Experimental Study on Properties of Modified City Wall Soil

Area of Science:

• Civil Engineering
• Material Science
• Geotechnical Engineering

Background:

• Kaifeng city wall earthen sites face deterioration due to high groundwater levels, salinity, and capillary action.
• Environmental erosion causes cracking, peeling, and efflorescence in the earthen structures.
• Effective reinforcement strategies are crucial for preserving these historical sites.

Purpose of the Study:

• To investigate the effectiveness of lime and sodium methyl siliconate in reinforcing earthen sites.
• To quantify the impact of these materials on the mechanical properties and water absorption of imitation site soil.
• To understand the microstructural changes induced by the reinforcement.

Main Methods:

• Preparation of 16 imitation site soil samples with varying proportions of lime and sodium methyl siliconate.
• Testing of samples using direct shear, disintegration, and scanning electron microscopy (SEM).
• Analysis of changes in shear strength, cohesion, internal friction angle, and water absorption rate.

Main Results:

• Both lime and sodium methyl siliconate improved the shear strength of the soil.
• Shear strength increased by up to 38.16% with lime and 10.81% with waterproof material.
• Cohesive force increased by a maximum of 59.23%, and internal friction angle ranged from 36.72° to 41.61°.
• Mass water absorption decreased by 2.76-27.77% with the addition of waterproof material.

Conclusions:

• Lime and sodium methyl siliconate are effective in reinforcing earthen sites against environmental erosion.
• The reinforcement improves mechanical properties and reduces water absorption, prolonging the lifespan of the structures.
• Chemical reaction products fill micro-pores and cracks, enhancing soil stability.