The pot life depends on the curing chemistry, temperature and the presence or absence of catalysts. Amine cured epoxies cure at or around room temperature, anhydrie cured ones at high tempertaure. If the amine is aromatic, it may also cure at higher temperatures. High temperature curing resins usually require catalyst/accelerator. It may also depend on, whether you are using liquid or solid resin. So please specify your system. Cooing may also extend the lifetime.
The pot life depends on the curing chemistry, temperature and the presence or absence of catalysts. Amine cured epoxies cure at or around room temperature, anhydrie cured ones at high tempertaure. If the amine is aromatic, it may also cure at higher temperatures. High temperature curing resins usually require catalyst/accelerator. It may also depend on, whether you are using liquid or solid resin. So please specify your system. Cooing may also extend the lifetime.
For your application you may have to use some solvent and decrease application the temperature as suggested by Khairiah and Alisa. If you don't want volatiles you may also use a mixture with aliphatic low viscosity epoxy resins. However, they don't have the strength of aromatic ones. After your mixture have diffused in the microcracks you may then postcure at the desired temperature for your system.
If these solutions do not work for you then you will have to consider another type of chemistry. such as unsataturated polyesters or acrylics.
I may add as a suggestion specialty resins called 3P based on isocyanate/water glass combination, product of Polinvent Ltd. (http://polinvent.com/?page_id=13) designed for various purposes, including injection. The pot life can be varied in a considerably wide range.
Polyester resins cure fast than epoxy resins and as you said the strength of polyester resins is lower than epoxy resins and adding solvent or changing their compounds may cause cracks. thank you so much.
@Ahmad. In your answer you mention changing the the resin/hardener ratio to increase the potlife. Please check the physical properties of the hardened resin carefully as if you offset the stoichiometric ratio you may have undercured resins with inferior properties.
Ahmad, actually with unsaturated polyesters you can use some initiators that will give you a pot life greater than 24h even at room temperature. The resin won't start polymerizing unless you heat it above the activation temperature.
You can perform the impregnation at, say 40C, the viscosity will be OK at this temperature but the yield of reaction if the impregnation process proceeds fast - will be low. Upon impregnation place the sample into freezer.
So the impregnation of the rock takes around 10hrs? My suggestion is to soak the rock samples in one part of the two part mixture overnight before adding the second component to create the resin.
Maybe higher air pressure around the sample may help force the liquid into the small gaps?