Creation of cracks of known sizes in reinforced concrete beams and performance evaluation of silane in concrete bridge decks

Abstract

Cracks are a major concern for the durability of concrete as they allow the harmful chemicals from outside to penetrate the concrete surface. Investigating the effect of various crack sizes is vital to further evaluate the surface treatments' performance. In this research, a novel technique is developed to create cracks of known size consistently in reinforced concrete beams using a very simple methodology which applies direct tensile load that cracks the beam. A variety of crack sizes is created ranging from very small (<1/100 inch [0.25 mm]) up to ½ inch [12.7 mm] and based on the results, a simple process is outlined which can be used to create predetermined crack sizes consistently. Silane is investigated as a surface treatment material, using Transmission X-ray Microscopy (TXM) and Optical Staining Techniques. The TXM results revealed that samples with silane coatings exhibited eight and half times less penetration of outside chemicals as compared to non-silane samples at a depth of 2 mm. In some samples, defects on the surface of the silane coating such as cracks, caused the coating to lose its efficiency. Quantitative measurements made using optical staining techniques show that silane thickness for all the 14 samples was 2.5 mm. This work shows in field applications that silanes are a useful and practical tool to significantly reduce the permeability of concrete.