Feasibility of roundpole timber and lime concrete composite flooring


The feasibility of using a layer of roundpole timber topped with a layer of lime concrete for flooring applications was investigated to obtain environmental and energy benefits compared with conventional construction. Because lime concrete is weaker than Portland cement concrete, the composition was optimised. A lime:aggregate ratio of 1:3 and a water:lime ratio of 1:2 gave a 28-day strength of 9 N/sq mm. Panels were constructed using five 3.4 m Douglas Fir poles (which tapered from 130 to 100 mm in diameter) laid side by side and overlaid with a layer of concrete. Portland and lime concretes were compared. Different quantities of shear connectors were used to bond the poles to the concrete, and panels were tested under three-point bend over a 3 m span. Lime concrete dramatically reduced the deflection compared with timber alone, and the system was considered suitable for medium span domestic flooring. Lime concrete slabs exhibited greater deflection and lower failure loads than Portland cement slabs.

Primary author(s): Hodsdon T

Source: Struct.Eng.

             Vol.81, No.4, 2003, p.15-16


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