation, the asphaltene component of the bitumen increases and maltene content decreases which imparts hardness to asphalt. Without being limited to any particular theory, it is found that the rejuvenator does not convert asphaltenes to maltenes, rather, these contain maltenes and when added to reclaimed asphalt pavement (RAP) material it balances the asphaltene concentration in oxidezed binder by replenisheing the maltene levels.

The present disclosure also relates to a process for preparing the rejuvenator. The process comprises the steps of blending Bio-Oil A and Bio-Oil B at a predefined stirring speed to ensure homogenization with and without additive. Mixing time is further optimized to ensure homogenization.

The present disclosure also relates to a paving composition used for bituminous layer construction. Paving composition comprises reclaimed asphalt pavement (RAP) material (consisting reclaimed aggregate and oxidized bituminous binder), virgin bitumen binder and the rejuvenator as described in detail above. The paving composition comprises 30 % to 80 % w/w of reclaimed asphalt pavement material extracted from old bituminous/asphalt layers through milling or ripping and crushing, 70 % to 20 % w/w of freshly crushed natural aggregate conforming to the requirement laid down in Govt of India Ministry of Road Transport and Highways Specification for Road and Bridge Work for utilization in bituminous mixes, 2% to 4 w/w % fresh/virgin bitumen binder i.e. viscosity graded bitumen or Performance grade bitumen binder or Polymer modified bitumen binder, either conforming to Bureau of Indian Standard specification IS:73 Indian Standard Paving Bitumen Specification or ASTM standard D3381/D3381M “Standard specification for viscosity graded asphalt binder for use in pavement construction, or AASHTO M 320 Standard Specifcation for Performance Graded Asphalt Binder or IS 15462 “Specifcation for Polymer Modified Bitumen” and alike specification globally, 2 to 6 w/w % rejuvenator, by weight of residual asphalt/bittumen content in the reclaimed asphalt pavement (RAP) material. In accordance with an aspect, the amount of rejuvenator required is optimized to replenish the physical properties of oxidized binder in the reclaimed asphalt pavement material and to have improved mechanical properties of resultant asphalt mix. Said physical properties of the retrieved oxidized binder from reclaimed asphalt pavement material includes but not limited to penetration, softening point, viscosity, shear complex modulus (G*), and phase angle. The amount of rejuvenator is also optimized using the mechanical properties of resulting paving composition/mix including but not limited to resilient modulus, indirect tensile strength and marshal stability.

In accordance with an embodiment, the paving composition may further include additives. Such additives are those that are known to a person skilled in the art and include but are not limited to crosslinkers, fillers (such as talc, hydrated lime and carbon black), ground tire rubber, shredded waste plastic, adhesion promoter and antistripping agents. The amount of such additives can range from 0% to 4 % by weight based on the total weight of the paving composition. Resultant paving composition is intended to be utilized, in binder course i.e., Dense Bituminous Macadam and Bituminous Macadm, and Wearing course i.e. Bituminous concrete/Asphalt concrete, and Semi Dense Bituminous Concrete and alike bituminous wearing courses.

The present disclosure also relates to a process of preparing a paving composition using the reclaimed asphalt material. The process comprises hot mix recycling, the process wherein the reclaimed asphalt (RA) including the rejuvenator is mixed with new materials such as vergin bitumen and aggregates in a central hot mix plant or in hot in place /in-situ process to produce a recycled mix.

In accordance with the present disclosure, the hot in-plant /central plant recycling process for preparing the paving composition, comprises mixing together reclaimed asphalt pavement material having nominal aggregate size equal to or less than 37.5 mm, virgin/fresh aggregates, bitumen and rejuvenator, wherein the rejuvenator is added in reclaimed asphalt pavement material in such a way to ensure better diffusion in short span of time in drum or batch type hot mix plants. Reclaimed asphalt pavement material is usually heated through (but not limited to) conductive heating while natural aggregates are super-heated to obtain resultant paving asphalt mix after mixing of all ingredients at a desired temperature. In accordance with an aspect the Reclaimed asphalt pavement material is heated to a temperature in the range of 130°C to 150°C. The hot-in plant- recycling method comprises the steps of combining 30 to 80 w/w% Reclaimed Asphalt Pavement Material (RAP), 70 to 20 w/w% virgin aggregate, 2 to 4 w/w % fresh/virgin bitumen, and 2 to 6 w/w % rejuvenator by weight of residual asphalt content in the RAP.

