Road structure – process – or apparatus – Pavement – Including bed
Patent
1989-11-16
1992-01-21
Britts, Ramon S.
Road structure, process, or apparatus
Pavement
Including bed
404 43, 404134, 404 75, E01C 300
Patent
active
050823930
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a method for forming the foundation of ground and road constructions on beds having a low carrying capacity such as clay, peat, mud and water.
BACKGROUND OF THE INVENTION
PRIOR ART
Road and ground constructions consist essentially of a wearing course disposed on the top, and, below it, a base course formed in varying thicknesses from a well-defined sand or gravel material. In cases where the ground layers have a particularly low carrying or load-bearing capacity, subbases can be added, these also being formed from a defined composition. A characteristic feature of conventional road and ground surfacings is that the base courses can only tolerate small tensile stresses. The function of the base course is essentially one of load distribution or, in other words, increasing the surface area influenced by the point loads which are exerted on the wearing course to an acceptable level. The tensile stresses which are formed in the base course are dissipated as friction in the underlying earthen mass.
Conventional road surfacings are made up of base courses and wearing courses whose bulk density is at least as great as that of the underlying ground. Consequently, road surfacings having considerably different bulk densities exist for various soil types. For example, well-graded, packed, sandy gravel has a bulk density of 1800-2000 kg/m.sup.3 ; clay, 1500-1600 kg/m.sup.3 ; and peat, 1000-1100 kg/m.sup.3.
Bitumen stabilization is used to increase the tensile strength of base courses and, especially, the ability to withstand short-term loads. Various construction procedures including, for example, the use of fiber fabric mats, increase the tensile strength of both the base course and the underlying earthen mass. Cement or lime stabilization of the underlying ground, or the like, is primarily intended to increase rigidity. At the same time, the tensile strength also increases. Other measures for increasing the load-bearing capacity of the base courses and for transferring tensile stresses include laying out horizontal piles with end anchors or grillages of wood. Concrete, either plain or reinforced, is also used as a construction material. The concrete generally constitutes a wearing course, but also contributes to distributing point loads along the underlying ground layers. By virtue of the reinforcement, the tensile strength of the concrete is considerably improved. Even if the density of the concrete is 2300-2400 kg/m.sup.3, the reduced thickness required for the base course results in a corresponding reduction in the intrinsic load exerted by the entire construction. Plastic-molded concrete tends to shrink over time, thereby causing uncontrollable crack formations to occur. Therefore, concrete surfacings are generally provided with joints intended to function as crack inhibitors. With such joints, the capacity of the wearing course to tolerate tensile stresses caused by bending moment is reduced. In order to prevent extensive settling due to such joints, the base course is typically chosen to be relatively thick, thereby increasing the load exerted by the entire construction. The load can be reduced to some extent by producing the wearing course from light ballast concrete. In the United States, for example, light ballast concrete with a density as low as 1600 kg/m.sup.3 has been used with good results. Concretes having lower densities, however, have too little abrasion resistance and are quickly and easily worn down by traffic.
The load exerted on the underlying earthen masses can be reduced even further in several ways. Materials with low bulk density, such as slag, haydite and cellular plastic, have been used to reduce the weight of road embankments. Piles driven into the ground may also be used to transfer the load from the roadway down to deeper-lying earthen layers having a higher load-bearing capacity and rigidity than those lying above. The piles can be provided with pile helmets, or a reinforced, continuous concrete slab can be cast and supported by th
REFERENCES:
patent: 394583 (1888-12-01), Lee
patent: 3012533 (1961-12-01), Tellefsen
patent: 3315578 (1967-04-01), Wesch et al.
patent: 3479786 (1969-11-01), Kreier
patent: 3589250 (1971-06-01), Sedisatmo et al.
patent: 3626702 (1971-12-01), Monahan
patent: 3673750 (1972-07-01), Bokvist et al.
patent: 3804543 (1974-04-01), Best
patent: 4318361 (1982-03-01), Sluys
patent: 4531859 (1985-07-01), Bettigole
patent: 4696429 (1987-09-01), Ortwein
patent: 4856930 (1989-08-01), Denning
Berge Olay
Berntsson Leif
Ringesten Bjorn
Britts Ramon S.
Schoeppel Roger J.
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