Dealing with Plastic Settlement Cracking: Case Studies and Lessons Learned скачать в хорошем качестве

Dealing with Plastic Settlement Cracking: Case Studies and Lessons Learned

Presented by Oscar R. Antommattei, Kiewit Engineering Group The topic of cracking has always been of great interest to the concrete industry. Concrete is known to be prone to cracking; thus, implementation of proper selection of design, reasonable materials properties and construction best practices are expected to reduce, mitigate and control risk of cracking (in some cases, eliminate cracking). The phenomenon of plastic settlement cracking has been known for many years. Plastic settlement is typically referred to water bleeding in plastic concrete that allows solids to settle as bleed water rises. Cracking occurs in the plastic concrete over an embedded object that is retraining the plastic concrete, thus a crack is expected to form over this embedded object. Research studies have attempted to describe this phenomenon and some cracking patterns have been associated to plastic settlement by either simplification of models or deducing from limited observations in isolated conditions. In general, the main goal is to reduce cracking without significantly affecting the design, construction and materials properties; however, limited reporting of field practitioners have not helped resolving discrepancies in the understanding of plastic settlement cracking in the field. This presentation provides a field practitioner’s perspective about plastic settlement cracking and examples from real projects.