Innovative Test Technique to Evaluate “Self-Sealing” of Concrete

Abstract

Concrete is prone to cracking when subjected to tensile forces because of its low tensile strength. The cracking potential is an even bigger concern when concrete is relatively young and is in the plastic stage. Cracks induced early can grow with time because of drying shrinkage and with application of service loads. Concrete, which is otherwise impermeable, allows for free passage of moisture and other deleterious chemicals when it is cracked, leading to reduced durability of the material and, in many cases, reduced service life of the structure. The severity of some of these issues can be alleviated because of an inherent property of concrete known as “self-sealing.” As the name suggests, “self-sealing” allows for the cracks (of limited width) to be sealed on their own over a period of time. However, currently there is no standard test technique to quantify this property of concrete and other cement-based materials, such as mortar. An innovative and straightforward technique was developed by the authors and is presented in this paper. In this technique, a standard crack is induced in concrete cylinders using a standard crack-inducing jig (SCIJ). The specimens are then inserted in special rubber sleeves and this assembly is then subjected to a constant water head. The reduction in flow through the cracked specimen is measured at a given time to compare the performance of different specimens. This technique can also be used to compare the performance of concrete mixes modified using various admixtures. This paper describes this innovative test technique and includes sample test results to explain the analysis process proposed by the authors.

Durability and Self-Sealing Examination of Concretes Modified with Crystalline Waterproofing Admixtures

“…Although the average crack width for both specimens is very similar but the initial flow rate is higher for CWA specimens. This confirms that equivalent crack sizes of CWA samples, proposed in [ 32 ], are greater than control mixes while their actual crack width is the same. In other words, two samples with the same surface crack width do not necessarily have the same water flow rate.…”

“…According to the Robertson study et al, the concrete panels containing similar hydrophilic CWA as the one in this work, performed well, showing low half-cell values and no apparent evidence of corrosion after 10 years of exposure in a real-field corrosive environment [ 31 ]. Authors also performed various testing and evaluated different durability properties of CWA concrete [ 13 , 14 , 15 , 18 , 32 , 33 ]. The authors’ findings of assessing the permeability and self-sealing of CWA concrete with two different common cement types revealed that adding CWA to the concrete mix reduced the water permeability coefficient by three times while increasing the self-sealing ratio at a faster rate [ 13 , 14 , 18 , 33 ].…”

Electrical Resistivity of Concrete for Durability Evaluation: A Review

“…In addition, authors are also studying the effect of selfsealing on resistivity of concrete. Previous work done in this area (self-sealing) is reported elsewhere [114,115].…”

Monitoring the Self-healing of Concrete from the Ultrasonic Pulse Velocity

“…There was no possibility of a visual analysis of the cracks and their sealing, since the specimens would be compromised, and the readings of the ultrasound pulse velocity would not be continued. Therefore, the authors recommend future studies containing ultrasonic test and image analysis in parallel, with more specimens and using a cracking method that would allow standardization and identification of the exact location of the cracks, such as those applied by Gupta and Biparva [27] and El-Newihy et al [28]. and drying cycle, again being related to the availability of anhydrate particles in the early ages.…”