An investigation into deep penetrating treatments of concrete structures to improve durability
Creators: name: Govinnage Don, Dilanka
Publisher: name: RMIT University
Year: 2024
Subjects: classificationCode: 400505
subject: Construction materials

description: Reinforced concrete has been established as the most widely used construction material in the world. Corrosion caused in reinforced concrete structures by ingression of contaminants which is costing developed countries approximately 2.5% of national annual GDP is a major challenge faced by the corrosion engineers and asset managers. Research to date has discovered several innovative ways in retarding the degradation of reinforced concrete structures. Use of sealer products is one of the ways in fighting the battle against corrosion. While there are several types of sealer products with different properties this research is focused on a penetrating sealer product. <br><br>This research study aimed at evaluating the effects of a hydrogel based penetrating sealer treatment on the mechanical and durability properties of concrete and its ability to delay reinforcement corrosion due to chloride ingress and carbonation. <br>A comprehensive review of literature identified the different types of sealers currently utilized in the construction industry and their characteristics, factors influencing the performance of a sealer treatment, as well as experimental procedures adopted in evaluating the performance of sealers in the laboratory. Also, a review of literature on chloride transport models are examined. The significance of the X-ray computed tomography imaging technique as a method of mapping the concrete pore matrix is also discussed. The major gap in knowledge is identified as the inadequacy of research undertaken to understand the effect of penetrating type sealers incorporating long term performance characteristics and the little utilization of modern imaging techniques such as X-ray computed tomography in these studies.<br><br>A comprehensive experimental program was planned and conducted to understand the effect of the hydrogel based penetrating sealer treatment on the mechanical and durability properties of six types of concrete mixes different characteristics. Performance parameters investigated include compressive strength, Poisson's ratio, modulus of elasticity, air and water permeability, ultrasonic pulse velocity, electrical resistivity, surface hardness, chloride diffusion and carbonation. Results of the experimental study indicated that hydrogel based penetrating sealer treatment had no significant effect on the mechanical properties. But, sealer treatment initially has a significant improvement on the air permeability. However, this improvement reduces with time. In addition, the improvement is more pronounced in 1 day treated specimens than 28 day treated specimens. Furthermore, treatment was found to affect different types of concrete in different ways. Treatment improved the water permeability of GGBS and high strength concrete but had no effect on OPC concrete mixes. An anomalous behaviour was observed in low strength treated specimens when exposed to water.<br><br>Another major component of the research is developing a novel method of using X-ray computed tomography imaging in determining the pore structure of concrete. This was successfully achieved and the suitable parameters for concrete X-ray imaging were established. A software program was developed as a part of the project using Python programming language to analyse the data from CT X-ray scans. Functions of the program were limited to determining the sizes of pores and tabulating them.<br>