In accordance with an aspect, the in-plant process is used for the construction of a new binder course as well as wearing course layers.

The present disclosure also relates to a hot-in place- recycling process for preparing a paving composition. The process comprises of removing at least a layer or a portion of the paving/road, to obtain pieces of pavement, heating the so obtained pieces of pavement and reducing the size of the heated pieces of pavement to obtain Reclaimed Asphalt Pavement Material. The Reclaimed Asphalt Pavement Material so obtained, virgin aggregate, virgin binder, and the rejuvenator of the present disclosure are mixed to obtain the paving composition. In accordance with an aspect, the hot-in-place-recycling process may be carried out within the vicinity of the pavement and may be used for resurfacing the top layer of a pavement. Said process may re-use up to 100% of the Reclaimed Asphalt Pavement Material. The amount of virgin aggregate added in the process is in a range of 0 to 40 %. The amount of rejuvenator is added in the range of 2 to 6%. The amount of virgin binder is added in a range of 2 to 4%.

In accordance with an aspect, the natural aggregates are required to be heated to a temperature in the range of 150 to 190°C to obtain the paving composition with variable Reclaimed Asphalt Pavement Material concentration.

The paving composition may be at lower laying or paving temperature i.e 120 to 140°C and can be compacted at lower compaction temperature i.e 90 to 120°C to achieve minimum field density levels i.e 92 % of theoretical maximum specific gravity.

In accordance with the present disclosure, recycling of asphalt pavements has the advantages of decreasing the demand for natural resources, such as natural aggregate and virgin bitumen thus reducing the production of waste material while reducing cost. Desirably the amount of the Reclaimed Asphalt Pavement Material that is intended to be recycled is maximized and the amount of new material that is added to the recovered asphalt is minimized.

The invention will now be described with respect to the following examples which do not limit the invention in any way and only exemplify the invention.

Examples

Example 1: Sample preparation and characterization tests for analysis of binder samples with the rejuvenator

(a) Sample preparation: For the purpose of sample testing, a virgin bitumen binder (“binder”) was aged, and the effect of the rejuvenator was tested on the aged binder. Ageing of the binder was performed as per ASTM D 2872 and AASHTO R28. Briefly, short-term ageing was performed on 35 g of sample which was kept in a Rotational Thin Film Oven (RTFO) at a temperature of 163°C for a period of 85 min. The RTFO aged binder was kept in Pressure Aging Vessel (PAV) at a pressure of 2 Mpa and temperature of 100°C for a period of 20 h, 16 h and 12 h to simulate long-term ageing for a period of 5, 8 and 10 years. The aged binder so obtained from PAV was utilized for further studies.

A rejuvenated binder was prepared by mixing the composite oil composition (“inventive rejuvenator” or “composite oil composition comprising Bio-oil A and Bio-oil B in a 70: 30 w/w ratio”), to the aged binder.

(b) The samples prepared above were then tested for rheological properties. The tests performed are summarized below: Table 1 Physical and Rheological Tests for characterization of bitumen binder samples

Example 2: Results of characterization tests on binder samples with the reju Venator

(a) Results of Penetration Test on Rejuvenated binder: The penetration test is used to examine the consistency of a sample of the binder. 5% by weight of the aged binder of Bio-oil A, Bio-oil B, and the composite oil composition was added as rejuvenator and the penetration test was performed as described in Table 1. As seen in Fig. 1, the inventive rejuvenator improves the properties of the aged binder as compared to the samples containing only Bio-oil A or Bio-oil B.

Differently aged binders simulating long term and short term aging r was then tested with different amounts of the rejuvenator. Aged binder was rejuvenated with 2%, 4% and 6% doses of inventive rejuvenator. As seen in Fig. 2, it was found that a dose of 3%, 4% and 5.4 % composite bio-oil rejuvenator by weight of aged binder is able to restore the penetration value of differently aged binder i.e 12, 16 and 20 hr. to the level of virgin bitumen binder VG (virgin binder) 30. (b) Results of Softening Test on Rejuvenated binder: The softening point is defined as the temperature at which a bitumen sample can no longer support the weight of a 3.5-g steel ball. 5% by weight of the aged binder of Bio-oil A, Bio-oil B, and the composite oil composition was added as rejuvenator, and the softening test was performed as described in Table 1. As seen in Fig. 3, the composite oil improves the properties of the aged binder as compared to the samples containing only Bio-oil A or Bio-oil B.

