Interaction Between Superplasticizers and limestone Blended Cements-Rheological Study
I. Torresan, R. Magarotto, and N. Zeminian
Appears on pages(s):
cement; limestone; superplasticizer
Recent interest in energy saving has stimulated the use of by-product materials in portland cement. After the introduction, in 1992, of the new standard specifications for cements, with the European Norm ENV 197/l, limestone blended cements have had a widespread diffusion, especially the CEM II AL portland cement, containing from 6 to 20% of limestone. Now, great attention is being paid to limestone blended cements in the manufacture of concrete, particularly for ready-mix concrete. Also, many evaluations of their performances compared with those of normal Portland cement have been undertaken in recent years. Some controversy has arisen, regarding problems of incompatibility which could eventually emerge between limestone cements and the admixtures traditionally used with normal portland cement. was therefore made to gain an insight into the elect of limestone on hydration and rheological properties of cement pastes. In this paper several types of limestone and clinker are taken into account and their chemical and physical characteristics are reported. Some superplasticizer admixtures have been tested and the behaviour of clinker/limestone blends in different proportions investigated in terms of their rheological properties (mini slump tests) and their capability of adsorbing the different superplasticizers. The absorption characteristics of various types of limestone and the dispersive efficiency of superplasticizers were studied, especialIy concerning limestone’s porosirnetric characteristics.