Chapter 25

Flexible Stone and Prefabricated Construction

Compiled by Guangdong Fortune Stone New Material Co., Ltd.

Key Points

• The essence of prefabricated construction is an industrialized transformation of building production methods: walls, floors, stairs, and balconies are prefabricated on factory assembly lines and assembled on site. Structures can be prefabricated, and facades likewise need to be “prefabricated”—this is the key issue of the “last mile” of prefabricated construction.
• Prefabricated construction imposes four new requirements on facing materials: factory prefabrication, lightweighting, dimensional precision, and durability matching the service life. Flexible stone has a self-weight of 3–5 kg/m² and dimensional tolerance ≤ ±1 mm, supports factory assembly-line pre-adhesion, and is highly compatible with the production logic of prefabricated construction.
• There are three integration paths between flexible stone and prefabricated construction: factory post-adhesion, on-site dry fast installation, and facing for light steel and modular buildings. The three paths correspond to different component types and site conditions, each with its own process logic and key control points.
• Scheme design must address four matches: matching with prefabricated exterior wall panels, matching with prefabricated interior wall panels, matching with modular coordination, and matching with prefabrication rate evaluation.
• Flexible stone has three boundaries in prefabricated construction: it is not suitable for the reverse-casting process; structural joints should be disconnected and elastic sealing should be used; and the single procurement cost compared with coatings needs to be comprehensively weighed from a full life cycle perspective.
• The environmental controllability of factory post-adhesion is superior to on-site wet work; the interface bonding quality between flexible stone and prefabricated concrete can be verified through both factory inspection and on-site pull-off tests; modular customized cutting is the key means to reduce on-site secondary processing.

25.1 The “Four New Requirements” of Prefabricated Construction for Facing Materials

Prefabricated construction transfers a large number of on-site processes to the factory, imposing requirements on facing materials that differ from traditional cast-in-place construction. These can be summarized in four aspects: factory prefabrication, lightweighting, dimensional precision, and durability matching the service life.

25.1.1 Factory Prefabrication

Facing materials must adapt to the factory’s production rhythm, be able to complete adhesion and curing in the factory environment, and have stable and controllable quality.

Traditional facing materials each have limitations in this requirement: coatings require on-site spraying and cannot be prefabricated in the factory; ceramic tiles and stone can be pre-adhered in the factory, but are heavy and require special back construction and anchoring measures. Flexible stone uses special bonding agents for thin-set adhesion; the factory environment has controllable temperature, humidity, and cleanliness, and adhesion quality is more stable than on site. Prefabricated-purpose flexible stone supports the factory assembly-line pre-adhesion process, enabling facing application before prefabricated wall panels and prefabricated beams and columns leave the factory, with mechanized precision construction, precise dimensions, uniform color, and high flatness, solving the problems of large on-site manual application errors and irregular splicing.

25.1.2 Lightweighting

The hoisting and transportation costs of prefabricated components are directly related to component self-weight. The heavier the facing layer, the heavier the component, the higher the requirements for hoisting equipment, and the greater the transportation cost.

Flexible stone has a self-weight of only 3–5 kg/m², about 1/6 of ceramic tiles. Taking a 6 m × 3 m prefabricated exterior wall panel as an example: with flexible stone facing, the facing layer self-weight is about 54–90 kg; with ceramic tile facing, the facing layer self-weight is about 270–450 kg. Each panel can be reduced in weight by 200–360 kg. For a 30-story residential building with 200 exterior wall panels, the total weight reduction is about 40–72 tons. The resulting downgrade of hoisting equipment, reduction in transportation trips, and improvement in installation efficiency are important economic drivers for choosing flexible stone in prefabricated construction.

Prefabricated wall panels and modular components have limited self-weight. When traditional stone and ceramic tiles are too heavy, it is very easy to cause component load overruns and inconvenient transportation and hoisting. Flexible stone is thin, light, and flexible, does not increase the structural burden of prefabricated components, and facilitates factory batch production, full-vehicle transportation, and on-site hoisting and assembly.

25.1.3 Dimensional Precision

Prefabricated components of prefabricated construction are produced in factories, with dimensional deviations measured in millimeters. The facing layer, as part of the component, must have dimensional precision matching the component.

Flexible stone uses factory die-cutting or precision cutting, with dimensional deviations controllable within ±1 mm, meeting the precision requirements of prefabricated components. Prefabricated-purpose flexible stone products have regular dimensions and precise tolerances, adapting to standardized batch construction, with uniform splicing gaps and unified overall effects, meeting the high-standard acceptance requirements of prefabricated projects.