Differently aged binders simulating long term and short term aging, was rejuvenated with 2%, 4% and 6% by weight of the composite oil composition. As seen in Fig. 4 a doses of 3%, 4% and 5.3 % by weight of aged binder of the composite oil composition is able to restore the softening point of differently aged binder for 12, 16 and 20 hr duration to the level of virgin bitumen binderVG30.

(c) Results of Flash Point Test on Rejuvenated binder: The flash point reflects the safety of asphalt in the process of mixing at a high temperature. The higher the flash point, the safer the asphalt. The flash point test was applied according to the procedure described in Table 1 to characterize the safety of virgin, aged, and rejuvenated asphalt.

As seen in Table 2 below, the rejuvenator is able to restore the softening point of aged bitumen binder.

Table 2: Effect of the rejuvenator on flash point of aged bitumen

(d) Results of Dynamic viscosity Test on Rejuvenated binder: The Rotational Viscometer (RV) is used to determine the viscosity of asphalt binders at the high temperature range of manufacturing and construction. The RV test was conducted according to the procedure described in Table 1. Differently aged binder for 12,16 and 20 hrs time period was rejuvenated with 2%, 4% and 6% dose of the inventive rejuvenator. It was found that a dose of 3%, 4% and 5.5 % by weight of aged binder was able to restore the viscosity value of differently aged binder to the level of binder VG 30 as shown in Fig. 5.

(e) Rutting Behavior and Fatigue Behavior Test on Rejuvenated binder: Rutting reflects the irrecoverable deformation of asphalt during loading process. It is one of the major causes of distress in the asphalt pavements, especially at high summer temperatures and under heavy axle loads. On the other hand, in order to resist fatigue cracking a binder should be an elastic that it’s able to rebound. The rutting and fatigue behavior was tested according to the procedure described in Table 1 using the Temperature Sweep test conducted on Dynamic Shear Rheometer (DSR)

As seen in Fig. 6, rutting resistance factor decreases with increase in temperature. The PAV aged binder shows high rutting resistance due to increased stiffness. The parameter G*/sin5 describe the irrecoverable deformation of asphalt during loading. The temperature sweep test was run with a temperature range of 40°C to 76 °C, at a frequency of 1.59Hz. it is observed that rutting resistance factor decreases with increase in temperature. Rejuvenated binder with 4 % composite rejuvenator shows better rut resistance in comparison to virgin binder VG 30, in terms of higher G*/sin5 value on all temperature ranges. It indicates that the invented rejuvenator while reducing the stiffness of aged binder maintains higher rut resistance characteristics in comparison to virgin binder at elevated temperature ranges.

In addition, to resist fatigue cracking a binder should be elastic enough to rebound after application of load, therefore, the viscous portion of shear modulus g*sin5 should be minimum. G* sine d value of virgin, pav aged and rejuvenated binder is measured in a strain-controlled mode at 1.59 Hz frequency using temperature sweep test at a temperature range of 40 to 10 °C . It is found that invented rejuvenator is able to impart elasticity to stiff binder at lower temperature ranges. As per performance grading DSR based bitumen specification, the temperature at which G*sin5 < 5000Kpa defines the fatigue cracking behaviour of bitumen lower the failed temperature value indicates better fatigue resistance potential of bitumen. Failure temperature of PAV aged bitumen is 16°C as seen in Fig. 2. However, the rejuvenated binder with 4% composite rejuvenator was exhibiting improved elasticity till the IOC temperature as the case with virgin vg 30 grade bitumen. Therefore, when the inventive rejuvenator is added to aged bitumen binder, the fatigue resistance of the rejuvenated or recycled binder is improved at lower temperature.

(f) Multiple Stress Creep Recovery Test on Rejuvenated binder: Creep is a phenomenon that strain increases gradually over time when stress is a constant value. In this test, specimen is subjected to a constant load for fixed time period and then allowed to recover at zero load for a fixed time period. A Multiple Stress Creep Recovery Test (MSCR) test can reflect the nonlinear rheological response of modified asphalt under a large stress. The test was performed as described in Table 1. As seen in Figs 8 and 9, the cumulative deformation of aged sample is minimum, as aging causes the non-deformability of asphalt. The addition of rejuvenator increases the cumulative deformation of aged asphalt. The higher the dosage of rejuvenator, the higher the deformability of rejuvenated asphalt. Thus, the deformation recovering capacity is improved by aging effect. 6% rejuvenated asphalt has a cumulative deformation curve with close to that of virgin asphalt, which demonstrates that the trend of cumulative deformation under different stress varies.

