Flexural stress enhancement of concrete by incorporation of algal cellulose nanofibers

Using nanofibers as a reinforcement material in the concrete and its positive effect on the concrete strength is one of the most popular topics in recent years. In the present study it was demonstrated that the nanofibers derived from waste algae (Cladophora sp) increased 2.7 times the flexural stress of the concrete. Firstly, the cellulose nanofibers were derived from Cladophora sp algae which stand in the nature as a waste and can be collected in tones. The obtained cellulose nanofiber and the commercial cellulose were characterized by Fourier Transform Infrared (FT-IR) Spectroscopy, Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), X-ray diffractometry (XRD) and Scanning Electron Microscopy (SEM) methods. Then, various amounts of the cellulose nanofiber and the commercial cellulose were added in the cement paste. Before the flexural stress tests, the concrete samples were left to dry for one week. Flexural stresses of the concrete samples were measured by the three-point bending test. The flexural stress of the control concrete sample (with no nanofibers) was measured as 2.21 MPa. The flexural stress of the concrete sample added 1.0 g cellulose nanofiber (derived from algae) were measured 5.96 MPa. On the other hand, it was determined that the commercial cellulose fibers decreased the flexural stress of the concrete samples. The used Cladophora sp algae in this study has a worldwide potential of extreme algal blooming in the aquatic ecosystems and the algal blooming of Cladophora sp causes to eutrophication of water sources. In this study it was proven that removing of algal mats from nature and using them as a reinforced material in concrete can be wisely solution instead of the synthetic cement paste additives.