The following introduces how to handle cracks in closed-end floor slabs.

　　The following introducesClosed floor slabsHow to handle cracks

　　Use low water-cement ratio concrete, dry cast-in-place concrete, and control temperature during the concrete hardening phase to improve surface temperature (such as covering, heating), and reduce the temperature difference between the inside and outside of the concrete with closed wooden flooring. Surface lighting should be done at least three times, each time for 1-2 hours, to prevent surface micro-cracks and reduce the deformation caused by the concrete's own shrinkage.Closed floor slabsConstruction process for machinery: excavate the foundation pit, set a sand cushion layer (the drop should not exceed), and compact it into a platform for laying grids.

　　The vertical coordinate is aligned with the main load direction, and the vertical and horizontal rebar overlaps must be tied. U-shaped nails should be fixed to the ground at intervals on the laid grids. The closed floor slab equipment must be backfilled in a timely manner, and the number of layers for the closed floor slab equipment is determined according to technical standards. When there are embedded steel plates on the top of the foundation as a column support surface, the top of the thick steel plate should have design elevation and flatness.

　　It must meet the specifications, with the surface of the thick steel plate leveled, free of welding slag, spatter, mixed mortar, and other stains. The steel cushion plate must meet the following requirements: add a steel cushion plate between the steel concrete column and the foundation, and then perform secondary pouring on the pebble concrete foundation. The area of the steel cushion plate should be determined based on the concrete strength grade, the load of the column base, and the tightening tensile strength of the anchor bolts.

　　Closed floor slabsIt is a high-strength geosynthetic material made from polypropylene, extruded and then stretched both horizontally and vertically. This equipment has certain tensile strength in both directions and is widely used for soft soil structure reinforcement solutions. It is mainly suitable for the improvement of roadbed engineering for roads, railways, and airports, and is applicable for the foundation improvement of large parking lots, port freight stations, etc.

　　Applicable for tunnel reinforcement for railway slope protection, suitable for secondary reinforcement of steep slopes after one-way tensile closed load-bearing equipment, further enhancing the steep slope and maintaining soil and water. The main purpose of pit structure reinforcement: closed load-bearing equipment is mainly suitable for river embankment and roadbed structure reinforcement, slope protection, tunnel wall structure reinforcement, large airports, underground parking lots, port freight stations, etc.

　　The thickness of the floor is generally selected based on design points, depending on the spacing between steel columns. The floor slabs for enhanced structures generally have a spacing between steel columns that should not exceed 3 meters. Many steel frame spans reach 5-6 meters or more, in which case frame beams need to be added. Angle iron, channel steel, or supports can be used on the bottom plate. In other words, the spacing between beams should not exceed 3 meters. For some small and medium-sized buildings, such as private houses and steel structure office buildings, the spacing between steel columns is generally 1-2 meters, or even 1 meter, in which case a floor slab of 0.8mm is sufficient.

　　In general steel structure factories, the spacing of steel columns is usually between 2-3 meters, and a 1.0mm floor slab can be used for a spacing of 2-2.5 meters. Closed floor slabs use a 1.2mm floor slab, which generally meets the construction needs of typical steel structure projects. Of course, we strongly recommend referring to the span table for unsupported floor slabs in China for selection.