Page 50 - RoadCem Manual - PCT BV

Surfacing layers
Road surfacing can be made in many different ways and using many different materials. Relevant options and material properties are presented in Appendix 5. It is noted that all traditional surfacing options can be used on a top of a RoadCem base:
• Asphalt;
• Concrete paving stones;
• Concrete slabs, etc.
It is noted that it is also possible to use RoadCem based layer as a surfacing option.
Foundation material
Different foundation materials are used in road construction and these can be separated into bound and un-bound foundation material. In appendix 5 the most important properties of foundation materials are given. It is possible to compare the traditional materials and a material with RoadCem based on these properties.
The properties of a material modified with a binder and RoadCem are dependent on the properties of the aggregate present and the amount of cement/fly-ash, RoadCem and water. These properties are discussed in chapter 5.
3.2.5 Construction and execution factors
In addition to the factors already discussed we also need to consider the prevailing conditions that are expected during the actual construction of the pavement. Factors of importance are:
• Weather expectations during construction of the product;
• Optimal moisture content of a material for achieving MPD (maximum proctor density)
• Equipment that is available;
• In-situ material characteristics and properties;
• Costs for the different materials;
• Costs for “installing/treating” the materials.
The weather has an influence on the execution of the task. For example when it is warm or it is too windy then more water needs to be added to the cement mixture as more evaporation would take place under these conditions and this needs to be compensated for. With temperatures higher than 20o Celsius and/or with strong winds approximately 1% extra water needs to be added in relation to the optimal water content to achieve MPD during compaction. This is essential for achieving the right binding for cement bound pavements.
Attention must be paid with freezing weather also. A concrete mixture cannot bind when it is colder than -4oC. Addition of RoadCem reduces the temperatures at which one can carry out the work up to - 10 oC.
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