Capillary absorption in concrete and the Lucas–Washburn equation

Capillary absorption kinetics of concrete–ethylene glycol system was studied with respect to concrete matrix porosity and liquid viscosity. Porosity of specimens was altered by air-entraining agents and superplasticizers. Liquid which doesn’t react with cement gel was chosen for the experiment in order to study the reasons for deviation from Lucas–Washburn equation observed in concrete–water system. Viscosity of ethylene glycol changes from ∼23 to 2 mPa s in the temperature range from 20 to 100 °C. The values of the capillary coefficient were determined at 20, 60 and 100 °C using Neutron Radiography and were found to be in the range from ∼1.5 to 4.9 mm h−1/2. The results show that the Lucas–Washburn equation in concrete–ethylene glycol system is valid only for ∼25 h, which indicates that swelling and rehydration of cement gel are not the main reasons for deviation observed in concrete–water system.