The creep recovery test was conducted at low and high stress level of 0.1 kPa & 3.2 KPa. Shown in Fig. 10, it is seen that aged binder shows the lowest compliance value compared to virgin and rejuvenated aged binders which means aging would reduce creep recovery ability of binder. The creep recovery test shows that addition of inventive rejuvenator at 6% by weight of the aged binder replenishes the creep recovery characteristics of aged binder to virgin state and improving the elastic component of aged binder. (g) Flow Behavior of the Rejuvenated binder: For viscoelastic characterization of bituminous binder study of flow behavior and effect of variable shear rate on viscosity of binder is necessary to understand mixing and compaction temperature. Shear thinning behavior of PAV aged, Virgin binder (VG 30) and rejuvenated binder containing variable doses of invented rejuvenator @ 2% to 8% is studied at steady shear mode using Dynamic Shear Rheometer at 60° C temperature For superpave mixing through gyratory compactor shear rate is around 500 1/s which also simulates the field compaction and mixing conditions. As seen in Fig. 11, that the invented rejuvenator is able to reduce the viscosity of aged binder at variable shear rate and able to maintain rejuvenated binder viscosity as equivalent to virgin binder with 4 % rejuvenator dose at 511 1/s shear rate.

Example 3: Effect of inventive rejuvenator on reclaimed asphalt pavement mixtures

(a) Preparation and Physical properties of Reclaimed asphalt pavement (RAP) mixtures with composite oil composition: In order to study the effect of addition of composite rejuvenator on mechanical properties and performance of HMA mixes with a high percentage of RAP (Reclaimed asphalt pavement) content a comparative mechanical characterization HMA mixes was carried out with and without rejuvenator. RAP was subjected to screening and crushing for segregation as coarse and fine RAP and stockpiled separately at project site for utilization purpose. Coarse RAP primary comprises the fraction 100% passing from 13.2 mm sieve while fine RAP consists of 100 % passing fraction from 9.5 mm sieve. Coarse and fine RAP were subjected to sieve analysis to determine their gradation. Residual binder content in the RAP is determined through binder extraction test by carrying out quantitative separation of aggregate and bitumen.

Trial mix blends with 30, 40 and 60 and 80 % RAP content were prepared by mixing the coarse and fine RAP with virgin aggregate and stone dust in such a manner that the resultant blend shall satisfy the stipulated gradation requirement for DBM grade II mix as prescribed in MoRTH specifications for Road and Bridge works, Vth revision. The mix design was carried out using Marshall method of mix design for Hot Mix Recycling. Optimum quantity of virgin bitumen to be added in the recycled mix is determined on the basis of the minimum binder content requirement as stipulated in MoRTH specification for DBM, grade II mix and various mix design parameters. Rejuvenator was added in the virgin bitumen and mixed well at 1300°C temperatures through stirring to ensure uniform distribution. Table 3, gives the properties of recycled bituminous mix with 30, 40 and 60 and 80 % RAP at optimum binder content without rejuvenator while Table 4 gives the properties of the recycled bituminous mix with 30, 40 and 60 and 80 % RAP with the rejuvenator.

Table 3: Marshall Test Results of Dense Graded Bituminous Mix -II at Optimum Bitumen Content with variable RAP content without rejuvenator

Table 4: Marshall Test Results of Dense Graded Bituminous Mix -II at Optimum Bitumen Content with rejuvenator and variable RAP content Observations:

Marshall test results shows that the inventive rejuvinator is able to maintain the all mix design parameters for DBM grade II mix as stipulated in MoRTH specification 5th revision. (b) Mechanical Properties of RAP mixtures with inventive rejuvinator:

The Indirect Tensile Strength Test is used to determine the tensile properties of the bituminous mixture which can further be related to the cracking of the pavement test was performed with confirming the standard guidelines of ASTM D 6391. The test results are summarized in Table 5 below.

