Nantong construction engineering general contracting Shi Ming Jiayuan business and living building projects department

August 2007

I. Overview of the Project

Zibo Shi Ming Jiayuan Commercial and Residential Project is located at the intersection of Nanqiyuan Road, Yanying Road, Linzi District, Zibo City, with a total construction area of 4 1 1,000m2, including 5000m2 underground, 36,000m2 above ground and 2,890m2 building basement. The building has 2 floors underground, 4 floors above the podium, 1 # above the building 18, and the height is 550. The height is 7 1m, the second floor underground is for parking garage and equipment room, the first to fourth floors above ground are for business and office, and the fifth and above floors are for residence. The building structure is frame shear/frame structure, the floor is cast-in-place reinforced concrete floor, and the foundation is reinforced concrete raft foundation. 0 # floor thickness 1. 15m.

According to the architectural features and specification requirements, the post-cast strip is set in the podium and the main building from the foundation slab, and the width of the post-cast strip is 800 mm ... The post-cast strip is set as follows:

1# Building: North-South post-pouring belt is set at 0.7m east of Axis 40.

2# building: a north-south post-pouring belt is set at 1 .8m on the west side of axis, and a north-south post-pouring belt is set at 1.8m on the west side of axis 33.

Skirt building: an east-west post-pouring belt is set at 2.4m south of X axis, and an east-west post-pouring belt is set at 3.2m north of S axis.

According to the design requirements of the construction drawing, the post-cast strip should be constructed after the main body construction is completed and 12 floors above the ground.

See the figure on the next page for the specific arrangement of post-cast strip:

Second, the template construction of post-cast strip

1, foundation slab, wallboard post-cast strip

1. 1 According to the design requirements and minutes of the blue prints.the design, 20*30BW expansion waterstop is adopted for the post-cast strip.

20*30BW expansion water stop is located in the post-pouring belt of foundation slab, post-pouring belt of basement roof and post-pouring belt of external wall, all of which are located in the thickness center of post-pouring belt and fixed near the side wall of post-pouring belt.

1.2 braking of post-cast strip if:

Both sides of post-pouring belt of foundation cushion (north-south direction) 1.2. 1 precast fine stone concrete strips. Do the bottom reinforcement protection layer, and after the lower floor reinforcement fabric is bound, use high-grade mortar to block the reinforcement spacing in the post-cast strip to prevent slurry leakage at the bottom. Because the raft of the main building is1.7m thick, the gate of the post-cast strip of the main building is supported by multi-layer wooden keel and steel bars. The gate of post-cast strip of podium adopts steel wire mesh, with φ 14 steel bar as keel, and the horizontal spacing is 180mm, and the vertical spacing is 100. At the same time, φ 14 horizontal spacing 1m horizontal support is used in the middle position of post-cast strip, and 380MM vertical spacing is used in the concrete raft outside post-cast strip. The horizontal spacing is 1000MM, and the tension nodes are fixed by welding, so as to ensure that the whole steel wire mesh and steel skeleton have sufficient strength and rigidity, so as to ensure that the steel wire mesh does not expand and leak slurry during concrete pouring.

1.2.2 The bottom plate of the podium is 300-thick waterproof board, and the post-cast strip is made of steel mesh. Three φ 14 steel bars are used as the skeleton to bind the steel mesh pieces, which are welded and fixed on the side of the post-cast strip to ensure that the steel mesh does not bulge or leak slurry during concrete pouring.

1.2.3 when the wallboard post-cast strip is designed, double-layer 5mm eyelet lead wire mesh is used in the beam, and the back is fixed firmly with φ 14 steel bar;

2. Treatment of post-cast strip of beam and slab

2. 1 In order to ensure the safety of the structural support system, the formwork of post-cast strip adopts an independent support system, and the connection with the platform formwork is disconnected, which will not affect the dismantling of the platform formwork. The spacing of steel pipe support is 1200mm, and the design spacing module of standard floor is 1200mm, and the bowl-type quick release system is adopted. Because the design width of post-cast strip is 800mm and the width of bamboo plywood used is 1220mm, the width of both sides is 2 10mm, which can ensure that the formwork support on both sides of post-cast strip is 2 1200mm after being removed. The keel of the post-cast strip is disconnected from the adjacent slab, and the length shall not exceed 1300mm, so as to ensure that the formwork removal of the two side slabs is not affected. Template of slab post-cast strip is shown in the following figure:

2.2 The beams on both sides of the post-cast strip are cantilever structures, and dense supporting steel pipes should be adopted in the middle of the beam bottom. If there is a post-cast strip in the beam, double-layer 5mm eyelet lead wire mesh is used, and the back is fixed firmly with φ 16 steel bars; According to the spacing between steel bars, bamboo plywood is used to support the plate to ensure the accuracy of the protective layer of steel bars.

