Common Causes And Solutions For Cracks On The Surface Of Anti-static Terrazzo

Common causes and solutions for surface cracks on anti-static terrazzo
1, Common cause analysis
Grassroots issues
Inadequate backfill soil or frozen base layer: The ground backfill soil is not compacted or the base layer freezes during winter construction, resulting in uneven thickness or insufficient strength of the cushion layer, which can lead to surface cracking.
Incomplete cleaning of the base layer: Before construction, the base layer was not cleaned thoroughly, resulting in oil stains, floating dust, or loose particles, which affect the adhesion between the terrazzo and the base layer.
Improper joint treatment of prefabricated components: For example, if the joints or end joints of prefabricated concrete floor slabs are not poured tightly, it will result in insufficient overall integrity and stiffness of the floor slab, and it is easy to crack when the load is concentrated.
Material and proportioning issues
Cement mortar has high shrinkage: The cement mortar ratio for the terrazzo surface layer is unreasonable, the proportion of additives is inappropriate, or the aggregate gradation is poor, resulting in shrinkage stress exceeding the material's tensile strength.
The problem of adding anti-static materials: Uneven dispersion of anti-static conductive fibers or powders can cause stress concentration due to local differences in conductivity, leading to cracks.

Construction process defects
Unreasonable grid design: The grid area is too large or the grid strip is too narrow, forming a narrow stress concentration zone that is prone to cracking at the grid zone.
Improper construction process:
The interval between the construction of the cushion layer and the surface layer is too short, and the contraction of the cushion material is not stable before the surface layer construction is carried out.
The concealed cable pipeline is too high, and the surrounding mortar is not tightly fixed, forming weak points.
Surface polishing problem: The polishing timing is too early or too late, resulting in incomplete repair of surface pores or insufficient compactness.
Maintenance and environmental factors
Inadequate maintenance: Failure to timely cover and moisturize after construction resulted in rapid evaporation of surface moisture, leading to shrinkage cracks.
Temperature stress: Changes in temperature difference can cause thermal expansion and contraction of materials. If expansion joints are not set or the spacing between expansion joints is too large, it is easy to cause cracking.
Load concentration: The ground is subjected to long-term heavy object crushing or local impact, exceeding the material's bearing capacity.
2, Solution and preventive measures
Grassroots processing optimization
Compaction of backfill soil: Ensure that the backfill soil at the base layer is compacted layer by layer, with a compaction coefficient of ≥ 0.94, to avoid false paving.
Winter construction protection: During winter construction, the base layer should be covered with insulation materials to prevent freezing, and the construction temperature should be ≥ 5 ℃.
Thoroughly clean the base layer: Before construction, remove oil stains and floating dust, rinse with a high-pressure water gun and air dry, and if necessary, apply interface agent to enhance bonding.
Material and proportioning control
Optimize the cement mortar ratio:
Cement: sand=1:2~1:2.5, water cement ratio ≤ 0.45, adding an appropriate amount of water reducing agent to reduce shrinkage.
Anti static conductive fibers or conductive powders should be evenly dispersed to avoid local aggregation.
Use low shrinkage materials: choose low alkali cement or add expansion agent to compensate for shrinkage stress.
Construction process improvement
Reasonable grid design:
The partition area should be ≤ 16 square meters, and the width of the partition strip should be ≥ 10mm. Copper or glass strips should be used to ensure that the partition joints are straight.
Narrow and narrow areas (such as corridors) need to shorten the spacing between grids to avoid stress concentration.
Standardize construction procedures:
After the construction of the cushion layer, it needs to be cured for more than 7 days, and the surface layer construction can only be carried out after the shrinkage is stable.
Concealed pipelines need to be firmly fixed, and the surrounding mortar should be densely filled to avoid hollowing.
Timing of surface polishing:
After the strength of the terrazzo reaches 70% of the design value, it will be polished, with coarse grinding followed by fine grinding, and air holes repaired before polishing.
Maintenance and Environmental Management
Moisturizing maintenance: Cover with plastic film or grass curtain after construction, keep the surface moist for at least 7 days, and avoid drying shrinkage cracks.
Set expansion joints: Set expansion joints along the axis direction of the building, with a spacing of ≤ 6m, a joint width of 5-10mm, and filled with elastic sealing material.
Control load: During the initial use of the ground, avoid heavy objects from crushing it, and reinforce local impact areas.
Crack repair methods
Shallow crack repair:
Clean the debris inside the crack and blow it clean with high-pressure air.
Inject epoxy resin adhesive or marble adhesive, fill it to the surface level, dry and polish.
Deep crack repair:
Slot 5cm on both sides of the crack, with a depth of ≥ 10mm, to form a V-shaped groove.
Apply interface agent in the groove, fill with professional repair mortar, and compact layer by layer until it is level with the original ground.
After the strength of the material to be repaired meets the standard, it shall be polished and polished.
Large scale fracture repair:
Chisel out the terrazzo surface layer in the fractured area, pour a fine stone concrete cushion layer again, and lay steel wire mesh for reinforcement.
Reinstall the terrazzo surface layer according to the original process to ensure consistency in color and texture.
3, Summary of preventive measures
Design phase: Reasonably plan the grid layout and clarify the requirements for setting expansion joints.
Material stage: Strictly control the quality of cement, sand, and anti-static materials to ensure accurate proportioning.
Construction phase: Strengthen grassroots treatment, process connection, and maintenance management to avoid rough construction.
Acceptance stage: Focus on checking the straightness of the dividing joints, surface flatness, and crack conditions, and rectify them in a timely manner.