RECYCLING OF OLD ASPHALT PAVEMENTS & STABILIZATION : RWANDAN EXPERIENCE HORIZON GROUP LTD SEPTEMBER, 27 TH 2017

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1 RECYCLING OF OLD ASPHALT PAVEMENTS & STABILIZATION : RWANDAN EXPERIENCE HORIZON GROUP LTD SEPTEMBER, 27 TH 2017

2 The paradox of life lies exactly in this: its resources are finite, but itself is endless. Such a contradictory state of affairs is feasible only because the resources accessible to life can be used over and over again. I.I. Gitelson,

3 Contents 1. Introduction 2. Methods of recycling of old pavements 3. Cold In-place recycling 4. Recycling and Stabilization of gravel road 5. Conclusion

4 Introduction With the continuous construction of asphalt roads network in Rwanda, rehabilitation of those networks has become equally important We have observed Three kinds of methods used: Overlaying the old asphalt pavement with new asphalt Recycle the existing pavement, followed by laying a wearing course Removing the existing materials and reconstruct The technology of recycling AP is common in some countries (EU, US, Southern Africa, Brasil, etc)

5 What do we do? Remove and dump? or Recyle and reuse?

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7 Methods of recycling of old pavements (cont d) Cold, In-Place Recycling. The pavement is removed by a recycler to a depth up to 3-5cm. The material is pulverized, sized, and mixed with an additive. An asphalt emulsion or a recycling agent is added, then the material is placed and compacted. An additional layer is optional, such as a chip seal, or 3-5cm of hot-mix asphalt. Hot Recycling. At a central plant, RAP is combined with hot new aggregate, and asphalt or a recycling agent to produce AC, using a batch or drum plant. The RAP is usually obtained from a recycler, but could also be from a ripping/crushing operation.

8 Methods of recycling of old pavements (cont d) Hot, In-Place Recycling. The pavement is softened by heating, and is scarified or hot milled to a depth of 2-3cm and mixed. New hot mix material and/or a recycling agent is added in a single pass of the machine. A new wearing course may also be added with an additional pass after compaction. Full-Depth Reclamation. All of the asphalt pavement section and a portion of the underlying materials are processed to produce a stabilized base course. The materials are crushed and additives are introduced; the materials are then shaped and compacted, and a surface or wearing course is applied.

9 Rehabilitation options Actual practice in Rwanda

10 Cost comparison and energy

11 A case for Rwanda Horizon Group Ltd introduced to the Local Construction Sector, recycling technology for old asphalt road by acquiring recycler, the MPH 125 This machine performs cold In-Place recycling or full depth reclamation technology The recycling machine used is MPH 125 connected to a specialized bitumen tanker and water boozer

12 Cold In-place Recycling The binder used: foam bitumen Ratio: depending on the existing materials and the bearing capacity needed, the mix could be: - Cement: 1-2% - Foam bitumen: 2.5-4% - Reaction water: Variable Procedure used: Pulverizing the existing materials to design depth The bitumen and water are mixed in the rotor chamber of MPH 125 Recycled materials are first compacted using pad foot roller, leveled using grader and then compacted Road Kibagabaga- Kinyinya

13 Applications So far, we have successfully used this equipment to rehabilitate a number of roads including among others; Kibagabaga-Deustche Welle road 2Km ( CoK) Main round about-serena Hotel, 1.2 Km CoK Kamembe Airstrip( Regional Airport) Rusizi urban road 2.2 Km ( Western Province)

14 Practical example: Rusizi Before During After

15 stabilization of Natural soils There is scarcity of gravel wearing course materials and strict environmental practice to open borrow pits. In face of these new Development imperatives, Traditional Road Construction and Rehabilitation Methods are certainly unsustainable and the need for more sustainable approaches cannot be overemphasized. A number of soil stabilization alternatives and Methods exist: Traditional stabilizers: cement and lime, Cementious stabilizers : anyway solution Chemical stabilizers: claycrete

16 Stabilization: Claycrete Since the main mandate of Horizon Group is to promote sustainability, it has pioneered the use of Claycrete given its quality over the others HG has sponsored a research on this product and conducted by a number of experts from different institutions. Claycrete is an ionic liquid based product with SGS certificate that is being used to stabilize soils with weak engineering properties into more durable layers. The conducted engineering tests proven the suitability of the stabiliser on specific type of soil

17 Stabilization (Kagasa-Batima road) particle size distribution it was seen that after soil stabilization with Claycrete II, the gradation curve has shifted downwards which means that the percentages of passing decreased except for the samples taken at and This is an indicator of soil properties improvement.

18 Atterbeg limits(pi) Before stabilization, the biggest value of PI was 17% while the lowest value was 14%. After stabilization, the biggest value became 13.7% while the lowest value was 9.2%. The plasticity index has reduced on average by 31% after soil stabilization. This indicates that there was decrease in percentage of clay fraction.

19 CBR CBR (soaked) test Before stabilization, the CBR values of the soil samples ranged from 17 to 30 and after stabilization, CBR values ranged between 31 and 46. On average, this corresponds to 40% increase in CBR values CBR at 95%, Before stabilization CBR at 95%, After 1-10days Recommended values for CBR for 10 foundation courses is min 30 for 5 gravel road 0 15 Mileage

20 Applications So far, we have implemented more than 25km of roads: Kagasa-Batima road ( 12 Km) ( Eastern Province) Rwamagana road ( 6Km) ( Eastern Province) Zindiro Masiza road (14 Km) ( CoK) ongoing

21 Benefits a) Considerable reduction in project implementation period b) Costs savings: Less expenditure on imported materials Low transportation costs Savings between 20-40% of the total construction costs c) Environmental gains: Fewer trucks movements, saving energy and reducing impacts on local communities Reduction in CO2 emissions Conserve natural resources

22 Challenges on Recycling Unknown technology by potential clients and other stakeholders, thus limited buy in of the technology Lack of guidelines in different African countries limiting its full application Few experts in this field Relatively high initial investment in equipments

23 Conclusion Recycling of old asphalt pavement and natural soil provides required performance of roads over their life period Recycling technology contribute to effectively and efficiently manage demolition waste and save cost on projects We urge the concerned institutions to embrance the technology to be fully implemented since it has been proven technically feasible More research are needed in different African countries to develop customized manuals/guidelines

24 Thank you