Unknown (1990) Admixtures for concrete : proceedings of the International Symposium held by RILEM (The International Union of Testing and Research Laboratories for Materials and Structures) and organized by RILEM Technical Committee TC-84AAC and Departmento de Ingenieria de la Construccion Escuela Tecnica Superior de Ingenieros de Caminos, Canales y Puertos Universitat Politécnica de Catalunya, Spain, Barcelona, May 14-17, 1990. [Online]. London New York : Chapman and Hall. Available from: http://access.bl.uk/ark:/81055/vdc_100058316839.0x000001