Chemical evaluation of cement-based sandcrete wall deterioration: Fid-Bau Portal

Chemical evaluation of cement-based sandcrete wall deterioration

Odigure, Joseph O.

Cement-based structure stability could be characterized not only by their mechanical strength, soil geophysics and loading condition, but also the resistance to various physical and chemical factors that could initiate its corrosion. The contribution of water and various water-based solutions in the environment, to cement-based structure durability could be either physical as in seasonal flooding of the structure or chemical often initiated by the presence in the solution of organic or inorganic compounds or gases. Irrespective of the corrosion type, its destructive effect could be attributed to the build up of internal stress and weakening of the structure matrix. This work is aimed at investigating the role of chemical changes in the sandcrete matrix in the formation and development of macrocracks in cement-based sandcrete walls. Collected sandcrete samples were analyzed using titrimetric and granulometeric methods. Results showed that the percentage composition between the top and bottom of SiO₂ was high in all the sandcrete blocks samples analyzed ranging from 76.72% to 80.30%. This indicates high permeability of ground level structure. The acidic nature of the soil in some area varying from pH = 5.89-6.11 could seriously undermine the structures strength. The percentage compositions of CaO were generally very low ranging from 3.83% at the ground to 4.44% at the top levels. For most points there were percentage compositional differential across cracked points horizontally and vertically. This is an indication of either poor cement quality or non-compliance to standards' requirements. There is a need to develop a model equation for the migration of minerals' hydrates in sandcrete wall.