Executive Summary : | The adoption of prescriptive norms for concrete durability has led to premature failures, prompting a shift towards a rational paradigm of "durability design" based on quantifying physicochemical processes. Moisture transport in concrete has been extensively studied, but there is limited data on the hygrothermal behavior of concrete exposed to real environments, which is crucial for modeling deterioration. The proposed project aims to study the interaction of concrete with its meso-climate to assess the influence of diurnal and seasonal changes in ambient temperature, relative humidity, solar radiation, wind, and rainfall conditions on temperature and relative humidity distributions in cover and core zones. The obtained data will help resolve the need for non-isothermal and surface-layer related non-homogeneity effects in the modelling of transport processes. The recorded data will also enable the inverse modelling of hydraulic diffusivity and boundary fluxes based on suitable parametrizations. This is critical for the simulation of moisture distribution in concrete matrix, but remain unsolved due to the absence of relevant variables in existing models. The developed metamodel will be used to simulate moisture influential depth in typical concretes and combine with models for carbonation prediction to enable rational selection of concrete cover thickness for different climatic zones of India. Experimental work will involve continuous measurements of temperature and relative humidity, permeability, sorption, and absorption tests, and estimation of isotherms, pore size distribution, and capillary porosity of concrete at different ages. The outcome will reduce the gap between scientific models and practical observations, enabling pragmatic durability design. |