Research on Performance Deterioration of Multi-Walled Carbon Nanotube–Lithium Slag Concrete under the Coupling Effect of Sulfate Attack and Dry–Wet Cycles

Abstract

Sulfate attack is one of the main factors affecting the durability of concrete structures. In recent years, multi-walled carbon nanotubes (MWCNTs) have attracted the attention of scholars for their excellent mechanical properties and durability performance. In this paper, the influence of sulfate attack and dry–wet cycles on the performance of multi-walled carbon nanotube–lithium slag concrete (MWCNT-LSC) with varied MWCNT content (0 wt.%, 0.05 wt.%, 0.10 wt.%, and 0.15 wt.%) and varied water–cement ratios (0.35, 0.40, and 0.45) were investigated. In addition, scanning electron microscopy (SEM) and X-ray computed tomography (CT) tests were conducted to analyze the microstructure and pore structure of the concrete. The results showed that concrete incorporated with MWCNTs could effectively mitigate sulfate attack. The resistance to sulfate attack of concrete was negatively related to the water–cement ratio when the dry–wet cycle was fixed. The MWCNT-LSC showed the best compressive strength at the water–cement ratio of 0.35 and 0.10 wt.% MWCNTs. The SEM test results showed that the MWCNTs filled the pores and cracks within the specimen and formed bridges between the cracks, enhancing the resistance to sulfate attack. The CT test results also showed that the addition of MWCNTs could reduce the porosity of concrete, refine the pore size and inhibit the generation and development of cracks, thus optimizing the internal structure of concrete and improving its resistance to sulfate attack.

Under Sulfate Dry–Wet Cycling: Exploring the Symmetry of the Mechanical Performance Trend and Grey Prediction of Lightweight Aggregate Concrete with Silica Powder Content

“…Therefore, concrete materials in Western China are highly susceptible to sulfate attacks, especially in Inner Mongolia. The sulfate ions from the salt lakes can infiltrate the concrete through groundwater, rainfall, and natural seepage, subsequently triggering a series of deterioration reactions that impact the concrete's service life [29][30][31][32]. Simultaneously, the concrete endures damage from rainfall, evaporation, water level fluctuations, and other factors, placing it in a detrimental cycle of dryness and wetness, as well as sulfate corrosion [33][34][35].…”

A Review on Cementitious and Geopolymer Composites with Lithium Slag Incorporation

“…Furthermore, the mechanical properties of cementitious materials with LS incorporation have been thoroughly investigated, thus encompassing parameters like compressive strength [ 50 , 51 ], tensile strength [ 52 , 53 ], elastic modulus [ 54 ], and flexural strength [ 49 ]. Moreover, the durability of LS-based cementitious composites has received significant attention, including studies on chloride migration [ 55 , 56 ], sulfate attack [ 57 , 58 ], shrinkage [ 56 , 59 ], freeze–thaw resistance [ 57 ], acid corrosion [ 60 ], and creep [ 50 ]. Furthermore, the utilization of LS in the construction materials industry not only mitigates environmental pollution but also significantly enhances economic benefits.…”