Evaluation of concrete cover depth for green concretes exposed to carbonation

Abstract

Carbonation resistance of fly ash concrete (FAC) and recycled aggregate concrete (RAC) has been extensively tested in the past decade, but there are still no recommendations for their application in codes of practice. Therefore, the main objective of this study was to determine the minimum concrete cover depth of RAC and FAC exposed to carbonation to satisfy the required service life. In this study, the relationship between concrete compressive strength at 28 days (fcm) and inverse effective carbonation resistance (R−1ACC) was established. The analysis was carried out on all data available in the literature in order to establish this relationship for FAC and RAC made with different replacement percentages. After establishing a relationship between R−1ACC and fcm, a prediction of the service life was made using the fib‐Bulletin 34 (2006, Model code for service life design (1st ed.). Lausanne: International Federation for Structural Concrete (fib)) prediction model for all exposure classes to carbonation. For same concrete class, it can be concluded that in the case of RAC there was no significant difference in the duration of the service life compared with natural aggregate concrete, even at 100% replacement of natural aggregate with recycled ones. For concrete up to 35% of fly ash in total cementitious materials, concrete cover for satisfying the required service life of 50 years was 40% higher compared with Portland cement concrete, and more than two times higher in case of concrete with 40–70% fly ash.

Influence of supplementary cementitious material on CO2 balance of cracked RC members in their whole life cycle

“…For the XC2, XC3 and XC4 exposure classes, the mean value of the environment relative humidity (RH) is 79%±9%, 65%±10% and 75%±16%, respectively, where the former values are the mean values and the later ones are the standard deviations [45]. Table 4 shows the corrosion initiation times of the tensile bars in concrete with load-induced microcracks, which are predicted by Eq.…”

Geographic division of exposure environment for concrete structure based on fuzzy clustering‐rough set information entropy

“…The relative humidity of the environment has a significant influence on the carbonation rate of concrete. 23 Research shows that the relationship between the carbonation rate and the relative humidity is parabolic, and the carbonation rate reaches a maximum when the relative humidity is 70%. 21 Precipitation (rain) will increase air humidity, and each precipitation will make the building surface experience dry-wet cycles and damage from wet and dry cycles is far greater than damage from immersion.…”

Measurement of Apparent Building Damage by Using a Single Image

“…e damage on concrete surfaces is a critical factor because the deterioration of both concrete and reinforcement involves water as a participator or medium. Concrete surfaces function as a barrier to prevent the invasion of harmful external substances such as water, oxygen, carbon dioxide, and chlorine salts [1,2]. Surface concrete quality is a critical factor of surface damage and affects its overall quality and service performance.…”