INVESTIGATION INTO POROSITY INDICES OF NANOFIBER-REINFORCED CONCRETE

A literature review has been carried out on the eff ects of carbon nanotubes (CNT) and macrolevel fi ber on concrete porosity indices. The results are presented of investigations into the porosity of nanomodifi ed concrete with dispersed reinforcement (nanofi ber reinforced concrete) in terms of the kinetics of water absorption of nanotubes and hard fi ber. For dispersed reinforcement, use was made of various hard fi bers and their combinations: polymer, basalt, steel wire ones and those from wave-, anchor-, and straight profi le sheets. It has been established that the introduction of dispersed fi bers results in a change of concrete porosity indices. Hard fi bers break up relatively large capillary pores into smaller ones. In this case, the fi ber coarseness and its amount in a volume are important. In integrated fi ber reinforcement, the size of capillary pores either decreases or does not change at all with respect to the initial concrete. Intense mechanical mix agitation contributes to raising the porosity index. Hard fi bers of a more rigid structure tend to demonstrate a higher propeller eff ect in mixing. The presence of diff erent-scale hard fi bers makes it possible to avoid a propeller eff ect and the need to increase the concrete porosity index.
A literature review has been carried out on the eff ects of carbon nanotubes (CNT) and macrolevel fi ber on concrete porosity indices. The results are presented of investigations into the porosity of nanomodifi ed concrete with dispersed reinforcement (nanofi ber reinforced concrete) in terms of the kinetics of water absorption of nanotubes and hard fi ber. For dispersed reinforcement, use was made of various hard fi bers and their combinations: polymer, basalt, steel wire ones and those from wave-, anchor-, and straight profi le sheets. It has been established that the introduction of dispersed fi bers results in a change of concrete porosity indices. Hard fi bers break up relatively large capillary pores into smaller ones. In this case, the fi ber coarseness and its amount in a volume are important. In integrated fi ber reinforcement, the size of capillary pores either decreases or does not change at all with respect to the initial concrete. Intense mechanical mix agitation contributes to raising the porosity index. Hard fi bers of a more rigid structure tend to demonstrate a higher propeller eff ect in mixing. The presence of diff erent-scale hard fi bers makes it possible to avoid a propeller eff ect and the need to increase the concrete porosity index.
Author:  S. A. Zhdanok, S. N. Leonovich, E. A. Sadovskaya
Keywords:  nanofi ber-reinforced concrete, porosity, nanocarbon tubes, hard fi ber, dispersed reinforcement, concrete
Page:  417