The addition of sodium carbonate found to influence the pH of common brick clays to varying extents. The effect varies depending upon the soluble salts presence in the clays. The higher the soluble salts the lesser will be the effect on improvement of plasticity by addition sodium carbonate.
In some clay mines its is usual practice to add barium carbonate into the clay to dilute the effect of soluble salts so that the sodium carbonate can be added subsequently for improving the plasticity.
In the opposite way to reduce the plasticity addition of chemicals like NaCl, FeCl3 or Al2(SO4)3 can be added. Air bubbles in a clay body can reduce the plasticity.
To be contd…………
