1. Field of the Invention
The present invention is directed to a machine for finishing uncured concrete placed including uncured concrete placed in a hole in a slab and for paving concrete surfaces.
2. Background of the Invention
With reference to the section of road shown in FIGS. 5-8 of the drawings, a common practice for repairing damaged sections of concrete slabs 2 forming the road is to cut out and remove a damaged section and pour and finish a concrete patch in the remaining hole. The area around lateral control joints 5 formed in the slabs 2 which have degraded over time are areas that are commonly in need of repair. The concrete slab 2 forming a road is typically poured as a generally continuous slab. The slab may be approximately nine to twelve inches thick. Saw cuts are then cut into the slab 2, commonly about one third of the thickness of the pavement, to provide an area of weakness at which cracks will naturally form in the slab 2. Longitudinal joints 6 are formed longitudinally along the slab 2 to separate lanes that are typically twelve feet wide. Lateral control joints 5 are formed laterally across the slab 2 typically approximately fifteen feet apart.
Damage at the lateral control joints 5, typically starts with chipping and spawling of the edges of the joint 5, forming a small depression which then grows as tires continuously pound against the defect and water seeps into the cracks therein and freezes further expanding the defects. Over time cracks will also form extending outward from the joint 5. In addition, cracks may form across the slab between control joints 5 which is more common when the spacing between control joints 5 is increased, such as for example thirty foot spacings.
A typical procedure for repairing a slab having a degraded control joint 5 is to cut out and remove a specified amount of the concrete slab 2 on either side of the degraded joint 5. The width of the slab to be removed may vary depending on specifications established by the jurisdiction in charge of the road repair. Typically, the jurisdiction or owner will specify removing at least two to three feet of the concrete slab 2 on either side of the joint 5 and in some cases up to approximately five feet on either side of the joint 5.
In repairs, cuts 11 are made through the concrete slab at the distance specified from the crack on both sides. Holes are then drilled in the fragmented section to be removed. Expansion pins are then inserted into the holes and expanded to lock the pins in the holes. The pins are connected together by a harness that is then lifted with an excavator or the like to lift the pins and the fragmented section connected thereto from the rest of the concrete roadway or slab 2 to leave a hole 15 in the roadway to be filled with a patch 17.
After the fragmented section is removed, concrete is placed or poured in the remaining hole 15 and leveled and finished to present a relative smooth upper surface. Shovels and rakes are still commonly used to level out high spots. Vibrators held by hand or mounted on a mobile truss and inserted into the uncured concrete are also used to level the concrete by vibrating and increasing the fluidity of the poured mass so it levels by gravity. Once the poured concrete is generally leveled, screeds are then used to finishing the concrete to generally smooth out the upper surface filling any voids and compacting the concrete. Screeds used for finishing concrete may be as simple as a 2×4 board drawn over the concrete at a level to which the concrete is to be finished. Truss screeds comprising an elongated truss or rigid member with a motor mounted thereon to vibrate the truss may be used for screeding. In addition, motor driven rollers pulled by hand over a section of concrete to be finished or mounted on a mobile frame are also known for use in finishing poured concrete. Such screeds are typically referred to as roller screeds.
Road patching operations, particularly in and around cities, often must be completed between evening and morning rush hours while maintaining at least one lane in each direction open to traffic. Quick curing concrete is used in such patching operations. Such quick curing concrete can be formulated to cure to the degree required to support traffic within as little as approximately 4 hours. The water content of the quick curing concrete is relatively low such that its viscosity is high and its fluidity or slump is low. Such quick curing concrete is more difficult to level and finish even using motor driven roller screeds that are pulled by two workers.
As shown in U.S. Pat. No. 5,562,361, it is also known to mount rollers to a frame and drive each roller by a motor projecting outward therefrom. The rollers are supported on the surface adjacent the concrete to be leveled and finished which can be the surrounding slab as discussed above or forms surrounding a mass of concrete or other structure. The rollers not only level the uncured concrete but propel the machine across the concrete and along the forms or surrounding surface. The exposed motors connected to the rollers are prone to damage and increase the overall width or length of the roller assembly and may make it difficult to use such machines for leveling concrete close to curbs or other structures. In addition, such machines are made relatively long to accommodate a wide variety of widths of areas to be finished making the machine difficult to maneuver into place which may be done using a crane to lift the machine in place.
There remains a need for a system for finishing concrete used to patch sections of a road which can be readily used in situations in which access to lanes adjacent the lane repaired may be limited and which is easy to use by a limited number of operators. There also remains a need for a system for finishing concrete which can rapidly move to the mass of concrete to be finished and quickly transition from a traveling mode to a finishing mode and which overcomes the limitations of existing finishing machines.