Influence of silica fume and metakaolin on carbonation rate of concrete: relationship with strength, absorption and w/c ratio

<p></p><p>Abstract Silica fume and metakaolin are high reactivity additions that can be used with partial cement replacement or the simple addition principle, increasing the amount of binder in the composite. On the other hand, the carbonation process is important for the service life of reinforced concrete structures due to its influence on steel reinforcement corrosion. This research aims to investigate the influence of silica fume and metakaolin used as addition or partial cement replacement on concrete carbonation. Furthermore, the relationship of carbonation with absorption, water/cement ratio and compressive strength of the concrete was investigated. Thus, a 1.0: 2.25: 3.00 concrete mixture with 0.5 water/binder was fixed and 10% cement addition and replacement was used. In the case of the use as addition, the unit mixture was changed to 1.0: 2.05: 2.73 with water/ binder 0.5, as an inherent consequence of the addition. The results indicate that the compressive strength, the absorption and the water/cement ratio influence the carbonation rate and, when related to the carbonation coefficient using an index considering the joint influence of these quantities, are highly representative. An example of this is the proposed coefficient designated as K(sorptivity.water/cement)/compressive strength.</p><p></p>