Slabs on grade

Slab on Grade

One of the most widely used applications for Welded Wire Reinforcement is in slabs-on-grade. This very common form of reinforced concrete construction varies greatly in its design requirements. The use of WWR is a positive and economical way to assure that your slab will perform for its intended purpose. Use Ivy Steel & Wire produced WWR to help you achieve customer satisfaction and reduce placing time.

Residential

In this slab of approximately 4 inches of uniform thickness, the primary purpose of WWR is to keep the shrinkage cracks that form (concrete will usually have some cracks) from growing too wide for the slab to perform its proper function. Cracks will take the form of shrinkage cracks or surface crazing cracks. Shrinkage cracks may not show up for thirty days, where crazing cracks can show up in thirty minutes, depending on the curing conditions. The latter cracks generally don’t have a negative effect on the slab.

The size and shape of the slab between joints will have an effect on the location and size of the shrinkage cracks. In all cases these cracks will stay a minimum size if the proper size of WWR is used. The steel will hold the cracks small enough that the aggregate interlock will allow the slab to transfer a load from one side of the crack to the other. A common style of WWR used in these applications is 6x6-W1.4/W1.4, supplied either in sheets or rolls. The mesh should be supported in the upper third of the slab. Some builders prefer a mesh style of larger wires placed further apart that allows the workers to step through the mesh rather than on it. Either style can give the proper amount of steel to do the job. When certain areas, such as driveways, can receive heavier loads, WWR is the right choice to solve the problem. By recommending a heavier mesh, IVY’s engineers will work with you to show how you can speed-up your job and save money.

Structured action at-crack in plain, nonreinforced pavement.

Structured action at-crack in welded wire reinforcement.

Soil Conditions

If soil conditions require a stronger slab, WWR can provide the solution. The large range of wire sizes and patterns available from Ivy Steel & Wire will allow you to speed construction and save money.

It is very important to know the condition of the supporting soil, since it must provide an adequate support for the slab-on-grade. Inconsistent supporting capabilities of the base under the slab are major factors in causing cracks to form.

Expansive clays can produce large forces on the slab and should be dealt with in different ways than a slab on sandy soil. Tests should be performed on the soil that can give the engineer enough information to conduct an adequate design. These slabs are usually stiffened with cross beams of reinforced concrete, trenched into the soil, forming supports that allow the slabs to resist the forces of the expansive clays and carry the vertical loads applied to them.

Light Industrial Slabs

Welded Wire Reinforcement can be placed faster than individual rebars on light industrial floors and at the same time assure you of a quality job.

Although these slabs are generally larger and expected to carry heavier loads, the design requirements are easily met with WWR. Sheets instead of rolls are usually called for to provide the three primary purposes for reinforcing slabs-on-grade.

Shrinkage Control

Temperature Control

Moment Capacity

Millions of square feet of slabs have been constructed and reinforced with WWR. Several design procedures are available to the engineer to assist him in determining the proper steel area. The Wire Reinforcement Institute is an excellent source for this information.