2018-11-1_PR Comm Packet - Laserfiche WebLink

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The expansion joints are also degrading from inadvertent use of the wrong dry-floor expansion joint plate to cover the refrigeration tubing in the expansion joint channel. The joint was originally designed with two slightly different width plates. The wider of the two plates was to be used during the cooler months of the non-ice season, designed to provide an acceptable expansion joint gap for roller blades to navigate during the air temperatures normally seen during the first and final few months of the dry-floor, inline skating season. The narrower plate was to be used during the heat of summer, to provide an acceptable gap during those months. Unfortunately, the smaller plate was abandoned many years ago and currently the larger plate is being used for the entire roller blade season, pinching the expansion joint gap tight during the warm summer days when the concrete rink slab expansion is the greatest. The stress of the plate pushing against the adjacent steel expansion joint stops has caused the welds to fail on both sides of the plate as well as the adjacent concrete surfaces. Degradation of the expansion joints from this practice seems to be worse on the two southerly joints. The northwest expansion joint concrete is degrading in the recessed channel area of the joint where the refrigerated pipe and sand is placed during the ice skating season. The concrete in the channel is breaking up and we are not exactly sure what is causing this. One possible cause is that the concrete in the channel may have not been totally consolidated during the original installation, allowing further degradation as water supplied to this joint potentially infiltrates into the porous concrete and, upon freezing and expanding, spalls the concrete surface. The hairline cracks were reviewed, and while none appear to currently require any repair, their frequency has significantly grown over the past twenty-five years. We feel most of the hairline cracks are the result of the repetitive stresses induced on the concrete slab when thermal movements occur, summer heat-to-winter refrigeration cooling. The cracks have been slow to develop, for there were few observed in the initial years of operation. While the hairline cracks at this time are not serious enough to require reconstruction of the rink slab, they will continue to grow and expand over time and will, at some point, need to be addressed to maintain a usable surface for summer inline skating activity. It is difficult to predict when this may be required but our intuition says that the rink slab is good for at least 10 years before to needing a major overhaul or reconstruct. The biggest concern for the concrete degradation at the hairline cracks is that water infiltration into the cracks followed by freeze/thaw cycles will begin to spall the concrete surface adjacent to the cracks. Unfortunately, the end of the ice skating season in early to mid-March leaves the slab exposed to many freeze/thaw cycles each year. While the hairline cracks are not everywhere, they are beginning to cover a more significant area of the slab and should be monitored to document surface degradation. The refrigerated slab, when designed, had significant budget restraints and as a result did not include perimeter slab movement expansion joints, rather design allowed the slab to simply push the perimeter soils and pavement when movement occurred. While this saved initial construction dollars it is now causing issues with the rink-edge condition that allows water to easily get under the slab at rink edge. This condition, along with the degradation of the drainage 181818