Abstract: The present invention includes methods relating to the setting of fluids or slurries in a wellbore. In one embodiment, a method of isolating a portion a wellbore by preparing a sealant composition comprising a fluid component and a polymeric additive component, placing the sealant composition into a wellbore and subjecting the sealant composition to ionizing radiation. The ionizing radiation can cause bonding between polymeric additive components and create a polymer matrix within the sealant composition that increases the mechanical strength of the sealant composition.