RELEVANCE OF COLD ASPHALT IN ROAD MAINTENANCE
Engr. (Dr) Eyo, T.B;
MNSE, MNIHTE, FIMC, MASCE.MARRA.
National Technical Secretary, Nigerian Institution of Highways & Transportation Engineers (NIHTE) President, National Asphalt Pavement Association (NAPA), Managing Director/CEO; Besteng Nig Ltd, Director Emeritus, Federal Roads Maintenance Agency (FERMA)Abuja
ABSTRACT
RP300 cold asphalt formally FERMA COLD Asphalt is the first ever indigenous government owned cold asphalt produced from 100% locally available materials. The production process involves specially formulated concentrate which allows for a superior bonding strength that effectively ‘binds’ the aggregate tightly together to produce a strong, trafficable, long lasting and skid resistance waterproof surface. It is unique, in that it satisfies the engineering properties of binder and wearing course Marshal mix design FMW&H specification of the conventional hot mixed asphalt in addition to immersion index% test/boiling test. Cold Asphalt is a high-performance cold patch pavement material that is easily applied any time of the year under any weather condition. The advantage of cold asphalt is that it can be produced and used especially in the yuletide period (mid December– mid January) and also in the rainy seasons when most commercial asphalt plant are not operational. It has so far been used for direct labour works by FERMA in almost all states including highly trafficked Benin-Shagamu road and Third Mainland bridge in Lagos.
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INTRODUCTION
Effective road construction and maintenance cannot exclude the use of Cold Asphalt. The use of cold asphalt reduces fatality rate on the nation’s highways as prompt attention is paid to patching of potholes. Presently, if pothole of a square meter (1m2) is to be patched, hot asphalt would not readily be available for such a small square meter patch since no asphalt plant will batch asphalt for a one square meter patch. As a result, potholes are opened and left for days for accidents to occur.
With Cold Asphalt, one can place a few bags in the booth of the car, depending on the number and size of potholes, patch the potholes no matter how small, and then roll with vehicle tires. In effect, one man can patch a pothole with ease. It requires less equipment and is less labor intensive as only one man can patch and roll with vehicle tires. Cold asphalt could either be produced at ambient temperature and laid at cold or produced at elevated temperature and laid at ambient temperature. FERMA COLD asphalt is produced at elevated temperature and laid at ambient temperature.
FERMA COLD Asphalt now known as Blemddan Cold asphalt is the first ever indigenous government owned cold asphalt produced from 100 % locally available materials. The production process involves specially formulated concentrate which allows for a superior bonding strength that effectively ‘binds’ the aggregate tightly together to produce a strong, trafficable, long lasting and skid resistance waterproof surface. It is unique, in that it satisfies the engineering properties of binder and wearing course Marshal mix design FMW&H specification of the conventional hot mixed asphalt in addition to immersion index% test/boiling test. FERMA Cold Asphalt is a high- performance cold patch pavement material that is easily applied any time of the year under any weather condition. The advantage of cold asphalt is that it can be produced and used especially in the yuletide period (mid December – mid January) and also in the rainy seasons when most commercial asphalt plant are not operational.
FERMA cold asphalt has so far been used for direct labour works by FERMA in almost all states including highly trafficked Benin-Shagamu road and Third Mainland bridge in Lagos. The report has been very promising.
Until recently Cold Asphalt has not been popular in the nation’s road maintenance program. A lot of road product vendors have introduced different kinds of cold asphalt from within and outside the country to the Federal Roads
Maintenance Agency (FERMA) yet cold asphalt has not been fully introduced into the nations highway program. In 2011, FERMA decided to award /pilot study (research contract) projects to the underlisted contractors with the purpose of studying the efficacy in terms of service performance and also availability of the product for use as additional or complementary to the use the of hot mix asphalt for road works. The pilot study involved four different types of cold asphalt including in-house cold asphalt produced in-house by FERMA Research and Development Division (See table enclosed). The terms of reference of this report is on the performance and efficacy of the cold asphalt pilot study which would indirectly be used as a criterion for payment of claims in the interim certificates among other objectives.
DESIGN OF COLD ASPHALT
Cold asphalt is designed in two (2) ways depending on the whether you are using emulsion or straight run bitumen. Cold asphalt with emulsion is designed cold and laid cold, while the one with straight run bitumen is produced hot and laid cold. Cold asphalt referred to here is designed with 60/70 and modified with a (patented)proprietary anti tripping agent. All relevant unaged or tank bitumen tests are carried out the same way it is done on Marshal mix design. Individual aggregate property test and gradation are carried out the same way the conventional HMA asphalt is designed.
PRODUCTION OF FERMA COLD ASPHALT
Initially, the FERMA 2/5TPH mini asphalt in all the 36 states were procured to produce hot mix asphalt only. This was labour intensive and uneconomical. The mini asphalt plant was later enabled to produce cold asphalt. The benefit of using mini asphalt plant for production of cold asphalt is that it allows one to plan production and stockpile vis a vis maintenance works than hot asphalt. Unlike the hot asphalt which cakes after a day and the surplus after a days work is always discarded, cold asphalt can always be reused in future date as it has a shelve life of about one year. With zero wastage one can return unused cold asphalt back to bag or stockpile for future use.
INNOVATIVE PRODUCTION OF COLD ASPHALT FROM FERMA 70/80TPH HOT MIX PLANT AT KUJE.
Hitherto, FERMA Cold asphalt was produced from 2/5TPH FERMA mini asphalt plant. An innovation in the production of Cold asphalt was made late in 2017. FERMA 70/80 TPH conventional hot asphalt plant has now been enabled to produce Cold asphalt. Cold asphalt used on Keffi-Gitata Road maintenance was produced from this innovation.
It therefore means the remaining 6no. 70/80 tph FERMA asphalt plant and any other conventional hot asphalt plant in the country can be enabled to produce both Hot and Cold asphalt. Like the Cold asphalt itself, this is the first of its kind in the country. With this, asphalt can be hauled to any distance without fear of being caked.
It can effectively be used for pothole patching and asphalt works on;
- Highways
- Car parks
- Estate roads
- Filling Stations etc.
- Unlike conventional one, it can be produced for the smallest size of pothole,
- No wastage, left over can be returned into the bag or stockpile and used within six months
- No more cutting and leaving of potholes opened on the road for accident to
- Production of and laying of asphalt can be planned out on different
- The antistripping properties used allows it to be used for overlay at even lower thickness than the conventional hot mix asphalt.
- The antistripping agent increases the bonding between aggregates and
- No specialized equipment is required in laying the cold asphalt
- The concentrate can also be used to produce recycled cold asphalt from scarified pavement
COLD ASPHALT is available in loose stockpile, 25kg bag ready for application on a prepared surface. Product can be stored for up to 12 months if stored in bags. It could also last for same period if stockpiled and covered with tarpaulin.