Mechanical Properties and Shrinkage of Ultrahigh‐Performance Concrete Containing Lithium Carbonate and Nano‐Calcium Carbonate

Abstract

Early strength generation is essential for the successful application and usage of Ultrahigh-Performance Concrete (UHPC) in reinforcing concrete structures. The work contained in this paper focused on evaluating the effects of lithium carbonate (Li2CO3, denoted as LC) and nano-calcium carbonate (NC) on the early mechanical properties and autogenous shrinkage of UHPC under normal temperature curing conditions. In the study, scanning electron microscope (SEM) was utilized to investigate and quantify the morphology of the early hydration products. The corresponding results indicated that the 1-day comprehensive strength of the UHPC increased significantly with the addition of Li2CO3 and NC. Likewise, the addition of NC mitigated the loss of the 28-day compressive strength. For the materials evaluated, the 1-day compressive and flexural strengths reached peak values of 72.1 and 13.9 MPa, respectively, for optimum dosages of 0.075%∼0.1% Li2CO3 and 3%∼4% NC, respectively. The results also indicated that the combined LC-NC dosage had profound effects on the early autogenous shrinkage of UHPC, which could, however, be minimized by adjusting the Li2CO3 and NC dosages. That is, the combined dosage of the two early strength enhancers shortens the hydration induction period of cement whilst concurrently accelerating the hydration rate of the cement. The early strength agent increases the number of crystals in the hydration product and the crystal grain size becomes larger. These make the microstructure of the slurry more compact after hardening and therefore improve the overall performance of UHPC.

Concrete Performance Attenuation of Mix Nano-SiO2 and Nano-CaCO3 under High Temperature: A Comprehensive Review

“…T. Wang et al [ 78 ] concluded that the 1-day combined strength of UHPC increased significantly with increasing amounts of Li 2 CO 3 and NC, and that NC was effective in mitigating the loss of the 28-day combined strength of UHPC. After modification, the UHPC combined strength and flexural strength increased by about 68% and 38%, respectively, over the control sample.…”

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.…”