President’s Message As this is the fi nal issue of the Concrete Beton for 2011, it is a good time to refl ect on what has happened this year in the industry, and in Concrete Society circles. he year started with concern over The Concrete Society has been as busy the outlook for 2011 with many as ever this year; with no global crunch Tpredicting a contraction in the being felt by the Head Offi ce staff. The construction industry. This has clearly appointment of the CEO, John Sheath, been evident with very competitive at the start of this year has brought tendering and reduced demand for with it a tangible difference to the way materials. Material price increases in which the Society strives to serve do not appear to have followed the its members. This effort has gone into discounting offered by consultants aligning the Society with the latest and contractors, with some steady legislation, which governs the way we increases seen at regular periods operate in South Africa. throughout the year in ‘base’ construc- The focus of many discussions in As we look forward to the Christmas tion materials. the Society is how we can best serve break, I want to take this opportunity But the year has ended with a lit- our members. How can we ensure to wish all - a blessed and safe holi- tle more optimism creeping into the that we remain a relevant contributor day - and trust that 2012 will bring industry. While the outlook for 2012 to the construction industry land- some new challenges and many new does not look rosy by any stretch of the scape and not just become another opportunities. imagination, there has been a steady association or society that has mem- increase of inquiries from developers bers? These discussions are ongoing and the private sector. and we trust that in the months and If government is able to improve years ahead you will see the evidence on its ability to spend the budget al- of these discussions in the way we Nick van den Berg located to the various departments serve our members as well as being then this could certainly go a long way an active contributor to the construc- President to shore up the workload for 2012. tion industry. The Concrete Society of Southern Africa Cover: 15 Alice Lane Towers won the Fulton Awards ‘Innovative Technologies’ category and received a Commendation in the Fulton Awards ‘Unique Design Aspect’ VISION: To be the most relevant forum for those who have an interest in concrete and to promote the related services of the CSSA members. MISSION STATEMENT: To promote excellence and innovation in the use of concrete and to provide a forum for networking and for the sharing of knowledge and information on concrete. President: N van den Berg, Offi ce Bearers Vice President: WP Boshoff (Dr), Past President: FB Bain, Treasurer: GS Gamble, Branch Chairmen: E van der Klashorst, A van Vuuren, R Maliehe, P Everitt (Prof). Elected Council Members: P Flower, B Perrie and C Kalis, Chief Executive Offi cer: PJ Sheath, Administrator: NL Pols, Honorary Members: N Stutterheim (Dr), WM Johns, DP Samson, CJ Thompson, AR Dutton, F Loedolff (Prof), MO de Kock (Prof,) MG Alexander (Prof), The late AC Liebenberg, The late R Copp, The Late D Davis (Dr),Editorial Committee: Chairman: WP Boshoff (Dr), G Fanourakis (Prof), GPAG van Zijl (Prof), E Kearsley (Prof), H Beushausen (Dr), Editor: C Dalglish, Design and Layout: Crown Publications, PO Box 140 Bedfordview, 2008. Printed by Tandym Print. OFFICIAL PUBLICATION OF: The Concrete Society of Southern Africa; Physical address: Suite 301, The Hillside, 318 The Hillside Street, Lynwood 0081; Postal address: PO Box 75364, Lynnwood Ridge, 0040. Telephone: 012 348 5305 Fax: 012 348 6944 Email: [email protected] Website: www.concretesociety.co.za The Concrete Society of Southern Africa, CSSA, its directors, offi cers, employees, representatives and agents are not liable for any death, harm or injury caused to any person or any loss, destruction or damage caused to any person’s property or possessions arising from goods supplied by or services rendered by the CSSA. © COPYRIGHT All editorial material published in the Source Book is reserved to the Concrete Society. Requests for permission to use any of the material, in part or in full, should be addressed to the President of the CSSA. Although the CSSA does its best to ensure that information is accurate, no liabilities for negligence are accepted by the CSSA, its offi ces, its members, publishers or agents. Concrete Beton Journal 3 No. 129 • November 2011 FULTON AWARDS WINNER 15 Alice Lane Towers The impressive 15 Alice Lane Towers, Sandton, project won the 2011 Fulton Awards for ‘Innovative Technologies’ and was awarded a com- mendation in the ‘Unique Design Aspects’ category. The 24 000m² iconic land- mark building stands 90m high and is comprised of six levels of basement parking and 17-storey offi ce space, with two sculpted towers linked by a vertical atrium. he iconic property has created an exceptional addition to the Tever-changing Sandton skyline precinct. 