Traditional Cement Particles

Due the attractive surface forces between cement particles, the particles are locked in a relatively open structure. A large amount of mixing water is necessary to get a good workability. This high w/c ratio results in a large amount of pores between the cement particles what will give a low strength and an insufficient durability to the hardened matrix. 

Micro structure in the Binder

Ultra fine fillers: micro silica, consists of amorphous silica particles with a average diameter of 0,1 – 0,2 µm and a specific surface of 25.000 m²/kg. Micro silica is super puzzolanic and converts the less useful calcium hydroxide crystals into the useful calcium silicate hydrate. The micro silica particles must be dispersed very well in the matrix to reduce the water/ cement ratio and to get the maximum density from the hardened matrix.

Compressive Strength

High or very high compressive strengths are possible. The final strength is depending on the type of binder, size, quality and type of the aggregates and type and amount of reinforcement. Compacting under pressure and/or an extra heat treatment will give extreme high compressive strengths.

Traditional HSC: 50 – 100 MPa
Contec binder with granite or Diabas: 120 – 200 MPa 
Contec binder with bauxite: 220 – 270 MPa 
Contec binder with bauxite and fibres: 200 – 400 MPa 

Strength, impermeability and wear resistance also depends on aggregates

Since the Contec Binder has a very high strength, ordinary aggregates are the weakest components. The  The image shows how fracture occurs in the aggregates and not in binder. Significant improvements are achieved by using very strong aggregates. Not only the strength, size and type of the aggregates but also the surface structure is important.

Cement pasta with superplastizers

With super plasticizers it is possible to eliminate these surface forces which result in much denser packed cement particles. Less mixing water is necessary to get a good workability. The decreased w/c ratio and denser packed cement paste will result in finer pores between the cement particles and thereby a higher strength and a better durability to the hardened matrix. 

Density

The modification from the cement paste by using geometrical principles for the highest possible dense packing from cement, ultra fine particles and aggregates with different diameters will result in a packing density from 0,70 – 0,90. This is the same packing density like in for instance ceramics and glass.

Wear Resistance

Due to the high strength of the binder we can control the abrasive properties as demanded. This is particularly beneficial for installation of thin screeds, industrial flooring, wear protection areas and in heavy industry in general. Because of the extreme strong bonding zone between binder and aggregate we take full advantage of high quality aggregates.

Cement paste with puzzolanic particles

By adding ultra fine fillers well dispersed between the dense packed cement particles a much denser cement paste will be developed. A significantly reduced amount of water is required to achieve the same good workability. A decreased w/c ratio and the very densely packed cement and ultra fine fillers will result in extreme fine pores between the cement particles which will give a much higher strength and a far better durability to the hardened matrix.

Chemical resistance

Due to the puzzolanic particles and the fine micro structure the final product will have impermeable properties and aggressive substances cannot penetrate the concrete. Resistance to chemicals, oil, chlorides etc. is significantly higher compared with traditional concrete

Bonding to fiber and mesh

Due to the fact that the interface zone is less porous and consists of large amounts of small particles there is a much better bonding on the reinforcement. Bonding on 6mm steel bar is 4 – 5 times higher than in traditional quality concrete. Also fibers are extremely well anchored in the dense matrix. This makes it possible to use large amounts of small and smooth fibers like for instance 0.4 x 12.5 mm and 0.15 x 6 mm steel fibers. Up till 800 kg/m3 is possible.