Industrial Concrete Slab Repair

This repair sounds terrible to me. I don't think the plate will be tight enough in sawn slots to eliminate vertical movement. The concrete may not flow properly under the plates. What's wrong with just drilling the old slab, epoxying in epoxy coated rebar?

You must allow expansion at your saw point, rienforced concrete has an expansion rate simliar to steel. .0010 mm per 10 C per 10 feet.

You would be served drilling 3/4 rebar on 4 inch spreads.

The other option is a z lock or tongue this will allow the slabs to work off each other, the cold joint is the grout.

Concrete is never greater in dimension than the day it is placed. It shrinks as it cures, with that shrinkage starting within 2-4 hours of placement. While it may have an expansion coefficent similar to steel, there is not much temperature variation in a slab-on-grade, so expansion should be of no concern. The bigger issue is contraction, as it is inevitable and generates significant tensile stresses, as evidenced by the somewhat regular cracking interval that one observes in the absence of saw-cut joints made as quickly as practical after placement and finishing.

Even if you install dowels that are intended to transfer load from one side of a construction joint to the other, you will not have succeeded in transferring significant load. There will be enough play or space around the dowels on either side of the joint that you will not get anywhere near the load transfer that you desire. If you are determined to use dowels, do not use deformed rebar, use smooth dowels.

I once had a lengthy discussion about this very issue with a very highly-respected structural engineer who stated that the use of dowels in construction joints was a waste of time and money.

Hello Guest,

I think we need additional information in order to help you. My initial feeling is similar to Post #2 made by Timetraveler. It seems to be a very bad idea.

I'd need the following information:

A. Existing Concrete Slab info:

1. slab thickness,

2. slab compressive strength (obtained by Windsor Probe or coring sample),

3. reinforcement size, spacing, and number of layers if applicable, and placement/configuration E.W..

4. Distances to nearest transverse construction joint,

5. Distance to nearest longitudinal construction joint,

6. Distances to nearest transverse and longitudinal expansion joints.

B. Proposed Concrete Slab info:

1. Slab thickness, any haunches?,

2. design compressive strength

3. Reinforcement size, spacing, and number of layers if applicable, and placement/configuration E.W.

4. Distances to nearest transverse construction joint,

5. Distance to nearest longitudinal construction joint,

6. Distances to nearest transverse and longitudinal expansion joints.

C. Vertical Load Information

1. Magnitude,

2. Spacing of vertical loads, if multiple and applicable,

3. number of vertical loads,

4. Are the loads wheel loads? Type of wheels/tires? Type of vehicle(s)

5. If wheel loads, maximum speed of vehicle?

6. If loads are from a rack system, what are the spacings of the vertical rack members E.W. as well as their respective baseplate dimensions. How secured to floor?

7. are there confined or defined travel corridors for vehicles? Are two vehicles permitted to pass one another while traversing over this joint?

D. Other vital information:

1. What type of floor slab are they? Industrial, warehouse, manufacturing, chemical etc?

2. Specialized floor slab type? Trap-Rock industrial flooring system?

3. What are the required flatness specs?

4. Are any vibrations present from equipment, etc?

5. Allowable slab expansion and tolerances? Slab restraints?

After looking back over my shopping list I realized that I'd rather strongly suggest that you to hire a structural engineer/PE to design this slab joint and anything else. There's way to may unknowns and questions to adequately steer you in the correct direction within the confines and limits of this forum. You can use my list to provide the SE/PE answers he's bound to ask like myself.

Good luck!