A rheological system includes a sample chamber, a compressed air system configured to provide compressed air to pressurize the sample chamber, and a rotor configured for rheological measurement of a material with variable volume, the rotor including an elongated shaft extending to a measurement portion having a widened geometry relative to the elongated shaft. The rotor is dimensioned such that a compression ratio of at least 5 to 1 is achievable while maintaining material cover of the sample over the entirety of the measurement portion of the rotor, the compression ratio being defined by a decompressed volume of a sample when the sample chamber is not pressurized to a compressed volume of the sample when the sample chamber is pressurized. Methods of taking rheological measurements with such a rotor are also disclosed.