Concrete Construction Standards

process flow

Construction preparation → find elevation. Play the horizontal line of the surface layer → grass-roots treatment → sprinkling water to moisten → plastering cake. Wiping standard rib→brushing plain cement paste→pouring fine concrete→mopping surface layer. Calendering→maintenance→cutting joints→protection of finished products.

 

Construction preparation

  1. Material requirements

Cement: 32.5 Portland cement shall be used. Ordinary Portland cement and slag Portland cement.

Sand: coarse sand: mud content not more than 5%.

Stone: the maximum particle size of stone used for coarse aggregate should not be larger than 2/3 of the surface layer thickness, and the particle size of stone used for fine concrete surface layer should not be larger than 15mm.

  1. The main machinery

A concrete mixer, a plate vibrator. Transport trolley. Bucket. Half bucket. Broom. 2m yardstick. Iron roller. wooden trowel. Broom. Steel wire brush. chisel. Hammer. Iron trowel.

Concrete Construction Standards

Construction workmanship

  1. Find the elevation. Play the horizontal line of the floor: according to the existing +50cm horizontal elevation line on the wall, measure the horizontal line of the concrete floor, and play on the surrounding walls, and be connected with the corridor outside the room. Stairway platform. The elevation of the tread echoes, consistent through.
  2. Grass-roots treatment: first clean up the dust, then shovel off the paste skin stuck on the grass-roots level, brush off the oil stain with alkaline water, and finally rinse the grass-roots level with water.
  3. Sprinkling and wetting: sprinkling and wetting the surface of the grassroots layer one day before wiping the top layer.
  4. Wiping gray cake: according to the surface elevation line, pull the line horizontally and vertically, wipe the gray cake with the same proportion of concrete with bean stone, the distance between horizontal and vertical is 1.5m, the elevation of the gray cake is the surface elevation.
  5. Wiping standard rib: In order to ensure the smoothness of the floor of the larger room, the standard rib (or called punching rib) should be wiped with the good gray cake as the standard, and the bar-shaped standard rib should be scraped flat with the scraper, as the standard for the thickness of the surface layer of the concrete.
  6. Brush the combined layer of cement paste: before laying the concrete surface layer, brush a 1:0.4-0.5 (cement: water) of cement paste on the wetted grass-roots level, don’t brush too large an area, brush with the paving stone concrete, to avoid the surface layer of hollow drum caused by the long time drying of cement paste.
  7. Pouring fine concrete.

(1). Stirring of concrete: the strength level of the concrete surface layer should be tested according to the design requirements, such as design without requirements, should not be less than C20, the ratio calculated by the laboratory according to the raw materials, the application of mixers for mixing, slump should not be greater than 30mm, and according to national standards “concrete structural engineering construction and acceptance of concrete” provisions of the production of concrete test blocks, each floor construction should not be less than a group. When the floor area of each floor project exceeds 1000m2, one set of test block shall be made for each additional 1000m2, and calculate by 1000m2 if it is less than 1000m2. When the mixing ratio is changed, the test blocks shall be made accordingly.

(2). Surface layer of concrete paving: Mix the concrete paving to the ground floor of the grass-roots level (cement slurry combined layer to be paved with the brush), followed by 2m long scraping bar along the standard bar scraping, and then use the roller (commonly used for the diameter of 20cm, length of 60cm concrete or iron roller, thicker thickness should be used plate vibrator) round trip. Rolling vertically and horizontally, if there is a concavity, fill it with concrete of the same ratio, until the surface layer of watering phenomenon, scatter a layer of dry mix cement sand (1:1 = cement: sand) mix, to be scattered evenly (sand to pass 3mm sieve), and then scrape the bar with 2m long (operation from the room to retreat outward).

8.Smoothing layer . Calendering.

When the grey surface of the surface layer absorbs water, rub it hard with a wooden trowel. Smooth and mix the dry cement and sand mix with the slurry of the fine concrete to make the surface layer to be tightly combined.

The first time wiping and pressing: use iron trowel to gently wipe and press the surface layer once until it is pulp.

The second time wiping and pressing: when the surface layer of mortar is initially set, and there are footprints on the surface layer of the ground but not sagging, use iron trowel to wipe and press the pit for the second time. The sand holes are filled and leveled, and the pressure must not be missed.

The third time wiping and pressing: when the surface layer of mortar before the final condensation, that is, people step up a little footprints, with iron trowel light without erase marks, available iron trowel for the third time to light, this time to wipe and press hard, all the wiping pattern pressure is pressed light, to achieve the surface surface layer of the surface dense and smooth.

  1. Maintenance: 24h after the surface layer wiping and pressing (can cover the plastic film maintenance when necessary), watering maintenance, not less than 2 times a day, the maintenance time is generally not less than 7d (the room should be closed during the maintenance of prohibit access).
  2. Parting joints cutting: underground garage wear-resistant concrete ground construction, in order to avoid the structure of the column around the ground cracking, must be set between the ground and the structure of the column parting joints, slit width 5mm, the separation joints in the ground after the strength of fine stone concrete reached 70%, with the grinding wheel cutting machine cutting. Before cutting, must be elastic line, to ensure that the width of the grid seam straight. Column edge, ventilation. Electricity. Water tank room. Separate joints should be set at the edge of equipment foundation, 100mm from the equipment foundation edge, filled with elastic material.

