Cold recycling with foamed bitumen in India: WR 00 rehabilitates motorway in Golden Quadrilateral
WR 00 rehabilitates motorway in Golden Quadrilateral The Golden Quadrilateral is a gigantic motorway network. Stretching,6 km, it connects the Indian metropolises of New Delhi, Chennai, Mumbai and Calcutta. The four-lane sections are currently being rehabilitated and extended to six lanes. Indian construction company Larsen & Toubro (L&T) is carrying out this work as part of a PPP project on the south-eastern section, the NH- near Chennai. L&T will operate the stretch for 1 years. The company consequently opted for technically advanced yet cost-effective rehabilitation using cold recycling technologies from the Wirtgen Group. L&T processed a total of approx. 1,000m from October 01 to April 013 with a WR 00 Cold Recycler and Hamm 30 and 311 Compactors. In the process, the company used the resources from the extremely worn road surface to carefully create a durably solid base course that only required covering with an asphalt layer to cm thick. a technical, an organizational and an ecological viewpoint, prompting the authorities to recommend the use of this innovative road construction method. One-stop planning, construction and operation The contract for expanding the 3-km-long section between Chennai in the state of Tamil Nadu and Tada in the state of Andhra Pradesh was awarded to L&T Chennai Tada Tollway Ltd., or L&T CTTL. The 100% subsidiary of Larsen & Toubro Infrastructure Developments Projects Ltd. is responsible for the planning, construction, operation and maintenance of the stretch. Because L&T CTTL will operate the motorway as a license holder for a period of 1 years after construction, the responsible parties were very keen to use a construction method that permits long-term economical use. And precisely that is ensured by in-situ cold recycling with the WR 00 from Wirtgen. India s Ministry of Transport has been expanding the national motorway network for many years. The focus is on expanding existing sections and improving the quality of the existing roadways. In this context, the NHAI (National Highway Authority of India) also investigated the option of using cold recycling. The results were impressive from Cold recycling: Eco-friendly and cost-effective There are many reasons why this method is so costeffective, one of which is the low requirement for construction materials. In-situ recycling requires only small amounts of new aggregates or asphalt. This was a crucial advantage in rehabilitating the NH- as there
Project data Chennai-Tada Project NH- Start: 1 October 01 Finish: 30 April 013 Construction firm: L&T IDPL (Larsen & Toubro Infrastructure Development Projects Ltd) Equipment: WR 00 Cold Recycler with foamed bitumen system Streumaster SW 16 MC binding agent spreader Hamm 30 and Hamm 311 Compactors The costs for rehabilitating the existing road surface, expanding the motorway from to 6 lanes on a PPP basis and the construction of toll stations were estimated at roughly. billion rupees ( 10 million). L&T CTTL has operated the motorway since April 009 and is the license holder for this section for 1 years. Cold recycling with foamed bitumen along a stretch of approx. 1 km with a width of 9 m. Area processed: 11,73 m 6 º 7 º 76 º 0 º º º 9 º 96 º 36 º 3 º Chandigarh Mi Km 100 100 00 00 300 00 300 UTTARAKHAND º Bikaner SIKKIM 79A 79 79 º 76 3. º 6 60 60 0 º 7 Bhubaneshwar Konark 16 º Pondicherry (Yanam) 1 º 6 7 PondicherryPondicherry (Puducherry) Lakshadweep Port Blair Pondicherry (Karaikal) Islands º Kanniyakumari The newly expanded motorway section connects Chennai (formerly Madras, the capital city of the state of Tamil Nadu and the largest city in southern India) with numerous major cities along the country s east cost. The Golden Quadrilateral is a motorway network that connects Indian metropolises New Delhi, Mumbai (Bombay), Chennai (Madras) and Calcutta. After construction of the motorways from 1999 01, all,6 km are planned to be expanded from four lanes to six by the year 01. // 3
