The quality of construction projects is related to the safety of people's lives and property and the vital interests of owners. Construction enterprises must fully participate in the whole process of dynamic quality management, ensure that every material and every working procedure are qualified, so as to build products that meet the design and use functions, and then complete the mission entrusted by an era more important than Mount Tai. Let me share with you the quality management of construction projects and the measures to prevent common faults. Welcome to read and browse.
First, the significance of construction quality management
Construction engineering is a special product that provides living and production space for human beings, and the reliability of engineering quality is directly related to people's life or property safety. Construction quality is the core of whether the project can complete its special mission.
In recent years, under the general requirement of zero tolerance for engineering quality accidents by governments at all levels, all responsible units have earnestly performed their duties and standardized construction management measures have been seriously implemented. At present, major quality accidents in construction projects are almost extinct. However, some common quality defects have seriously affected the use function of buildings, leading to continuous disputes between builders and owners. How to eliminate or reduce the quality defects that affect the use function has become an urgent task for project management supervisors, and it is also the fundamental requirement for continuous improvement and upgrading of project quality.
Second, "methods and elements of project quality management"
1, construction quality management method.
Work quality determines process quality, and process quality determines finished product quality. Therefore, an efficient and reasonable management system and a comprehensive and rigorous implementation attitude are the bridges for construction enterprises to cast high-quality projects.
Applying the idea of total quality management, under the guidance of the quality policy of the top managers of enterprises or organizations, we will implement comprehensive, whole process and full participation. The basic principle of quality management is PDCA cycle, that is, planning, implementation, inspection and disposal. The overall goal of the project is that all processes are qualified at one time. The principle of dynamic control is used in each process to realize the preparation of construction organization design in advance, ensure the quality of the process in the process, evaluate and identify the process results afterwards, and rectify and rectify.
2. Factors affecting the construction quality.
① Human factors, including the quality consciousness and activity ability of decision makers, managers and operators; There is also the qualification of the project parties responsible for the main unit, which is essentially a question of people's quality and ability. Only legally qualified personnel can manage and produce qualified products.
(2) Technical factors, mainly through the organization and management of survey and design, construction technology, materials and equipment, test and detection, etc. Optimize the technical scheme and give full play to the role of technology in ensuring quality. In terms of construction technology, it is mainly to carry out drawing survey and lofting of the proposed project, make quality technical disclosure by using quality acceptance specifications and related standard atlas, preset quality control points for key working procedures and difficult sub-projects and conduct dynamic tracking inspection to ensure that the quality control points are always under control.
③ Management factors, organization, management system and operation mechanism directly affect the realization of construction project objectives. Whether it is reasonable to decompose, contract and entrust the tasks and objectives of the project implementation also has an important impact on the quality objectives of the project. The project management organization can effectively control the positions, teams and groups, professional subcontractors, materials and machinery involved in each process, and establish the three inspection system and process template system, so that people, materials and machines can work together efficiently, and it is possible to create qualified finished products.
(4) Environmental factors, such as geological, hydrological, meteorological and other natural environments where the project is located; Working environment such as lighting, ventilation and safety facilities on the construction site; Management environment such as organization and coordination of multi-unit and multi-specialty cross construction. In order to successfully complete the project quality objectives, we must understand and master the objective environment.
⑤ Social factors, such as the consciousness of material suppliers and mechanical equipment lessors, the standardization of construction project transactions, the concept of industry supervision, the level of consulting services, and the construction of a clean government, have an impact on the project quality.
Third, the hazards of common quality defects in construction projects
With the continuous development of new technologies, new materials and new processes in construction engineering, construction engineering gradually presents the characteristics of super-mass, super-high-rise and long span. Common quality defects in building engineering include: engineering pile fracture, water seepage in post-pouring zone of basement, shrinkage cracks in shear wall, structural cracks at the junction of high and low floors, insufficient strength of standard curing test blocks of concrete, excessive deviation of rebar spacing, unqualified welded test blocks of rebar, excessive positive and negative deviation of slab thickness, excessive vertical deviation of shear wall, cracks on the whole surface of concrete, shrinkage cracks at the joint between masonry and concrete, splayed cracks in masonry windowsill, cracks in plastering and hollowing, water seepage around the nozzle of through wall, and high lightning protection grounding resistance.
The above problems fall into two categories:
1, which is directly related to the use safety of the foundation main structure and will lead to major accidents of life and property loss, must be eliminated or rebuilt in the construction process, otherwise it is strictly prohibited to deliver it according to the corresponding laws and regulations.
