Construction technology of basement structure base plate with tamping and wiping
The conventional design of basement and garage floor requires the construction of concrete levelling layer before the construction of flooring paint, in view of the practice is prone to delamination, hollow drum, cracking, sand and other quality defects, therefore, it is necessary to improve and innovate the process: cancel the concrete levelling layer, through the use of "basement structure floor pounding with smoothing construction technology", so that the flatness of the completed surface of the floor structure reaches the floor finishing standards, can be directly on the structure plate construction of flooring paint.
In this paper, we will introduce the construction cost analysis of the basement structure baseboard with tamping and smoothing with specific cases.
(I) Construction preparation
1、Construction control points, in advance of the team, management personnel to do construction technology and safety of the bottom line.
2、Responsibility to the person, and make a fine division of labor to ensure that the whole process of construction control without dead ends.
3、Get the weather information in advance and choose non-rainy weather for concrete pouring.
4. Make concrete supply guarantee plan in advance to ensure timely and consistent concrete supply from the concrete mixing plant.
5. Check the construction machinery and equipment in advance to ensure their accuracy and working condition.
6、The main machines, equipment and materials invested in the construction include.
(1) Concrete transfer pumps.
(2) Concrete slabs, plug-in vibrators.
(3) Aluminum alloy scrapers.
(4) Ф100 5m long drum.
(5) Concrete lifting machines.
(7) Elevation control brackets.
(8) #5 GB channel steel.
(9) Levels (more accurate and calibrated).
(10) Leveling towers (with flat blisters, accuracy to 0.5 mm).
(11) Finished product protection materials: concrete curing film, geotextile fabric or old carpet; old formwork; warning tape, etc.
(ii) Construction and maintenance
Elevation control→Pouring concrete, vibrating and compacting concrete→Promote the surface of concrete by aluminum alloy scraper in the long direction of channel steel→rolling and leveling roller, lifting slurry (or lifting slurry machine)→leveling scraper→taking out channel steel→filling square groove with the same batch of concrete→wiping the surface manually after initial setting→concrete power trowel wiping→watering and curing→protection of finished product.
2、Construction process control
(1) The concrete pump is adjusted and the pipes are installed.
(2) After concrete is poured to a certain length according to the pouring order and direction determined by the construction plan, and the density of vibration, the concrete surface is scraped preliminarily according to the aluminum alloy scraper in the direction of the channel steel length.
(3) After the concrete has a certain strength (when the feet step on no pit), use roller to roll flat and concrete slurry extractor to extract slurry, when there is a low place found in the rolling process, timely fill with concrete, repeatedly rolling back and forth until the whole surface is smooth.
(4) In the process of leveling, the air in concrete should be discharged as much as possible and then leveled with scraper, the stones on the concrete surface should be beaten down and the surface pores should be evenly eliminated; the water on the concrete surface should be removed in the process of leveling; in the process of leveling, the scrape marks should be controlled as much as possible and the local column corners and wall edges should be leveled with great care.
(5) Before the initial set of concrete, take out the channel steel carefully and fill the square groove with the same batch of concrete; after the initial set (when there are light marks on the foot), wipe the surface by hand, after the initial wipe, the surface layer has been flat, but the surface finish is poor and the wipe marks are heavy, before the final set of concrete (when there are no marks by hand), wipe the surface with concrete power trowel, under the pressure and rapid rotation speed of the concrete power trowel blade, the surface of concrete becomes more and more dense, smooth, flat and glossy.
There are two types of power trowel, walk behind power and rideon power trowel.
(6) After the completion of trowel, concrete curing will be carried out.
(1) Elevation control, and in the elevation control of the installation of all ground-related buried parts (such as the catchment ditch catchment well cover outside the frame, man-proof door frame, etc.).
(2) Whether the elevation control is accurate or not directly affects the smoothness of the ground, and the elevation of steel brackets must be checked twice after welding.
(3) The control of concrete slump, in the process of smoothing concrete slurry, it is especially important to control the concrete slump (120~140mm). If the slump is too small, the concrete pump pipe is difficult to transport, easy to plug, burst pipe, the concrete pump wear serious. If the slump is too high, it will cause high water-cement ratio, high shrinkage, easy to surface flooding, and prolong the time of finish and not easy to control.
(4) Use commercial concrete, add high efficient water-reducing agent (special concrete proportion design), water-reducing agent can reduce the water-cement ratio and reduce the slump without changing the concrete's easy properties, and make the concrete have better easy properties and fluidity when the slump is small, so as to meet the requirements of concrete ground slurry finish.
(5) In the control of the collapsing degree, we adopt the three-point control method: assign someone to control the concrete mixing plant, before and after the concrete pump, and at the site of concrete pouring to measure the collapsing degree and strictly ensure that the collapsing degree is within the required range. No concrete that does not meet the requirements is allowed to be used to ensure the continuity of concrete construction, shrinkage and consistency of initial setting time.
(6) Surface finish time and process mastery, master the surface finish time of concrete, first of all, to ensure that the concrete collapse degree meets the requirements. Make the concrete from start to finish solidification time is consistent.
(7) Before the first pouring, use the same ratio, collapsed concrete to do one or two initial and final setting time determination, master the data, and basically determine the operation time of several procedures for surface coating, and then deal with the actual situation during on-site construction.
The basement garage structure floor of the original slurry wiping surface has good integrity (no delamination or fracture, and not easy to hollow drum or sand), high strength (general project C30, after maintenance, the general strength can reach C35, strength significantly higher than C25 concrete levelling layer), to ensure normal construction and maintenance (film moisturizing maintenance time of not less than 7d), put into use after the construction of floor paint, the subsequent basically do not need to consider additional maintenance of the structure floor, the overall stability is good.
(III) Diagram of construction practice
Elevation control requirements
Explain: The elevation control is divided into not more than 4.5m/span according to 1/2 of the column distance of the structure, part of the bottom plate steel binding is finished, use level to control the two ends and the middle cable to control the elevation, weld the steel bracket firmly, the lower part of the steel bracket should increase concrete pad, put 5# channel on the steel bracket, the elevation of the top surface of the channel is the finished elevation of the ground.
1、Channel steel support frame installation: weld the support frame symmetrically along the middle axis of channel steel installation, and make sure the top installation height of the horizontal pole of support frame is: height of completed surface of structure - channel steel height, error should be controlled within 1-2mm.
2、Channel steel installation: put the channel steel frame on the support frame and fix it with wire (don't weld to avoid hard to dismantle); the height of channel steel surface is the height of finished surface of the structure. The installation error should be controlled within 3mm.