ABLE CASTABLE INSTALLATION INFO
Able Refractory Products manufactures a complete line of both dense and
insulating castables. To achieve the best refractory lining, carefully
follow the methods and techniques listed below.
Select the Able Refractory Castable or Gunning Mix best suited to meet the service requirements of your- particular job. Some items to consider are operating temperatures, peak temperatures, strength, abrasive resistance and thermal conductivity.
Estimate the quantity of material required for the job using our
All Able Refractory Castables are packaged in multi-wall bags consisting of several layers of paper and a moisture resistance liner. Carefully
store all castables up off the ground in a dry location protected from
the weather. If you stock Able Refractory Castables, it is very important to
rotate your stock in such a manner that the oldest material is used first.
Able makes castable which can be cast, poured, gunned or troweled.
Regardless of the method of installation, use tools and equipment which are
as clean as possible and free from all old mortar; portland cement, lime and
dirt. Obtain a source of clean water to use in mixing the castable.
We recommend our Able Refractory Castables be mixed in a paddle-type mixer as this gives us a rapid mix (avoid excessive mixing times), and the positive mixing action results in a uniform mix. Able castables may also be mixed in a wheelbarrow, mortar box or bucket.
Refer to the Able catalog for the recommended water to castable mix
ratio. Remember excessive amounts of water reduce the refractory concrete's
strength. Use clean water which is suitable for drinking. The ideal water
temperature is 500F to 700F.
Mix the material in batch sizes that can be installed quickly; under five (5) minutes is suggested.
It is not recommended to install castables at temperatures near freezing
or at temperatures above 900F. Lower temperatures decrease the
rate at which castables set up. And conversely, higher temperatures increase
the rate at which castables set up. In both cases, the extreme temperatures
may reduce desirable physical properties.
If using forms, thoroughly waterproof them. This avoids the absorption of moisture from the refractory concrete. The moisture is necessary in the castables to hydrate the cement and thus, develop proper strength. A little vibration may be necessary in the castables to eliminate voids, especially in corners and around anchors. Be careful not to over vibrate the castables, as the finer particles tend to float to the surface. If vibrating is causing too much separation, a thorough tamping or puddling of the castable should be done in place of the mechanical vibration. Insulating castables should only be hand tampered or puddled to prevent material segregation.
Excess castable should be disposed of and not remixed for the next pour. The cement has started to hydrate, and if used it will result in a concrete with reduced strength.
In pneumatic applications, carefully control the amount of water and air pressure used to prevent excessive rebound loss and slumping of the refractory concrete.
In both methods of placement, pouring or gunning, care should be used to minimize planes from one application to another, for these result in planes of structural weakness.
Rake off the surface of the castable level, but do not smooth it slick
with a trowel. A smooth surface closes off the surface pores to retard the
escape of moisture during initial cure out and firing.
The set times on Able castables, as with all castables, vary from one
product to another, but generally the time required for Able dense castables
is shorter than the time required for Able insulating castables. Generally,
forms can be removed from side walks after twelve (12) hours for dense
castables and twenty-four (24) hours for insulating castables. Forms for
suspended roofs or arches require double the time of side walks.
After curing is complete, a minimum of twenty four (24) hours after installation, castable firing can be started. The curing and firing process, once started, should be followed through uninterrupted.
Some moisture will still be present in the cast-able, so gradually bring the temperature to 2250F and hold for twenty-four (24) hours. This dries out the physically retained water. Note, rapid initial heating above the boiling point generates steam pressure within the castable, which destroys the strong bond and causes spalling and cracking. If excessive steaming occurs during this firing process, hold the temperature until steaming subsides. Then raise the temperature 250F per hour to 6000F and hold for twelve (12) hours. Then raise the temperature 500F per hour to 12000F and hold for twelve (12) hours. Then raise the temperature 500F per hour to the desired operating temperature. Hold at this temperature until the heat balance through the material is established to obtain the ultimate ceramic bond. Heat-up is to be continuous and uninterrupted. All temperatures are to be measured at the surface face of the refractory. Cooling should not exceed a rate of 1000F per hour.
Consult your Able Refractory sales engineer for proper procedures on more rigid cure out and firing schedules for unusually thick linings, and for any questions.