Discussion on Improvement of Construction Quality of Prefabricated Buildings

Ge Hong

(Henan Shengda Construction Co.,LTD,Zhengzhou,Henan 450046)

Abstract:With the continuous development of Chinese construction industry,people's requirements on construction are also rising.Many developed countries in the world have begun to pay attention to the industrialization process of the construction industry.That is,part of the construction is prefabricated in the factory and assembled on site in advance.This portable and efficient industrial production and assembly mode is the basic original intention of prefabricated construction.Assembly construction technology has many advantages,such as fast production speed,high efficiency,reduced manpower,green and environmental protection.It is an important symbol of modernization in modern construction industry.Drawing lessons from the success of foreign construction industrialization,the whole construction industry has set off a boom in the industrial production of prefabricated construction.However,with the continuous expansion of this boom,the cast-in-place structure system has been changed,and the disadvantages of prefabricated construction have gradually emerged.Drawing lessons from the successful way of foreign construction industrialization,the whole construction industry has set off a boom in the industrial production of prefabricated construction.However,with the expansion of this craze,the cast-in-situ structure system has been changed,and the disadvantages of prefabricated construction have gradually emerged.

Key words:prefabricated buildings;construction quality;improvement research

Speaking from the specialty of building engineering,the prefabricated building design is sufficiently standardized,with high degree of production industry,high degree of construction and assembly,integration of decoration,modernization of management,various intelligent applications are adopted to realize"four sections and one environmental protection",which is an extremely reasonable and efficient production mode.Chinese prefabricated construction industry started late and is still in the early stage of development.Therefore,it is imperative to vigorously develop this green,environment-friendly,energy-saving and efficient new construction industry in line with Chinese national conditions.How to guarantee the quality of prefabricated construction,promote the development of prefabricated construction industry,how to break the original layout of construction industry,solve the quality problem of the prefabricated buildings,realize the coexistence of benefits and quality,and lead the prefabricated construction industry to the development direction we want,the following problems should be considered.

I.Process Flow of Prefabricated Building Construction

The construction process of prefabricated buildings can be roughly divided into three parts:foundation engineering,main structure engineering and decoration engineering[1].Among them,the foundation engineering part and the decoration engineering part are basically the same as other ordinary cast-in-place buildings,which will not be explained too much,but the difference lies in the main structure engineering.The main structural engineering can be roughly divided into factory prefabricated components,transportation and installation;the fixing and construction of support parts;steel bar assembly and welding,mold grouting;steel bar assembly of cast-in-place structure,bottom die,install embedded parts;casting and maintenance of castin-place concrete,laid layer by layer until the top layer.Therefore,the prefabricated components are an important part of the whole prefabricated construction process.

II.Concrete Advantages of Prefabricated Construction

In the process of China's modern economic development,prefabricated construction can effectively promote the production of prefabricated molds and related parts used in construction,so that the production of construction is more accurate and more high-speed;at the same time,it can effectively improve the environmental protection of construction,improve the cleanliness of the overall construction environment,minimize the construction pollution,and promote the development of Chinese construction industry towards energy conservation and environmental protection[2].Prefabricated construction breaks the conventional production mode,vigorously develops industrial production,reduces the consumption of human resources,shortens the construction period and solves many technical problems.Prefabricated buildings have higher seismic performance,better fire resistance,stronger sound insulation and are more suitable for people's living environment.

III.Quality Problems in Prefabricated Construction

Quality control is an important link in the realization of prefabricated architecture.In order to improve the management and innovation system of the construction industry and achieve the goal of the rapid rise of Chinese construction industry,all kinds of quality problems in the process of prefabricated architecture should be systematically summarized and studied and solved.The common quality problems of prefabricated construction can be divided into the following situations.