25.1.4 Durability Matching the Service Life

The design service life of prefabricated construction is usually 50 years. If the facing layer ages in 10 years, it means that the facing needs to be renovated multiple times during the building’s full life cycle, which is at odds with the prefabricated construction concept of “build once, use long-term.”

The Technical Standard for Prefabricated Concrete Buildings clearly states that when facing materials with good durability are used, the durability of the facing can be the same as that of the exterior enclosure system. Flexible stone has a weather resistance test of ≥2000h, and flexible stone products using high-flexibility emulsion can reach 3500h weather resistance, with a design service life of 10–15 years, which can be extended to more than 20 years with regular maintenance, far superior to the 5–8 years of coatings. It is a feasible choice for “durability matching the service life” of the facing layer of prefabricated construction. Prefabricated-purpose flexible stone has weather resistance, aging resistance, waterproofing, and crack resistance, requiring no maintenance and no frequent renovation in the later period, with low operations and maintenance costs, conforming to the development trend of low-carbon buildings.

Table 25-1 Comparison of Facing Materials for Prefabricated Construction

25.2 The “Three Integration Paths” of Flexible Stone and Prefabricated Construction

The integration of flexible stone and prefabricated construction is not simply applying flexible stone to prefabricated components, but selecting an adapted integration path according to the production process of prefabricated construction. Through engineering practice verification, there are three feasible paths.

25.2.1 Factory Post-Adhesion

Process logic: After prefabricated components complete casting, curing, and demolding in the factory, flexible stone adhesion is completed within the factory.

Process advantages are manifested in four aspects:

Controllable environment. Temperature, humidity, and cleanliness in the factory are controllable, bonding agent curing conditions are stable, and adhesion quality is more reliable than on site. The factory environment avoids uncontrollable factors such as wind, rain, temperature differences, and dust in on-site construction, and the batch consistency of bonding strength is significantly better than on-site construction.

No involvement of casting and vibration. Flexible stone is adhered after concrete curing is completed, so there is no risk of displacement, grout leakage, or contamination during casting and vibration. The essential difference between this path and the reverse-casting process is: the reverse-casting process places flexible stone at the bottom of the mold before pouring concrete, while factory post-adhesion adheres flexible stone after the concrete has hardened. The former has risks of grout leakage contamination and demolding damage, while the latter completely avoids these risks.

Can be composited with insulation. Factory post-adhesion can be composited with insulation layers to form “structure + insulation + facing” integrated components. Components complete the entire enclosure system assembly in the factory, and only installation is required on site.

Quality can be inspected. Adhesion quality can be inspected piece by piece in the factory, and non-conforming products are not shipped. Pull-off test sampling can be conducted before leaving the factory to ensure bonding strength meets standards.

In the factory post-adhesion process, the breathability and flexibility of flexible stone are key. The enterprise’s independently developed large-particle-size high-permeability flexible stone emulsion technology adopts large-particle-size core-shell structure design, combined with toughening agents and antibacterial flame-retardant functional additives, achieving synergistic optimization of toughening, antibacterial, and flame-retardant properties. This technology, from the perspective of filler particle size and interfacial phase volume fraction, increases the ratio of soft shell thickness to filler particle size through large-particle-size design, controlling the interfacial phase volume fraction within the optimal range, achieving a balance between breathability and flexibility, and providing better material adaptability for the factory post-adhesion process.

Applicable scenarios: prefabricated exterior wall panels, prefabricated interior wall panels, prefabricated balcony slabs, prefabricated columns and beams, etc.

Key control points: Prefabricated components need to be cured to the specified age after demolding, and the surface moisture content must be ≤10% before adhesion; the component surface needs to be cleaned of floating dust and release agent residue, and primer should be applied if necessary; after adhesion, curing in the factory is required until the bonding agent is fully cured before transportation; during transportation, the flexible stone facing needs to be protected to avoid impact damage.

25.2.2 On-Site Dry Fast Installation

Process logic: After prefabricated components are installed on site, flexible stone is applied on site using the dry fast installation process.

