Flowable material to isolate or treat a surface

A flowable material to isolate or treat a surface comprising a plurality of manufactured composite particles, wherein each composite particle comprises:

• a degradable core, and
• a sealant layer at least partially encapsulating the core, the sealant layer comprising a hydratable sealant material that is capable of absorbing water and swelling,
• the core being relatively dense compared to the sealant layer, and the composite particle having a specific gravity greater than one,
• wherein the sealant layer when hydrated absorbs water and swells to form a barrier layer containing a continuous layer of the sealant material, the barrier layer having a low water permeability effective to prevent leakage of water and contaminants.

A flowable material to isolate or treat a surface comprising a plurality of manufactured composite particles, wherein each composite particle comprises:

• a core, and
• a sealant layer at least partially encapsulating the core, the sealant layer comprising a pozzolanic material that is capable of absorbing water and swelling,
• the core being relatively dense compared to the sealant layer, and the composite particle having a specific gravity greater than one,
• wherein the sealant layer when hydrated absorbs water and swells to form a barrier layer containing a continuous layer of the pozzolanic material, the barrier layer having a low water permeability effective to prevent leakage of water and contaminants.