Mining
How Microfine Cement Can Improve Grouting in Mines
Grouting is a technique that involves injecting a fluid material into the cracks or pores of a rock or soil mass to improve its strength, stability, or water tightness. Grouting is widely used in underground engineering, especially in mines, where water seepage and rock fracture are common problems that affect the safety and efficiency of mining operations.
One of the most common grouting materials is cement, which has the advantages of low cost, high strength, and good durability. However, ordinary Portland cement has some limitations when it comes to grouting in fine-grained or microfractured rock or soil. ordinary Portland cement has a relatively large particle size and low specific surface area, which means it cannot penetrate well into small cracks or pores. Moreover, ordinary Portland cement has a long setting time and high viscosity, which make it difficult to inject and control.
Different grouting methods
To overcome these limitations, Kangjing researched microfine cement as a grouting material that has a much finer particle size and higher specific surface area than ordinary Portland cement. Microfine cement can penetrate deeper and fill smaller cracks or pores than ordinary Portland cement, resulting in better tightness and reinforcement of the grouted rock or soil mass. Microfine cement also has a shorter setting time and lower viscosity than ordinary Portland cement, which make it easier to inject and manipulate.
Microfine cement is a type of Portland cement that has been ground to a very fine powder with a specific surface area of more than 800 m2/kg. For comparison, ordinary Portland cement has a specific surface area of about 300 m2/kg. The high fineness of Microfine cement gives it some distinctive properties that make it suitable for grouting applications.
* High permeability, which means it can flow easily through small openings and fill the voids or cracks in the rock or soil mass. This improves the tightness and sealing effect of the grout, preventing water seepage or gas leakage.
* High compressive strength, which means it can resist the external pressure and support the load of the surrounding rock or soil mass. This improves the stability and reinforcement effect of the grout, preventing collapse or deformation.
* High durability, it can resist the chemical attack and physical erosion from the groundwater or environment. This improves the longevity and reliability of the grout, reducing maintenance costs.
There are different types of Microfine cement available in our company, depending on their composition, fineness, setting time, etc. Some examples are:
K700
A Portland cement based grouting material composed of microfine particles with a specific surface area of more than 600 m2/kg, D95 under 22μm. It has excellent permeability, strength and durability properties. It is recommended for concrete crack injection, rock injection in tunnels and caverns, soil injection for stabilization and water tightness
K1000
A sulphate resistant, low alkali ultrafine cement developed for special applications such as injection and grouting. It has a specific surface area of 700-800 m2/kg, DN95 under 16μm.
It has superior sulphate and chloride resistance, as well as good penetration ability and tightness.
K2000
A rapid setting microfine cement developed for rock and soil injection. It has a setting time of 2 to 4 hours. It is a rapid setting microfine cement that can improve productivity and cycle times. The average particle size is around 2.4μm (2000mesh). It is recommended for pre- or post-stabilization injection in caverns and mines, grouting tunnel structure, soil stabilization and preventing settlement.
