Hydraulically bound materials (HBM) including cement bound granular material (CBGM) can be used as a structural layer in the design of any high-performance pavement. These materials, which consist of aggregate and cement, are both more cost-effective and sustainable when compared against asphalt and concrete. The process does not require the use of primary aggregates and frequently we opt for recycled materials such as crushed demolition materials, redundant sub-base and road plannings.
Depending on the intended end use, a material requires only a thin wearing surface applied in order to accept heavy traffic. In certain circumstances, and dependent on customer requirements, the material can directly take traffic. This has been advantageous in certain industries such as distribution when the comparable cost of concreting an entire yard has proved too costly.
Suitable aggregates to be incorporated into the material are grading to the required profile. In the case of recycling redundant sub-bases, the surface will be loosened using a dozer mounted tine ripper. All machinery is GPS controlled to ensure the required grades are attained.
The area is then proof rolled and any soft compressible formation materials that are identified are over-excavated and replaced with granular material. The surface is then dampened down by a tractor-drawn bowser.
The required pre-determined addition of cement binder is then spread over the surface treatment area using a computer-controlled binder spreader.
Mixing takes place to incorporate the binder into the material, and during this process a control addition of water is added.
On completion of mixing, materials are immediately re-graded to the required profile and then compacted using a twin drum compactor.
Testing is then performed to confirm that the specified project requirements have been met.