Effect of Hydrogen Nanobubbles on the Mechanical Strength and Watertightness of Cement Mixtures

Abstract

This study analyzed the effects of applying highly concentrated hydrogen nanobubble water (HNBW) on the workability, durability, watertightness, and microstructure of cement mixtures. The number of hydrogen nanobubbles was concentrated twofold to a more stable state using osmosis. The compressive strength of the cement mortar for each curing day was improved by about 3.7–15.79%, compared to the specimen that used general water, when two concentrations of HNBW were used as the mixing water. The results of mercury intrusion porosimetry and a scanning electron microscope analysis of the cement paste showed that the pore volume of the specimen decreased by about 4.38–10.26%, thereby improving the watertightness when high-concentration HNBW was used. The improvement in strength and watertightness is a result of the reduction of the microbubbles’ particle size, and the increase in the zeta potential and surface tension, which activated the hydration reaction of the cement and accelerated the pozzolanic reaction.

Influence of Water with Oxygen and Ozone Micro-Nano Bubbles on Concrete Physical Properties

“…With the decrease in the micro-nano bubble diameter, the negative zeta potential as well as surface tension increase. This contributes to maintaining high stability of the micro-nano bubble in the liquid [34]. Water is pulled by the surface tension into the capillary that is created between the particles.…”

“…Due to the high negative potential, water is further dispersed in the cement mixture microstructure. This contributes to the formation of a homogeneous and tight mixture [34].…”

“…It has been demonstrated that replacing tap water with micro-nano air bubble water reduces the weight absorption, capillary absorption of concrete and the penetration depth of pressurized water [30][31][32][33]. Kim et al [34,35] noted that the application of micro-nano hydrogen bubble water reduced the internal pore diameter and increased the apparent density of the tested materials.…”

“…Micro-nano gas bubble water also improves cement composites in terms of mechanical properties. Taherpour Komishani et al [37] observed correlations of compressive strength increasing along with the replacement ratio of ordinary water to water with micro-nano air bubbles [31][32][33][34]36,38]. Arefi et al [31] noticed that the concretes prepared by applying water with micro-nano air bubbles had approximately 19% higher compressive strength, in comparison to the reference concretes.…”

Mechanical Strength and Hydration Characteristics of Cement Mixture with Highly Concentrated Hydrogen Nanobubble Water

“…Kim et al experimentally confirmed the pore size distribution and porosity in the hydrate due to the high concentration of HNB through mercury intrusion porosimetry (MIP). In this study, as the CH (about 1 µm) was gradually consumed and became an irregular shape, C-S-H (<0.1 µm) gradually developed, resulting in a smaller internal pore size and improved watertightness and durability [ 51 ]. The hydration degree (α) of the cement paste cured in water for seven days, as determined via Bhatty’s method, was 46.56% for Case A, 57.97 % for Case B, and 67.17 % for Case C. Compared to Case A, the hydration degrees for Cases B and C showed improvements of 11.41% and 20.61%, respectively.…”