Abstract

BERNAL LOPEZ, Susan et al. Modeling of the compressive strength of alternative concretes using the response surface methodology. Rev.fac.ing.univ. Antioquia [online]. 2009, n.49, pp.112-123. ISSN 0120-6230.

In this paper is to present the compressive strength reported by alternative concrete at ages of curing of 7, 28, 90 and 180 days. These materials were produced applying alkaline activation processes to binary systems based on granulated-blast furnace slag (GBFS) and high purity metakaolin (MK). As alkali-activator a waterglass solution (Na₂SiO₃.nH₂O + NaOH) was used and its dosages were adjusted in order to get a SiO₂/Al₂O₃ molar ratio between 3.6 and 4.4. The results at 28 days of curing were analyzed through the statistical methodology of response surface (M.S.R). As study factors have been considered: the amount of MK into the binder (CMK) and the SiO₂/Al₂O₃ molar ratio in the binder (Rm). From the proposed statistical model the compressive strength contours, as function of the binder variables, are identified and it is predicted that concretes elaborated from alternative binders with a GBFS/(GBFS+MK) ratio of 0.9 and Rm of 4.2, it is possible to obtain compressive strengths up to 74 MPa. It important stand out that concrete composed by binary systems of GBFS/MK to develop compressive strengths up to 56 MPa at 7 days of curing and up to 80 MPa at 180 days of curing, which is expected for high mechanical performance materials.

Keywords : Granulated-blast furnace slag; metakaoline; alkaline activated binders; compressive strength; response surface methodology.