Table 5: Indirect Tensile Strength at variable RAP content with and without rejuvenator

The Resilient Modulus test was also performed to analyse traffic loading conditions with varying temperatures to evaluate pavement surface responses. Bituminous mixes behave as viscoelastic material in such a way that both temperature and loading condition influence the stiffness of the mix. The test were performed as per the ASTM D 4123-82 standard test. The results of the test are summarized in Table 6 and 7 below. Table 6: Resilient Modulus at variable RAP content without rejuvenator

Table 7: Resilient Modulus at variable RAP content with rejuvenator

Observations:

Indirect tensile strength test results and resilient modulus values shows that the recycled bituminous mix with composite bio oil rejuvenator has requisite stiffness with sufficient moisture resistance characteristics for utilization in road works.

Example 4: Field trial of reclaimed asphalt with rejuvenator

Field trial of reclaimed asphalt pavement material recycled with invented rejuvenator with variable RAP contents i.e 40, 50 and 60 % were carried out on Service lane of NH-56 Bypass-, part of Varanasi Ring Road Project under NHDP (Phase- VII). Demonstration trial with 40 % RAP content is carried out from chainage 763+ 510 to 763 + 448, With 50 % RAP from chainage 763 + 448 to 763 + 402, with 60 % RAP from 13 + 172 to 13 + 197 in service lane portion of NH-56 bypass a). Reclaimed Asphalt/ Bituminous Material (RAP/RBM) and virgin material ^Around 500 kg. of RAP material obtained from GR-Infra project site at Varanasi ring road project. RAP was extracted from the distressed bituminous layers of the same project site though cold milling process. Milled RAP were further subjected to screening and crushing at the project site for segregation as coarse and fine RAP and stockpiled separately at project site for utilization purpose. Coarse RAP primary comprises the fraction 100% passing from 13.2 mm sieve while fine RAP consists of fraction 100 % passing from 9.5 mm sieve. Coarse and fine RAP were subjected to sieve analysis to determine their gradation. Residual binder content in the RAP is determined through binder extraction test by carrying out quantitative separation of aggregate and bitumen. Virgin coarse natural aggregates, belonging from basaltic rock groups were obtained from the project site and used to meet out the gradation requirement. Table 8 gives the gradation of coarse and fine RAP along with residual binder content and moisture content:

Table 8: Characterization of Coarse and Fine RAP Material

After binder extraction physical and mechanical properties of reclaimed uncoated aggregates as well as virgin natural aggregates were determined to check their suitability for utilization in dense Bituminous Macadam Mix. Table 9 gives the properties of aggregates obtained from coarse RAP after binder extraction and virgin aggregates utilized in job mix : Table 9: Properties of Coarse RAP and Natural Aggregates c. Bitumen Binder: VG 40 bitumen binder is utilized to replenish the deficit binder content in the recycled mix bituminous mix. d. Proportioning of Aggregate and Development of Job Mix: A trial mix blends with 40, 50 and 60 % RAP contents were developed by mixing the coarse and fine RAP with virgin aggregates and stone dust in such a manner that the resultant blend shall satisfy the stipulated gradation requirement for DBM grade II mix as prescribed in MoRTH specifications for Road and Bridge works, Vth revision. Table 9, 10 and 11 show the recycled mix blends with 40, 50 and 60% RAP contents.

Table 9: Gradation of Natural Aggregates and RAP blended for 40 % RAP

Utilization Table 10: Gradation of Natural Aggregates and RAP blended for 50 % RAP

Utilization

Table 11: Gradation of Natural Aggregates and RAP as supplied and blended for 60 % RAP Utilization

Job mix for 40, 50 and 60 % RAP content is developed using Marshall method of mix design as stipulated in Asphalt Institute manual MS 20 for Hot Mix Recycling. Job mix is prepared to carry out Hot-in-Plant Recycling using Marini batch type hot mix plant having hot/coarse and cold/fine RAP feeding capacity. Total binder content in the recycled mix at 40 and 50 % rap content was kept 4.75 % by weight of mix while for 60 % RAP content job mix is prepared at 4.5 % total binder content by weight of mix. Inventive Rejuvenator is added in the virgin bitumen and mixed well at 130° C temperatures through stirring to ensure uniform distribution. Table 12 provides the job mix composition at variable RAP content along with the Marshall properties of recycled mix:

