Rehabilitation and improvement of road network is a main strategic movement by any government in order to provide a better infrastructure facilities which can heavily affect to rapid development. The same phenomena were applied during the last two decades in Sri Lanka and as a result many roads were gotten new shape and ultimately facilitating the commuters. Though, the government and the client of these road network, the Road Development Authority (RDA) anticipated the significant life time of such rehabilitated roads, the unsatisfactory conditions or pre-mature failures were observed in many roads all over Sri Lanka. The pre-mature failures were, surface cracking, ravelling, stripping the top layer of bitumen, corrugations, even base failures and so on.
The burden issue in such cases are the early rectification cost, in some cases the responsibility may fall in to the contractor and then to the RDA. In many cases the root cause is not clearly identified and costly & time consuming conventional rectification methods are adopted. However, in many foreign countries, the advanced method such as supplication of geo-synthetics is being used to avoid such pre mature failures of road sections in greater extents. To strengthen the base course and asphalt layers the geogrids and geo-composites can be effectively used respectively. At present, the availability of quality soil (with higher CBR (California Bearing Ratio)) is very limited and due to the strict environmental regulation by the government, the availability is further restricted.
To cope up with the limitation, unavailability and even the cost of time, the application of geo-synthetics has gained huge attention by the construction industry in Sri Lanka, and Access Engineering PLC has been frontrunner in this regard during last decade. Typical geo-synthetics are geotextiles, geogrids, geo-nets, geo-membranes, geo-synthesis clay liner, geo-cells and geo-composites. Among them for the road construction projects and to improve the base course and asphalt construction, the geo-grids and geo-composites can be used respectively and those have been used successfully in many countries.
The main advantages to the construction industry can be listed as follows but not limited to;
- Space saving
- Time saving
- Cost saving
- High construction quality control
- Technical superiority
- Material availability
- Environmental sensitivity
APPLICATION FOR THE ASPHULT AND BASE LAYERS
Different geo-synthetics have been used by various construction companies in Sri Lanka during last few years, but the application for strengthening the asphalt layers and to substitute for the sub-base soil were minimized. However, Access Engineering PLC (AEPLC), with deep understanding and with greater literature reviewed, geo-synthetics called, geo-composite has been successfully used their road construction projects. The proper approvals were received from the implementation agency of RDA.
By application of Geo-composites in between binder and wearing asphalt layers, the propagation and development of pre mature cracks are mitigated. This geo-composite is strong enough to withstand the extra pressure created by wheel loads or any other and lifetime of the asphalt layer is extended. At present in many road projects, different contractors deploy this application with the approval of RDA. This geo-composite can only be used to strengthen the asphalt layers, and different strength classes are available. But most useable one is the strength class of 100 kN/m.
Scarcity of good sub-base soil is a serious issue in the road construction industry at present. To meet such challenges, the application of geo-synthetics is a sound solution and again it has been successfully used by Access Engineering PLC.
In the Berei Lake Road Project (BLRP)), the complete subbase layer (300 mm thickness) was removed by introducing the two geo-grid layers. This application further helped enhance the given design as the underneath existing ground consisted of a peat layer. The remarkable saving was the time due to this application. Time saving was approximately one and half months. As a whole, the usage of geo-synthetics has proved the advantages in all three project constrains in construction industry, namely, time, cost and quality. With the ever increasing strict environmental restrictions and scarcity of natural materials, the application of such a geo-synthetics can attract the construction industry in a greater extent.