Lesson 11. Steps to Achieve Q1–Q4 for Foam Block, Aerated Concrete, Polystyrene Concrete, and Expanded Clay Concrete

In the previous lesson, we examined the preparation of rough walls made of brick, concrete, and reinforced concrete, and saw how their properties influence the choice of materials and the sequence of work. To effectively apply the analytical‑restrictive method and minimize the risk of mistakes when moving to real projects, it is important to understand the characteristics of each base material: its porosity, absorbency, and strength. This knowledge reveals the “hidden part of the iceberg” and develops your professional intuition.

In this lesson, you will study the preparation of walls made of foam block, aerated concrete, polystyrene concrete, and expanded clay concrete, as well as learn the step‑by‑step algorithm for achieving Q1–Q4 levels for these bases.

Foam Block

Foam block is a lightweight porous building material made of cellular concrete, used for walls and partitions. It is produced by adding a foaming agent to a cement‑sand mixture, creating small air bubbles evenly distributed throughout the volume. This gives the material a porous structure. Foam blocks provide good thermal insulation and are easy to process, but they are less strong than aerated concrete blocks.

Aerated Concrete Block

Aerated concrete also belongs to the category of cellular concretes but differs in how pores are formed. A gas‑forming agent is added to the cement‑sand mixture, creating small gas bubbles. The mix is poured into molds, initially hardens, and then undergoes autoclaving (steam curing under pressure). This improves strength and structure. Aerated concrete blocks have high thermal insulation and are easy to lay, but they require protection from moisture due to high absorbency.

Polystyrene Concrete Block

Polystyrene concrete is produced from a cement‑sand mixture with added polystyrene granules, which form a porous structure. The granules are evenly distributed throughout the block, providing excellent thermal insulation. These blocks are lightweight and insulating, but less strong compared to other block types.

Expanded Clay Concrete Block

Expanded clay concrete is made from cement‑sand mix with added expanded clay or ceramic gravel as filler. Unlike cellular concretes, expanded clay blocks do not contain fine air bubbles. They are durable, moisture‑resistant, and suitable for both exterior and interior work, though their thermal insulation is lower than foam or aerated concrete.

Steps to Achieve Q1–Q4 in Rooms with Low and Medium Humidity

Since foam block, aerated concrete, polystyrene concrete, and expanded clay concrete share similar properties, the sequence of steps is the same for all.

Q1

1. Surface cleaning, application of two layers of deep‑penetrating primer.
2. Application of gypsum plaster using guide profiles and reinforcing mesh.
3. Leveling plaster with a straightedge.

Q2

1. Surface cleaning, application of two layers of deep‑penetrating primer.
2. Application of gypsum plaster using guide profiles and reinforcing mesh.
3. Leveling plaster with a straightedge.
4. Leveling plaster with a trowel.
5. Smoothing.

Q3

1. Surface cleaning, application of two layers of deep‑penetrating primer.
2. Application of gypsum plaster using guide profiles and reinforcing mesh.
3. Leveling plaster with a straightedge.
4. Leveling plaster with a trowel.
5. Smoothing.
6. Application of deep‑penetrating primer.
7. Application of a continuous layer of gypsum or polymer putty up to 1 mm.
8. Sanding putty with 120 and 180 grit abrasives.

Q4

1. Surface cleaning, application of two layers of deep‑penetrating primer.
2. Application of gypsum plaster using guide profiles and reinforcing mesh.
3. Leveling plaster with a straightedge.
4. Leveling plaster with a trowel.
5. Smoothing.
6. Application of deep‑penetrating primer.
7. Application of a continuous layer of gypsum or polymer putty up to 1 mm.
8. Sanding putty with 120 and 180 grit abrasives.
9. Application of deep‑penetrating primer.
10. Application of a continuous layer of polymer putty up to 0.5 mm.
11. Sanding putty with 240 and 320 grit abrasives.

Steps to Achieve Q1–Q4 in Rooms with High Humidity

Q1

1. Surface cleaning, application of two layers of deep‑penetrating primer.
2. Application of cement plaster using guide profiles and reinforcing mesh.
3. Leveling plaster with a straightedge.

Q2

1. Surface cleaning, application of two layers of deep‑penetrating primer.
2. Application of cement plaster using guide profiles and reinforcing mesh.
3. Leveling plaster with a straightedge.
4. Leveling plaster with a trowel.
5. Smoothing.

Q3

1. Surface cleaning, application of two layers of deep‑penetrating primer.
2. Application of cement plaster using guide profiles and reinforcing mesh.
3. Leveling plaster with a straightedge.
4. Leveling plaster with a trowel.
5. Smoothing.
6. Application of deep‑penetrating primer.
7. Application of a continuous layer of cement putty up to 1 mm.
8. Sanding putty with 120 and 180 grit abrasives.

Q4

1. Surface cleaning, application of two layers of deep‑penetrating primer.
2. Application of cement plaster using guide profiles and reinforcing mesh.
3. Leveling plaster with a straightedge.
4. Leveling plaster with a trowel.
5. Smoothing.
6. Application of deep‑penetrating primer.
7. Application of a continuous layer of cement putty up to 1 mm.
8. Sanding putty with 120 and 180 grit abrasives.
9. Application of deep‑penetrating primer.
10. Application of a continuous layer of moisture‑resistant polymer putty up to 0.5 mm.
11. Sanding putty with 240 and 320 grit abrasives.

Conclusion

We have examined the preparation of walls made of foam block, aerated concrete, polystyrene concrete, and expanded clay concrete, and seen how the properties of these materials influence the technology of achieving Q1–Q4 levels. The main differences lie in the initial stages: double priming and mandatory use of reinforcing mesh. These steps compensate for the high absorbency of the materials and reduce the risk of cracks during drying.

Understanding the logic of these processes helps distinguish preparation errors from decorative coating defects and allows you to work confidently with different types of bases. This increases your competence as a craftsman and reduces the likelihood of problems at the finishing stages.

In the next lesson, we will analyze typical mistakes and nuances of preparing mineral bases that can lead to defects. This will help you identify potential issues more accurately, explain them to clients, and make the right decisions before starting decorative work.