Analysis of the Effect of Nano-SiO2 and Waterproofing Agent on the Water Transportation Process in Mortar Using NMR

Menghua Wang,Kanjun Ying,Huadong Wei,Tao Meng

doi:10.3390/app10217867

Menghua Wang, Kanjun Ying + Show 2 more

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https://doi.org/10.3390/app10217867

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Abstract

Moisture diffusion in cement-based materials significantly impacts its durability. In this study, we analyzed the effect of adding a waterproofing agent and nano-SiO2 (NS) on the water transportation process in mortar using capillary water absorption tests and nuclear magnetic resonance (NMR) technology. The results indicate that the combined action of the waterproofing agent and nano-SiO2 drastically reduce the capillary water absorption coefficient and have a more significant impact than only adding the waterproofing agent. The moisture diffusion in different sections of the mortar during the water absorption process is obtained from the NMR test results and two function models. Comparative studies indicate that the NMR test results have good correlation with the capillary water absorption test results and provide accurate process data. The NMR analysis results offer a new analytical method to characterize the porosity of cement-based materials by continuously monitoring small-pitch sections.

Highlights

As a complex porous medium containing solid, gas, and liquid phases, concrete is vulnerable to several types of damage, with water content being one of the main influencing factors [1,2].Several deleterious substances like chloride can enter cement-based materials through moisture diffusion
The average of the test results of the two specimens was considered of more than 95% for 28 days
KIMwaterproofing waterproofingagent agenthas hasno noobvious obviouseffect effecton onthe thecapillary capillarywater waterabsorption absorptioncoefficient coefficient S,S, it can slightly improve the impermeability of cement mortar

Summary

Introduction

As a complex porous medium containing solid, gas, and liquid phases, concrete is vulnerable to several types of damage, with water content being one of the main influencing factors [1,2].Several deleterious substances like chloride can enter cement-based materials through moisture diffusion. As a complex porous medium containing solid, gas, and liquid phases, concrete is vulnerable to several types of damage, with water content being one of the main influencing factors [1,2]. Glanville studied the permeability of concrete in the 1930s [3]. The Feldman Sereda model suggests that only free water (capillary water), adsorbed water, and structural water (interlayer water) can transport inside cement, whereas crystal water cannot [4]. In reality, other than in underwater engineering applications, concrete material rarely reaches a saturated state wherein its internal structure is full of liquid water. Considering the process of capillary flow, permeability cannot be used to suitably describe the transport of water in unsaturated porous materials, and gas phase transportation must be considered [5,6]. The total transmission effect is represented by Darcy’s law, which considers the water saturation degree to be a descriptive variable [5,7,8]

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