The density of fly ash in concrete is the lowest, about 2.4, and the density of pulverized coal mixed with cement is even lower (due to its high carbon content), about 2.2. The density of cement is around 3.0.
If the content of fly ash in concrete is too large, coupled with the slump of concrete mixture is too large, in the construction of the pulping process will be more fly ash particles floating to the concrete surface, resulting in the concrete surface strength is too low, resulting in the wheel pressure after the mortar with, serious will reveal stones.

Because fly ash needs to react with hydration products of cement to trade hard substances, there are too few cement particles on the surface of concrete and too many fly ash particles, so there are not enough cement products for fly ash to react again, so the surface strength of concrete is too low

Concrete slump required by construction personnel is easy to cause sand on the surface of concrete

The original site mixing concrete construction slump for 10-30mm, and since the use of ready-mixed concrete, construction personnel on the ground concrete construction slump requirements are more and more large, individual sites even require concrete slump greater than 200mm.
They just own effort, without a care coagulation coagulation on the surface of the land, the ultimate strength when the concrete construction slump is greater than 150 mm mortar of fly ash particles is easy with the slurry process and the rise to the surface of the concrete, on the surface of the concrete strength is low, cannot afford the walking vehicle frequently, it is easy to appear on grey sand ground.

Concrete surface sand problem solution

(1) The strength grade of road surface or concrete ground of industrial factory should not be less than C20. In determining its mixing ratio, p.O42.5 cement should be used, and the dosage of fly ash should not be more than 20%, and fly ash cement should not be used.

(2) When using ready-mixed concrete to pour concrete floor, the construction slump shall not be greater than 150mm.

The picture

(3) when the use of fly ash cement construction ground surface layer, shall not use cement mortar direct plastering method, should use dry hard mortar leveling, and then use cement dilute slurry slurry plastering smooth pressure method. Because this method has no slurry process, there will be no fly ash floating, there will be no concrete surface sand phenomenon.

(4) There is a simple and economic solution to the existing sand on the surface of concrete: Use concrete seal curing agent for hardening treatment, this is a kind of lithium based chemical hardener, completely through penetration, do not change the appearance of the original concrete surface, the main effect is to improve the hardness of sand concrete surface, wear-resisting degree, the effect after its treatment is permanent.

Concrete sealing curing agent floor construction process

(1) remove all kinds of sundries on the ground, enclosure and finished product protection.

(2) rough grinding of 30# metal sheet: grind with 30# diamond metal mill, and polish it repeatedly in vertical and horizontal direction until the carbonization layer on the surface of concrete is cleaned, the flatness is basically smooth, the whole is uniform and smooth, and the dust on the ground is cleaned up.

(3) rough grinding of 50# metal sheet: grind with 50# diamond metal sheet and polish vertically and horizontally until the abrasion marks left by the 30# process are eliminated and the ground dust is cleaned.

(4) rough grinding of 120# metal sheet: add a large amount of water on the ground, grind with 120# diamond metal grinding plate, and polish vertically and horizontally until the abrasion marks left by the 50# process are eliminated, and use water push device and water absorption machine to clean the mud on the ground.

(5) Base hardening A: Sealed concrete curing floor A agent 1:6-1:8 water dilution (decide) according to the actual conditions to pour on the concrete surface, and the dust will dilute constantly repeated push uniform coating, keep the floor wet more than 4 hours, lets the diluent infiltration and fully reaction, if the diluent is ground during blot, the supplementary spilt diluent keep the floor wet, More than 4 hours of natural health preservation after hardening treatment.

(6), hole crack repair: with concrete repair mortar, cement, sand with repair ground more than 10mm large holes and cracks.

(7), 50# resin mill fine grinding: with 50# resin mill grinding processing, horizontal and horizontal cross uniform grinding, eliminate the 120 metal sheet process scratches, such as small holes, add A certain amount of agent A grinding, repair concrete surface fine holes.

(8), 100# resin mill fine grinding: with 100# resin mill grinding processing, horizontal and horizontal cross evenly polished, eliminate 50# resin scratches, and the ground dust clean, fully dry.

(9), base hardening B: the concrete sealed curing floor hardener B original liquid spilled on the surface of concrete, and the dust push hardener kept repeatedly pushed coated evenly, keep the ground wet for about 4 hours, so that the hardener fully permeated, during which if the hardener was sucked dry by the ground, then added to pour

(10), 200# resin piece fine grinding: add a lot of water on the ground with 200# resin piece fine grinding, horizontal and horizontal cross uniform polishing, eliminate 100# resin piece scratch, mud temporarily not clean.

(11), 400# resin piece fine grinding: add a lot of water again with 400# fine grinding treatment, horizontal and horizontal cross evenly grinding and polishing, eliminate 200# resin grinding piece scratches, and clean the ground mud, waiting for the ground to dry naturally.

(12), 800# resin polishing: polishing with 800# resin grinding, horizontal and horizontal cross polishing.

(13), 3000# sponge polishing pad polishing: the use of high speed polishing machine and 3000# sponge polishing pad processing, horizontal and horizontal cross polishing, clean the ground.

(14) The garbage is packed for transport.

(15) Clear enclosure protection facilities.

(16) Project acceptance, withdrawal.