Cross section of the structure: 1) Horizontal corrugated steel sheet 2) vertical corrugated steel sheet 3) connector 4) thermal insulation 5) crushed aggregate, bitumen gravel or cement stabilization 6) bituminous or concrete surface.
Unprejudiced innovation saves mineral aggregate
The main element of this rnethod is an insulated course consisting of corrugated steel sheets that are placed on top of one another to form several layers, both vertically and horizontally. The sheets are joined together in layers using standard connectors, such as rivets, screws, or similar, to form a grillage kind of structure that spreads the bearing weight. A thermal insulation will be placed on the corrugations ot the steel plates. The insulation can be of cellular plastic, mineral wool or peat. The corrugated steel plates will be rolled at the construction site in a rolling facility situated in a truck, by using modern technology. The steel will be delivered to the site in roils. The steel plates will be rolled to fit the space curve formed by the grade line. The bearing base course will be protected from corrosion by cathodic protection.
A chip layer stabilized by concrete or without stabilization, will be placed on top of the base course. This layer wili be shaped by a motor grader along the vertical alignment. The pavement can be a traditional asphalt pavement or a thin concrete pavement made on strong concrete that can be spread wlth a traditional asphalt spreader.
Cross section of the structure: 1) Horizontal corrugated steel sheet 2) vertical corrugated steel sheet 3) connector 4) thermal insulation 5) crushed aggregate, bitumen gravel or cement stabilization 6) bituminous or concrete surface.
When a base course made of steel, with thermal insulation, protects the road embankment underneath from getting wet and frosting, this layer can be made of till taken from the road alignment or right next to it. Sand and gravel that often have to be transported for long distances are not needed at all.
A base course made of steel and furnished with thermal insulation can also be used in the rehabilitation of existing roads so that part of the structural courses of the road can be utilized. The bearing base course can also be renewed by this method, having half of the road under traffic at a time.
The method presented above can also be applied to the construction of railroads and airports. Rails can be connected directly to the top layer of corrugated sheets. Because the bearing base course is light, it will be con- nected to the till embankment underneath by ribs and landanchors which prevent moving. lf the embankment underneath will sink down later, the base course can be lifted by pumping fast setting concrete underneath the structure. The base course with the rails to be connected on it can be made in a factory as big elements that can easily be assembled on site. The benefits of this structure will become evident especially when building railroads tor speed trains that do not tolerate unevenness caused by frosting.
While constructing roads, streets, airports and railroads in permafrost areas, the base course can be made on a frozen soil, because the thermal insulation in the base course and slopes will prevent the ground from melting during the summer time. The method has the following advantages: the bearing capacity and life span of the base course can be forecasted based on the traffic volume and distribution. The structure can be recycled in a steel factory and rolled again. The melting will save 75% of the energy compared to the production from ore.
Sufficient bearing capacity and thermal insulation enable the usage ot light concrete pavement which can be spread by using a traditional asphalt spreader. A concrete pavement lasts longer than an asphalt pavement and its light color improves traffic safety. Road embankment can be made of till which is cheap and, while kept dry and protected from frost, has a greater bearing capacity than sand and gravel, The driving distances for embankment material get shorter, and sand and gravel ridges get saved. lt is easy to landscape the areas where till has been taken outside the road.
The use ot this method will provide even roads, streets, airports and railroads that do not have frost problems.
When corrugated steel sheets contain 40% recycled steel, it will have a new field of utilization.
For further information and your comments, please contact the inventor and patentee: Esko P�ntynen, Finnish Maritime Administration, P.0. Box 158, 00141 Helsinki, Finland; fax +358-0-1 808 555.
ESKO P�NTYNEN, Finnish Maritime Administration