Enhanced ohmic heating and chloride adsorption efficiency of conductive seawater cementitious composite: Effect of non-conductive nano-silica

Nano-silica (NS) as a non-conductive nanofiller was utilized to promote performance improvement of conductive seawater cementitious composite (NS-CSWCC) manufactured by ohmic heating (OH) curing at -20 degrees C. NS exhibited great advantage on improving the heating efficiency of OH cured sample. The peak temperature and temperature-increase rate of NS-CSWCC samples increased from 52.7 degrees C and 0.27 degrees C/min to 73.4 degrees C and 0.43 degrees C/ min with NS contents varying from 0 to 0.8 wt%. The enhanced mechanism of NS on heating efficiency was thoroughly clarified. The mechanical property results showed that NS-CSWCC sample with 0.8 wt% NS addition endowed the compressive strength of 83.5 MPa, meeting an increase of 36.4% comparing with that of the sample with no NS addition, indicating the advantage of NS addition on improving the mechanical properties. Besides, NS could also lead to higher Cl- binding ratio of OH cured samples. To be specific, the Cl- binding ratio of the sample with 0.8 wt% NS addition met an increase of 35.1% comparing with the sample incorporating no NS. Detailed micro-physicochemical analyses were conducted to reveal the mechanism behind increased Cl- binding efficiency.

Automated summary

This study utilized nano-silica (NS) as a non-conductive nanofiller to promote the performance improvement of conductive seawater cementitious composite (NS-CSWCC) manufactured by ohmic heating (OH) curing. The results showed that NS greatly improved the heating efficiency of OH cured samples, and increasing the NS content enhanced the peak temperature and temperature-increase rate. Furthermore, NS addition improved the mechanical properties and Cl- binding ratio of the composite material.