First, the wall’s U-value for the intended building must be determined, which is done as follows:
1- The energy requirement of the target region is obtained from the table on pages 65 to 74, which, for example, applies to all buildings in Tehran (average heating requirement).
The term “heating requirement” refers to the necessity of using non-electric energy.
2- By referring to the table on page 77, the type of usage is specified (for example, residential, which is Usage Type A).
3- Determine the building group in terms of energy savings, for which we refer to the table on page 81.
In the table on page 81, depending on whether the project is located in a large city or a small city and whether its floor area is less or more than 1,000 m², the building group is determined.
For example, if a project has a 2,500 m² building area and is located in Tehran, it belongs to Group 2.
4- The final step is to refer to the table on page 27, where Uw for non-electric energy in Group 2 is 1.01. This means that the sum of the k-values of the materials used in the building’s exterior wall must be less than 1.01 to be acceptable. Considering that the Uw of a 20 cm LECA wall with plaster and mortar is 0.831, it is acceptable. The 15 cm wall, with the obtained value of 0.997, is slightly on the borderline but still acceptable.
The performance of LECA walls against sound can be determined by reviewing tables (18-2-2) on page 16, (18-2-5) on page 18, (18-2-8) on page 19, (18-2-11) on page 21, (18-2-14) on page 23, and clause 18-2-7-4 on page 24 of Chapter 18, and comparing them with the results obtained from tests on walls constructed with LECA.
The issue of cracking is related to various factors, which include the following:
1- If different materials are used in the wall, such as LECA and clay bricks or LECA and conventional bricks, the likelihood of cracking increases due to the non-uniform expansion and contraction coefficients of the materials. If all products used in the wall are uniform, this likelihood is minimized. Considering the wide variety of LECA products, it is recommended to construct a homogeneous wall using a single product type.
2- If the thickness of plaster on the wall is excessive, cracking is more likely. Given the standard tolerance of LECA blocks in width (±3 mm), if the plaster thickness is not excessive, the likelihood of cracking is very low.
3- One influential factor in cracking is the shrinkage coefficient caused by drying. Based on test results obtained during the technical certification process, this value is less than 0.065, and therefore, no cracking can occur in the block itself.
4- If the block material strength meets the standard, minor cracks can occur due to vibrations from low-intensity earthquakes in the upper floors of tall buildings or from overall building settlement.
5- If the allowable span and height are not observed during wall construction, the likelihood of cracking increases, though this is unrelated to the type of material used.
6- If the metal components of the structure, especially columns and braces, are not covered with chicken mesh, there is again a possibility of cracking, which is also independent of the type of material.
7- If the applied plaster or gypsum has a coarser particle size than the standard during execution, cracking can still occur.
8- Overall structural settlement, as mentioned in point 4, can be a contributing factor to cracking, particularly for horizontal cracks.
There is no issue with using stone on LECA walls. Compared to clay bricks, stone façades have been applied for years on 8 mm-thick clay brick walls. In a 15 cm LECA block, the wall thickness is 33 mm, so there will be no problems. Moreover, the strength of the stone attachment is significantly higher than on clay brick walls.
Leca, like all other products, absorbs water and therefore its use as an exposed exterior façade is not recommended.
Yes. If the mason has constructed the wall carefully, this is possible, and in some sections of the National Library of Iran project, this method has been used.
Structural lightweight concretes are those that, despite having a density of less than 1800 kg/m³, achieve a compressive strength of over 17 MPa. Producing such concrete is only possible using strong and lightweight aggregates. In 2006 (1385 in the Iranian calendar), Leca successfully modified its processing to produce structural lightweight aggregates in Iran.
Since the highest sound insulation in a Leca wall is achieved when both sides are plastered with mortar, the above method is not recommended.
Yes, but it is recommended to use a grinder or grooving machine, as this results in a much cleaner finish.
No, Leca blocks are cut using a grinder.
Yes, they can be used without any problem.
To calculate the approximate number of blocks, the following method is used:
Total wall area of the building: 22,000 m² = 2.2 × 10,000
Lateral walls: 7,333 m² = 22,000 ÷ 3
Internal walls: 14,666 m² = 2 × (22,000 ÷ 3)
External walls: Number of 20 × 19 × 49 blocks required: 73,330 = 10 × 7,333
Internal walls: Number of 20 × 10 × 40 blocks required: 176,000 = 12 × 14,666
Building industry, agriculture, textile industry (washing of denim fabrics), pharmaceutical industry, and wastewater treatment plants
According to the company’s strategy of outsourcing block production to external suppliers, this is not only possible but is also welcomed and supported.
Lightweight, very low thermal conductivity (λ = 0.09–0.101 W/m·K), capillary impermeability, neutral pH (~7), high porosity, and fire resistance are among the main features of Leca.
Leca lightweight aggregate
ChatGPT said:
Leca concrete blocks, with a low specific weight (560–680 kg/m³) in hollow types and thermal conductivity of λ = 0.12 W/m·K, can be used in many climates without the need for conventional insulation. In addition to their lightweight and thermal and acoustic insulation properties, these blocks offer other features such as good workability, suitability for vertical mortar application, variety in shapes and sizes, and the ability to be produced in different sizes and forms according to customer requirements.
For seedling cultivation, 3–0 mm particles are used; for root retention, 10–3 mm; and for drainage under pots and surface decoration of pots, 20–10 mm particles are used.
The important point in answering this question is that, due to the highly variable conditions required for the growth of different plants, it is better to explain that Leca has characteristics such as lightness, high porosity, capillary impermeability, neutrality, and absence of nutrients. If cultivation conditions require these features, Leca can be used. Therefore, a definitive answer cannot be given because the growth requirements of various plants are very diverse.
Yes, it can be used.