Generally speaking, construction waste concrete perforated brick is mainly used for load-bearing structure, and its strength grade should be MU 10 from the economic point of view. Although it is possible to produce porous bricks higher than MU 10, it is not economical. From this point of view, construction waste concrete perforated brick is suitable for mixed structures with six floors or less. Construction waste concrete hollow brick can replace KM clay sintered hollow brick for frame infilled wall, and construction waste concrete brick can be used for rural buildings below three or four floors.
The design calculation, joint structure and construction technology of concrete perforated brick building with building waste residue refer to the Code for Seismic Design and Construction of Porous Brick (KP Type) Buildings (JGJ68-90).
The design values of masonry compressive strength and masonry shear strength of construction waste concrete perforated brick are taken as KP 1 type perforated brick. The stress situation of the former is basically similar, and the latter is greatly improved compared with the small concrete hollow block masonry in the mortar joint surface and joint situation, and its masonry shear strength is expected to increase. The specific data need to be further determined by experiments.
When using construction waste concrete perforated brick, it is necessary to keep the holes vertical and the blind holes upward, so as to pave mortar during construction.
The construction of concrete perforated brick with building waste residue should follow the construction technology of small concrete hollow block as far as possible, such as the storage of on-site brick, the mastery of water content on the surface of brick during construction, the on-site management during construction, and the pretreatment before painting inside and outside the masonry wall, which can never be equated with the operation of KP 1 clay perforated brick. Therefore, before construction, the construction personnel should be trained in the construction knowledge of small concrete hollow blocks.
Anti-crack and anti-seepage measures of concrete perforated brick wall with building waste residue;
Attention should be paid to the use of construction waste concrete perforated brick to build buildings:
(1) Ensure the quality of perforated bricks, and produce them in strict accordance with enterprise standards. Only after passing the inspection can they leave the factory. It is forbidden to leave the factory before reaching the age.
⑵ Waterproof and moisture-proof measures should be taken during on-site transportation and stacking.
(3) Strictly control the watering quantity of perforated brick and masonry during construction, and pay attention to prevent the completed masonry from being affected with damp.
(4) The base of masonry and plastering mortar should use medium-coarse sand, and foaming additives should not be added.
In addition to the construction factors, the following points should be paid attention to in the architectural design of concrete perforated brick with building waste residue:
(1) Selection of architectural modeling:
Generally speaking, the shape of the building is simple and the vertical and horizontal walls are well connected. This formulation is more common, but not necessarily. Although the cracks in complex buildings are complicated, it is often difficult to estimate them in advance, but the actual project proves that the length and width of cracks are smaller than usual or even no cracks appear, so as long as the structural layout is handled properly, complex buildings are not bad.
⑵ The expansion joints of buildings should be set in strict accordance with the specification requirements, and generally should not be connected.
⑶ Slope roof with heat insulation function is an effective measure to prevent cracks between roof structure and wall structure due to temperature difference expansion. Combined with the trend of building energy saving and the current architectural style, the sloping roof scheme is the first choice to prevent the temperature difference cracks in the external wall. At present, all new residential areas in Taizhou have adopted this scheme, and the splayed joints caused by temperature difference under the windows of the top external walls are obviously reduced.
(4) For flat roofs, wall structural columns should be added to the outer side of the external longitudinal wall at the top floor and two or three bays at the expansion joints, regardless of whether the lower floor is provided with a column every bay, which is beneficial to reducing the temperature difference cracks of the external wall at the top floor. Except for the seismic structure, horizontal lacing has no obvious effect on preventing cracks caused by temperature difference expansion.
5] Building foundation treatment should be cautious, especially in soft foundation or construction sites with complex geological conditions. Structural cracks caused by improper foundation treatment cannot be confused with cracks caused by using blocks.