Process of fracturing subterranean, oil-and/or gas-bearing formations by injecting an aqueous fracturing fluid into a wellbore at a rate and pressure sufficient to penetrate into the formation, and to initiate or extend fractures in the formation, wherein the aqueous fracturing fluid is obtained by mixing at least an aqueous base fluid and an aqueous polyacrylamide concentrate having a concentration of 3.1 to 14.9% by weight of polyacrylamides, relating to the total of all components of the aqueous polyacrylamide concentrate, and wherein at least a part of the aqueous fracturing fluid injected additionally comprises a proppant.