Civil Engineering Reference
In-Depth Information
(a)
(b)
(c)
(d) (e)
19.3
Freshly produced MgO porous blocks with different aggregate
type and PC blocks as controls (Liska et al., 2012a): (a) PC with Lytag,
(b) MgO with natural aggregates, (c) MgO with Lytag, (d) MgO with
ash mix and crushed glass aggregates and (e) MgO with limestone
and crushed glass aggregates (larger blocks).
the degree of carbonation, with almost complete carbonation was achieved
with those optimisation studies (Unluer, 2012). Numerical modelling of the
carbonation process and particle packing calculations are being used for
further optimisation of these systems.
19.5.2 Concrete
In PC concrete formulations, using either PC alone or with 20% ash and/or
slag content, as is common practice in China, the impact of up to 20% of more
than ten different commercially available reactive MgOs, showed in general
very little sign of strength enhancement (li, 2012). However, one particular
MgO, which was produced as part of a controlled commercial trials process
in Xiuyan Deman Magnesium company in China, under controlled calcination
conditions, resulted in up to 27% increase in compressive strength with the
optimum of 4% reactive MgO content. All MgO contents led to an increase
in strength with the 15% MgO content leading to up to 10% increase (li,
2012). Despite the insignificant change to strength caused by the majority
of the MgOs tested, there were indications that there was a reduction in
permeability with the addition of a small percentage of MgO (li, 2012) but
more detailed investigation is being performed to verify this.
Investigations of the effect of MgO on PC-slag and PC-ash blends, in
comparison to PC concrete, presented evidence of the presence of different
hydration products in different compositions although again with minimal
