More stories about Joints

  • WWF Through Joints?

    We are planning to place a slab on grade containing welded wire fabric. Should the fabric be continuous through sawed contraction joints?

  • Long-Term Curling

    We finished pouring slabs for a 500,000-square-foot warehouse in June 1998. Technicians got excellent F-numbers when they measured each slab pour for flatness and levelness.

  • Crack Around Columns

    We placed concrete for the footings and floor slab of an industrial building. The interior column footings are 18 inches deep and contain a bottom and top mat of reinforcing bars. The 6-inch-thick floor slab contains welded wire fabric.

  • Troubleshooting: D-Cracking

    D-cracking--a series of cracks roughly parallel to joints, edges, or transverse and longitudinal cracks--is typically found in pavements or other flatwork.

  • Isolation and Expansion Joints

    Slabs on grade may contract, expand, or settle under service conditions. If these movements are restrained, slabs can crack or buckle.

  • Troubleshooting: Blowup

    Blowups are usually caused by compressive forces produced when concrete expands during hot weather. If the concrete is prevented from moving, the expansive forces cause vertical displacement of the slab at each side of the crack or joint.

  • Slab Curling: Causes and Prevention

    We just had our first experience with slab curling. What causes it and what can be done to avoid it?

  • Square Dowels Control Slab Curling

    Curling at floor joints is a common problem. However, field observations and experimental studies have shown that substantial reductions in curling can be achieved by using proprietary square steel dowels fitted with a clip-on device that puts the sides of the dowel in contact with a compressible...

  • A Closer Look at Bridge Expansion Joints

    Years ago, many bridges had unsealed joints. A simple gap in the deck accommodated small movements, and finger-plate joints or similar systems accommodated larger movements.

  • Tie Slab to Wall?

    We plan to pour a 4-foot-square slab that's surrounded by a perimeter wall on three sides and an existing slab on the fourth. We plan to match the grade of our new slab with that of the existing slab. Strips of material for isolation (expansion) joints have been placed along the entire perimeter of...