There was no large accumulation of cement, sand and gravel, and no mixer truck roaring. On the morning of January 17, at the construction site of No. 1, No. 5 and No. 6 buildings of the Country Garden Lanjiang Huafu Project in Lingao County, Hainan, the construction party superimposed the prefabricated components such as floor slabs, stairs and internal partition wall panels one by one through the dry construction method. The entire construction site looks neat and orderly.

At the same time, in Gaofeng New Village, Yacha Town, Baisha Li Autonomous County, villager Fu Fenglian was cleaning the new villa that she had just moved in. A year ago, this village was still a wasteland. In just 8 months, the construction party transported prefabricated stair panels, balconies, awnings, wall panels, gates... from the prefabricated component factory. 59 small villas were "built" like building blocks. On December 31 last year, 498 villagers of 118 households moved from big mountains to Gaofeng New Village, celebrating the New Year in their new home.

In a short period of time, the construction can be completed safely and environmentally and quickly delivered to use. The above two projects have a common name-prefabricated buildings.

In recent years, from the country to the locality, prefabricated buildings have received unprecedented attention. In 2016, the nation proposed to strive for about 10 years to make prefabricated buildings account for 30% of new buildings nationwide. In 2017, Hainan started with government-invested public construction projects such as schools and hospitals and gradually promoted prefabricated buildings to the market. The prefabricated building area has risen from 0 square meters in 2017 to 11 million square meters in 2020.

What is the charm of prefabricated buildings? Compared with traditional methods, what are the advantages of prefabricated buildings?

Factory made "parts"

Building components are prefabricated by assembly lines, with fewer workers and more environmentally friendly construction

On January 13, in the prefabricated buildings industrial base of Hainan Construction Industrialization Co., Ltd. in the Old Town Economic Development Zone of Chengmai County, the construction workers twisted the steel bar intersections with iron wires to fix them, and then poured concrete. The floor slab of precast concrete used for the building was finished. It only took 24 hours to produce a prefabricated PC floor slab, which could save half of the time than making it on the construction site.

“The buildings produced by industrialization projects are also called prefabricated buildings. Simply put, they are factory-built parts and on-site assembly of houses.” said Guan Yuancheng, the person in charge of the prefabricated building industry base of Hainan Construction Industrialization Co., Ltd. Compared with the traditional building construction method, the construction method of prefabricated buildings has multiple advantages. The full use of building industrialization can save energy by 70%, save 80% of water, save 20% of materials, and save 20% of land, without dust and pollution, and can reduce construction waste by 70%.

Guan Yuancheng said that in the context of the current green ecological development and the shortage of labor and raw materials, the traditional cast-in-place construction method requires a large amount of labor, a large number of formwork and scaffolding. Energy consumption is large. Dust pollution is serious. It is not in line with the green development concept. The components of the prefabricated building are produced intensively in the factory. Production water and formwork can be recycled. It can reduce wet work and dust pollution at the construction site, achieve energy saving, water saving, land saving, and material saving, with significant economic and social benefits.

In the prefabricated construction industry base of Hainan Construction Industrialization Co., Ltd. , migrant workers who used to be exposed to the sun and dust every day have become operators on the production line, responsible for different processes such as steel bars tying, concrete pouring and finished product handling. "The working environment here is good and the production efficiency is high." said Lin Yucheng, a worker who had worked in traditional construction sites. Most of the building components are processed in factories to avoid on-site dust and mud pollution and realize green construction. At the same time, many migrant workers on construction sites have become industrial workers here, and they can also enjoy the "dividends" brought by the reform and development of the construction industry.

From construction sites with flying sand and rocks and roaring machines to spacious and bright factory workshops with clear processes, for construction workers, the prefabricated construction model changes not only the workplace and experience, but also their work concepts.

