Progress with precast, prefired bricks

Precast, pre?red castables are saving customers time while delivering a better performance and meeting more complex requirements.

High-temperature environments rely on heat-resistant castables to protect or repair equipment, such as kilns, boilers, incinerators, or furnaces. Usually, these are cast in place – where the materials are mixed, poured, and set at the customer’s location. While this is an established process, an alternative approach results in both improvements in performance and reduced downtime.

Precast, pre?red (PCPF) bricks and refractories are becoming an increasingly attractive proposition. The castables are produced offsite and delivered to the customer’s plant – dried out, shaped to the customer’s requirements, and ready to install.

Calderys creates ready-shaped products for conventional castables, low-cement castables, plastic refractories, and insulating castables. These products are used for all types of workplaces, from high-temperature environments to construction projects such as bridges and buildings.

The company’s ready-shaped products are mixed and set in moulds in a quality-controlled industrial environment, at one of Calderys’ facilities, which means they are more likely to deliver longer and better performance than cast-in-place products. Furthermore, the installation time is more than halved, because there is no dry-out time at the customer’s end.

Additionally, the company’s design and technical expertise means that it can cast more complex geometric shapes that cannot be achieved with the standard pressing process without modi?cations or brick cutting onsite.

Better performance

There are numerous bene?ts to precast shapes over their cast-in-place counterparts.

Ready-shaped products are manufactured in a controlled environment, which means there is greater assurance to the customer of consistent quality and durability of the material.

Rudraksh Kulkarni, one of Calderys’ precast, pre?red experts, says “the ready-shaped blocks and shapes are made in our own facility, overseen by our trained quality supervisors. The physical and mechanical properties are better than regular casting.”

In regular casting, the castable material is mixed and applied in situ. Calderys offers an installation service, but customers can also hire local workers if they prefer.

However, it is becoming increasingly challenging to ?nd workers with the right skills – and, Calderys, being the producers, has real in-house experts who understand and know the material to be mixed and poured well.

“The quantity of water used – the ratio of water to castable – and how the castable solution is poured in place is vital in ensuring the best performance,” says Rudraksh.

With ready-shaped products, the castables are delivered as a ?nished product. They minimise the need for human intervention. The controlled environment of the manufacturing facility protects the properties within the materials – high mechanical strength, thermal conductivity, thermal shock resistance, low abrasion, and resistance to cracking (spalling) – and ensures they mix accurately.

Divyendu Tripathy, Thermal Marketing Director at Calderys says: “With precast shapes, we are attempting to eliminate any uncertainty and address the shortage of skilled labour. Calderys provides engineering and installation services for their precast shapes at customers’ sites. Installation of precast shapes is simple and doesn’t have the same challenges around quality.”

“There is less manpower required for the mix or the pour, which minimises human error. It is very important to follow the installation operations properly, as it can impact the performance of the lining.”

“And, of course, because this process requires less manpower and mechanised operations at the site, there are fewer safety risks.”

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Read the article online at: https://www.worldcement.com/special-reports/18102023/progress-with-precast-prefired-bricks/