Expansion of maxilla. Spreading the midpalatal suture; measuring the widening of the apical base and the nasal cavity on serial roentgenograms: By N. A. Hugo Thörne, L.D.S., Assistant Chief, Orthodontic Department, Eastmaninstitutet, Eastman Dental Clinic, Dalagatan 11, Stockholm, Sweden

Abstract

The world’s tallest skyscrapers are taking concrete to ever higher altitudes. Indeed, high-strength flowable concrete has become a material of choice for the construction of tall buildings. However, technological challenges associated with using concrete in super-tall buildings are daunting. For instance, Dubai’s Burj Khalifa, the world’s tallest building completed in 2010 standing 828-m tall with 163 floors, had plans to take concrete higher abandoned somewhere around an altitude of 580-m due to pumping challenges. In 2012, the Holy City of Makah’s Royal Clock Tower became the world’s second tallest building, standing 601-m tall. This building also experienced the dares of pumping concrete beyond 520-m in height. The City of Jeddah’s Kingdom Tower is expected to exceed one kilometer in height upon completion and will take concrete higher than ever before in stringent hot weather conditions. This article discusses the experience with flowable and self-consolidating concrete in skyscrapers, examines the opportunities and technical challenges facing SCC construction in super-tall buildings and highlights needed innovations and technological breakthroughs.