During grouting reinforcement construction, the slurry mixture ratio is primarily determined based on the following aspects:

Engineering geological conditions

Soil Type: For sandy soils, due to their larger pores and good permeability, the slurry needs to have good fluidity, and the water-cement ratio can be appropriately higher, such as 1.0:1 to 1.5:1. For clayey soils, with smaller pores, the slurry's viscosity should be moderate, and the water-cement ratio is generally between 0.75:1 and 1.0:1.

Porosity and Permeability: For strata with high porosity and strong permeability, to ensure the slurry fully fills the pores, an increased amount and fluidity of the slurry are required, which can be achieved with a relatively higher water-cement ratio. Conversely, for strata with low porosity and poor permeability, the water-cement ratio should be reduced to enhance the slurry's concentration.

Engineering Requirements

To strengthen the foundation, if the purpose is to enhance bearing capacity, the slurry requires higher strength, which can be achieved by reducing the water-cement ratio and increasing the amount of cement. For the purpose of preventing seepage, the solidified mass of the slurry should possess good impermeability, and some additives can be added to enhance the slurry's impermeability properties.

Design for Strength and Durability: Based on the engineering design requirements for the strength and durability of reinforced soil, the appropriate slurry mixture ratio is determined through testing. Generally, when higher strength requirements are needed, the amount of cement should be increased, and the water-cement ratio should be decreased.

Viscosity Performance Specifications

Fluidity: Good fluidity in slurry allows for better diffusion within soil pores. Generally, a funnel viscometer is used to measure slurry fluidity. Adjustments can be made to the water-cement ratio and additives of the slurry, based on different strata and grouting process requirements, to control its fluidity.

Optimal viscosity ensures that slurry remains stable during the injection process, preventing separation and sedimentation. Viscosity is typically controlled by adjusting the composition and concentration of the slurry, such as adding bentonite, fly ash, and other admixtures to increase slurry viscosity.

Setting Time: The setting time should be moderate to allow the slurry to fully fill and solidify within the soil pores. For cement slurry, the setting time can be adjusted by adding retarders or accelerators. In cases of grouting in strata with high groundwater velocities, to prevent the slurry from being diluted by the water flow, a cement-silica gel double liquid slurry can be used. The setting time is controlled by adjusting the ratio of the two liquids.

On-site Testing

Indoor Testing: Prior to construction, indoor slurry mixing tests are typically conducted to simulate on-site geological conditions. Performance tests are then carried out on different slurry mix ratios, such as fluidity, viscosity, setting time, and compressive strength, to filter out slurry mix ratios that meet engineering requirements.

On-site Grouting Test: Prior to the formal construction, an on-site grouting test will be conducted to verify the effectiveness of the slurry mix determined by indoor tests in actual construction. This includes observing the slurry's spread and the soil reinforcement effects. Based on the results of the test grouting, further adjustments and optimizations to the slurry mix will be made.

Experience Data Reference

Ordinary cement slurry: The general water-cement ratio is between 0.5:1 and 1.0:1.

Cement - Water Glass Double Liquid Mixture: The common volume ratio of cement slurry to water glass is 1:1 to 1:0.5, with the concentration of water glass generally at 30-40Be, and the water-cement ratio of the cement slurry ranges from 0.8:1 to 1.0:11.

Cement Mortar: The cement mortar used for compacting grouting typically contains 0.5-1.5 times the amount of sand as the cement, with a water-cement ratio of 0.4-0.6.