Experimental and Theoretical Investigation of Precast Concrete Hollow-Cored Slabs used as Horizontal

Preservation of structural timbers On 20 August last year, we included a letter from Mr P. A. Campbell of the State of Victoria, Australia, questioning dependence simply on 'prorecess control’ for the treatment of structural timbers (as opposed to direct sampling of degree of penetration), with particular reference to radiata pine. In our column for the following 15 October, correspondents with firms concerned with carrying out such treatments (Mr G. O’Brien of Permacrib, Cheltenham, and Mr G. J. Cavanagh, of Pinex Timber Products, Auckland, NZ) responded, claiming reliability for the procedures concerned. On 18 February this year, we included a letter from Mr M. Connell, of Hickson Timber Products, advocating the benefits of a process-type specification for timber products as against a results-type specification. Mr Campbell has now sent us two further letters on the subject, including also a copy of a letter to him from John Falloon (Minister of Forestry, Wellington, New Zealand). Mr Campbell explains his receipt of the latter following our October correspondence: I wrote to the Director of the NZ Forest Research Institute (NZ FRI) asking for details of its treatment procedures that ensured ‘the full penetration of CCA preservative through the heartwood of radiata pine’. They did not reply, so after 2 months I wrote to their Minister. Verulam