Visual inspection: Extensive crazing, block and longitudinal cracks. are no quarries in the Chennai region. Also, only small amounts of cement, water and bitumen are needed, explains Arashdeep Singh, cold recycling specialist at Wirtgen India. This yields tremendous savings in transport costs. And he can list other advantages, too: The energy requirement for heating is also very low due to the materials being processed cold. They conducted a visual inspection of the section and took samples from along the entire stretch of motorway. The results were a very mixed bag. In some places, the pavement was still fit for traffic, but about 1 km displayed massive damage to the entire bituminous surface: crazing as well as block, transverse and longitudinal cracks were discovered, as were deep ruts. Only the bitumen is processed on site at a temperature of 17 C. The cost-effectiveness and environmental friendliness also convinced the responsible parties at Larsen & Toubro. Which is not surprising, as they rank amongst the top 10 most eco-friendly companies in the world, according to US magazine Newsweek. 30,000 vehicles each day The cause for the heavy localized damage was readily identifiable: in 01, some 30,000 vehicles used this stretch every day, approx. 30% of which were heavy goods traffic to and from the busy ports of Chennai and Ennore. The basis: initial evaluation The NH- was not the first cold recycling project for L&T. Consequently, they knew what needed to be done: a thorough survey of the road surface condition is crucial to the success of in-situ recycling projects. This task was assigned to the specialists of the Indian Institute of Technology at Chennai University of Technology. All transport to northern India is routed from those ports via the NH-. In the light of these baseline conditions, the planners decided on a design with million ESALs (ESAL = Equivalent Standard Axle Load) that can meet the most challenging demands. They also stipulated a minimum useful life of 0 years.
The WLB 10 S produces foamed bitumen with variations in the different parameters, such as the bitumen temperature, water volume and air pressure. These preliminary tests facilitate the mix design, i.e. the definition of a suitable mix formula. The WLM 30 laboratory mixer perfectly complements the WLB 10 S. Under the hood, a powerful mixer with sturdy paddles creates the mix as it would be created in the mixing chamber of a recycler. The twin-shaft pugmill mixer has a capacity of approx. 30 kg. WLB 10 S: Cold recycling simulation on a laboratory scale In order to develop the ideal formula for rehabilitating the damaged sections of motorway, specialists for construction materials at L&T CTTL carried out suitability testing together with engineers from IIT Chennai. Their most important tools were involved the WLB 10 S laboratory system with a WLM 30 laboratory mixer from Wirtgen. This system allowed us to test the foaming properties of various grades of bitumen, process samples from the field with foamed bitumen and determine the optimal formula, explains Iraj Ghamsemi, Project Manager at consulting firm SNC-Lavalin, who provided ongoing project assistance on behalf of NHAI. Ultimately, the laboratory tests determined the following construction process and the new design of the motorway section in question: Pre-spreading with crusher dust and 1% Portland cement (OPC 3) Cold recycling of the complete road surface (0 cm) with the addition of % water to achieve the optimum moisture content (OMC) of 6.3%, % foamed bitumen Compaction of the cold recycling layer Paving over the recycled layer with an asphalt surface course to cm in thickness. Recycling set in action: the WR 00 from Wirtgen pushes the bitumen and water tankers in front of it. A Hamm 30 P Compactor directly behind the recycler ensures excellent initial compaction. //
Job mix design: Table showing gradation of RAP, crusher dust and cement, percentage for blending adopted can also be seen in the table: IS SIEVE (mm) Passing To Retained Cold Mix BLENDING Percentage for blending RAP S Dust Cement RAP Dust Cement 0% 19% 01% Total % of Passing MID LIMIT Lower Limit 0.00 100.00 100.00 100.00 0.00 19.00 1.00 100.00 100.00 100 100 37.0 100.00 100.00 100.00 0.00 19.00 1.00 100.00 93.0 7 100 6.0 100.00 100.00 100.00 0.00 19.00 1.00 100.00.0 77 100 19.00 9.06 100.00 100.00 7. 19.00 1.00 9..0 66 99 13.0.1 100.00 100.00 70.0 19.00 1.00 90.0 7.00 7 7 9.0 7.9 100.00 100.00 63.11 19.00 1.00 3.11 61.0 9 7 6.70 6. 100.00 100.00 9.9 19.00 1.00 69.9 1.00 0 6.7 0.66 91.6 100.00 0.3 17.0 1.00.93.0 3 6.36 31.0 7.7 100.00.96 1.1 1.00 0.17 33.0 1.1 1.3 60.1 100.00 1.66 11. 