An intermediate floor was removed from a warehouse. The walls were constructed with 6-inch unreinforced concrete block. No modifications were made to the wall when the floor was removed. I need to perform emergency repairs to stabilize the wall. To make the repairs quickly, I plan to bolt deep steel beams at 12 feet on center along the inside of the warehouse walls. To provide fire protection for the steel, I plan to form and cast concrete around the steel beams later. Can I use concrete block as permanent forms for the concrete or grout? Or will the grout or concrete rupture the block with "wet pressure?"
Using steel beams is one way to reinforce a concreteblock wall after the wall is finished, but it may not be the most cost-effective. You may instead consider temporarily bracing the wall and then installing reinforced concrete-block pilasters at the same intervals you were placing the steel beams. The pilasters could be tied to the existing block wall by knocking holes in the existing block and grouting in anchor bolts, or by tying reinforcing rods to the reinforcement in the new pilaster. The design of reinforced concrete masonry pilasters is discussed in NCMA-TEK 125. It may also be possible to install vertical reinforcing at regular intervals in the back face of the wall by knocking out the face shells and cleaning out the cores. Reinforcing bars can be placed into the cores. Then formwork can be installed over the interior face, and the cores grouted with fluid grout. Try to remove block faces without cutting any horizontal reinforcement. Smaller sections of vertical reinforcing can be worked around the exposed horizontal steel and then adequately spliced. If you use the steel beam, adequate fire protection can be provided by concrete block without grouting the space. Standard concrete block or special column cover units can be used. The design of steel column fire protection is described in NCMA-TEK 128.