Construction technology of lightweight insulation castable

The construction process of lightweight insulation castable involves multiple key links, including preparation before construction, mixing of ingredients, pouring vibration, curing, and baking. The following is a detailed construction process and precautions compiled from various search results:

1、 Preparation before construction

base treatment

The grassroots needs to be thoroughly cleaned to ensure that there are no debris, oil stains, or loose particles.

Anchors and hooks should be installed firmly according to design requirements, and coated with anti rust paint or plastic caps to prevent corrosion.

Template production and isolation measures

The template should have sufficient strength and rigidity, with tight joints and no leakage of grout. The surface should be coated with release agent or waterproof paper.

If lightweight castables come into contact with refractory castables, they need to be isolated with plastic film or waterproof paper.

Trial block production

According to the design mix proportion, trial mix the casting material and make cubic test blocks for room temperature compressive strength and bulk density inspection. Construction can only be carried out after passing the inspection.

2、 Ingredients and Mixing

Proportion control

The measurement error of binders and additives is ≤ 2%, and the error of lightweight aggregates is ≤ 5%.

The amount of water added needs to be precise, usually 15-17%. Too much will affect the strength, and too little will affect the setting.

Mixing process

Portland cement binder: storage time ≤ 60 minutes;

Alumina cement, sodium silicate, phosphate: ≤ 30 minutes.

Using a forced mixer, first wet the lightweight aggregate with 1/2 water, then add the binder, powder, and remaining water. Stir for at least 5 minutes until the color is uniform and the aggregate is kneaded into a ball by hand.

Time requirements for different binders:

3、 Pouring and vibration

Layered pouring

The layer thickness should be controlled between 300-500mm, and the vibration time for each layer should be shorter than that of refractory castables to avoid excessive vibration causing the aggregate to float up.

Special part treatment

When pouring onto refractory castables, the latter should be cured for at least 24 hours and isolation measures should be taken.

During pipeline construction, attention should be paid to space limitations, anchor components should be treated with rust prevention, and plastic film should be laid on the surface of insulation cotton to prevent water leakage.

surface treatment

After vibration, the surface should be flat and compact, without cracks. Loose materials should be cleaned and moistened at the joints before pouring.

4、 Maintenance and baking

Maintenance system

Cement bonding: Cover with wet grass bags for moisture retention in summer, and dry naturally but freeze resistant in winter.

Water glass/phosphate combination: Waterproof measures and dry curing are required.

Baking requirements

Heat up according to the baking curve provided by the manufacturer, and it is strictly prohibited to quickly heat up or come into contact with open flames. The total baking time should be ≥ 72 hours.

The baking quality directly affects the lifespan of the lining, and it is necessary to control the slow evaporation of moisture.

5、 Common problems and precautions

Expansion joint treatment

Lightweight castables generally do not have expansion joints, but expansion space needs to be reserved around boiler parts or pipelines.

environmental control

The construction environment temperature should be between 5-30 ℃, with anti exposure to sunlight in summer and anti freezing in winter.

Prevention of Material Waste

Hardened castables cannot be reused, and the amount of ingredients must be used up within the specified time.

summary

The construction core of lightweight insulation castable lies in base treatment, precise proportioning, layered vibration, and scientific maintenance. Process details need to be adjusted for different binders (cement, water glass, etc.) and working conditions (pipelines, furnace walls, etc.). Strictly following the specifications can ensure thermal insulation performance and service life, and avoid problems such as cracking or insufficient strength.