Basic skills in concrete pouring

Basic skills in concrete pouring
Concrete recycling is a key process, the quality of its concrete, structural integrity have a direct impact. Therefore, the requirements of pouring the concrete should be dense, can be full of templates, steel and embedded parts to ensure the correct position, a good combination of old and new concrete after the concrete surface smooth and form removal, clean, accurate size and so on.
One. Three basic skills placement
Concrete construction, concrete conveying a different way, with a variety of templates, but the final forming of concrete quality of the decision by the pouring process.
1. The whole placing
Is to maintain the overall pouring concrete layer, the overall segment. Such as frame building, each of the columns, walls, beams, floor, staircase, balcony ... ... and so form a whole together. Due to temperature, geological and other reasons, the structure of the joints, settlement, sub-seismic construction joints, etc.; layered construction; each segment, all the components within the layer, is a whole. A section of the pouring of concrete layer should be a complete, without leaving a construction joint.
2. After the first addition, the first away in recent
After the first addition is a column, wall, beam placement procedures. Pouring should be pouring outside corner of the columns and walls, and then pouring the external columns and walls in other parts, and finally pouring the internal columns, walls and beams. Its role is to make the wall corner to corner posts and chromium crusher correct positioning of the template to ensure that building form.
After the first distant past, is the floor, floor or base plate of the concrete pouring process. In accordance with the direction of incoming concrete, first for the far post for the past. The laying of concrete slab to facilitate transport to facilitate feeding; easy to tamper and closing surface; if feed too much, but also easy to be returned.
3. Mortar first
The fabric into the mold before the template layer of concrete mortar with the strength of the same quality, so that there is adequate or surplus at the bottom of the mortar, concrete base to ensure full, angular Founder, smooth appearance.
Pouring floor or ground floor before the template side next to the thin layer of thickness of 15mm, extension of about 600mm, the width of the same face of the mortar, concrete placing will be lower mold.
Beam placement before the end of the beam covered with a thickness of 15mm, length 600mm mortar for the end of pulp.
II. Key concerns concrete pouring
1. Time interval, the initial setting and final setting time
Cement in concrete with water to completely harden after mixing with 4 stages: the initial response phase, telogen, setting and hardening of the period. The length of time required, because different varieties of cement. The initial reaction of about 30min, resting period of about 120min, only the concrete period of time with elastic, plastic and viscous rheology.
2. Layer thickness
Layer thickness is 200mm or so, before the layer of depth when tamping 20 ~ 50mm.
3. Pour off the high degree of
Pour off the high degree of freedom should not exceed 2m. Otherwise, string tube should be used, or chute, the concrete tube or chute along the string whereabouts to avoid concrete segregation.
4. Mortar bottom
Before pouring the vertical structure, the bottom should be filled with 50 ~ 100mm thick cement concrete the same ingredients.
5. Die stability
In the cement mill process, should always observe the template, frame, steel, embedded parts, and set aside the case of holes, and when there deformation, the shift should take timely measures to deal with.
III. Construction joints of the lien and precautions
As concrete pouring non-consecutive time, the two poured to form a joint, this joint is the construction joint.
1. Set construction joints
Location of construction joints shall meet the design requirements and construction technology programs. The location of construction joints should remain in the structure of the shear stress is small and easy construction of the site.
2. Treatment of construction joints
1) The initial setting of concrete, you can not continue pouring immediately above the new concrete, or new concrete in the vibrator, it will damage the already clotted internal structure of concrete and affect the combination between old and new concrete. To the compressive strength of concrete has been poured to 1.2N/mm? Later allowed to continue pouring concrete.
2) before pouring, to the debris at the construction joints, remove loose gravel, etc., and cutting hair, washed with water, not water to fully wet.
3) prior to pouring concrete, advised in a layer of construction joints and concrete grout or cement mortar equal to the composition and thickness of about 15 ~ 15mm. First tamping concrete mortar and the original, and then pouring concrete.
4) tamping at the construction joints to be detailed and should make new and old concrete into a whole and enhance moisture conservation.