"The production and installation of PC components need to be accurate and accurate to the millimeter level." said Guan Yuancheng. This requires workers who used to focus on manual labor to transform into knowledge workers with multiple skills and knowledge. He believes that prefabricated buildings are the development trend of the construction industry, and the application and promotion of prefabricated buildings in the market will promote the development of the construction industry from a labor-intensive traditional industry to a technology-intensive modern industry. The prefabricated building has a high degree of industrialization and can save labor costs in total. According to Wu Liangren, the production director of Gaofeng New Village Resettlement Project, in just over 8 months, 59 two-story residential villas were "built" in the Gaofeng New Village project. There were only 112 workers in the entire project, including the workers in processing plants and logistical personnel. This saves a lot of manpower compared to traditional construction projects.

Wu Liangren said “At present, our country's building structure system is mainly based on cast-in-place reinforced concrete structures, and the production methods are relatively extensive. The dust generated during the production process often becomes an important pollution source of inhalable particulate matter in cities. The factory-based production method of prefabricated buildings can greatly reduce the pollution caused by on-site construction and improve the environmental friendliness of construction”.

"Assembly" the house on site

Assemble parts into buildings, saving time and effort to reduce total cost

On January 15, at the construction site of the Danzhou Sports Center project under the blue sky and white clouds, the huge circular steel structure looked like a "suspended" bird's nest in the air. These assembled steel structures are prefabricated in the factory and then transported to the site to be assembled.

"Prefabricated technology and smart construction have greatly accelerated the construction speed." said Xiao Zuofei, deputy general manager of the Hainan Branch of CSCEC No.1 Bureau, the construction party. The Danzhou Sports Center "One Place, two Stadiums" project is the first prefabricated building in Hainan Province. For the stadium project, the assembly rate reached 51%. Since the steel structures used in the project are all prefabricated and processed in the factory, the on-site construction process has been reduced by 30%, and the roof can be successfully sealed in about 70 days.

According to reports, the stadium adopts a space tube truss steel structure as a whole, and the total steel consumption is expected to reach more than 9,100 tons. The number of consumables is large and the construction is difficult. The construction party has assigned an independent code to each steel pipe and each block, combined with the single continuous side assembly technology to achieve accurate assembly while increasing the construction speed. In addition, during the hoisting process, the construction party uses three-dimensional simulation technology as the support to build a virtual platform for steel structure construction operations to realize the system simulation of large-scale steel structure construction and ensure safe, accurate and fast hoisting.

"Lightweight partition wall panels are the most commonly used prefabricated parts. Standard panels are stacked in classification according to the BIM model, and non-standard panels are sent to the cutting room for on-site "reconstruction", so that the breakage rate is far below the industry's average of 10%. Using factory prefabricated partition panels to replace traditional manual block installations can cut the construction period by half." said Sun Jian, a relevant person in the project technology department.

Compared with the traditional cast-in-place building model, the prefabricated building construction model is more standardized, integrated, and informationized. Liu Lianwei, deputy director of the Provincial Department of Housing and Urban-Rural Development, believes that prefabricated buildings can guarantee the quality and accuracy of construction projects due to their advanced production methods and scientific assembly methods.

Prefabricated building can not only reduce manpower, but also reduce the process of mixing mortar, plastering, and wall laying at the construction site, reducing the investment of a large number of wooden formwork, and avoiding a large amount of construction waste. It is a green, low-carbon, and efficient new construction method. It is also the mainstream trend of the development of the construction industry in the future.

In 2019, Hainan Vanke Company constructed No. 8 and No. 9 buildings of Phase 12 of Tongxinjiayuan in Sanya City. This project is one of the first projects in Hainan that meet the national prefabricated building evaluation standards. After the completion of the project, Hainan Vanke Company calculated that in terms of efficiency improvement, the use of aluminum formwork improved work efficiency by 16.67% compared with traditional wooden formwork; the use of integrated bathroom and integrated kitchens improved work efficiency by 50% compared with traditional kitchen and bathroom construction; interleaving construction was achieved, which improved efficiency by 23%.

In terms of compressing labor, the use of aluminum formwork reduced labor by 26% and the plumbers and electricians by 30% compared with traditional wooden formwork. In terms of energy saving and emission reduction, buildings No. 8 and 9 saved about 1,266 cubic meters of wood, reduced cement by about 586 tons, reduced sand and gravel consumption by about 1,360 cubic meters, and reduced water consumption by 628 cubic meters.

