Commercial polymeric macro fibers Concrix ES having 500 µm diameter were treated to attain stronger adhesion with cement matrix. In order to improve their wettability with water, low pressure inductively coupled oxygen plasma treatment was used. Thus treated fibers were investigated from chemical and physical perspective. A direct horizontal optical static method enabling contact angle measurement directly on the fiber surfaces revealed that fibers treated only 5 s exhibited significantly better water wettability (approximately two times) while their mechanical properties were not influenced, as found by fiber tensile strength tests. Fiber morphology changes were observed by scanning electron microscopy – in contrast with reference fibers, the surfaces of treated samples were significantly roughened. The XPS analysis confirmed an exchange of surface atoms by oxygen ones within the 5 s of plasma treatment. A practical indicator of executed modification, pull out tests of selected fibers from cement paste samples (water to cement ratio 0.4), were done. It was shown that plasma treated fibers exhibited stronger chemical interaction with cement matrix by approximately 30%.Keywords: Plasma, oxygen, wettability, contact angle, pull-out tests, macro fibers
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