2. The unqualified parts that affect the normal service life of the project must be eliminated in the construction process or reinforced and rectified according to the specifications, and can be put into use only after passing the inspection; If it directly affects the normal use of the owner, it must be maintained in accordance with the Regulations on Quality Warranty of Construction Projects. Rework or reinforcement requires extra quality cost and time, and demolition and reconstruction is the biggest failure of management and investment.
Fourth, the causes and prevention of common quality defects
The following through several common quality problems as an example for analysis.
1, water seepage in the post-pouring zone of the basement.
(1) drawings, the construction unit must implement according to the qualified construction drawings, accurately grasp the quality of waterproof and additional layers, the lien practice of post-cast strip, the closing time and technical requirements.
(2) For a long time before the pouring of post-cast strip, the reinforcement in post-cast strip should be corroded and drained, and sundries should be removed when pouring, which is one level higher than the concrete on both sides, vibrated and compacted, and the maintenance should be strengthened. It is not advisable to get on the bus within 14 days after pouring the roof post-cast strip.
③ Quality control of commercial concrete. Including concrete strength, slump, workability, aggregate gradation, silt content, mixture ratio, cement variety, fineness, strength, setting time, stability, alkali content, factory date, inspection report, admixture quality, water-cement ratio, etc.
④ Treatment of water seepage in post-pouring zone. In rainy season, underground water will seep out to the ground or wall along the through cracks of concrete, which will affect the normal use of the garage. When processing, find the leakage point and block the leakage channel, and generally use glue injection processing.
2. The strength of standard concrete block is insufficient.
(1) Quality and strength control measures of commercial concrete must be effective. Commonly used additives include pumping agent, water reducer, retarder, early strength agent, impermeability agent, antifreeze, expansion agent and so on. Compatibility tests must be conducted between the same batch of admixtures and between admixtures and cement.
(2) Control the time from mixing, transportation to molding of commercial concrete. Before initial setting (cement slurry begins to lose plasticity), the concrete must be poured into the formwork and vibrated, and the height of the formwork shall not be greater than 2m to avoid concrete segregation. The compactness of vibrating determines the pouring quality of concrete. It is best to leave no construction joints in the beam and slab of the wall column. When the strength grades of wall column and beam slab are different, cold joint should be avoided through organizational measures.
(3) Concrete curing. Generally, natural curing (watering, coating and curing liquid) is started before the final setting of concrete, and the curing of concrete mixed with P, P.O and P.S lasts for 7 days, and the curing of concrete mixed with P.F, P.P, P.C or with retarding and impermeability requirements lasts for 65,438+04 days. While maintaining the floor, the maintenance of the wall column is the most important.
④ According to some unreasonable progress node requirements of developers, the construction period of each floor of the main structure of high-rise residential buildings is about 4 ~ 5 days. After floor positioning and setting-out, the upper wall column, upper formwork and supporting turnover materials are followed. Tower crane will inevitably vibrate the floor during unloading. At this time, the concrete strength of beam and slab is just low, and vibration will lead to floor cracking and affect the development of concrete strength.
⑤ Treatment of insufficient strength of concrete standard curing test block. On-site strength testing should be carried out for solid components, and the number of samples should be appropriately increased; When the physical testing power is still insufficient, the original design unit must be invited to conduct a safety review; When the review does not meet the requirements of the specification, the structural reinforcement scheme must be issued, and the reinforcement can be carried out according to the scheme only after passing the inspection.
3. Cracks at joints between masonry and concrete members.
(1) Between masonry and the bottom of beam and slab, and between masonry and concrete wall column, the shrinkage rate is different due to the different elastic modulus of materials. The usual practice is: the distance between the masonry and the beam bottom 170 ~ 200mm, and after the masonry strength has developed to about 7 days, it will no longer shrink, and then the plug will be closed. Rolling bricks? ; Masonry can also be reserved 30mm away from the bottom of the beam, and filled with micro-expansive mortar after the masonry no longer shrinks.
(2) Before the wall is brushed, stick anti-crack steel mesh at the joint of concrete and masonry materials, with a height of 300 ~ 400 mm, and ensure that the steel mesh does not shift after the bottom ash is plastered. The treatment of plastering cracks at the bottom of beam is to remove decorative surface materials to masonry base layer by layer, fill the cracks with non-shrinkage grouting materials (or special high-strength glue) until they are dense, and then restore decoration layer by layer.
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