Great development potential

Enlarging the market scale and improving the supporting system of the industrial chain are the keys

As of the end of 2020, Hainan Province has put into production 13 prefabricated component production bases, and the area of projects constructed with prefabricated buildings has reached 11 million square meters after review throughout the year, which is 2.5 times that of 2019 and 13.3 times that of 2018.

"Prefabricated buildings are the direction of the future construction industry. Hainan supports the promotion and development of prefabricated buildings. We are optimistic about the market here and built a factory in Danzhou." said Yin Changcheng, chairman of Hainan Chuanglan Yizhu Prefabricated Construction Technology Co., Ltd. At present, the company has set up production bases in Hainan, Hebei and other provinces to undertake prefabricated component business.

"Although the technology has become mature, the prefabricated construction industry is still in the policy promotion stage." said Chen Yongfu, director of the Survey, Design and Technology Division of the Provincial Housing and Urban-rural Construction Department.

The industry believes that when the technology and application scale in the field of prefabricated construction form a system, the cost will gradually drop. "Currently, the obstacles for the promotion of prefabricated construction is mainly due to high cost and supporting industry issues, but these are short-term. Once the prefabricated construction market develops, these problems will not be a problem." said Zhang Wei, who is in charge of Prefab Factory of China Railway Fourth Bureau Group Construction Engineering Co., Ltd. As labor costs in the construction industry rise, the cost advantage of traditional methods will weaken. In contrast, the industrialized prefabricated buildings have more development potential. He is confident that the demand for the prefabricated construction market in Hainan will continue to grow in the future.

According to Chen Yongfu, since 2017, Hainan Province has promoted the leapfrog development of prefabricated buildings in all aspects from policy guidance, technical system construction, production capacity layout, exchanges and cooperation to pilot demonstrations, and fully implemented the concept of green building.

On the upstream side, in order to coordinate the production capacity layout of prefabricated buildings in Hainan, except the existing prefabricated building industrialization bases in Chengmai, Ding'an, and Wanning, and the proposed prefabricated building industrialization bases in Sanya, in principle, the new production capacity of prefabricated building components in Hainan Province should be concentrated in the Lin'gao Jinpai Port Development Zone in the west of Hainan Island to facilitate the formation of industrial clusters and scale effects.

In terms of market cultivation, Hainan Province has adopted preferential policies to encourage more projects to adopt prefabricated buildings or increase project assembly rates. At present, Hainan's projects constructed with prefabricated buildings are gradually being promoted from government-invested public construction projects such as schools and hospitals to commercial housing, office and commercial buildings, and public transportation sites.

In order to promote the collaborative innovation and development of the entire industry chain, since 2018, the Provincial Housing and Urban-rural Development Department has actively signed cooperation agreements with China Academy of Building Research, China Construction Science & Technology Group, East China Construction Group, China Metallurgical Construction Research Institute, Beijing Zhuzong Group and Hainan University, etc. Let the construction-related research institutes, universities and enterprises play the role of think tanks in the development of the prefabricated construction industry in Hainan Province. In addition, Hainan Province has established a technology innovation alliance for the prefabricated construction industry. Through industrial alliances, organize and develop construction companies, design companies, component companies, interior decoration companies, quality supervision and other industry entities, and coordinate innovation and development of the entire industry chain.

Well-known construction companies such as Vanke and Country Garden are also keenly aware that the transformation and upgrading of the construction industry is imperative, and have begun to accelerate the application of prefabricated construction technology in development projects.

"Our current Anju Housing Project,which adopts prefabricated construction, can save construction period of 3 to 6 months." introduced Lin Wang, deputy general manager of Hainan Vanke Management Enterprise Co., Ltd.  The Vanke Yazhou Anju Housing Project in Sanya City, which is constructed by the "5+2+X" construction system, will use aluminum film, climbing frames, all-concrete exterior walls, prefabricated internal partition walls, laminated panels and other prefabricated components. The municipal road pipeline network will be first, decoration and gardens will be interspersed for construction. Multi-spatial, multi-discipline, and all-round interspersed construction will speed up the construction period.