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Articles

Effect of Using Ozone Modified Waste Hempfiber on Some Fresh and Hardened State Properties of Cementitious Systems

Abstract

It is known that various fibers are used to improve the brittle behavior of cementitious systems. In the production of artificial

fibers used for this purpose, greenhouse gas emissions, which have become one of the biggest ecological problems of our

day, occur in addition to economic reasons. This situation has caused the use of natural fibers in cementitious composites

to become widespread. In addition, the reuse of waste materials in the construction sector has gained importance due to

the increase in greenhouse gas emissions. In this context, the use of hemp waste fibers, which have an important potential

in the development of environmentally friendly building materials, has become widespread in cementitious systems.

Since the low surface roughness and hydrophobic structures of natural fibers negatively affect the mechanical performance

and durability of mortars, the fibers need to be modified with chemical and physical processes. In this study, the effect of the

use of waste hemp fibers modified with ozone gas on the performance properties of cement-based mortars was investigated.

Hemp fibers with a length of 6 mm were surface modified with ozone gas for two different periods (45 and 90 minutes)

and were replaced with 0.5% aggregate by volume. In all mixtures, polycarboxylate-ether based high performance water

reducing admixture was used by keeping the water/cement ratio 0.52 and the flow value 180±20 mm constant. The flow,

pressure and flexural strength of the mixtures were examined comparatively with the control mixture. It was observed that

the flow performance of the mixtures was negatively affected by the use of fiber.

It was determined that the need for the admixture increased in mortar mixtures containing hemp. The water reducing

admixture need of the mixtures was not affected by the fiber surface modification. With the addition of fiber, a significant

decrease was observed in both the pressure and flexural strength of the mixtures. It was observed that the 45-minute ozone

surface modification process applied to eliminate mechanical strength losses increased the pressure and flexural strength

of the mixtures by strengthening the fiber-matrix interface.