Swelling Potential of Clayey Soil Modified with Rice Husk Ash Activated by Calcination for Pavement Underlay by Plasticity Index Method (PIM)

Table 3

Chemical oxide composition of the additive materials.

Materials	Oxides composition (content by weight, %)
	SiO2	Al2O3	CaO	Fe2O3	MgO	K2O	Na2O	TiO2	LOI	P2O5	SO3	IR	Free CaO
Clay soil	22.45	28.09	2.30	10.66	4.89	12.10	14.33	0.07	—	5.11	—	—	—
Rice husk ash	56.48	22.72	5.56	3.77	4.65	2.76	0.01	3.17	0.88	—	—	—	—

IR is the insoluble residue; LOI is the loss on ignition.