mbt schoenen Masonry Crack and control measures _4

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Masonry Crack and control measures

Often through the foundation. Especially for soft soil, the local-based processing is not the time, it is easy to produce diagonal wall at the bottom of the window wall cracks and vertical cracks. Vertical and horizontal walls in the housing case of uneven settlement of foundation, will bear a greater wall shear stress, somewhat less when the structural stiffness, strength of construction quality and materials can not meet the requirements will cause the wall cracking. In addition, when a difference of more housing layers without setting settlement joint, the easier the transfer of parts produced in the vertical cracks,[link widoczny dla zalogowanych], often accompanied by such large cracks due to uneven sinking. 2.4 The force cracks. Stress cracks appear in the seismic area and more buildings, although there is beam, pillar, cast concrete panels as a whole connection, but can not completely ensure that no cracks. Such as occurred in the house at the bottom of the vertical cracks in the windowsill, the majority is due to the larger vertical wall of windows, foundation, after the deformation under load is uneven, window wall, play a role in counter-beams caused. In the reinforced concrete strip foundation, the foundation of the general foundation beams were not set, relying on beam, structural columns, etc. to enhance the overall stiffness of the building, the local base by the load is large, ledge wall deformation is too large to reverse cracking. Some stress cracks due to uneven settlement and the formation of the two factors of thermal stress resulting from stress, we refer to this situation is also classified as stress cracks. Such as reinforced concrete span Slab cracks, if uneven settlement of foundation, reinforced concrete cast panels will sink while the other side by the bearing edges and constraints, this will result in concrete Slab internal tensile stress,[link widoczny dla zalogowanych], And, mostly across the lien at the construction joints, in accordance with the requirements of specifications: the location of construction joints should remain in the structure of the shear stress is small and easy construction of the site. Therefore, the plate bearing the constraints in the other, the concrete role of the internal tensile stress, coupled with concrete roofing board by temperature effects, tensile stress generated inside the concrete around the bearings in the constraints,[link widoczny dla zalogowanych], the required place the weakest position of board to release energy, so the cracks in the plate span. 2.5 shrinkage cracks in the concrete masonry structures relative to other structures more prone to shrinkage cracks. Because in the Masonry of which, 114 Innovation for ScienceandTechnologyInnovationHerald hardening of concrete in the air, which gradually evaporate the water more easily, so that the pores in the formation of negative pressure, with the reduction of air humidity, negative pressure increases, resulting in contraction,[link widoczny dla zalogowanych], when the contraction produced by the tensile stress limit than its own tensile strength of concrete will crack when the resulting shrinkage cracks. Such cracks, no direction, smaller cracks is 0.1 ~ 0.3mm. 3 masonry cracks prevention control measures 3.1 1) First, to prepare ground treatment, strict control of uneven settlement of foundation, especially for soft soil, fill the necessary foundation reinforcement to avoid uneven settlement of foundation. 2) in strict accordance with specifications set in place the provisions of settlement joint, to minimize the differential settlement of the foundation is poor, set the foundation in seismic zone proper beam, a reasonable set expansion joints, the maximum distance of not more than 50m. 3) pouring concrete masonry structure after the place, covered in plastic film and its idiot or linoleum, to strengthen the concrete's moisture,[link widoczny dla zalogowanych], heat conservation. 4) The construction of rational organization, in the process of making the next concrete materials, mixing, pouring, vibration and other aspects of strict process control. Improve the performance of cement and reasonable to reduce the amount of cement to reduce water-cement ratio, concrete units to strictly control the water in the 170kg / m below the water-cement ratio 0.6 below, a good selection of coarse and fine aggregate. 3.2 '3 .2.1 Construction control measures to ensure the stable block in the use of general just before the light block factory is less stable. Shrinkage deformation of the large masonry, the shrinkage deformation is characterized by a relatively fast early development, after gradually slowing down. Therefore, before using to ensure that material has been reached with age, the volume has been basically stable, the shrinkage deformation. 3.2.2 To strictly control the water content of the water prior to use light blocks the rate of demanding, strict control according to different block when the moisture content of masonry. Moisture content to use standard products, before the block on the wall waterproofing must do to avoid the rain soaked block of construction, resulting in the wall due to shrinkage cracking. 3.2.3 using the correct construction methods must be relatively large light block shrinkage deformation characteristics, take the right construction methods and control measures. 4 Conclusion cracks in masonry structure is a more common phenomenon. These phenomena remind us that early stage of design and construction should take measures to prevent it. If you are experiencing cracks in the building, we must first identify and analyze the causes of cracks and deformation, to assess the extent of structural damage to determine the effective reinforcement measures.
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