1.00 7.10.0 1 33 0.600 10.9.93 100.00.7.73 1.00 1. 1.00 1 0..7 0.6 100.00 3.77 7.7 1.00 1.0 19.00 1 6 0.300 3.7 3.00 100.00.9 6.6 1.00 10.63 17.00 10 0.10 1.9.6 9.9 1..6 0.99 7. 1.00 7 17 0.07 1.6 13.33 91.96 1..3 0.9.70 7.00 10 Upper limit Curve chart representing gradation curve for blended material of fines is required to make them suitable for treating it with foamed bitumen. The fines plays an important role in imparting strength to the bitumen stabilized material as they form a mastic fully coated with bitumen and spot welds the larger size aggregates. This phenomenon increases the cohesion in the material and imparts more shear strength. 19 % crusher dust was added to improve the grading of the RAP material. This not only improved grading by increasing fines but also provided an angular sand skeleton that improves the shear strength of the mix. A percentage addition of 1 - % of fresh fine aggregate is recommended in TG for heavily trafficked road. 1. The gradation of RAP material obtained was not suitable for treating it with foamed bitumen as the percentage passing 0.07 mm sieve was less than %. Generally RAP sample are coarser and addition. The Atterberg limit of the material was found to be non plastic as it was cohesion less and threads of 3 mm dia could not be formed by rolling the material. The cohesion less nature of the material is due to the fact that reclaimed layer consisted of only bituminous
layer. Since the plasticity index was less than 1, no pre-treatment of material with lime is required. 3. 1% cement OPC 3 grade was added to improve the stability and better dispersion of foamed bitumen in fine particles of the mix.. The optimum moisture content of 6.3 % is similar to that of cohesion less soil. The maximum dry density achieved was 09 kg/m 3. Design parameters for pavement design: Design life: 0 years Design traffic: msa The value of resilient modulus of BSM ranges from 600-100 mpa and the value set for this project was 00 mpa. Existing pavement (mm) 0 0 0 0 00 BC-1 DBM- DBM-1 WMM GSB SUBGRADE (CBR 10) 00 Rehabilitated pavement (mm) % Foamed Bitumen Vs ITS(kpa). VG10 grade bitumen with 6 % foament water content at a temperature of 10 C produced best foam with expansion ratio of 1 and half life of seconds against a minimum requirement of expansion ratio and half life time 6 seconds. 0 0 0 00 BC BSM-1 WMM GSB SUBGRADE (CBR 10) 6. As indicated in the above shown graph optimum bitumen content for the mix is.0 % and it gives the highest value of ITS dry and wet at that percentage. 00 BC BSM-1 WMM GSB DBM = Bituminous Concrete = Bitumen Stabilized Materials = Wet Mix Macadam = Granular Sub Base = Dense Bitumen Macadam 6 // 7
surface. An SW 16 MC binding agent spreader from Streumaster then spread the cement uniformly across the area. Directly behind this, a powerful WR 00 recycler rated at 0 kw (63 BHP) pushed a bitumen and water tanker ahead of it. These were coupled to the recycler with push rods. Behind the wheeled machine, various heavy duty Hamm compactors compacted the prepared base course. In this way, the WR 00 recycled some,000 m per day with a working depth of 6 cm and a typical speed of 7 m/min. Ahead of the recycling set, the SW 16 MC from Streumaster spreads cement across the road surface. An electronic control system ensures maximum precision. Recycling set in action As soon as the formula for the cold recycling mix was finalized, it was time for the Wirtgen WR 00 recycler to take center stage. This machine granulates the road surface with a robust.0-m-wide milling and mixing rotor, mixing the granulate with binding agents and other additives. In this way, it transforms a ramshackle road surface into a high-quality and hard-wearing base course in a single pass. And it achieves this with minimal energy and transport costs. Indeed, no other road construction process uses resources so economically. The addition of the binding agent and other additives is an extremely simple task. On the NH-, a grader in front of the recycler spread the crusher dust over the road Precise addition of binding agent The WR 00 is a true all-rounder. Depending on equipment version, it can process soil or road surfaces with water, bitumen, cement or lime. On the NH-, it was equipped with a foamed bitumen system. This produces a foam consisting of