Traditionally cast iron manhole covers were used globally for protecting underground sewerage and other utility systems from the external environment. However, owing to their shorter lifespan and expensive manufacturing processes, the use of such manhole covers is significantly reduced.
Now most urban development projects use precast concrete manhole covers. These covers exhibit superior chemical and fire resistance, higher flexural strength, and increased thermal conductivity.
This blog explores the manufacturing process of precast manhole covers that are used to cover modern manhole chambers in detail. This information will help you understand the steps involved in the process with ease so keep on reading till the end to learn more.
- The Precast Concrete Manhole Covers Manufacturing Process
- Assessing the Structural Requirements
- Mixture Creation
- Designing the Manhole Covers
- Creating the Mold
- Filling the Mold with Rubble
- Concrete Pouring
- Concrete Vibrating
- Curing and Setting
- Stripping the Manhole Covers
- Adding Post-Finishing Textures
- Transportation and Installation
- The Benefits of Using Precast Manhole Covers
The Precast Concrete Manhole Covers Manufacturing Process
Following are the detailed steps involved in the manufacturing process of precast concrete manhole covers
1. Assessing the Structural Requirements
First of all, the structural requirements for the precast manhole covers are assessed. This involves calculating the necessary specifications and estimating how much load-bearing capacity the cover needs to have. This assessment is done to ensure the final precast concrete manhole cover meets the project’s durability as well as aesthetic bequeathments.
2. Mixture Creation
After that, the precast concrete mixture is created by mixing water, cement, and fine and coarse aggregates in appropriate proportions. The formulation of this mixture is based on the calculations done in the previous step.
3. Designing the Manhole Covers
This step involves designing the shape and size of the manhole cover. This requires careful planning as the builders use this design to determine the dimensions of the molds.
4. Creating the Mold
After the design, wooden or steel molds are created. These molds give the manhole covers their shape and ensure these shapes have complete structural integrity.
These molds are lined with plastic which ensures the concrete doesn’t stick to the surface. This plastic also makes the demolding process easier and faster.
5. Filling the Mold with Rubble
In this step, a very fine layer of rubble or mold is placed on the mold which makes the concrete setting process faster. You can use small pebbles or stones and then compress them if necessary to make the rubble denser.
6. Concrete Pouring
The concrete pouring process requires extreme caution. You need to make sure the concrete pouring is done very slowly and that there are no bubbles on the surface during the process.
Modern manufacturers use machines for concrete pouring which ensures each mold gets an equal amount of concrete.
7. Concrete Vibrating
After pouring, the concrete is vibrated to make sure all the bubbles are removed and the surface is uniform and level. The vibrations result in a very dense and strong structure which enhances the durability of the manhole covers.
8. Curing and Setting
In this step, the level or uniform concrete is allowed to stay in the mold for a certain amount of time to facilitate its setting. This creates a strong and hard structure which is then moved to the storage space.
9. Stripping the Manhole Covers
After curing, the precast manhole covers are stripped out of the molds and then sprayed with water to ensure there is no residue in the final structure.
10. Adding Post-Finishing Textures
This is an optional step that involves creating patterns, shapes, or logos on the manhole covers while the concrete is in the liquid state. After applying the finishing textures, the concrete is allowed to set and gain strength. Upon drying, you get a smooth concrete manhole cover surface with the exact design and texture that you want.
11. Transportation and Installation
After completion, the manhole covers are packed and transported to the construction site. The off-site production of these covers streamlines the construction process.
In this case, the site preparation and precast manhole cover manufacturing can happen at the same time. Upon arrival, you can easily install and seal these covers in their places which further saves you time.
The Benefits of Using Precast Manhole Covers
Following are a few reasons why you need to choose precast manhole covers for urban areas
- These covers allow for easy installation. There is no need to wait for additional setting time since these covers arrive at the site of construction in the finished form.
- For larger projects using precast concrete manhole covers can reduce labor costs by reducing the amount of work that is needed to be done on the site of construction.
- These manhole covers can bear heavy loads with ease which makes them more durable than cast iron covers.
- Precast manhole covers are weather-resistant and they require very little maintenance.
- These covers give you greater freedom in terms of colors and textures.
- These covers provide foolproof protection to underground systems by keeping them tightly sealed.
- Precast concrete manhole covers are pest-resistant as well.
Conclusion
The construction process of precast manhole covers involves several careful steps each ensuring the final product you get is both durable and aesthetic. From designing molds to pouring concrete and from curing to installation each step involves careful planning and execution.
The use of precast manhole covers in your commercial and domestic projects ensures greater design flexibility as well as cost efficiency. These covers are also more durable owing to their high moisture, heat, and chemical resistance.
Consider the precast manhole covers for your next project if you are looking to save both time and money without sacrificing quality.
Visit Naran Precast Concrete Co. today to order our top-quality precast and GRP manhole chambers and manhole covers for your upcoming projects to get the best value for your money.