Influence of clay minerals on the effect of PCE superplasticizers: Problems with the effectiveness of a polycarboxylate superplasticizer in concrete

摘要

Conventional PCE superplasticizers fail, in particular, in the presence of bentonite as a contaminant in concrete. Other common clay minerals, such as kaoline or mica, have a less antagonistic effect. The negative impact of clay minerals on PCEs can be mitigated by various measures. In case of problems with the effectiveness of a PCE superplasticizer in concrete, it is recommended to carry out tests concerning the presence of clay contaminations. The methylene blue test is in particular recommended, by which the amount of extremely harmful bentonite can be determined quantitatively.