hot bitumen, water and air in special-purpose expansion chambers. The requisite quantities of additive are precisely metered via the control system to produce a foam with the specified properties. This is then injected via a spray bar directly into the milling and mixing chamber, explains engineer Arashdeep Singh. The total quantity of foamed bitumen required is determined by microprocessors, as is the quantity of water. This may sound complicated, but it isn t: the operator simply enters the desired quantities and the requisite parameters on a control panel in the cab. The intelligent From the air-conditioned cab of the WR 00 from Wirtgen, the driver has an outstanding overview of the tanker in front of him and all activities on both sides. A mirror at the rear of the recycler also allows him to check the lane behind the WR 00.
Cold recycling: a quick cure for distressed roads It s very much like a disease: making the right diagnosis is the best way to ensure a fast and lasting recovery. This is also the basis for choosing the right medicine and the suitable dosage. The same holds true for cold recycling. The first step involves a thorough examination of the damaged roadways. This includes visual inspection and the taking of material samples. To this end, the NH- underwent an in-depth inspection in August 01. Experts from L & T together with the team of IIT Chennai recorded the condition of the carriageways and took numerous samples. The core samples showed that in some areas the asphalt pavement was damaged through its complete thickness of 0 cm. After analyzing the composition, numerous test specimens were produced using the WLB 10 S laboratory system and the WLM 30 laboratory mixer. Examination of these specimens yielded the following results:. Addition of lime The existing material was not plastic, as it originated exclusively from the bituminous part of the pavement. Because the plasticity PI was < 1, no lime had to be added. 3. Addition of cement The addition of 1% OPC 3 cement improved the stability and the distribution of the foamed bitumen amongst the fine fractions.. Optimum moisture content At 6.3%, the optimum moisture content (OMC) was within the range for non-cohesive soils.. Addition of foamed bitumen Bituminous recycled material is evaluated, among other methods, by determining the Indirect Tensile Strength (ITS). A bitumen share of % proved to be the optimum mixture for the roadway to be recycled. 1. Share of fine fractions with an undersize of 0.07 mm The share of fine fractions with an undersize of 0.07 mm was less than %. That is not enough, as cold recycling with foamed bitumen requires a share of at least %. This is because as soon as the foamed bitumen comes into contact with the rock particles, the bitumen bubbles burst into tiny particles. These seek out the fine fractions and bond to them especially to particles smaller than 0.07 mm in diameter. This produces a bituminous bound filler that acts as a mortar between the coarse-grained particles and imparts the recycled layer a high degree of shear strength. This is also why roadway layers treated with foamed bitumen are brown instead of black. 6. Properties of foamed bitumen The most important parameters of foamed bitumen are the half-life period and expansion ratio. The expansion ratio describes the maximum volume of foamed bitumen achieved in relation to unfoamed bitumen. The half-life period is the time in which the maximum foamed bitumen collapses to half of its volume. In this project, a VG10 bitumen produced an optimum foam with an expansion ratio of 1 and a half-life period of seconds at a temperature of 17 C. Due to the low share of fine fractions, the decision was made to add crusher dust to increase the overall fine fraction share to 10%. // 9
