Abstract
Here we explore the structural properties and damage sensing of cementitious mortars after a freeze-thaw process (F-T) as a function of nano-modification. For this purpose, carbon nanotubes were added at 0.2–0.8 wt.% cement using two different dispersive agents. F-T resulted in reduced fracture energy in nano-modified specimens prepared using superplasticizer as a dispersant while the opposite held true for the surfactant-containing ones. All nano-modified mortars possessed significantly higher fracture energy compared to the plain specimens after F-T (up to 73% improvement). The acoustic emission activity was lower after F-T, while acoustic emission indicators revealed a more tensile mode of fracture in both plain and nano-modified mortars.
Highlights
Over the last two decades, carbon nanotube (CNT) modified cementitious composites [1,2,3,4,5,6] have been investigated with focus on two main aspects: a) the improvement of their performance and b) the production of multifunctional, smart and self-sensing materials [7,8,9]
The current study investigated the durability of CNT-modified cementitious mortars after freeze-thaw process (F-T)
Structural properties were assessed based on the dynamic elastic modulus, compressive strength and fracture energy of notched specimens under 3-point bending configuration
Summary
Over the last two decades, carbon nanotube (CNT) modified cementitious composites [1,2,3,4,5,6] have been investigated with focus on two main aspects: a) the improvement of their performance and b) the production of multifunctional, smart and self-sensing materials [7,8,9]. The ability of CNTs to bridge micro-cracks and delay their propagation [10,11,12] has been proven beneficial for the fracture behavior of cementitious materials [13,14]. Mechanical and fracture studies combined with acoustic emission (AE) measurements demonstrate the enhanced damage sensing capability of cementitious materials modified with carbon nano-inclusions [18,19]. An environmental parameter of huge significance for the fracture behavior and integrity of cementitious materials is the freeze-thaw (F-T) cycling encountered in cold environments. F-T can damage cementitious materials by creating internal cracking due to cold temperature cycling
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