Precast Concrete commonly used by Real Estate Developers

In general, property developers, real estate developers, and construction contractors often face various challenges during project execution, such as:

• Extended construction periods, which delay returns on investment, increase loan interest costs, and, for some projects, add expenses such as sales gallery rental fees.

• Delayed building utilization or project handover, due to uncertainties in site activities—such as rain—or restrictions on working overtime (for example, projects surrounded by residents who need rest during evenings or weekends).

• Nuisances to neighboring communities during construction, such as waste, dust, noise, vibration, and odors from materials. Even with preventive measures, these impacts often escape the site boundary, resulting in frequent complaints. In some projects, this even leads to construction slowdowns or temporary shutdowns, and is also environmentally unfriendly.

• Congested construction sites, filled with materials, equipment, tools, and machinery that obstruct workflows. This also generates dust, waste, and noise pollution, affecting safety and worker health.

• Material wastage, which is often difficult to control and results in higher construction costs than necessary.

• Labor shortages, which increase labor expenses.

• Inconsistent quality, as workmanship varies significantly among workers.

These recurring challenges have led many stakeholders to adopt construction technologies that help mitigate or resolve such issues. One widely recognized solution is Prefabricated Construction Technology, which addresses the three root causes of most problems:

• Reduced labor demands, replacing manpower with machinery and tools. Many of the issues mentioned above stem from human-related variability in some form.

• Shorter construction periods, because activities that previously had to be carried out sequentially can now be performed in parallel.

• Reduced on-site activities, shifting many tasks to controlled factory environments. With fewer on-site operations, site congestion and pollution decrease accordingly.

 

This technology is based on the principle of separating building components—such as columns and beams—for off-site factory production as precast elements, while on-site work such as excavation and piling continues in parallel. Once components are produced, they are transported to the site and installed by connecting each piece together.

 

Precast components can be made from various materials—such as steel, concrete, or timber, individually or in combination—each with different production and installation processes. This leads to various named construction systems. The most widely known today is the Precast Concrete construction system, where components are cast in concrete—commonly referred to simply as the “precast system.”

Concrete is popular due to several advantages: high durability, wide availability, and reduced issues with internal steel corrosion when proper concrete cover is provided. Thus, Precast Concrete has become a preferred method for many types of projects. MKL therefore presents this system from the perspective that project managers should understand, structured according to the principles discussed earlier:

 

Segmentation of Construction Components

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• Box-Girder Bridge Components:
  Commonly seen in Thailand projects such as the Bang Pa-In – Nakhon Ratchasima Motorway, high-speed railways, and expressways. The bridge is divided transversely into approximately 12–14 sections per span and produced using the Short Line Method.

 

Factory Production

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Currently, precast concrete production facilities can be categorized into two main types: manual and automatic systems. The manual system can further be divided into on-site production, in the form of a mobile yard, and off-site production, in the form of an industrial casting yard or factory. For simplicity, these will be collectively referred to as “factories.”

Note:
One of the purposes of on-site production is to reduce transportation-related costs and issues, such as delivery expenses, damage during transport, or time restrictions imposed by road regulations. However, attention must be given to construction-related vibration at the project site—such as vibrations from pile driving—which may affect the strength development of freshly cast concrete components.

 

 

 

 

• Consumable materials, such as form oil, sealants, and surface retarders, must be properly controlled. Overuse leads to unnecessary costs and potential defects. For example, excessive use of oil-based form oil can cause excessive surface air voids, which are restricted by many precast product specifications.

• Dimensional checks during mould assembly must not be overlooked. Significant deviations from design dimensions are difficult to correct—especially in large precast components typically cast with high-strength concrete. Oversized components also increase weight, reducing structural safety factors and causing unnecessary material waste.

• Large moulds, such as those used for bridge segments, may require external vibrators to be attached at various points and operated periodically during casting. This is because internal vibrators cannot reach certain areas. Without external vibration, cavities or honeycombs may form, leading to costly and time-consuming repairs.

• New workers should not be immediately assigned to critical tasks that affect product quality. Frequent defects are often observed when a team undergoes personnel changes, resulting in increased repair costs.

• Embedded items must be firmly fixed. Otherwise, they may shift during casting. Once the concrete hardens, its high strength makes cutting or drilling extremely difficult compared to masonry walls.

• The factory should maintain production records and statistics, such as the number of defective units per production cycle and material consumption rates. This information aids in quality monitoring, cost control, training program development, and continuous improvement of production processes.

• Project owners should station a representative at the factory, such as a construction consultant, to monitor product quality. Reinforcement and embedded items inside precast components—such as electrical conduits—cannot be inspected once the components are installed on site. Even if defects are found later, concrete removal for correction may compromise structural integrity.

 

Parallel Operations

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As previously mentioned, the Precast Concrete system involves separating construction or building components for off-site production, while allowing other on-site activities—such as excavation and pile driving—to proceed simultaneously.
In conventional cast-in-place construction, many major tasks must be performed sequentially; for example, if the beams on the first floor have not been cast, the second-floor beams cannot be cast either.

In contrast, with the Precast system, beams for various floors can be cast at the factory at the same time, then stored at the stock yard awaiting transportation for installation. During this waiting period, repair or touch-up teams can also work on the components in advance. This parallel workflow significantly shortens overall construction time.

 

Installation

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Each precast component, once completed, is transported and assembled on-site according to design specifications. Components are connected using different materials, devices, and methods depending on the project. To maintain continuity, MKL presents examples of installation principles using precast components from the structures previously mentioned:

• Underground MRT Tunnel Segments:
  Installation uses an Erector machine. Components are joined within the same ring and between adjacent rings using curve bolts or straight bolts, inserted into bolt holes through pre-installed sockets, depending on the designer’s choice.

 

 

• Precast Segmental Box Girder Bridges:
  Commonly found in Thailand, these use an Erection Truss, in either the overhead or underslung configuration. Components are connected with a post-tensioning system.

• Residential Buildings:
  Mobile cranes—and in some cases shuttle lifts—are commonly used.

 

 

Jointing systems fall into two main categories: Dry Joint Systems such as bolting and welding, and Wet Joint Systems such as dowels combined with non-shrink grout.
Designers today continually refine joint systems to improve installation speed, structural performance, and long-term reliability.

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Summary

Given that the key objectives of construction work consist of scope, quality, time, and cost, comparing the conventional cast-in-place method with the Precast Concrete system (under an identical scope) shows that:

• Time is faster because many activities can occur in parallel.

• Cost is lower when the production volume is large enough to achieve economies of scale.

• Quality is theoretically higher because components are produced at a factory, at ground level, where workers and inspectors can work more comfortably and consistently. Labor skills can also be standardized more easily.

However, installation quality—especially joint performance—must be closely monitored. Any system involving joints inherently carries risks such as water leakage and durability issues. The quality of connections depends on various factors: worker skills, preparation methods, joint design, and materials/equipment used.

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Additional Considerations

It is important to understand that every system has both strengths and weaknesses. When adopting the Precast Concrete system, one should study not only the advantages but also the limitations to plan appropriate mitigation. For example, in a bearing-wall precast system, walls serve as part of the structural system, meaning they cannot be demolished like conventional masonry walls.