# New Frontiers in Sustainable Geotechnics
## 2 Laboratory Testing for Geotechnical Design
### Laboratory Testing and Theoretical Modeling of Deformations of Reinforced Soil Wall [5]  
From a scientific point of view, an important element of this work was analyzing the effect of friction between the backfill and the side walls of the test box on the measured displacements. For the investigated case, it was shown that the impact of this element caused a reduction in the value of external loading of more than 60%. The final results may be particularly useful in the design process of structures used in transportation engineering (bridge abutments), where deformation limit values cannot be exceeded [5]. Influence of Laboratory Compaction Method on the Compaction and Strength Characteristics of Unbound and Cement-Bound Mixtures [6]  
For mixtures with a higher cement content, the optimal moisture content difference depending on the laboratory compaction method used can be significant, so the laboratory compaction method should be chosen carefully, particularly for moisture-susceptible materials. This paper also reveals that by increasing the proportion of rubber in the mixture, the compaction and strength characteristics differ significantly when the compaction method is used. Therefore, when using alternative and insufficiently researched materials, the compaction method should also be chosen carefully [6]. Effect of Chitosan Solution on Low-Cohestivity Soil's Shear Modulus G Determined through Resonant Column and Torsional Shearing Tests [7]  
In this study, the effect of using a biopolymer soil stabilizer on soil stiffness characteristics was investigated. It was shown that chitosan solution added to medium-grained materials substantially improves their shear modulus G (up to 3 times), even for solutions with relatively low chitosan concentrations (1.5 g of chitosan per 1 kg of dry silica sand). The results obtained in this study and the known chitosan properties suggest that chitosan solutions can be a very effective and eco-friendly short-term stabilizer for temporary geotechnical structures, e.g., working platforms [7]. The Effect of MICP on Physical and Mechanical Properties of Salt with Different Fine Particle Contents and Pore Ratios [8]  
Microbial-induced calcium carbonate precipitation (MICP) is a new soil remediation technology which can improve the physical and mechanical properties of soil by transporting bacterial solution and cementation solution to loose soil and precipitating calcium carbonate precipitation between soil particles through microbial mineralization. Based on this technique, the effects of different fine particle contents and pore ratios on the physical and chemical properties of silt after reinforcement were studied. The content of calcium carbonate, the ability of silt to fixed bacteria, unconfined compressive strength (UCS), permeability coefficient, and microstructure of samples were determined. The results showed that the permeability coefficient of cured silt can be reduced by 1 to 4 orders of magnitude compared with that of untreated silt. In particular, the permeability of MICP-treated silt A is almost impermeable [8]. The Effects of Hydroxypropyl Methylcellulose (HPMC) on the Reinforcement of Sand by Microbial-Induced Calcium Carbonate Precipitation (MICP) [9]  
Existing MICP treatment technology seems to be more suitable for deeper soils due to its high permeability. In this study, HPMC, a cohesive material combined with Sporosarcina pasteurii-induced calcium carbonate precipitation, was used to improve the surface layer of the soil. The addition of HPMC effectively improved the ammonia absorption rate and reduced the release of ammonia in the process of MICP technology, which is of great significance for environmental protection.