Cement-Treated Base (CTB) is a strong, frost-resistant base for a concrete or asphalt pavement wearing surface. CTB is made up of native soils, gravels/manufactured aggregates blended with engineered quantities of cement and water. Pavements with CTB are much stronger and more rigid than a non-stabilized granular base. Cement-Treated Base is engineered so the thickness of the base is less that required for granular bases carrying the same weight and traffic. Properly engineered CTB can distribute loads over a wider area reducing the stresses on the sub-grade and acting as the load-carrying element of a flexible pavement or a sub base for concrete.
When mixed with a high-intensity, high-output, twin-shaft continuous mixing plant, its slab-like characteristics and beam strength are unmatched compared to granular bases that can fail when aggregate interlock is lost. This happens when wet sub-grade soil is forced up into the base by traffic loads. Hard, rigid CTB is practically impervious. It resists cyclic freezing, rain, and spring-weather damage. Cement-Treated Base continues to gain strength with age even under traffic. This reserve strength accounts in part for CTB’s excellent performance.
The rigidity of Cement-Treated Base reduces deflection, rutting in the base and other asphalt strains. The versatility of cement is critical to the success in this pavement solution because site conditions and soil types (from gravel to clay's) can easily change during or between projects and cement acts as a "universal stabilizer."
Cement-Treated Base, as described above, is a mixture of aggregate material, granular soils combined with prescribed amounts of cement and water that hardens after compaction and curing to form a durable paving material. A cement concrete wearing course is placed on the CTB to complete the pavement structure. CTB is widely used as a pavement base for highways, roads, streets, parking areas, airports, and materials handling and storage areas.
In CTB construction the objective is to obtain a thorough mixture of an aggregate/granular material with the correct quantity of cement and sufficient water to permit maximum compaction. The CTB must be adequately cured to both let the cement hydrate and to harden the cement-aggregate mixture.
The fundamental control factors for quality Cement-Treated Base are:
Proper cement content
Adequate moisture content
Rapidmix Continuous Mixing Plant - Volumetric or Continuous Weigh?
Continuous mixing—When the output of the mixer is equivalent to the input of materials and the mixer can be operated without interruption to charge or discharge material.
Rapid offers 2 types of continuous mixing plants:
Volumetric measurement (C)—When the ingredients of concrete are flowing continuously and measured by volume, by using a calibrated rotary opening, a calibrated fixed-gate opening, or a combination of these, so that a known, predetermined volume of each ingredient is obtained in a designated time interval, the method of measurement is volumetric. Continuous volumetric measurement with multiple ingredients requires that the proper relationship among those ingredients be maintained. It is this calibration of speed and volume which provides a smooth continuous release of materials resulting in your next homogeneous mix. See our Volumetric Rapidmix plants: 400C or 600C.
Continuous Weigh (CW)- Materials are continuously weighed from the aggregate hopper via load cells which weighs the material from the hopper to the mixing chamber. On route, the material from the silo, is collected in weigh hoppers where the silo material is then dispensed into the mixing chamber for an accurately weighed and mixed final product. You may review our Rapidmix Continuous weigh plants: 400CW or 600CW.
Both types of plants will mix your materials, this determination is sometimes specified by the source of work or an engineer. Please contact us if you have any additional questions.