15 Alice Lane Towers was de- veloped by Zenprop Property Holdings together with Tiber Property Group. The construction of this landmark building with the curved asymmetric shape of the towers proved a formidable chal- lenge for the professional team and the contractors. Commissioned and built during a global economic recession this building is a statement of faith in the future of Johannesburg and a measure of what can be achieved when well-integrated teams face challenges. In various ways, this project has benefi tted from innova- tive technologies applied to a project by a highly skilled team. Concrete technol- ogy played a large part in bringing its various benefi ts directly to bear on the correct elements in this project. The right benefi t from the use of concrete has been applied to the appropriate parts of the whole. It is in this context that the project represents excellence in the use of concrete. The Team From a construction procedure and planning point of view, the site was Client: Tiber Property Group & Zenprop Property Holdings highly restricted due to the fall of the Principal Agent 1: Capital Expenditure Projects (CAPEX) land, the necessity to keep access and Principal Agent 2: Paragon Architects visibility for the ABSA Capital offi ces and the high-value residential towers next Subcontractor: Tiber Bonvec Construction door. Much of the materials handling Submitted by: Sotiralis Consulting Engineers had to be accomplished on part of the basement construction site, and this Concrete Beton Journal 4 No. 129 • November 2011 INNOVATIVE TECHNOLOGIES made logistics and management com- plicated. The basement façade itself, for example, is defi ned by a coequal board-like pattern of differently sized precast concrete panels, selected for the ability to produce and fi nish them off-site and bring them to the site quickly and install them with minimal handling and storage. In this way, con- crete construction allowed interesting advantages to be added into an already diffi cult construction process. The externally visible architectural form or silhouette of the building is that of two towers whose north and south faces are defi ned by irregular curves, resulting in a canyon-like atrium space between the two towers. This atrium space is about 6m wide at its narrow- est, lowest point, and 11m wide at its widest point. The dramatic vertical space that results is enlivened by a series of precast concrete link bridges that have a fan-shaped arrangement advantages of rapid installation and associated time, handling and safety in plan and spiral upwards in this reductions in scaffold costs and other risks. Also, services such as lighting tight space. The ability of precast con- handling costs associated with more channels could be cast into the concrete crete to produce high-accuracy and conventional ways of constructing link bridges, reducing the number of trades high-quality fi nishes was a criteria in bridges. Interestingly, steel was rejected on site while improving the quality of selecting this construction technique as an option as steel bridges would have the fi nish. Unfortunately, and as a single for these elements, coupled with the involved more fi nishing trades with their drawback, the clients chose to paint Concrete Beton Journal 5 No. 129 • November 2011 COMMENDATION UNIQUE DESIGN ASPECT over the surface of the precast fi nish These unique façades alter dynami- plates, with pre-manufactured modular of the underside of the bridges, hiding cally according to light and atmosphere units lifted up onto the fl oor plates by what would have been a perfectly ac- changes due to their highly patterned tower crane, and then slid onto tracks ceptable and attractive interior fi nish and abstract surfaces. The entire fi xed to the slab edges. Limited num- for this type of building. façade was constructed off the fl oor bers of custom-made aluminium extru- The geometry of the tow- sions had to be formed, using ers themselves presented its CNC technology, which made own challenges, with each it possible to assemble and fl oor of both towers extend- waterproof the ever-changing ing to a different extent at façade profi le that resulted its edge. Modern scaffold- from the towers’ curved form. ing techniques and systems The ability to construct the were used to cantilever the façades off the fl oor plates slab edges from fl oor to fl oor, led to large cost savings in and the edge columns on terms of scaffolding, and all fl oors are cast as round construction time. It also en- elements set at sometimes hanced safety on site, limiting extreme angles.