What is the mixing ratio for C20/25 concrete?

For C20/25 concrete (standard), the mixing ratio is 1:3:5 (cement : sand : gravel). Per cubic meter, approximately 300 kg cement, 640 kg sand (0-4mm) and 1,180 kg gravel (4-16mm) are needed. The water-cement ratio is 0.55, meaning about 165 liters of water per cubic meter.

How much cement do I need per cubic meter of concrete?

Cement requirements depend on the concrete class: C12/15 (lean concrete) needs approx. 250 kg/m3, C20/25 (standard) approx. 300 kg/m3, C25/30 (foundation) approx. 350 kg/m3 and C30/37 (heavy-duty) approx. 400 kg/m3. That is 10 to 16 bags of cement (25 kg) per cubic meter.

What is the correct mixing ratio for epoxy resin?

The epoxy mixing ratio depends on the product. Common ratios are 2:1 (standard, by volume), 3:1 (slow curing), 5:1 (coatings) and 100:45 (by weight, EU standard). The exact ratio is always printed on the manufacturer packaging. Deviations lead to poor curing.

How do I dilute deep primer correctly?

Deep primer is diluted based on the surface: Apply undiluted on normally absorbent surfaces (coverage approx. 6 sqm/L). On highly absorbent surfaces, first apply diluted 1:1 with water, then roll undiluted. Use undiluted on drywall (approx. 7 sqm/L).

How much tile adhesive per m2?

Consumption depends on the trowel notch: 6mm notch approx. 2.5 kg/sqm, 8mm approx. 3.5 kg/sqm, 10mm approx. 4.5 kg/sqm, 12mm approx. 5.5 kg/sqm. For large format tiles (>60cm) using buttering-floating method, add approx. 50%. A 25 kg bag covers approx. 5-7 sqm with 8mm notch.

How do I calculate grout needs?

The formula is: kg/sqm = (tile length + tile width) / (length x width) x joint width x tile thickness x density. Example: 60x60cm tile, 3mm joint, 10mm thick: (0.6+0.6)/(0.6x0.6) x 0.003 x 0.01 x 1600 = 0.27 kg/sqm. For 15 sqm, approx. 4 kg of grout is needed.

How thick should leveling compound be applied?

Minimum thickness is usually 1-3mm, maximum per layer is 10mm. For leveling above 10mm, work in multiple layers. Consumption is approx. 1.5 kg/sqm per mm of thickness. With underfloor heating, plan at least 45mm of coverage.

What is the pot life of epoxy resin?

Pot life (working time) for most epoxy resins is between 20 and 45 minutes. Coatings and crack injections have approx. 25 minutes, casting resins approx. 45 minutes. After pot life expires, the mixture becomes viscous and unworkable. Larger quantities increase temperature and shorten pot life.

Which filler for which purpose?

Gypsum filler: Interiors, joints, holes (4h drying). Cement filler: Exterior and wet rooms (24h). Fine filler: Finishing before painting (2h). Repair filler: Quick hole filling (1h). 2K filler: Wood and metal, extremely hard (30 min).

How many bags of premix concrete do I need for 1 m3?

For 1 cubic meter of concrete, approximately 67 bags of premix concrete (40 kg each) are needed (one 40 kg bag yields approx. 0.015 m3). That equals about 2,680 kg total weight. By comparison: self-mixing with cement, sand and gravel costs about half, but requires more effort and a concrete mixer.

Tile Adhesive Consumption: How Many kg per m2? | Mixing Ratio Calculator

How to Calculate Tile Adhesive Consumption

Tile adhesive consumption depends on three main factors: the trowel notch size, tile size and substrate. The notch determines the height of the adhesive ridges and thus the quantity per square meter.

The formula is simple: the manufacturer states the consumption per sqm at a specific notch on the packaging. Typical values: 6mm notch = 2.5 kg/sqm, 8mm notch = 3.5 kg/sqm, 10mm notch = 4.5 kg/sqm, 12mm notch = 5.5 kg/sqm.

Which Notch for Which Tile?

6mm notch: For small tiles up to 15 cm edge length (mosaic, small wall tiles). The thin adhesive application suffices since small tiles have little weight and the contact area per tile is small.

8mm notch: The standard notch for medium tiles (15-30 cm). Covers most wall tiles and smaller floor tiles. A 25 kg bag covers approximately 7 sqm.

10mm notch: For large tiles (30-60 cm). Large tiles need a thicker adhesive layer to compensate for substrate irregularities and ensure full-surface bonding.

12mm notch: For XXL tiles (over 60 cm) and natural stone. The thick adhesive layer also compensates for larger irregularities. With large format, often additionally apply the buttering-floating method.

Buttering-Floating: When and Why?

The buttering-floating method (also called combined installation) means adhesive is applied to both the substrate and the tile back. This ensures 100% contact area -- no voids remain under the tile.

Buttering-floating is mandatory for: Large format tiles (>60cm), natural stone, porcelain stoneware with uneven backs, outdoor installation (terrace, balcony), high-load areas (garage, commercial).

The additional consumption is approximately 50% over single-side installation. With 10mm notch, consumption rises from 4.5 to approximately 6.75 kg/sqm.

Adhesive Types and Their Properties

Flex adhesive (C2): The standard for most applications. Classified as C2 per DIN EN 12004, indicating improved adhesion and deformability. Suitable for indoor and outdoor, floor and wall, most tile types.

Dispersion adhesive: Ready-mixed adhesive from a tub. Ideal for wall tiles indoors as it is easy to work with and low-odor. Not suitable for floor installation, wet rooms or outdoor use.

Natural stone adhesive: Specially formulated for marble, granite and other natural stones. White-colored to prevent discoloration (gray adhesive can cause dark spots on light natural stone). Contains no additives that could damage natural stone.

Large format adhesive: Extra-flowable with extended open time. Enables adjusting large tiles that are heavy and unwieldy. Often with fiber additive for slip-resistant wall hold.

Practical Example: 20 sqm Bathroom with 60x60 Floor Tiles

Tile: 60x60 cm porcelain stoneware. Adhesive: Flex adhesive C2. Notch: 10mm. Installation: Simple (no buttering-floating as porcelain stoneware has flat back). Consumption: 4.5 kg/sqm x 20 sqm = 90 kg. Bags: 90 / 25 = 4 bags of 25 kg. Water: 4 x 6.5 L = 26 liters. Reserve (10%): 0.4 bags = round up to 5 bags.

Cost: 5 bags flex adhesive at approx. 15 EUR = 75 EUR. Plus grout (approx. 2 kg for 20 sqm with 60x60 tiles and 3mm joint = 1 bag of 5 kg for approx. 8 EUR) and primer (approx. 4 liters deep primer for approx. 10 EUR).