Hydration of Early Age Cement Paste with Nano-CaCO₃ and SAP by LF-NMR Spectroscopy: Mechanism and Prediction

Abstract

<jats:p>In this paper, by testing the evolution of the physically bound water using the low-field nuclear magnetic resonance (LF-NMR) technology, the hydration process of cement paste with nano-CaCO<jats:sub>3</jats:sub> (NC) and superabsorbent polymer (SAP) at early age is investigated. Results indicate that the hydration process can be divided into four periods according to the zero points of the second-order differential hydration curve: initial period, acceleration period, deceleration period, and steady period. Firstly, with the increase in the water to cement ratio, the starting time of the hydration period is delayed, and the duration becomes longer. Secondly, the addition of NC leads to the speedy arrival of each period and shortens the duration of each period in the hydration process, and the optimal NC content is 1.5%. Thirdly, with the increase in SAP content, the starting time of the hydration period is delayed and the duration becomes longer. Finally, based on the experimental results and the existing hydration model, the modified hydration model considering the content of NC and SAP is proposed.</jats:p>

Comparative Overview of the Performance of Cementitious and Non-Cementitious Nanomaterials in Mortar at Normal and Elevated Temperatures

“…Nano-clay (nano-CaCO 3 ) acts as a promoter for cement hydration processes. The reasons for this is that nano-clay (Nano-CaCO 3 ) makes the diffused Ca 2+ accumulate on its particle surfaces, decreasing the nearby Ca 2+ concentration, and thus accelerating the chemical reaction of C 3 S [ 90 ]. Depending on the chemical morphology and composition of the crystalline, it can be of montmorillonite, kaolinite, halloysite, illite, or vermiculite type [ 91 ].…”

Effects of Nano-SiO2 and SAP on Hydration Process of Early-Age Cement Paste Using LF-NMR

“…en, the curve of A(t) in unit mass cement paste is obtained (see Figure 2). Figure 2 shows that the hydration process could be categorized into four stages: the initial, accelerated, decelerated, and steady periods according to the zero points (b 1 , b 2 , and b 3 ) of the second-order differential curve (see Figure 3) [25]. Figure 4 shows the influence of w/c on the T 2 signal amplitude (TSA) in unit mass cement paste.…”

“…An-ming et al [24] also found that the development of T 2 could well depict the kinetics of hydration, and the initial period, the accelerated period, and the steady period were categorized according to the difference in changing rate. Zhao et al [25] investigated the influence of nano-CaCO 3 and superabsorbent polymer on the hydration process of early-age cement paste and found that the T 2 of LF-NMR could well characterize the hydration process of early-age cement paste.…”

Effect of CaCO3 nanoparticles on the microstructure and fracture toughness of ceramic nanocomposites

“…Regarding building materials, recently, studies reported the effect of calcium carbonate (CaCO 3 ) on the microstructure and strength, particularly, compressive strength of nanoparticles for concrete, mortar, and cement paste [38,39]. Moreover, other investigations have shown the advantages of incorporating CaCO 3 nanoparticles in concrete, such as improving early compressive strength when compared with cement concrete control [40,41].…”