Cracks in the concrete Part 2

Cracks in the concrete Part 2

- cracks as a result of falling soil and differences in the relative decline of the foundation:
1 - because of shrinking and swelling soil due to leakage of water due to rain or a broken water pipe, the soil swell and increase in size and this movement more evident in the cohesive clay soil and then removing the reasons for shrinking soil, leading to cracks in the long low-rise buildings.2 - because of the mistake is a result of investment of the building, the loads lead to a drop in pressure causes the soil is a large and rapid in the case of sandy soil and if the loads decreased as a result of drilling, for example, the process of mistake is reflected, leading to cracks and fissures.3 - If the foundation of individual disparity space as a result of varying loads of the columns vary considerably, the Alhbutat inversely with the area of the base leading to a difference between landing foundations large and small.4 - Landing a result of equilibrium caused by geological agents or artificial or both, for example, in clay soil-leaning expected to move the foundations downward, with a tendency slowly if the increased inclination of 1 / 10 and occurs down the most in the case of snowfall or a shelf nearby.In summary, you must not exceed the maximum values of the total land surface of the foundations of the following values:Type of foundation soil type maximum drop (mm)The foundations of a single cohesive (clay) 70The foundations of a single cohesive (sandy) 50Cohesive mat 150Mat is a coherent 100And have found scientifically that there is a relationship between the value of the total land and the relative decline that may damage the origin and generally do not exceed the values of the total land mentioned in the previous table would aspired to be enough to bear the relative decline of origin without damage.The following table shows the relative values of Alhbutat allowable in terms of angle of rotation, for the various installations (known as the angle of rotation is equal to the relative decline between the two divided by the distance between the two columns).Decline in terms ofThe categorization of the angle of rotation1: 750 reduction is expected when there are problems for the devices are sensitive to the relative decline1: 600 has met the expected occurrence of large cracks in the frames of reinforced concrete non-specific statically significantly1: 500 met the required facilities to be free of any cracks in general.1: 300 reduction is expected to occur when cracks in the walls of buildings structural1: 250 the extent that he has noted a mile high buildings with the naked eye1: 150 reduction is expected to occur when large cracks in the walls of the buildings structural integrity.1: 100 reduction is expected to occur when cracks in the bearing walls of stone (the proportion of high barrier to moisture less than 25%).The minimum at which damage occurs in the structure of origin9-4 - cracks resulting from the increased loads unexpected or due to accidents or natural disasters or as a result use change and what the building: 1 - concrete members subjected to loads during implementation is much larger than those located in the course of the use of the building.2 - Removing the templates after three or four days where the weak resistance of the concrete and then put Alkovraj of the roof which is surmounted and poured directly.3 - Storage of construction materials and heavy equipment over the concrete elements, especially Alborndat (nails).4 - change the location of cargo and placements that are placed on the item Albetoni from those set forth in the drawings, causing excessive loads on the component designer.5 - concrete elements subjected to sudden unexpected shocks of the moving loads.6 - use of origin for purposes other than that allocated to it, was used as residential property Kmhvy or office building or store, which increases to more than three times the pregnancy original design of origin and this leads to the occurrence of cracks in the building elements of various stress of concrete, the values of more than allowed.7 - add the story of origin is calculated, leading to increased loads on the columns and foundations.8 - not to take the unexpected natural disasters such as earthquakes, floods, wind and fire, which lead to generate additional stresses were not taken into account.9-5 - cracks due to lack of maintenance and protection of the facilities:1 - The absence of protection for enterprises and private foundations and other structural elements, consisting of facilities such as isolation and the work of the necessary precautions to prevent cracking and protect the concrete surface to some private entities such as coastal installations, chemical plants, dyeing, cakes, paper, tunnels, roads and so on.2 - The necessity of origin protection against fires resulting from the disadvantages of electrical wiring connections or gas or flammable materials.3 - Failure to provide the necessary maintenance of facilities in the long term to a deterioration of the concrete and thus defects in the structural elements of different addition to the non-safety components and connections, and sewage works and storm water system and water supply and electrical wiring, gas, refrigeration and heating.