An Investigation on Effects of PP Fibers and Nano Particles on Physical and Mechanical Properties of Reinforced Concrete

摘要

This paper reports the effects of simultaneous application of polypropylene (PP) fibers and Sio2 and TiO2 nano-particles on some physical and mechanical properties of concrete. Fibers and nano-particles are used in different proportions in concrete mixture according the results of Design of Experiment analysis. Important hardened concrete properties such as 7-day and 28-day compressive strength, flexural strength, and water absorption were evaluated. Optimization of the mixture design was conducted in two stages. In first stage, SiO2 nano-particles and PP fibers with different proportions were added to the concrete mixture and 7-day and 28-day compressive strength, tests were carried out. The results were compared and mixture of sample with optimum strengths was selected for the second stage. In the second stage, TiO2 nano-particles were added to the optimum mixture and physical and mechanical properties of samples were evaluated. The results indicated that adding two weight percents of SiO2 nano-particles and PP fibers simultaneously, can effectively improve the cracking level and reduce the content of Ca(OH)2 and produce more Calcium-Silicate-Hydrate (C-S-H) resulting in a denser, more homogeneous Interfacial Transition Zone (ITZ) microstructure, respectively.