Micro-cements are superfine cements, ground in special mills to a defined particle size. Their use has become widespread in Japan and North America for the grouting of fine to medium grade sands, not groutable with ordinary cement grouts.
In Scandinavia, ultrafine and microfine cements are used extensively in the pre-grouting (and post-grouting) of rock tunnels for consolidation and water tightening of the rock.Rapid hardening cement or OPC might be used in cases of larger fissures.
Micro-cement grout has become an accepted means of overcoming the problems of toxicity, low strength and uncertain permeability associated with the chemical grouts normally used for fine granular soils.
As a consequence of its reduced maximum grain size, the permeation characteristics of the micro-cement grouts are comparable to those of chemical grouts,such as silicates and acrylamides.
The advantages of using micro-cements include:
Able to replace chemical fluids and gels
No toxicity or environmental problems
Higher strengths and durability than chemical gels
More economical compared to chemical injection
Better permeation and tightness characteristics than normal cements
Microfine and ultrafine Portland cements to cover the full range of grouting needs:
Ultrafine Cements – two grades, max. particle size <16µm and max. particle size < 12µm, for fine penetration injection grouting.
Microfine Cement - max. particle size < 20µm & max. particle size < 30µm sulphate resistant cement, for less demanding penetration injection grouting.
The micro-cements can be used in a variety of grouting applications in underground and civil engineering applications:
Rock injection - pre-injection, post-injection, rock stabilization, curtain grouting
Soil injection - stabilization, water tightening, control of ground water
Grouting of anchors - in rock and soil
Injection of cracks in concrete