Autoclaved aerated concrete block wall to prevent cracks and leakage construction technology?

Autoclaved aerated concrete block wall crack prevention and leakage construction technology specifically what is included, the following Zhongda consulting bidding teacher for you to answer for reference.

1. Preface

Taishan District 1 ~ 12 # building is located in Fuwan Road, Fuzhou City, underground one floor, seven floors above ground, with a floor area of 25,000m2.

This project has been carried out since September 2007 for the construction of the wall, and all masonry construction was completed in November, and the volume of about 1,500 cubic meters of gas-filled concrete blocks was completed in ****. During the construction process, we have basically prevented the cracking of the house wall and the quality of the block wall has been guaranteed by strengthening the on-site construction management and formulating practical construction measures. Until now, no obvious cracks and leaks have been found on the walls of the whole project.

According to the design requirements, the exterior wall wall material using autoclaved aerated concrete blocks. Block itself is a lightweight, sound insulation, good thermal insulation performance, construction convenience and other characteristics of the new building materials, in line with the current requirements of energy-saving buildings, but due to the block material has a significant water absorption rate is too large (up to 60% or more) and poor moisture and expansion and dry shrinkage of their own characteristics and construction factors caused by the construction of the wall construction is prone to a number of problems. At present, the block construction of the more commonly occurring problems are: cracking of the ash joints, plaster cracking, hollowing, leakage, insulation effect of sound insulation, etc., affecting the use of functionality. To avoid the above problems must be masonry, plastering process for the whole tracking control.

2. Selection control and material requirements

2.1 Material selection

(1) In order to ensure the quality, should choose the mature production process, maintenance conditions, good manufacturers of products, the selection of 07 compressive strength of not less than 5MPa blocks. Aerated concrete block out of the kettle 5 to 7 days of shrinkage accounted for 50% of the total shrinkage, should ensure that out of the kettle 28 days before not put into use, can greatly reduce the chance of cracks caused by its drying.

(2) different varieties of cement shall not be mixed, a variety of aggregates, admixtures, water, etc. should meet the requirements. Mortar should be used for special mortar with good bonding performance, strength grade not less than M5, should have good water retention.

2.2 Management of materials entering the field

(1) The material clerk purchases the materials 25-30 days before they are used according to the plan. And strictly in accordance with the requirements of the technical regulations for acceptance, unqualified block materials resolutely not to receive.

(2) materials should be classified and stacked after entering the field, and express signs, according to the date of production, specifications, quality levels were stacked in a covered place, good rain and drainage measures to avoid damage or pollution. Stacking height should not exceed 2m, stacking is recommended to maintain proper ventilation spacing, so that stacking in the middle part of the block can also be faster drying to reduce the water content of the block on the wall.

3. construction process prevention and control measures

3.1 masonry before processing

(1) before construction, the floor is washed clean, in the frame columns, the wall masonry side of the skin control line and the masonry height control line, reserved for the top brick position.

(2) masonry 1 ~ 2 days before sending the block and masonry surface sprinkling wet, water penetration into the surface layer is generally 0.7 ~ 1.0mm subject to the water content of masonry block mixing between 10 ~ 15%. To evenly sprinkle water to ensure that the moisture content of the block is basically the same, to reduce the difference in expansion coefficient due to the difference in moisture content, to prevent wall cracking. Determination of the moisture content of the block on the wall according to the dry density of the block, randomly sampling 3 blocks (or a number of blocks) using the weighing method for calculation, the moisture content of the block = (wet weight - dry density) / dry density × 100%, take the average of the number of samples compared to whether it is less than 15%.

(3) After communicating with the design unit, the construction unit, in the root part of the wall using the first 200mm high plain concrete guide wall poured and smoothed, so that the masonry is carried out on the horizontal plane. This enhances the strength and impermeability of the wall and increases the durability of the house.

3.2 Masonry construction control

(1) field arrangement placement before masonry, masonry should be staggered seams, the upper and lower skins lap length is not less than 150mm and 1/3 of the length of the block, otherwise 2?6 long 700mm tie reinforcement should be set up in the mortar joints. Wall corners and longitudinal and transverse blocking pallet ribs should be masonry at the same time, temporary interruptions should be built into diagonal hews, the horizontal length of not less than 2/3 of the height. sanitary, kitchen and other waterproofing requirements of the wall at the bottom of the use of C20 plain concrete floor beams platform can be 200mm in height. both sides of the window and door opening should be selected with the rules of the neat blocks in the "L"" "T"" "" zigzag joints block should bite the masonry to ensure the overall stability of the masonry.

(2) in order to eliminate the main structure and the enclosing wall due to temperature changes between the contraction cracks, masonry and wall columns at the junction, must be left with tie bars, spacing 500 ~ 600mm, specification 2?6, the ends into the wall is not less than 1000mm. every masonry 1.5m high should be used 2 Ф6 through the length of the reinforcement bar tie, in order to prevent contraction cracking of the wall.

(3) in the span or height of the wall to set up structural columns. When the length of the wall is more than 5m, set up reinforced concrete structural column in the middle. The junction of window sill and window wall is a relatively concentrated part of stress, easily affected by masonry contraction and cracks, so set up cast-in-place sill plate at the window sill to resist deformation. Door and window openings at the upper corners are also prone to cracks and drums, the use of ring beams instead of beams, in order to strengthen the integrity.