Subsequent compaction with the Hamm 311 Compactor. This 11-t compactor was designed specifically for the Indian market and is manufactured by Wirtgen India in Pune. workhorse from Wirtgen then handles everything else itself and doses the materials with the utmost precision, depending on the preconfigured volume, the working depth and the feed rate. Variable recycling width The width of the milling and mixing rotor cannot be altered. However, the addition of water and binding agents can be varied across the width by deactivating individual nozzles in the spray bar. The 9-m-wide surface of the NH- for example was recycled in four lanes. To this end, the WR 00 processed the first lane at its full working width of.0 m and the next two lanes at a width of.30 m (full working width + 10 cm overlap). On the final lane, water and foamed bitumen were only applied across a width of.10 m. 311 compactor Compaction technology for India, by India The subsequent compaction phase was carried out with a 311 Compactor from Hamm. We re particularly proud to be working with this compactor, explains Sanjay Bajaj, Sales Manager North at Wirtgen India. This compactor was developed by Wirtgen India and has been in series production at our factory in Pune since 01. The 311 was able to demonstrate its capabilities on the job site. And it did so admirably: all of the experts were impressed by the ease of operation and the high level of compaction. Compaction crucial to success The tremendously important compaction work directly behind the cold recycler was handled on the Chennai job site by a Hamm 30 P vibrating padfoot compactor. The aim of this compaction process is to reduce the cavities filled with air and water and thus increase the density and load-bearing capacity of the layers. The 0-t Hamm compactor was chosen because it boasts high compaction and penetration. Once the cold recycling phase is complete, rapid initial compaction using heavy-duty compactors is especially important. For the NH- project, L&T CTTL elected to use a compactor from Hamm, the 30 P.
Recycling, compaction, job done In the final pass, the moist surface was sealed with tandem and rubber-tyred rollers. Then we just had to clear everything away. The freshly recycled section that now serves as a new base course was subsequently re-opened to traffic in places just a few hours after being recycled. It doesn t get any quicker than that, said an enthusiastic Project Manager S. Elangovan from L&T IDPL, who was impressed with the high speed of this construction process. Final asphalt surface course Last but not least, a fleet of Wirtgen Group machines moved onto the job site following completion of the recycling work: to produce the to cm surface course above the recycled base course, M/S GVR Pvt Ltd a subcontractor of L&T IDPL used a Super 100- from Vögele together with a fleet of Hamm rollers. Service team of Wirtgen India provides perfect support A team from Wirtgen India headed by Service Engineer Siva Kumar provided support for the job site during the entire project. He assisted and advised and helped with configuration and maintenance of the recycler and rollers. So it is no wonder that all machines worked perfectly during the entire course of the project. Trainers from the service team of Wirtgen India had already taken care of training the machine operators in advance. At the headquarters in Pune, the machine operators were familiarized in depth with the special characteristics of cold recycling and the operation and maintenance of the machines from Wirtgen, Hamm and Streumaster. This ensured ideal prerequisites for a successful project. Cold recycling ideal construction method for India The quality of the new road surface, the speed of the construction work and the huge savings in fuel and construction materials impressed everybody involved in the cold recycling project. With minimum costs, we ve created a highly durable base course that will serve for a long time, said Project Manager S. Elangovan, summarizing the advantages. He also recognizes the potential of this road construction method for many other roads on the subcontinent: With cold recycling, we can upgrade our infrastructure to a high technical level in an environmentally compatible manner while making a sustainable contribution to the development of India. S Elangovan, Project Manager L&T IDPL NH-: We re blown away by the power, the performance and the reliability of the WR 00 and also by the cost-effective and eco-friendly cold recycling process. 10 // 11
Wirtgen GmbH Reinhard-Wirtgen-Str. 37 Windhagen Germany Phone: +9 (0) 6 / 131-0 Fax: +9 (0) 6 / 131-39 Internet: www.wirtgen.com E-Mail: info@wirtgen.com Illustrations and texts are non-binding and may include customized fi ttings. Subject to technical changes. Performance data depend on operational conditions. No. 0-6 EN-0/13 by Wirtgen GmbH 013. Printed in Germany