Table 12: Job Mix of Dense Graded Bituminous Mix-II with 40 , 50 and 60

% RAP Content f). Laboratory Analysis : Bituminous mix core sample were extracted from the project site. Extracted core samples were further tested. Few extracted core samples and marshall samples casted through plant mix with 40,50 and 60 % RAP were also tested to determine the properties of rejuvenated binder and to assess Indirect Tensile Strength and Resilient modulus of recycled DBM layer with variable RAP contents. g). Evaluation of Rejuvenated Binder: Bitumen extraction test is carried out as per ASTM D -2172 to quantitatively separate aggregate and bitumen of loose mix of variable RAP content collected from the discharge point of the hot mix plant. Rejuvenated binder is recovered from the reagents and tested for penetration value as per IS 1203. Table 13 gives the penetration value of rejuvenated binder: Table :13 Properties of Rejuvenated binder h). Indirect Tensile Strength Test : Indirect tensile strength test is conducted under dry and wet conditions on marshall samples (2 no. each) casted through plant mix at the project site to determine the resistance against potential water damage.

Table 14: Indirect Tensile Strength under Dry and Wet conditions i ). Resilient Modulus of Bituminous Cores with variable RAP Content: M_R tests on core samples as per ASTM D 4123-82 specification were performed in UTM machine. The resilient modulus (M_R) is defined as the elastic modulus based on recoverable strain under repeated load. Table 15 provides the Resilient Modulus (Mr) Value of Samples. Table 15: Resilient Modulus (Mr) Value of Samples

Observations:

From the laboratory and field test results it is found that the recycled Dense Bituminous Macadam mix (DBM-2) with variable RAP contents of 40, 50 and 60 %, rejuvenated through the inventive rejuvenator is having requisite Marshall Stability, ITS, Resilient Modulus and Field density as per mix design requirement. Results of extracted bituminous cores and marshal specimen casted through plant mix are also satisfying the various requirements as stipulated in MoRTH specification 5^th revision for Road and Bridge Work under clause 505 for Dense Bituminous Macadam Layer . During field trial it is found that the resultant recycled mix using rejuvenator can be easily compacted upto the requisite density at lower temperatures also between 105 to 120° C SPECIFIC EMBODIMENTS

Specific embodiments are hereinafter described:

A rejuvenator for recycling asphalt, comprising, a Bio-oil A, wherein the Bio oil A is a non-hydrogenated plant oil comprising 10-16% Palmitic Acid, 40-50% Linoleic Acid, 8-16% Oleic Acid and 15-22% Stearic Acid of the total amount of fatty acid, and, a Bio-oil B, wherein the bio-oil B is obtained from biomass pyrolysis and comprises 20% to 35% rosin acid, wherein the ratio of Bio Oil A to Bio-Oil B, is in the range of 1 : 100 to 100: 1. Such rejuvenator(s) for recycling asphalt, wherein the Bio-oil A is selected from a group of rapeseed oil, jatropha curcas oil, pongamia oil and castor oil.

Such rejuvenator(s) for recycling asphalt, wherein the Bio-oil A is jatropha curcas oil.

Such rejuvenator(s) for recycling asphalt, wherein Bio-oil B is a by-product of kraft process.

Such rejuvenator(s) for recycling asphalt, wherein the Bio-oil B is distilled tail-oil.

Such rejuvenator(s) for recycling asphalt, wherein the ratio of Bio-oil A to Bio-oil B is in a range of 80: 20 to 60:40 volume/volume of Bio-oil A: Bio-oil B.

Such rejuvenator(s) for recycling asphalt, wherein the ratio of Bio-oil A to Bio-oil B is 70:30 vol/vol.

A paving composition comprising, 30 % to 80 % w/w reclaimed asphalt pavement (RAP) material, 70 % to 20 % w/w freshly crushed natural aggregates, 2% to 4 w/w % virgin bitumen and, 2% to 6% w/w % rejuvenator by weight of residual asphalt content in the reclaimed asphalt pavement (RAP), wherein the rejuvenator, comprises, a Bio-oil A, wherein the Bio-oil A is a non-hydrogenated plant oil comprising 10-16% Palmitic Acid, 40-50% Linoleic Acid, 8-16% Oleic Acid and 15-22% Stearic Acid of the total amount of fatty acid, and, a Bio-oil B, wherein the bio-oil B is obtained from biomass pyrolysis and comprises 20% to 35% rosin acid, wherein the ratio of Bio Oil A to Bio-Oil B, is in the range of 1:100 to 100:1.

