Another type of Wet Mix Macadam is Water Bound Macadam. When the required size and quality of aggregate and stone dust for Wet Mix Macadam cannot be established, Water Bound Macadam shall be utilized for all road construction. The specifications and different uses of this material in road construction in explained in many pdf files. Water-bound Macadam work shall consist of clean and crushed aggregates, mechanically interlocked by rolling and bonding together with screening, binding material where necessary, and water, laid on a properly prepared sub-grade / sub-base / base or existing pavement, and finished in accordance with the requirements of the Specifications or as directed by the Authority Engineer. The Water Bound Macadam Road is a style of road construction in which the road's base is made with broken stones and the road's surface is bound with stone dust using water. It is one of the most often employed procedures in road construction. In 1820, it was named for the renowned Scottish engineer John Loudon Macadam.
Between 1750 and 1830, two Scottish engineers were active in promoting and expanding their distinct road construction systems, bringing macadam-type pavement into prominence. Thomas Telford and John Loudon Macadam constructed the foundation layer with relatively large stones on a flat roadbed. Macadam believed that a road should always be elevated to facilitate drainage and prevent water stagnation, hence extending the life of the constructed road. The thickness of each compressed layer of a water bound macadam road ranges from 10cm to 7.5cm, depending on the mixture's gradation and particle size. Water Bound Macadam Road Benefits
- The cost of creating Water Bound Macadam Road is relatively low, hence it is cost-effective.
- No expert work is required to build a WBM road.
- WBM roads are created with materials that are readily available.
- If these roads are regularly and adequately maintained, they might withstand daily traffic loads of around 900 tons.
Negative aspects of WBM Road
- Compared to other types of road construction, the cost of upkeep is rather expensive.
- Overall, Water Bound Macadam Road has a shorter lifespan.
- If these roads are not properly maintained, there is a great probability of traffic hazards and inconvenient conditions.
- As a result, the subsoil softens and yields because these roadways are permeable to rainwater.
Water-Bound Macadam Road is constructed primarily with three types of materials. Binding Material, Screening, and Coarse mixture or aggregate Binding material: The binding material that is to be utilized in the building of the Water Bound Macadam Road must be certified by the authorized engineer and must have plasticity index values of less than six. Screening: These are the components used to fill the extra space or void in the crushed layer of the coarse mixture during screening.Coarse Mixture: This is essentially broken stones and crushed mixtures used for each layer of the Water Bound Macadam Road. The process of constructing the Water Bound Macadam Road involves a number of processes. They are as follows: Preparation of the foundation or base The mixture is formulated in accordance with the gradient of the Water Bound Macadam Road. Using the created mixture, depressions and potholes are filled and compacted appropriately on the surface of the road. Offering Lateral Confinement It is accomplished by creating road shoulders with the same thickness as compressed water Bound. Macadam Road. The primary objective of the construction of a road's shoulder is to trim the inner sides vertically so that the future construction of the road surface remains between the two road shoulders and facilitates the subsequent laying of the coarse mixture. Distribution of Coarse Aggregates or Blends After the road shoulders have been constructed, the coarse mixture or aggregates are dispersed uniformly over the prepared base. The total thickness and number of layers of Water Bound Macadam Road are entirely dependent on the pavement design's specifics. For a standard roadway, a single layer of 75 mm compressed thickness is deemed sufficient. The compressed thickness can be given for roads constructed with 150 mm double layers.
Rolling After correctly spreading the slurry, the aggregate is compacted using a three-wheeled road roller or vibrating roller. The Water Bound Macadam Road is vitally important, hence competent operators are employed to ensure that no errors are made. A fault rolling operation could lead to the production of loops, such as uneven road wear or an uneven road surface finish. Screening After the rolling procedure is complete, screening is performed. With the use of screening the residual space following the compression of the mixture. Depending on the conditions of the site, the screening procedure may be implemented in three or more layers. Grouting and Irrigation The upper surface of the created Water Bound Macadam Road is swept, sprayed with water, and rolled after the screening process is complete. Once the surface has been sprayed with water, the wet screening is swept into the remaining space with a broom. Drying of the Surface The newly constructed road is allowed to dry and set overnight after the final rolling. If the extra space is evident the following day, sufficient screening is conducted. Construction of Roadside Shoulders
They are appropriately compacted and created alongside the cross slope through the procedure of filling the earth to the specified level. Once the newly constructed road has dried and is devoid of depressions, it can be used. Drums are used to barricade the route and evenly disperse traffic on the road. The drums are arranged as longitudinal impediments. Preservation and maintenance of WBM Road
- If any ruts or potholes appear on the newly constructed Water Bound Macadam Road within a certain time frame, the responsible authority should repair it by filling it with the necessary material and correctly combining it.
- The completed roadway must be dragged in order to eliminate the resulting unevenness. It could result in the deterioration of the constructed roadways.
- Fresh materials should be utilized in place of any deteriorated road materials.
- Depending on the volume of traffic, the surface of the constructed road must be replaced every two to five years.
- The loose mixture that accumulates on the surface of the road should be removed. The surface of the road in Lavelle should be resurfaced with new binding material and thoroughly compacted and hydrated.
Contact us for further information or any inquiries. Our team of professional sales executives is ready to answer all your questions and inquires.