While studying the effect of any admixture on the corrosion protection behavior of
concrete, it is essential to see its effect on the compressive strength of concrete also. In
view of this, compressive strength of above mentioned concrete mixes were determined
after curing for different ages. Change in the compressive strength of all the five types
of concrete mixes with curing ages is shown in (Figure 13). This shows that the
compressive strength of all type of mixes gradually increases with curing time. OPC
which shows maximum strength after 1 day curing shows minimum strength after 56
days. SRC blended with densified microsilica shows highest strength at all the curing
ages after 3 days. Improvement in the compressive strength after blending the two types
of cement with densified and undensified microsilica at a standard curing age of 28 days
have been shown in (Figure 14A (in %) and 14.B in (psi). These Figures show that
blending of densified microsilica increases the compressive strength of SRC by 32%
(2020 psi) and of OPC by 23% (1400 psi) while undensified microsilica increases the
compressive strength of OPC by 10% (610 psi) only. Thus, densified microsilica
appears to be more effective in increasing the compressive strength of SRC than OPC.
5. CONCLUSIONS
(i) Both OPC and SRC exhibit good corrosion resistance in seawater.
(ii) Blending of OPC with microsilica decreases the corrosion of rebars when the
concrete is exposed to a chloride atmosphere while it enhances the corrosion in
seawater.
(iii) Blending of SRC with microsilica suppresses the corrosion of rebars when the
concrete is exposed to seawater.
(iv) Microsilica causes drastic decrease in the permeability of chloride ion in OPC as
well as SRC concretes.
(v) Blending of microsilica increases the compressive strength of SRC concretes 10%
more than OPC concretes.
(vi) Densified microsilica appears to be a better admixture than undensified one.