(i)Template Design

There are two main problems in the process of template making and installation,one is that the corner plate is easy to break,the other is that the insulation layer of the outer wall plate is easy to break.The corner plate can ensure the stability of the prefabricated building construction overall structure,which is an extremely important component,but the corner plate volume is large,the overall is thin,so it is easy to break,whether in the transportation or installation process,it is easy to cause quality problems.In daily maintenance process,if operation is improper,the deviation of corner also will be produced easily and change the original angle.Cast-inplace corner plate is easy to occur the situation that failure to connect well with other parts,there will be also technical defects such as expansion and vibration.Insulation layer of outer wall board appears to be detached from wall body or fracture occurs very easily under normal circumstances.It mainly occurs in the process of design and construction.If three non-uniform materials are used as the decorative layer,insulation layer and structural layer of the outer wall,it is easy for the outer wall to break and fall off[3].

(ii)Component Connections

Both the grouting of the connecting part and the location of the component connections will affect the effect of the connecting part.When the wall panel is required to be connected longitudinally,but the grouting is not full enough,the grouting hole of the component is easy to be blocked,so that the construction personnel cannot accurately determine whether the interior of the grouting panel has been completely grouting.In addition,the grouting hole of the industrial mass production grouting board may be blocked or partially blocked,which may easily lead to insufficient grouting and incomplete connection[4].Besides,when the components are connected with the sleeve,the steel bar will be offset from the sleeve.According to the degree of deviation,whether the steel bar can be inserted into the hole is determined.There are safety risks of prefabricated buildings,big or small.

(iii)Burying of Pipelines and Components

The main problems of burying pipelines and components occur in the embedded pipelines of components.The pipelines of the embedded components block or fall off,resulting in the position deviation or installation difficulty of the embedded components.This kind of situation is generally due to the vibration of concrete caused by the bursting of the block or deviation of position caused by excessive vibration,therefore,it is extremely important to grasp the construction strength.

(iv)Technical Problems of Construction Personnel

Due to the development time of prefabricated construction industry is short,many construction personnel are familiar with the construction technology of cast-in-place concrete structure,but are not familiar with the construction of relatively simple prefabricated buildings,they don’t have too much experience in the installation and inspection of prefabricated components,and there is not enough practice in their operating principles and techniques,leading to installation failure or hidden trouble[5].

(v)Machinery

In the whole process of prefabricated construction,there are various types of mechanical appliances with different precision.It is necessary to ensure the complete matching of machinery and appliances as far as possible,optimize and update auxiliary equipment,and check frequently to ensure that all mechanical equipment can reach a good working condition.

IV.Measures of Solving Problems in Prefabricated Buildings Construction

In view of different problems in the construction process of prefabricated buildings,the construction technology and procedures should be adjusted at any time to give full play to the safety,reliability and durability of prefabricated buildings[6].Firstly,in view of the problem that the corner plate is easy to break off during transportation and hoisting,it is recommended to use the auxiliary tool -“Lshaped”spreader to transfer its force on the spreader and conduct hoisting to reduce its damage rate;secondly,according to the thickness and specifications of different components,make matching plastic or rubber and other inexpensive materials to protect the four corners of the components from damage,and these corners can also be reused,effectively protect the plate or other components in the process of transportation in the case of low resource;Finally,by reducing the span of the composite plate,the fracture of the composite plate during lifting is reduced.By strengthening the front degree around the embedded parts or the size of the truss bars,the problem of the embedded parts falling off of the composite plates can be reduced.By strengthening concrete vibration,the quality problems of prefabricated components caused by mortar separation or excessive one-time blanking can be prevented.

In the case of updating the precision of molds of various prefabricated components,manufacturing and assembly machinery should also follow up to reduce the frequency of quality problems of prefabricated components in the production inspection process,such as reducing the blockage of grouting holes during prefabrication.Reduce the production rate of waste components,and ensure the loss caused by the quality problems of components in the later installation process to the minimum.According to the technical problems existing in the construction personnel,it is required to strengthen pre-job training,strengthen the grasp of the construction personnel,and ensure that all construction personnel have a strong awareness of quality and safety,at the same time,take Regular professional training for construction personnel,constantly improve the technical quality of construction personnel,strengthen personnel management,intensify the exchange and communication between technical personnel,make mutual reference.Cultivate the sense of responsibility of construction personnel and ensure the construction quality,provide reliable talents for the development of prefabricated construction industry in China.