# Lunar Regolith Improvement by Inducing Interparticle Adhesion with Capillary Forces

## TL;DR

This study explores how to strengthen lunar soil using water and capillary forces, finding that grinding the soil improves its cohesion and strength.

## Contribution

The novel contribution is demonstrating that mechanical grinding enhances interparticle adhesion in lunar regolith, significantly improving its flexural strength.

## Key findings

- Lunar regolith simulant consolidated with water showed a flexural strength of 0.025 MPa.
- Grinding the regolith before consolidation increased the flexural strength to 0.123 MPa.
- Modified testing procedures enabled accurate measurement of small stresses in the consolidated material.

## Abstract

This paper concerns the assessment of the lunar regolith ability to consolidate in the presence of liquid water and develop and sustain cohesion after drying. This type of cohesion originates from interparticle adhesion and can be potentially improved through grading modification. The research was conducted using the lunar regolith simulant (EAC-1A) reproducing the PSD of real lunar soil delivered from the Moon. LRS was subjected to water and elevated temperature (equal to the highest temperature on the Moon) to produce specimens of consolidated material, CCR (Capillary-Consolidated Regolith) and to test flexural strength. In order to adapt to potentially small stresses, tests were performed according to the modified EN 196-1 procedure intended for Portland cement testing: specimens scaled to 20 mm × 20 mm × 80 mm (new molds with Polytetrafluoroethylene/Teflon® coatings reducing adhesion were created), supports spacing in the three-point flexural test reduced to 50 mm and apparatus adjusted to precisely apply small loads. CCR developed flexural strength exceeding 0.025 MPa. Then, analogous tests were performed using LRS subjected to grinding in a disc mill prior to consolidation. It was shown that simple mechanical grinding enabled the improvement of interparticle adhesion with capillary forces, resulting in improved flexural strength of the consolidated material (0.123 MPa).