(4) Aerated concrete blocks of different dry densities and strength grades can not be mixed, and aerated concrete blocks can not be mixed with other bricks, door and window openings and structural columns and wall ends of non-integral bricks, the use of non-toothed saws to cut and mold. The daily masonry height is controlled within 1.5m during the masonry process, and the masonry is stopped on rainy days. Masonry and frame columns, shear wall node joints point by point filled with mortar, and then each side of the 30mm deep groove; each brick after 5 skins of masonry, with embedded trowel inside and outside the mortar compaction of the mortar joints. To close the capillary holes. In the masonry to the bottom of the frame beam 200mm suspension, every 7 days, after the mortar solidification and dry stickiness, masonry by a certain contraction and settlement deformation, and then the top brick processing.

(5) after masonry, to do a good job of rain, shade, and appropriate water spray maintenance.

(6) Before plastering construction, 100×100 steel wire mesh is pasted at the junction of masonry block wall body and concrete beam, concrete column, and at the border of door and window openings and at the shaded corners, with a width of 200mm on each side, and the mesh is lapped evenly and firmly, and is nailed firmly with steel nails.

3.3 Plastering process control

(1) Plastering process: leveling - door and window frames - embedded joints and blocking holes - pre-embedded parts handling --Masonry surface cleaning, sprinkling wetting - top plate hook joints - hanging plumb line casing leveling - marking line --Dividing grid joints and dividing strips --Detailing --Bonding layer --Covering -Cleaning up.

(2) the grass-roots level using treatment cement mortar brushing, wall drenching, water will be wet wall every 7 days before plastering, masonry wall seepage depth of up to 8 ~ 10mm, moisture content between 10 ~ 15%, and the use of full scraping interfacial agent (Yi cement or special interfacial agent). Frame columns, beams and block junction, local plus hanging net, can strengthen the adhesion between grass-roots level and plaster layer. Because of the low strength of the aerated block, its wall should be done in the anodized corner 1.8m high, 50mm wide on each side with 1:2.5 polymer cement mortar corner, the corner of each side of the paste 100mm wide alkali-resistant mesh cloth.

(3) the thickness of each layer of plaster can not be too thick, each layer of control within 7 ~ 9mm, if the middle layer of plaster is too thick should be coated in layers, the selection of mortar materials should be compatible with the aerated concrete block materials, should be used in good water retention properties of the material. In order to prevent and reduce wall cracking, both internal and external walls are made of elastic putty or elastic paint.

4. Key technology to prevent cracks and leaks

4.1 Masonry should be carried out carefully according to the specification requirements. In masonry construction, when each block masonry before, with a brush to clean up the surface of the block floating sand (dust), deal with clean and then in the horizontal and vertical gray joints at the paving adhesive, adhesive should be full of paving uniform, because a little uneven thickness may affect the mortar fullness, mortar fullness must meet the requirements of the construction of the horizontal gray joints to achieve 90%, vertical gray joints 80% of the requirements. The thickness of gray joints is controlled at 5-6mm, the maximum should not exceed 8mm, vertical gray joints shall not appear transparent seam, blind seam; masonry wall should be flat and clean, no overflow of mortar or adhesive at the gray joints; blocks on the wall or just masonry blocks should not be subjected to external impact or random movement. If correction is required, the masonry should be resurfaced with adhesive, not to mention leveling and smashing the blocks. In order to avoid excessive deformation of masonry sinking and shrinking, the daily height of masonry should be strictly controlled within 1.5m.

4.2 Reasonable setting of tie reinforcement. The most common setting method of autoclaved aerated concrete block wall tie reinforcement is pre-buried or planted. Masonry and reinforced concrete wall column contact, the use of 2?6 steel reinforcement tie bar, with implantation or pre-embedded method, in advance of the construction in the block horizontal gray joints open long groove, into the reinforcing steel with adhesive or M10 cement mortar to fill to the groove on the flat. But there are also construction workers to take the construction without groove, the rebar will be buried directly into the block gray joints.

The use of slotted reinforcement method is more convenient, good quality. Because the method is reasonable implantation position is accurate, slotted embedded tendon tie solid, the problem is that slotted to use more labor. Slotting is now a special hand saw, slot width, depth of 10mm can be, but need to pay attention to is the brick chip to sweep clean, to ensure the quality of bonding.

4.3 different materials in contact with the flexible connection. Fill wall and column, wall, beam and plate interface joints should be made flexible. According to the autoclaved aerated concrete blocks own characteristics, in order to reduce the cracks between different materials and blocks, many places across the country on the application of blocks are required to carry out the provisions of the flexible treatment to adapt to changes in temperature and wet and dry environment. However, many construction workers are always accustomed to the traditional clay brick masonry methods, infill walls and columns (walls) dense seam masonry, the top of the wall and the beams and plates to take the ordinary brick or cement brick or diagonal brick masonry, ordinary cement mortar embedded joints. Some construction units in order to reduce the cost of the project, would rather use the traditional ordinary cement mortar embedded joints, but also do not want to spend money on the use of PU foam embedded joints. This hard connection processing, it will be difficult to overcome the disease of filling wall cracks.

To this end, or the requirement of interface joints using flexible processing: filled wall and reinforced concrete columns (walls) at the joint, masonry should be reserved 10 ~ 15mm wide, 30mm deep gap, the gap embedded in PE rods and play PU foam, and the outdoor side of the gap in order to waterproofing, should be in the PU foam outside the wall and then closed with elastic putty. The gap between the filler wall and the bottom of the beam or the bottom of the slab on the upper floor should also be reserved 10-25mm wide and 30mm deep, and the filler in the gap should be carried out at least after the wall masonry is completed for 7d (preferably 14d). At the top of the wall of each block on both sides of the middle part of the dry anticorrosion treatment of the wooden wedge wedge, fixed in the wooden wedge on both sides of the embedded fill can be adapted to the deformation requirements of the flexible connecting material. From the engineering practice, the use of flexible connection to deal with interface joints, crack control greatly improved.

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