FERROCEMENT APPLICATIONS IN HOUSING

4A Arawa Room Buildings
28. NZI Centre - Design of Multistorey Towers - Billings IJ, Thom CW Beca Carter Hollings & Ferner Ltd, Auckland
27. Auckland Trotting Club New Grandstand -Brown PB Thorburn Davidson Ltd, Auckland
29. Mid City Towers - an Efficient Precast Concrete Framed
4B Tiri Room Concrete Properties
42. Influence of Cement Paste Flocculation on its Rheological Properties - Nawa T., Eguchi H., Fukaya Y. Chichibu Cement Co. Ltd, Japan
4 7. Blended Cements Inhibit AAR Expansion - Kennerley RA New Zealand Cement Holdings Ltd
Building 48. Alkali-Aggregate Reaction in Concrete - a Problem in New Zealand Too - Poole RA, Glendon JE
Holmes Consulting Group, Christchurch
5A Arawa Room Walls
19. Structural Walls of Limited Ductility - Paulay T, Mestyanek JM
20.
22.
Experiments on Vertical Joints of Precast Concrete Wall Panel Structures Considering Restricting Effects of Horizontal Ties - Mochizuki S Musashi Institute of Technology, Japan
A Study on Failure Control and Ductility of Layered Shear Wall Frame System - Mochizuki M, Umeda M Kogakuin University, Japan
21. Modelling Fire Performance of Concrete Walls - Buchanan AH, Carr AJ, Munukutla R Department of Civil Engineering, University of Canterbury
-• Rowe G.H., Smith L. M., Freitag S.A., Doyle R.B., St John D.A. • Central Laboratories, Works Corporation
49. Strength of Cement-Aggregate Bond -Taylor MA University of California, Davis, USA
5B Tiri Room Steel-Cement Composites and Construction
50. Development and Commercialisation of Advanced Strength Steel Cement Composites - Busck C.J. Fibre Cement Technology Ltd, Auckland
51. Ferrocement Applications in Housing - Paramasivam P, Lee SL
69.
Top-Down Construction - Construction Joints in Underground Concrete Structure - Takahei Y. Takenaka Technical Research Laboratory, Japan
70. A Top-Down Method of Constructing Permanent and Temporary Concrete Retaining Walls Incorporating Soil Nailing -• Ashley A., Bird A. * Smith Lecuhars Ltd, Auckland
9
FERROCEMENT APPLICATIONS IN HOUSING
Department of Civil Engineering
National University of Singapore
Ferrocement is a type of thin-wall reinforced concrete with high
performance characteristics such as high tensile strength to weight ratio,
ductility and impact resistance. It can be cost competitive through
mechanized production and proper choice of mesh reinforcement. The
National University of Singapore has since early 1970 made a considerable
effort to popularize ferrocement through research and development. Several
studies have been conducted on the application and performance of prototype
ferrocement structural elements. Some of the applications such as
sunscreens, wall panels and secondary roofing slabs for high-rise buildings
are presented in this paper.
INTRODUCTION
Ferrocement is a composite structural material comprising a cement mortar
matrix reinforced with layers of small diameter wire mesh uniformly
distributed throughout its cross section. The uniform distribution and
dispersion of reinforcement in the ferrocement composite provide better
cracking characteristics, higher tensile strength, ductility and impact
strength. Ferrocement has a high tensile strength to weight ratio and
superior cracking behaviour in comparison to conventional reinforced
concrete. Hence it is an attractive material for the construction of thin
wall structures.
One of the earliest application of ferrocement was the boat built by Lambot
in France in 1849 and subsequently Nervi promoted its use in civil engineering structures in 194.0' s. Since then numerous investigations
have been carried out at different research establishments around the
world on mechanical properties and basic technical information on various
aspects of design, construction and applications. ACI Committee 549 has
published the State-of-the-art report on its properties and potential
applications [l].
In the early seventies, ferrocement construction was labour intensive and
being low level technology, suitable for rural applications in developing
countries. It does not require heavy plant or machinery. As a result, a
great deal of interest has evolved in Southeast Asia regarding the
potential application in the field of agriculture industry and housing. In
an urban area of developed countries, it must be viewed from different
perspective. Ferrocement can be cost competitive through mechanized
production and proper choice of reinforcement in order to overcome the
actute shortage of labour.
551
reinforcement consisted of two layers of fine welded galvanised wire mesh, 1.2 mm in diameter with a 12.5 mm square grid separated by a layer of coarse welded wire mesh of 150 mm square grid and 3. 2 mm wire diameter (Figure 2). The yield strengths of fine and coarse wire mesh were 370 MPa and 485 MPa respectively. For the mortar matrix, the mix proportions of cement : sand : water by weight were 1 : 2 : 0.5. The sunscreens were cast in steel moulds in a precast concrete factory. After the necessary curing, they were painted and transported to the site. A special lifting device was used during erection. Three stainless steel bolts were used to connect the sunscreens to the· existing structure at each support (Figure 1), one 16 mm in diameter at the rear and two 12 mm in diameter at the front. About 500 sunscreens were installed on the 11-storey apartment blocks in three different estates. A typical block after installation is shown in Figure 3. Figure 4 shows a close-up view. It can be seen that the slender design achieved by using a ferrocement imparts a graceful appearance to the building.
Figure 2 Reinforcement layout in steel mould
Figure 3 Sunscreens after installation
553
7.5
01
3 mm</) Skeletal size Mesh size 150mm x 150 mm
1,2mm r/J Wire mesh Mesh size 12-5mm x 12,5mm
Polystyrene foam
Cement mortar
75
( e)
1·2 mm <I> Wire mesh Mesh size 25mmx 25 mm
3 mm </) Shear connector (Truss type) at 600 mm
3 mm </J Skeletal steel Mesh size 150 mm x 150 mm
1-2 mm rt> Wire mesh Mesh size 12-5 mm x 12-5 mm
Polystyrene foam
Cement mortar
3mm ¢ Shear connector (Truss type) at 600 mm
3 mm <I> Skeletal steel Mesh size 150 mm x 150 mm
1-2 mm r/J Wire mesh Mesh size 25 mm x 25 mm
Polystyrene foam
Cement mortar
Figure 5 Reinforcement details of sandwich panels
555
Figure 7 Ferrocement secondary roofing slab
reinforcement should preferably be spot welded together in the factory and
delivered for use in the precasting yard. The tolerance of the cover can
be achieved by means of plastic spacers. Because of the reduced
thickness, the dead weight of the ferrocement slabs would remain
approximately the same as that of cellular concrete panels.
Test programme included tests to determine cracking and ultimate moment
capacity of the slabs at various ages. The effect of weathering and thermal stresses on the strength and initial absorption of the slabs were
investigated by alternate wetting and drying tests and simulated cyclic compression tests respectively. From the analysis of test results,
ferrocement slabs provide a significantly higher safety factor than
cellular concrete slabs from strength and durability requirements. With
regard to the cost, ferrocement panels are more expensive than cellular
panels. However, it is expected that the frequency of replacement will be
reduced, which may justify the higher initial investment. Figure 8 shows a
view of secondary roofing consisting of ferrocement slabs on a high rise
building.
roofing on high rise flat
557