Study on the effect of rice husk ash and nano silica on the early hydration kinetic characteristics of oil well cement

Abstract

To explore the feasibility of using rice husk ash (RHA) as a substitute for nano-silica (NS) in partially replacing oil well cement and establishing a green, low-carbon oil well cement system, this study explores the effects of RHA and NS on the early hydration kinetics of cement using isothermal calorimetry at 20, 30, and 50 °C. The hydration exothermic rate and cumulative heat release of oil well cement with varying RHA and NS dosages were analyzed by isothermal calorimetry. Based on the Krstulovic’-Dabic’ model, hydration kinetics were evaluated and validated through thermogravimetric analysis. Results showed that RHA accelerated the peak exothermic rate and increased its intensity by 11.09 % and 38.62 % at 20 °C and 30 °C, respectively, with temperature effects being more pronounced at 50 °C. Both RHA and NS shortened induction and acceleration periods, enhanced product nucleation and growth rates, and prolonged phase boundary reactions. As temperature rose, RHA's pozzolanic activity significantly boosted cement hydration. The kinetic model effectively described the early hydration characteristics, offering insights into RHA's role in cement hydration.