A process of preparing a paving composition, the process comprising mixing reclaimed asphalt pavement material having nominal aggregate size equal to or less than 37.5 mm; virgin aggregates, bitumen, rejuvenator and filler. Such process(s) for preparing paving composition, wherein the reclaimed asphalt pavement material is heated to a temperature in a range of 130 to 150° C and freshly crushed natural aggregates are heated to a temperature in the range of 150 to 190°C.

INDUSTRIAL APPLICABILITY

Recycling of asphalt pavements has the advantages of decreasing the demand for natural resources, in terms of natural aggregates and virgin bitumen required for resurfacing of bituminous pavement besides reducing the production of waste material generated during milling of bituminous layers while reducing the cost of construction. Desirably the amount of the Reclaimed Asphalt Pavement Material that is intended to be recycled is maximized and the amount of new material that is added to the recovered asphalt is minimized. Reclaimed asphalt pavement can be recycled “in-place (i.e. at the road location) or can be recycled in-plant” (i.e. the RAP is removed from the road surface and transported to an asphalt mix plant).

The present disclosure provides an alternative rejuvenating agent, a resultant paving composition and has sought to provide an agent wherein at least a proportion of the agent is a natural product obtained through naturally renewable resources. Incorporating a plant product instead of a petroleum product in asphalt recycling offers a potentially more sustainable product and may lead to price and supply advantages. The natural-product based rejuvenating agent has the required technical properties and its use is safe and easy to handle.

Claims

We Claim:

1. A rejuvenator for recycling asphalt, comprising: a Bio-oil A, wherein the Bio-oil A is a non-hydrogenated plant oil comprising 10-16% Palmitic Acid, 40-50% Linoleic Acid, 8-16% Oleic Acid and 15-22% Stearic Acid of the total amount of fatty acid; and a Bio-oil B, wherein the bio-oil B is obtained from biomass pyrolysis and comprises 20% to 35% rosin acid; wherein the ratio of Bio Oil A to Bio-Oil B, is in the range of 1:100 to 100:1.

2. A rejuvenator for recycling asphalt, as claimed in claim 1, wherein the Bio- oil A is selected from a group of rapeseed oil, jatropha curcas oil, pongamia oil and castor oil.

3. A rejuvenator for recycling asphalt, as claimed in claim 1, wherein the Bio- oil A is jatropha curcas oil.

4. A rejuvenator for recycling asphalt as claimed in claim 1, wherein Bio-oil B is a by-product of kraft process.

5. A rejuvenator for recycling asphalt as claimed in claim 1, wherein the Bio oil B is distilled tail-oil.

6. A rejuvenator for recycling asphalt as claimed in claim 1, wherein the ratio of Bio-oil A to Bio-oil B is in a range of 80: 20 to 60:40 volume/volume of Bio-oil A: Bio-oil B.

7. A rejuvenator for recycling asphalt as claimed in claim 1, wherein the ratio of Bio-oil A to Bio-oil B is 70:30 vol/vol.

8. A paving composition comprising:

30 % to 80 % w/w reclaimed asphalt pavement (RAP) material,

70 % to 20 % w/w freshly crushed natural aggregates 2% to 4 w/w % virgin bitumen and 2% to 6% w/w % rejuvenator by weight of residual asphalt content in the reclaimed asphalt pavement (RAP), wherein the rejuvenator, comprises a Bio-oil A, wherein the Bio-oil A is a non-hydrogenated plant oil comprising 10-16% Palmitic Acid, 40-50% Linoleic Acid, 8-16% Oleic Acid and 15-22% Stearic Acid of the total amount of fatty acid; and a Bio-oil B, wherein the bio-oil B is obtained from biomass pyrolysis and comprises 20% to 35% rosin acid; wherein the ratio of Bio Oil A to Bio- Oil B, is in the range of 1:100 to 100:1.

A process of preparing a paving composition, the process comprising mixing reclaimed asphalt pavement material having nominal aggregate size equal to or less than 37.5 mm; virgin aggregates, bitumen, rejuvenator and filler.

10. A process for preparing paving composition as claimed in claim 9 wherein the reclaimed asphalt pavement material is heated to a temperature in a range of 130 to 150° C and freshly crushed natural aggregates are heated to a temperature in the range of 150 to 190°C.