Durability properties of concretes made with CEM Ⅱ/B-LL and CEM Ⅱ/C-M (S-LL) cements

摘要

The inclusion of CEM Ⅱ/C-m N and CEM Ⅵ cements in the next version of DIN EN 197-1 means that more clinker-efficient cements will be covered by the standard. CEM Ⅱ/C-M cements contain at least 50 mass % clinker and CEM Ⅵ cements at least 35 mass %. Other main constituents are limestone, granulated blastfurnace slag, fly ash and pozzolans. Over the past years the German Cement Works Association (VDZ) has been involved in a series of research projects into the properties of concretes produced with some of these cements. This article describes the fresh and hardened concrete properties as well as the characteristic durability values of concretes made with CEM Ⅱ/C-M (S-LL) cements from these projects and other literature. Where possible, the results are compared with the evaluation criteria normally used in Germany and with the properties of concretes made with, for example, CEM I or CEM Ⅲ/A cements (reference concretes). The article also contains results from investigations with CEM Ⅱ/B-LL cements. CEM Ⅱ/B-LL cements are already included in DIN EN 197-1 but so far have only been used infrequently in Germany in the structural sector. Because of the availability of the raw materials they could, where applicable, become more important. The possible exposure-dependent applications of CEM Ⅱ/B-LL and CEM Ⅱ/C-M (S-LL) cements can be assessed with the aid of these data. The evaluation of in-house investigations and literature data that is presented shows that the essential requirements for fresh and hardened concrete properties for internal and external components can be fulfilled with CEM Ⅱ/B-LL and CEM Ⅱ/C-M (S-LL) cements. The limiting composition of 30 mass % granulated blastfurnace slag (sulfate-agent-free) is required for CEM Ⅱ/C-M (S-LL) cements. This means that theoretically about 3 million tonnes of granulated blastfurnace slag would be needed to produce all the internal and external components produced from ready-mixed concrete in Germany with CEM Ⅱ/C-M (S-LL) cements. According to relevant predictions this quantity will be available in Germany in the medium term although there are regional differences in availability. As far as their technical properties and the availability of the starting materials needed for their production are concerned this means that CEM Ⅱ/C-M (S-LL) and CEM Ⅱ/ B-LL cements have the potential to be used in wide sectors of concrete construction in Germany and in this way contribute to reducing CO_2 emissions from building with concrete.