1. General Provisions

To ensure the ultimate performance (wear resistance, weather resistance, yellowing resistance, temperature shock resistance) and design service life of the MicroRock Flooring System, the substrate shall be constructed as an integral part of the structural functional layer. This specification applies to newly-built rough housing projects with insufficient reserved floor height (typically 5–8 cm), which require height filling and professional substrate treatment to meet the construction requirements of the MicroRock topcoat.

 

2. Core Requirements

- Substrate compressive strength: ≥ 25 MPa (equivalent to concrete grade C25)
Substrate bond strength: ≥ 1.5 MPa
Substrate moisture content: ≤ 8%
Flatness: ≤ 3mm/2m
Surface condition: Sound and solid, no hollowing, cracks, oil contamination or laitance

 

3. Standard Construction Procedure

 

Step 1: Substrate Assessment and Preparation

- Inspection: Verify that the original floor slab is free from structural defects such as cracking and settlement.
Measurement: Accurately calculate the required filling thickness and determine material consumption.
Treatment: Shot-blast or grind the original floor to remove laitance and improve bonding between old and new concrete. Conduct thorough dust vacuuming before construction.

 

Step 2: High‑Strength Levelling Layer Construction (Core Procedure)

This layer serves as the structural base for polyurethane mortar, and its quality directly determines the overall success of the finished flooring.

Item

Requirements & Standards

Material Selection

Preferred Option: High‑strength cementitious self‑levelling mortar (base course type) • Compressive strength grade: ≥ C25 (25MPa), C30 is recommended. • Standard: Compliant with EN 13813 CT‑C25F4 or higher grade. Alternative Option: Fine aggregate concrete (on‑site mixing with small concrete mixer only; manual mixing is strictly prohibited) • Grade: ≥ C25. • Mix ratio (by weight): P.O 42.5 Cement : Medium Sand : 5‑12mm Fine Aggregate = 1 : 1.5 : 2.7. • Water‑cement ratio: ≤ 0.45.

 

Step 3: Anchor Groove Cutting and Stress Relief release

This procedure is critical to prevent cracking and delamination of the topcoat.

1. Cutting timing: Perform cutting after the levelling layer completes curing (approximately 28 days) and fully develops structural strength.

2. Anchor groove grid layout:
Cut cross-shaped grid grooves on the levelling layer surface with a professional cutting machine.
Grid spacing: 0.8m × 0.8m or 1.0m × 1.0m.
Groove dimension: Both depth and width shall be twice the designed topcoat thickness (e.g. 8mm×8mm groove for a 4mm topcoat).

3. Edge treatment: Cut parallel isolation grooves at 10–15cm away from walls, column bases and other boundaries.

4. Cleaning: After cutting, completely remove all dust and particles inside grooves and on the surface with an industrial vacuum cleaner.

 

Step 4: Final Substrate Surface Treatment

1. Shot-blasting / Grinding: Conduct overall light shot-blasting or grinding on the levelling layer to completely remove the surface cement paste film, expose solid aggregate, and form a uniformly rough surface.

2. Vacuum Cleaning: Perform thorough cleaning with an industrial vacuum to achieve a dust-free standard.

3. Application of Special Primer:
Material: Adopt polyurethane or epoxy dedicated primer matched with the MicroRock system.
Method: Apply evenly by roller or trowel to fully seal substrate pores without omission. Topcoat construction can only proceed after the primer is surface-dry.

4. Quality Acceptance (Before Topcoat Construction)

The MicroRock construction contractor must inspect and accept the finished substrate before construction:
Strength inspection: Random sampling test with rebound hammer, compressive strength ≥25MPa.
Moisture content inspection: Multi-point measurement with concrete moisture tester to meet standard requirements.
Visual & tactile check: Solid surface free of dust and loose particles.
Complete the process handover form to clarify quality liability of the substrate.

 

5. Precautions

- Direct application of polyurethane mortar on unqualified substrates (such as ordinary cement mortar), excessive moisture content or dusting base is strictly prohibited.
Large spacing of 4–6 meters for anchor groove cutting is forbidden, as it belongs to incorrect construction practice.
The underfloor heating system must be fully commissioned before topcoat construction and kept running throughout the drying period.
Recommended construction ambient temperature: 15℃–30℃, relative air humidity below 75%.

Shenzhen Simon United Building Materials Co., Ltd.

Guangdong Simon Huicheng New Materials Co., Ltd.