Closure to “Moisture Curve of Compacted Clay: Mercury Intrusion Method” by S. Prapaharan, A. G. Altschaeffl, and B. J. Dempsey (September, 1985, Vol. 111, No. 9)

This paper presents research considering hydraulic as well as swelling and shrinkage characteristics of potential recycled fine particle materials for compacted clay liner for sustainable landfills. Five locally available clay soils mixed with 10% (by mass) of NaP1 recycled zeolite were tested. The performed analysis was based on determined plasticity, cation exchange capacity, coefficient of saturated hydraulic conductivity after compaction, several shrinkage and swelling characteristics as well as, finally, saturated hydraulic conductivity after three cycles of drying and rewetting of tested specimens and the reference samples. The obtained results showed that addition of zeolite to clay soils allowed reduction in their saturated hydraulic conductivity to meet the required threshold (≤1 × 10−9 m/s) of sealing capabilities for compacted clay liner. On the other hand, an increase in plasticity, swelling, and in several cases in shrinkage, of the clay–zeolite mixture was observed. Finally, none of the tested mixtures was able to sustain its sealing capabilities after three cycles of drying and rewetting. Thus, the studied clayey soils mixed with sustainable recycled zeolite were assessed as promising materials for compacted liner construction. However, the liner should be operated carefully to avoid extensive dissication and cracking.

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

Materials ◽

10.3390/ma14081823 ◽

2021 ◽

Vol 14 (8) ◽

pp. 1823

Author(s):

Won-Kyung Kim ◽

Young-Ho Kim ◽

Gigwon Hong ◽

Jong-Min Kim ◽

Jung-Geun Han ◽

...

Keyword(s):

Mercury Intrusion Porosimetry ◽

Cement Mortar ◽

Stable State ◽

Pozzolanic Reaction ◽

Hydration Reaction ◽

High Concentration ◽

Mercury Intrusion ◽

Electron Microscope Analysis ◽

Mixing Water ◽

Cement Mixtures

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.

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