2.3 The beams on both sides of post-cast strip belong to cantilever structure. After the concrete pouring of post-cast strip is completed, the formwork in this part can be removed only after the concrete strength reaches the formwork removal strength. Before pouring the post-cast strip, the girders and platform supports on both sides of the post-cast strip shall not be removed, and a small square frame shall be erected with steel pipes to support the beam bottom. There are three sets of small square braces, one for the upper and lower two farewells and one for the middle.

Third, the post-cast strip steel binding

When binding steel bars, the amount of concrete pads and horse stools on both sides of post-cast strip should be increased to ensure the height and protective layer of steel mesh. The edge of horse stool and cushion block within the scope of post-cast strip should also be placed in encryption. Design requirements for post-pouring.

With the reinforcement encryption, the first construction must be carried out after the reinforcement binding on the side of post-cast strip is completed.

Fourth, concrete construction of post-cast strip

According to the design requirements of the construction drawing, the post-cast strip should be constructed after the main body construction is completed and 12 floors above the ground. Pouring from the lower layer to the upper layer in turn. The concrete in the post-pouring zone is poured with early-strength expansive concrete which is one grade higher than the original concrete design strength. See the table below for the concrete label of post-cast strip:

Remarks on strength grade of component concrete

Foundation 1 # main workshop and 2# main workshop C40S8

Independent column foundation and waterproof board C35S8 of podium

Basement walls, columns, beams and slabs 1 # and podium C50S8 of 2# main building

1# Main Building 1 Floor ~ Floor 5 Beam and Plate C40

Six-story and above beam and slab C35

Column beam slab C40 on the first floor of podium

Second and fourth floor beams and slabs C40

2# Building 1 ~ 9 Floor Beam C40

9 ~ 14 layer beam C40

One-layer to four-layer board C40

15 floors and above beam slab C40

Roof panel 1 #, 2# main building C35

Skirt C35

1, preparation before concrete pouring of post-cast strip

Embroidery of steel bars: As some steel bars have rusted, the rusty steel bars must be embroidered before formwork support, and the rust must be polished off with wire brush and sandpaper. At the same time, the reinforcement should be adjusted and the protective layer pad should be refilled to ensure the correct spacing and position of the reinforcement.

2. Clean the laitance and rust in the formwork, especially the construction joints, to prevent slag inclusion. Plug sponge strips at one side of the construction joint to prevent slurry leakage. The original formwork support of post-cast strip should be reinforced as appropriate to ensure the smoothness of joints.

3. Before pouring concrete in post-cast strip, the surface laitance and sundries shall be cleaned and chiseled. After laying out the thread, cut the construction joint along with a cutting machine to a depth of 1cm. The concrete surface of the original structure is watered and wetted 24 hours in advance, and then 30 ~ 50 mm thick cement mortar with the same composition as the poured concrete is paved, and the concrete is poured in time.

4. Commercial concrete shall be used for concrete, which shall be wetted with water before pouring to ensure good combination of new and old concrete. When pouring, we must pay attention to the fact that the vibration at the construction joint must be dense, but it cannot be too vibrating, which will affect the concrete strength here. When vibrating, it should be gradually pushed to the construction joint, which is 80 ~ 100 mm away from the edge of old concrete. When scraping with a big bar, the newly poured concrete surface at the construction joint should be 2mm higher than the already poured concrete, so as to ensure that there is no height difference between the concrete surfaces on both sides after brushing. When brushing, the construction joint should be strengthened to ensure a good combination of the two.

Verb (abbreviation of verb) Maintenance of concrete in post-pouring zone

2.3 Covering protection of post-cast strip: After the platform pouring on both sides of post-cast strip is completed, concrete strip with a height of 30㎜ will be poured at the edge of post-cast strip to stop curing water. Above the post-pouring belt, cover a layer of plastic film or striped cloth, and then cover a layer of bamboo plywood to keep the post-pouring belt free of sundries.

For concrete mixed with retarding admixture or with impermeability requirements, its continuous curing time shall not be less than 14d. Before the concrete strength reaches 1.2N/mm2, it is not allowed to dismantle the beam side formwork and trample the concrete, and it is not allowed to install formwork and brackets to store heavy objects and other loads that are easy to cause impact.

Matters needing attention about intransitive verbs

1, pouring of post-cast strip starts from the basement and goes up.

2. Due to the dense steel bars in the post-cast strip of the basement foundation slab, after embroidery and cleaning, the garbage will be rushed to the sewage collection well by the high-pressure water qiang in the post-cast strip, so that the concrete slurry will flow into the sewage collection well with the water and be pumped out by the sewage pump.

3. Pay attention to safety during the construction of external wall post-cast strip, to prevent materials from falling and hurting people, and at the same time pay attention to operation safety.

4. The independent supporting formwork of post-cast strip shall not be dismantled halfway, and the supporting formwork can only be dismantled after the concrete pouring of post-cast strip reaches 100% of the design strength.