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Abstract The naturally occurring wastes contain a large number of active groups. In this study, shrimp shell wastes were modified chemically to form chitosan. When mixing concrete with a natural polymer the result revealed a synergistic impact on the characteristics and functionality of the concrete structure. The formed chitosan was characterized by Fourier-Transform Infrared Spectroscopy (FT-IR), Thermogravimetric Analysis (TGA), X-ray Diffraction (XRD), and Scanning Electron Microscopy (SEM). Five concrete mixes were designed to achieve the study objective. For certain concrete mixes, admixtures such as a natural polymer (chitosan), and chemical (superplasticizer) were added with 0.05% by weight of the cement content. Those admixtures were added to study their behavior on the characteristics of the concrete mixes, and then compare test results with control concrete mixes. Also, the purpose of the experiment was expanded to study the impact of adding the admixtures to fibrous concrete, as this fibrous concrete faces interlocking due to steel fiber's presence in the fresh concrete mixture. The results indicated that concrete-embedded chitosan exhibited significant enhancement in the mechanical properties. Further, the surface shape of concrete was characterized by the presence of chitosan crystallites which spread and filled the spaces in the chitosan structure. Also, it’s noted that chitosan can delay the rate of cement hydration to a small value, which may help in hot weathering concrete.
Yehia et al. (Wed,) studied this question.