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- . .SYlva~ ~each Pavilion Floor .Sy8 e 2 Spalls on the bottom of joists and beams were observed as well as horizontal cracks near the bottom of joists were observed at many locations. The concrete appears to be lightweight aggregate and normal weight sand, Portland cement concrete. No vertical or diagonal tension cracks were observed. Diagonal cracks were seen in a spandrel at the ends of some cantilevered joists but these are thought to be related to corrosion of the reinforcing where a wood deck was bolted to the spandrel. One or two areas of spalling concrete were removed but many had fallen prior to this visit. The attached photographs illustrate the distress il)Jhe-concrete that was observed. The bottom reinforcing bars in the joists and at the bottom edges of beams are exposed 'at the concrete spa lis. The bars are surface corroded but it appears that there has been very little lose in the cross section of the steel, so far. The steel has definitely corroded enough however to cause the concrete spalls from the expanding oxidized metal. The present conditions are dangerous to pedestrians that can walk beneath the b'uilding. The spalling concrete is about 1'% inches thick and appears to fall In pieces 6- wide by lengths varying from 1 to 2 feet. These pieces could definitely cause minor injury at best and major injuries if a person was hit in the eye. We recommend that the area under the building be barricaded immediately to prevent persons from ~alking beneath it until repairs are completed. . The repairs should be completed as soon as possible to mitigate the deterioration of the structure before it jeopardizes the structural integrity of the building. RECOMMENDED REPAIR The repairs should include the following procedure: 1. Remove loose concrete from spalls. 2. Sand blast the entire exposed surface of th~ concrete and remove all loose concrete. 3. Repair any diagonal tension cracks that may be found with injection of low viscosity epoxy (SIKA OUR HIMOO LVL). 4. Sand blast and remove all corrosion from exposed reinforcing steel to biight metal. 5. Immediately coat the clean steel and the clean spalled concrete surfaces with SIKA ARMA TEe 110 for inhibiting corrosion and to provide a bonding agent for the patch described'below. 6. Apply a mixture of sand/cement grout and micro silica by the shot-crete method to rebuild the concrete to the original dimensions. Finish the shot-crete by troweling it to the original dimensions and to close and densify the surface of the patch. The patch must be applied within 8 hours of the sand blasting of the steel. Therefore, the repairs must be done in sections of sizes that can be started and completed in one day of work. The work must be protected from wind and moist cured until the patch is sufficiently cured and has gained strength to 3000 psi minimum. The 28 day strength of the grout must be 4000 psi minimum. 7. After the patching has cured the entire cleaned surfaces of the concrete structure must be coated with an elastomeric coating waterproof membrane. This will mitigate the corrosion of the reinforcing and resulting cracking and spalling of the concrete by sealing out the moist salty air. The surface coating should be inspected periodically and repaired as required to maintain the integrity of the seal. CAGlEY. CONn & ":UMPER Structural Engineers 3949 Bralton Houston. Texas 77063 C~GLeV =&ffi z Q, o ~ u ..,