Study on thermal conductivity of cement-based material with thermosensitive PNIPAM solution

Good thermal insulation performance is crucial for the application of cement materials, and reducing thermal conductivity is an effective strategy to enhance thermal insulation performance. Thermosensitive poly-N-isopropylacrylamide (PNIPAM) undergoes a phase transition around its lower critical solution temperature (LCST) of approximately 32 °C, and its incorporation can significantly improve the thermal insulation properties of cement. This study investigates the effects of adding PNIPAM in concentrations ranging from 0.3 % to 1.5 % on the thermal conductivity of cement-based materials at temperatures of 25 °C, 32 °C, and 37 °C. At 37 °C, the thermal conductivity of the cement sample decreased from 1.728 W/m·K to 0.811 W/m·K, representing a substantial reduction of 53.05 %. However, increasing the PNIPAM content also affected the hydration process of the cement mortars, leading to longer initial and final setting times and a slight decrease in both compressive and flexural strength. Additionally, the viscosity of the PNIPAM solution increased the overall viscosity of the cement mortar, resulting in reduced fluidity.