ATTEN: Manager Liu
ADD: Longhua Development Zone, Jing County, Hengshui City, Hebei Province
The formwork and support system should have sufficient stiffness. The spacing of radial slab support should be appropriate so that the stiffness of the slab and the beam does not lag far behind. For high-rise and small high-rise residential buildings, the edge of multi-span continuous slab side span is often simplified to be simply supported, which requires designers or construction managers to configure the reinforcement reinforcement strength in the construction process. The diameter of the reinforcement can not be too thin, and the spacing can not be too large. It is also suggested that the design department and designer should consider the edge fulcrum at the fixed end when reinforcing the support of the side span. When reinforcing the mid-span and inner support of the span, the edge support should still be considered as simple support, and the structural reinforcement ratio of the plate edge should be increased appropriately to protect the upper reinforcement in construction, so as to prevent the upper reinforcement from stepping on the lower part and the diameter of the upper reinforcement should be greater than 1. 0 mm to 12 mm, cold rolled ribbed bar is preferred. If the radiation structural steel with 45 degree crack prevention is properly disposed on the floor surface around the corner and column of the building, the composite high-efficiency water-reducing and early-strength agent can be mixed into the floor concrete to remove the formwork earlier, and the strength can reach 90% in 7 days.
In the support system of early demolition of formwork, the demolition strength of floor concrete and the construction load of floor after early demolition should be strictly controlled. In the case of funds permitting, it is advisable to allocate early demolition formwork of two flow sections to adapt to the operation mode of small flow sections, and also to adapt to the process and technology of cast-in-place floor in rapid construction. 1. According to the analysis of design reasons, it is suggested that owners and design units should reinforce the floor around the corner of the sun. To strengthen, the negative reinforcement should be changed from separate cut-off to full-length configuration along the room, and be appropriately encrypted and thickened. Practice over the years has fully proved that the 45-degree inclined cracks do not occur in the houses adopted or designed according to the above design methods, and the main contradictions in floor cracks can be solved satisfactorily, and the effect is obvious. Commodity concrete has been widely used in construction. Its quality control on site directly affects the quality of the structure after construction. However, due to the inconvenience of transportation and other reasons, it takes a long time to transport commercial concrete from mixing station to construction site.
In this way, the slump loss of concrete is great, and the high temperature loss in summer is even greater. In addition, the construction management is not strict and water is often added to the ready-mixed concrete at will, which seriously affects the quality of concrete mixtures, resulting in a larger water-cement ratio, concrete segregation, concrete hardening and slurry voids. The high rate weakens the interfacial bonding force between cement and aggregate in concrete, leaving hidden dangers for concrete cracks. Due to improper construction management, after the upper negative bending short steel bar is tied near the support of the floor, before the concrete pouring, some upper steel bars are often trampled and sunk by the staff, and have not been corrected in time, so that they can not effectively exert their ability to resist external loads. Cracks are prone to occur after the completion of construction of 4 concrete, waiting for the strength to reach the desired level. Only in this way can the construction of the next process be carried out. In the initial stage of concrete final setting, it is necessary to avoid large vibration of floor caused by construction load. However, in the rush-to-build stage, the next working procedure is carried out on the second day after concrete pouring, which results in concrete cracks. 5. The maintenance of mixed soil is very important for its strength elongation and improvement of various properties, especially the early proper maintenance can avoid surface dehydration and greatly reduce the initial expansion cracks of concrete. Happen.
However, in actual construction, due to rush construction period and watering will affect the elasticity and the work of construction personnel, so floor concrete often lacks sufficient and sufficient watering maintenance duration. Therefore, it is necessary to cover sacks or straw bales for a week or so in construction, and it is suggested that spraying curing fluid be used for maintenance, so as to reduce costs and improve efficiency, and to avoid or reduce the impact on construction.