In the late 1990’s UKCSA part financed, and was heavily involved in, a two year research project into cast stone in conjunction with the University of Dundee, under the UK government’s Department of the Environment, Transport and the Regions (DETR) “Partners In Technology” (PiT) programme. After extensive investigation, experimentation and research, the University of Dundee determined that “All Cast Stone products, and particularly when waterproofed, were found to be highly resistant to carbonation. Efflorescence did not occur in any of the test samples and weathering in Cast Stone was similar to that in control natural stone. The data also suggests that dry-cast, Cast Stone is no less vulnerable to frost attack than natural stone.” The results also indicated “that the waterproofer used in all test samples is probably the most important characteristic controlling surface weathering performance.”
The University of Dundee, in the PiT Report Executive Summary went on to indicate that “the performance and durability of Cast Stone was directly related to its underlying “quality”, as determined by its strength, and was not reliant wholly upon the use of waterproofer. To ensure that Cast Stone supplied from UKCSA manufacturers was of a suitable “quality” the minimum compressive strength was recommended to be increased to 35 MPa (35 N/mm2 ) for contracts commencing January 1st 2000 onwards. However, given it’s importance to the final performance of the material, it was also felt that specifications should consider making the use of an integral waterproofer mandatory.” The Full Report also concludes that: “In general, all dry Cast Stone Samples tested weathered in a similar way to the natural stone from the results of the accelerated weathering test.”
UKCSA took up all of the recommendations arising from the PiT study and research and every cast stone manufacturing Member of the UK Cast Stone Association has to regularly demonstrate that they use an integral waterproofer in their cast stone mixes and that they achieve a minimum cube compressive strength of cast stone of 35 MPa, as a condition of their continuing membership of the Association. The enhanced UKCSA Member cast stone cube strength requirement is at least 40% above the British Standard and ensures strong cast stone with outstanding durability and site handling capabilities.