Abstract
Reinforced concrete is an important material in the building industry but its durability is limited mainly due to corrosion of the steel reinforcement. In almost all cases, degradation of concrete is ultimately related to the presence of water and the transport of dissolved ions, particularly chloride, through the capillary pore network of the cement paste. Conventional characterisation techniques are often inadequate for producing reliable information to assess degradation, protection and repair of concrete. Alternative characterisation techniques are therefore urgently required and the research described here is in response to that requirement This thesis describes how Nuclear Magnetic Resonance (NMR) and Ion Beam Analysis (IBA) techniques have been developed to investigate cement-mortar. The NMR techniques employed are both quantitative and non-destructive. It is shown how NMR relaxation analysis can be used to deduce the pores size distribution of cement mortar based on the surface relaxation and fast diffusion model. NMR techniques can be used to gather time series information from any single sample. It is explained how information can be acquired about both capillary and gel pores, simultaneously. NMR imaging (specifically SPRITE) has been used to measure water transport in-situ through cement-mortar samples. Results are also presented assessing the application of both liquid phase hydrophobic silane treatment and for the first time vapour phase hydrophobic silane treatment on cement-mortar. Ion beam analysis has been applied to simultaneously measure chloride and water content in cement-bound samples. IBA results show how the transport of chloride and water are related in cement-mortar made with different binder compositions including Portland Cement (PC), Ground Granulated Blastfurnace Slag (GGBS), and Pulverised Fuel Ash (PFA). The three ion beam analysis techniques that have been described in this thesis, which have been used for the study, are the particle induced X-ray emission (PIXE), nuclear reaction analysis (NRA) and Rutherford backscattering (RBS) techniques. For the first time, results have been presented to show simultaneously acquired profiles of water, chloride and calcium in cement-mortar.