See the following diagram for the location of the dividing seam at the column edge.

Concrete Construction Standards

Quality acceptance criteria

1.Material of the surface layer . The strength (ratio) and density must meet the design requirements and construction specifications.

  1. The combination of the surface layer and the grass-roots level must be solid, without hollow drum.
  2. The surface must be clean, without cracks or peeling. Peeling. The surface must be clean, no cracks, peeling, pitting, sanding and other phenomena.
  3. The surface layer with floor drain, the slope conforms to the design requirements, no water flooding, no leakage. No leaking. No water accumulation. The joint with the floor drain (pipe) is tight and smooth.
  4. Pouring the floor floor with fine concrete once live, must be vibrated after compacting, according to the elevation of scraping, before the final setting of the concrete, not less than three times the calendering, maintenance for not less than 7 days, and finished protection.
  5. Each partition, regardless of size, must be completed at once, can not leave construction joints to avoid

Crouch appears, resulting in inconsistent color. Croucher is uneven or cracks appear.

  1. The protective layer of the coil can be wiped and smoothed with the fight, and the secondary surface can be accepted before the initial condensation.

(Click to view large map)

Concrete Construction Standards

Finished product protection

  1. In the process of operation, make sure that the door frame and all kinds of pipelines laid in the grass-roots level shall not be damaged by the two-wheeled truck carrying ash.
  2. Smooth out the footprints at any time during the course of surface layer troweling, and close all the accesses through the operation room. No pedestrians are allowed on the concrete surface during its curing . Transport materials.
  3. During the curing process after the surface layer is calendered and handed over, close the doorway and channel, no other workmen can enter the operation, so as to avoid the phenomenon of surface sanding.
  4. When the maintenance time of the surface layer meets the requirements, the operator can operate on the surface layer to prevent the hard tools from scratching the ground and prevent the surface layer from being polluted in the process of painting and sizing.
  5. All kinds of pipelines laid on the ground should have protection measures, and place temporary plug to protect them from being blocked by debris.
  6. Do not mix concrete and mortar on the surface layer of the concrete that has been done.

Should pay attention to the quality issues

  1. Sanding of the surface layer. Peeling: due to insufficient cement grade or using expired cement. Water-cement ratio is too large, not enough to wipe the number of times. Premature operation of other processes during maintenance is likely to cause sanding phenomenon. In the wiping and pressing process, the dry cement surface (should be sprinkled with cement sand mix) is uneven, thick and thin, forming a layer of uneven thickness on the surface of the cement layer, which is not well combined with concrete, causing the surface layer of peeling. If the surface layer has the phenomenon of water secretion, immediately sprinkle the dry mix with cement sand (1:1: cement: sand) and spread it evenly. The thickness of the surface layer should be consistent, and the wooden trowel should be pressed hard to make the surface layer and concrete closely combined as a whole.
  2. Surface layer hollow drum. There are cracks: due to the grass-roots level is not clean before paving concrete, such as cement slurry skin and oil, or after, when the cement slurry combined layer is too large to sweep with a broom, the surface layer is easy to cause the surface layer. The surface layer is easy to be hollowed out due to the slurry skin and oil stains. The slump of concrete is too big, and the moisture in the layer behind the rolling is too much, and the wiping and pressing process is not finished before the final setting, so the surface structure is not close and easy to crack.
  3. Surface layer smearing more, not light: the main reason is not enough iron trowel wiping and pressing times or too early, the last time when wiping and pressing should be evenly wiped and pressed to flatten and lighten the smear.
  4. The proportion of concrete must be strictly controlled. Construction consistency. If necessary, set up special guards.
  5. After the surface layer is vibrated out of slurry, pay attention not to scatter dry cement surface on it, but must scatter cement sand and dry surface dust to scrape flat and trowel, so as not to cause the surface layer peeling and cracking.

6.Do not use cement with insufficient strength grade or expired cement when constructing the surface layer; strictly control the water-cement ratio when preparing concrete. The water-cement ratio and slump should be strictly controlled.

  1. Treatment of construction joints: It is not allowed to leave construction joints on the fine stone concrete surface layer. When the construction interval exceeds the allowable time, when continuing to pour concrete, the surface of the croucher of the concrete that has been set should be brushed with a steel wire brush until the stone is exposed, the surface should be rinsed with water, and a layer of plain cement paste should be brushed with a water-cement ratio of 0.4~0.5, then pour concrete, and pounding and pressing should not reveal the joint.
  2. After the pouring of a large area of fine stone concrete grid joints cut parts by the construction staff to spring line, grid joints should not be more than 6 meters apart, a single slab area should not be large day 20 square meters.

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