Fiber Distribution In New Hybrid Fiber Reinforced Cementitious Composites (NHyFRC)

Fiber distribution is closely related to the properties of fiber-reinforced cement-based composites?FRC?in fresh state and hardened state.Therefore,the research on fiber distribution is of great significance to the study of material preparation,performance optimization and mechanism analysis of FRC.This paper utilized fiber number and distribution coefficient to study the fiber distribution of steel fiber?SF?-Polyvinyl alcohol?PVA?-CaCO₃ new hybrid fiber reinforced cement mortar?NHyFRC?by image analysis.Based on the analysis of fiber distribution influencing factors,this paper studied rheological properties in fresh state and mechanical properties in hardened state of SF-FRC,PVA-FRC and NHyFRC.The quantitative relationship was established by numerical fitting between fiber distribution and rheological,fiber distribution and mechanical properties,respectively.The rheological parameters?yield stress,plastic viscosity?and mechanical properties parameters?bending initial strength,ultimate strength,bending toughness,etc.?were quantitatively characterized by fiber characteristic parameter and fiber distribution parameters,respectively,in order to provide reference for optimizing the performance of NHyFRC in fresh state and hardened state.The article focused on the distribution of fibers,as well as the quantitative relationship with rheological,and mechanical properties,respectively.The main results and conclusions were as follows:?1?The analysis of fiber distribution influencing factors.Under unified production method of specimen,the distribution of SF in FRC is greatly affected by gravity effect,wall effect,and template geometry.The gravity effect can be weakened to a certain extent by establishing an appropriate hybrid fiber system and improving the preparation method of FRC.The template wall effect and geometric dimension can be reduced by reasonable specimen shape and size design.?2?The optimization of fiber distribution.Adjust the variety and amount of admixture and mineral admixture in matrix.When 10%fly ash,8%silicon ash and 0.7%water reducing agent were added,the number of SF in the section of specimen is the highest.When 15%fly ash,14%silicon ash and 0.7%water reducing agent were added,fiber distribution coefficient was the highest.Select the type and specification of hybrid fiber.Compared with the FRC of 6 mm PVA,the number of SF on the cross section of 12 mm PVA was larger and the distribution coefficient was higher.That is,the longer the PVA length,the better the SF distribute.?3?Fiber distribution and rheology.The rheological parameters of NHyFRC with fixed amount of water reducing agent were significantly correlated with fiber number and distribution coefficient,showing equations of cubic in two unknowns.The rheological parameters of PVA-FRC and NHyFRC were numerical fitted with fiber characteristic parameters,fiber number and distribution coefficient,showing equations of ninth degree in two unknowns.?4?fiber distribution and mechanical properties.The mechanical parameters of NHyFRC with the same flow expansion were significantly correlated with fiber number and distribution coefficient,showing equations of cubic in two unknowns.The mechanical parameters of SF-FRC,PVA-FRC and NHyFRC were numerical fitted with the fiber characteristic parameters,fiber number and distribution coefficient,showing equations of ninth degree in two unknowns.The mechanical parameters of SF-FRC,PVA-FRC and NHyFRC can be predicted by fiber characteristic parameters and the fiber distribution parameter.