scholarly journals Influence of Cracking on the Durability of Reinforced Concrete with Carbon Nanotubes

2021 ◽  
Vol 11 (4) ◽  
pp. 1672
Author(s):  
Jose Alexandre Bogas ◽  
Hawreen Hasan Ahmed ◽  
Tomás Diniz
Keyword(s):  
Carbon Nanotubes ◽  
Reinforced Concrete ◽  
Penetration Resistance ◽  
Chloride Penetration ◽  
Capillary Absorption ◽  
Concrete Durability ◽  
Cracked Concrete ◽  
Chloride Penetration Resistance ◽  
Drying Conditions ◽  
Strength And Durability

This study focuses on the influence of natural and artificially induced cracks on the durability of concrete reinforced with carbon nanotubes (CNT). Pre-cracked concrete mixes, unreinforced or reinforced with 0.1% CNT, are characterized in terms of capillary absorption, carbonation, and chloride penetration resistance, and compared to the uncracked reference concrete. The mechanical strength and durability properties were improved in uncracked CNT-reinforced concrete, without significantly affecting its density and workability. The efficiency of CNT was higher when the concrete was previously subjected to drying conditions. For all tested properties, the incorporation of CNT was effective in reducing the influence of artificial and natural cracks on concrete durability. The main contribution of CNT occurred in the crack surrounding region. Depending on the analyzed property and cracking conditions, the significant reduction of durability in cracked concrete may be 10–30% attenuated when CNT is incorporated. The effect was more pronounced in mechanically induced natural cracks, where CNT may better participate in their vicinity.

Chloride Penetration Resistance of Concrete Structures under Compressive Load

2012 ◽  
Vol 479-481 ◽  
pp. 120-123
Author(s):  
Fu Xiang Jiang ◽  
Yu Tian Wang ◽  
Tie Jun Zhao ◽  
Liang Liang Liu
Keyword(s):  
Mechanical Load ◽  
Concrete Structures ◽  
Compressive Load ◽  
Chloride Concentration ◽  
Penetration Resistance ◽  
Chloride Penetration ◽  
Concrete Durability ◽  
Complex Process ◽  
Apparent Diffusion ◽  
Chloride Penetration Resistance

The mechanism of concrete durability under uniaxial compressive load has been studied through chloride penetration experiments in this contribution. It has been found that there is a good corresponding relationship between chloride penetration resistance of concrete and the applied compressive stress level. With increasing of the applied compressive load, chloride penetration depth and content both decreased firstly. After the compressive load up to a critical level, they began to increase quickly. The apparent diffusion coefficient and chloride concentration at the surface also increase with the same rule. It is shown that chloride penetration of concrete is a complex process. So the effect of mechanical load should be considered as an important factor for prediction of service life of reinforced concrete structures in marine environment.

scholarly journals The Rapid Chloride Migration Test in Assessing the Chloride Penetration Resistance of Normal and Lightweight Concrete

2021 ◽  
Vol 11 (16) ◽  
pp. 7251
Author(s):  
Jorge Pontes ◽  
José Alexandre Bogas ◽  
Sofia Real ◽  
André Silva
Keyword(s):  
Lightweight Concrete ◽  
Chloride Transport ◽  
Penetration Resistance ◽  
Chloride Penetration ◽  
Migration Test ◽  
Simple Method ◽  
Chloride Migration ◽  
Binder Ratio ◽  
Chloride Penetration Resistance ◽  
Water Binder Ratio

Chloride-induced corrosion has been one of the main causes of reinforced concrete deterioration. One of the most used methods in assessing the chloride penetration resistance of concrete is the rapid chloride migration test (RCMT). This is an expeditious and simple method but may not be representative of the chloride transport behaviour of concrete in real environment. Other methods, like immersion (IT) and wetting–drying tests (WDT), allow for a more accurate approach to reality, but are laborious and very time-consuming. This paper aims to analyse the capacity of RCMT in assessing the chloride penetration resistance of common concrete produced with different types of aggregate (normal and lightweight) and paste composition (variable type of binder and water/binder ratio). To this end, the RCMT results were compared with those obtained from the same concretes under long-term IT and WDT. A reasonable correlation between the RCMT and diffusion tests was found, when slow-reactive supplementary materials or porous lightweight aggregates surrounded by weak pastes were not considered. A poorer correlation was found when concrete was exposed under wetting–drying conditions. Nevertheless, the RCMT was able to sort concretes in different classes of chloride penetration resistance under distinct exposure conditions, regardless of the type of aggregate and water/binder ratio.

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