System of protecting the edges of cast-in-place concrete slab on ground, construction joints

Abstract

An improved joint edge assembly, of the type used in the construction of concrete slabs, is disclosed. The assembly comprises a longitudinal joint rail, preferably of steel, which is supported off the ground by temporary formwork. The joint rail is secured to the formwork by mounting brackets. The joint rail comprises first and second joint edge members that are connected to each other by connectors with self-release elements. A plurality of studs extends downward and outward from each of the joint edge members into the concrete slabs provide a positive mechanical connection between the slab and the joint rail. As the concrete shrinks during hardening, the self-release elements of the connectors allow the joint to freely open. The joint edge assembly thus provides a self-releasing expandable joint between adjacent slab sections, and protects the edges of the adjacent slab sections from damage. A dowel aligner may also be integrated into the assembly, to allow proper positioning of dowels within the slab.

We claim:  
     
         1 . An improved joint edge assembly for the construction of jointed concrete slabs and protection of concrete slab joints, the concrete slabs separating after pouring, the assembly comprising: 
 a first elongated joint edge member;    a second elongated joint edge member;    connector or connectors that connect the joint edge members to each other, said connector(s) also including release elements that release the joint edge members from each other under the force of the slabs separating;    temporary formwork and formwork mounting members;    whereby the assembly of the joint edge members and connectors may be placed for the joint edge members to form and thereby protect edges of a concrete slab joint, whereby the slabs may be poured, and the joint edge members may release from each other under action of the slabs separating, to allow the joint formed by the joint edge members to open and minimize slab cracking at and adjacent the joint during separation, and whereby the formwork mounting members may be mounted on the temporary formwork and may support the assembly in position for the joint edge members to form the edges of the concrete slab.    
     
     
         2 . The apparatus of  claim 1  further comprising a dowel aligner connected to the temporary formwork, extending into the region where the first concrete slab is to be poured, 
 whereby the dowel aligner permits the placement of dowels prior to the pouring of the adjacent concrete slab.  
 
     
     
         3 . An improved joint edge assembly as in  claim 1  further comprising a plurality of anchors extending from each side of the joint edge assembly into the regions where the adjacent slabs are to be poured.  
     
     
         4 . An improved joint edge assembly as in  claim 3 , wherein the plurality of anchors are comprised of at least one steel stud with an expanded head.  
     
     
         5 . A method of forming an improved joint edge utilizing an improved joint edge assembly, for the construction of jointed concrete slabs and protection of concrete slab joints, the concrete slabs separating, the assembly comprising a first elongated joint edge member, a second elongated joint edge member, each side of the form assembly being anchored into the regions where the adjacent slabs are to be poured, joint edge members connected to each other, connected using release element(s) that release the joint edge members from each other under action of the slabs shifting, and a dowel aligner connected to temporary formwork, extending into the region where the first. concrete slab is to be poured, whereby the dowel aligner permits the placement of dowels prior to the pouring of the adjacent concrete slab, the method comprising: 
 placing the assembly of the joint edge members and connecting means for the joint edge members to form and thereby protect edges of a concrete slab joint, pouring the slabs to the joint edge members, and    allowing the joint edge members to release from each other under action of the slabs shifting with the anchors embedded therein and under action of the releasing elements of the connectors, allowing the joint formed by the joint edge members to open and minimize slab cracking at and adjacent to the joint during shifting and subsequently protecting the joint edge.    
     
     
         6 . An article made according to the method of  claim 5 .  
     
     
         7 . An improved apparatus for constructing, protecting, and preserving concrete slab joint edges, the assembly comprising: 
 joint edge members forming the respective edges of the concrete slabs;    one or more connectors that connect the joint edge members, the connector or connectors having release elements, allowing the joint edge members to separate while the concrete is shrinking during construction or shifting after construction;    temporary formwork and formwork mounting members;    whereby joint edge members are placed opposite to one another on temporary formwork to act as the concrete slab edges prior to pouring the concrete, whereby the connectors minimize cracking in the concrete slabs by allowing the joint edge members to separate from one another while the concrete shrinks during hardening; whereby the connectors minimize cracking in the concrete slabs by allowing the joint edge members to move relative to one another while the concrete slabs shift after hardening; whereby the joint edge members form the edge of the concrete slabs and protect the concrete slab edges from cracking or chipping after hardening;    
     
     
         8 . The apparatus of  claim 7  further comprising a dowel aligner connected to the temporary formwork, extending into the region where the first concrete slab is to be poured, whereby the dowel aligner permits the placement of dowels prior to the pouring of the adjacent concrete slab.  
     
     
         9 . An improved joint edge assembly as in  claim 7  further comprising a plurality of anchors extending from each side of the joint edge assembly into the regions where the adjacent slabs are to be poured.  
     
     
         10 . An improved joint edge assembly as in  claim 9 , wherein the plurality of anchors are comprised of at least one steel stud with an expanded head.