Experimental study of formwork tightness as a function of rheological properties of SCC

Several studies relating formwork pressure to rheology exist, however the relationship between rheology and leakage through formwork joints remains to be investigated. In practice, standard documents are used to define formwork tightness requirements, typically using a qualitative approach. To try bridge this gap in knowledge, we developed a test set-up to study tightness of formwork joints under pressure as a function of varying rheological properties. Coupled with standard rheology tests, this new test set-up provides means of linking flow rate, formwork pressure, flow area, and the rheological properties. The study seeks to provide insight on measurable governing parameters and thus inform formwork tightness requirements in a more quantifiable manner. This paper presents a test set-up designed to study the flow of fresh paste through small openings. It highlights a preliminary study on the pressure-driven flow of limestone paste through a bottom orifice in a cylindrical container. While this new device may not be directly representative of the actual conditions in formwork, it provides a good base for a fundamental study that can then be extrapolated to a more representative test operation. Preliminary results show a linear relationship between the flow rate and the applied pressure. The results also show that increasing the flow area by a factor of 2.33 had a higher impact than an increase in yield stress and viscosity by a factor of 2.54 and 3.80 respectively. However, more tests need to be carried out to obtain clear trends

Complex reconstructions in head and neck cancer surgery: decision making

Defects in head and neck after tumor resection often provide significant functional and cosmetic deformity. The challenge for reconstruction is not only the aesthetic result, but the functional repair. Cancer may involve composite elements and the in sano resection may lead to an extensive tissue defect. No prospective randomized controlled studies for comparison of different free flaps are available. There are many options to cover defects and restore function in the head and neck area, however we conclude from experience that nearly all defects in head and neck can be closed by 5 different free flaps: radial forearm flap, free fibula flap, anterior lateral thigh flap, lateral arm flap and parascapular flap