Effects of sodium dodecyl sulfate on nano carbon black-filled cement paste: performance and microstructure

Abstract

The conductive potential of nano carbon black (NCB) in cement paste is restricted due to its tendency to agglomerate. To address this issue, sodium dodecyl sulfate (SDS) is proposed as a dispersant to enhance the performance of the nano carbon black-filled cement paste. Additionally, the microstructure characteristics of the nano carbon black-filled cement paste with SDS are explored systematically from the perspective of micromorphology, hydration degree and pore structure. UV–Vis spectrophotometry (UV–Vis) proves that SDS can enhance the dispersion of NCB in suspensions. Adding 0.4% SDS to the nano carbon black-filled cement paste can effectively improve the fluidity, accelerate the setting time, decrease the resistivity and increase mechanical strength. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) reveal that SDS adsorbed on the surface of NCB plays a dispersing role in cement paste. Thermogravimetry (TG) indicates that well-dispersed NCB promotes the hydration of cement clinker, accelerates the formation of calcium silicate hydrates (C–S–H) and increases the content of Ca(OH)2. N2 adsorption-desorption (NAD) verifies that the accumulated hydration products effectively increase the specific surface area and decrease the total pore volume, indicating that SDS has a positive effect on optimizing the pore structure of the nano carbon black-filled cement paste.