Prediction of optimal biomaterial and curing duration for self-healing concrete through designed experiments and decision tree algorithm

Abstract

Self healing concrete structures have been considered in recent decades due to their potential to repair cracks in an efficient manner. The current study considers three different biomaterials namely Bacillus subtilis, Bacillus Flexus and Bacillus Licheniformis to be mixed with concrete at fresh state to evaluate compression strength after 7, 14 and 21 days of curing in water medium. The cracked specimens are further allowed to cure in open atmosphere for 12 days to evaluate crack healing and post healed compression strength. Taguchi full factorial experimental design has been adopted for conducting experimental trials and experimental results has been analysed using signal to noise ratio method, desirability function analysis through Mini tab 17.0. In case of initial compression strength, Bacillus subtilis mixed concrete cube specimen cured for 7 days exhibited lowest value of 70 MPa and attained 260% (252 MPa) improvement when cured for 21 days, but opposite trend is observed for final compression strength. The optimum biomaterial and curing duration for pre and post compression strength has been determined using decision tree algorithm. The recommended combination of input factors and significant influencing factor identified from both the analysis methods are in good agreement.

Keywords:
Biomaterial; Compression Strength; Decision Tree Algorithm; Self-Healing Concrete