Shrinkage cracking and mechanical properties of cementitious composites produced with multiwall carbon nano tubes and different types of polypropylene fibres.

This study was conducted to experimentally demonstrate the control the nano-, micro- and macro-scale cracking in cement-based composites by using nano-, micro- and macro-scale fibres. While micro, macro and hybrid system polypropylene (PP) fibres were used in concrete designs, micro-scale PP and multi-walled carbon nano tubes (MWCNT) were utilized in mortar mixtures. The progression of the cracks was monitored in accordance with a well-known standard and also with a modified method which enabled the investigation of plastic and restrained shrinkage. Fracture energy, flexural strength, compressive strength, modulus of elasticity and ultrasonic pulse velocity of the samples were also determined as the mechanical properties of the composites. Results showed significant improvements in the reduction of cracks, especially with hybrid fibres system. • Cracks at three levels (nano, micro and macro level) were controlled. • Effects of hybrid PP fibres on shrinkage and mechanical properties. • MWCNT dispersion without ultrasonification. • Modified test method was used for combined plastic and restrained shrinkage. • Flexural strength and fracture energy were improved by the use of fibres. [ABSTRACT FROM AUTHOR]