Process advantages are manifested in four aspects:

Dry construction. Special bonding agents are used for thin-set adhesion, requiring no wet work, no water curing, and no complex base preparation; flexible stone can be directly applied after substrate cleaning. Prefabricated-purpose flexible stone uses a full dry thin-set process throughout, reducing construction processes, improving construction efficiency, and adapting to the construction rhythm of prefabricated buildings—rapid assembly, rapid facing, and rapid acceptance. This path is consistent with the “dry” concept of prefabricated decoration. Technical Standard for Prefabricated Interior Decoration JGJ/T 491 clearly requires that decoration should adopt dry construction methods, without on-site wet work, and achieve component installation through mechanical connection, snap fixing, adhesive fixing, and other methods.

Efficient construction. Flexible stone construction efficiency is 30–50 m²/person·day, higher than the 10–20 m²/person·day of ceramic tiles, effectively shortening the project facing schedule.

No construction waste. The thin-set process produces little construction waste, and the site is clean. Dry construction without wet work curing significantly reduces on-site waste.

Strong adaptability. Flexible adjustments can be made according to actual on-site conditions, adapting to the installation deviations of prefabricated components. The flexible fitting characteristics of flexible stone can adapt to slight dimensional deviations of prefabricated components, making it less prone to hollowing and detachment.

Applicable scenarios: prefabricated building exterior wall facing, interior wall facing, and prefabricated renovation of existing buildings.

Key control points: After on-site installation is completed, the surface of prefabricated components needs to be cleaned and primed; joints need to be waterproofed and sealed according to the joint design requirements of prefabricated construction, and flexible stone should not be applied across structural joints; the construction environment temperature should be within 5–40°C, avoiding low-temperature or high-temperature construction; pull-off tests are required to verify bonding strength.

25.2.3 Facing for Light Steel and Modular Buildings

Process logic: Flexible stone is directly used for interior and exterior wall facing of light steel buildings and modular buildings.

Process advantages are manifested in four aspects:

Flexible adaptation. The flexibility of flexible stone can adapt to the slight vibration deformation of light steel walls, and it is not easy to crack or hollow during long-term use. Light steel buildings and prefabricated integrated houses have light structural self-weight and obvious flexible deformation of wall substrates, making it difficult for traditional rigid facing materials to adapt to their structural characteristics. The flexibility of flexible stone can follow the slight deformation of prefabricated panels and synchronously adjust with temperature-induced expansion and contraction, helping to solve the common problems of cracking, hollowing, and detachment of prefabricated facing, and reducing the repair rate after batch delivery.

Lightweight matching. Light steel buildings themselves are light, and the lightweight characteristics of flexible stone match them.

Fast installation. Modular buildings complete the main structure in the factory, and flexible stone can be quickly applied in the factory or on site.

Detachability. Flexible stone can be removed and replaced, adapting to the detachable and movable characteristics of modular buildings. Later maintenance is simple and renovable, adapting to the detachable and recyclable decoration concept of prefabricated construction.

In the application of light steel and modular buildings, the enterprise’s independently developed high-flexibility flexible stone emulsion technology provides support. This technology gives flexible stone flexibility at -30°C, withstanding 100 freeze-thaw cycles without cracking or peeling, and weather resistance of 3500h, capable of adapting to the slight deformation of light steel walls caused by temperature changes and wind loads, reducing the risk of cracking and detachment caused by substrate deformation. The accompanying enterprise independently developed inorganic silicone resin modified acrylic emulsion topcoat technology gives the topcoat layer stain resistance (whiteness recovery rate) of over 80% and weather resistance of 3500h, providing long-term durability assurance for modular building exterior facing.

Applicable scenarios: light steel villas, modular apartments, container buildings, temporary buildings, integrated houses, etc.

Key control points: Light steel wall substrates need to be leveled, and cement pressure boards or OSB boards should be laid as the flexible stone base if necessary; panel joints need crack prevention treatment to avoid flexible stone cracking due to substrate deformation; fixing methods can use a combination of bonding and anchoring to ensure no detachment under vibration conditions; wall breathability requirements need to be considered to avoid mold caused by trapped moisture.

Table 25-2 Comparison of the Three Integration Paths of Flexible Stone and Prefabricated Construction

25.3 The “Four Matches” of Flexible Stone and Prefabricated Construction

25.3.1 Matching with Prefabricated Exterior Wall Panels

Prefabricated exterior wall panels are the main body of the enclosure system of prefabricated construction. The application of flexible stone on exterior wall panels is mainly through the factory post-adhesion path. Prefabricated exterior wall panels with flexible stone adhesion completed in the factory are directly installed after arriving on site, with no on-site facing construction, realizing “factory prefabrication, on-site facing-free.”

From a full life cycle perspective, prefabricated exterior wall panels with factory post-adhesion require no on-site facing construction after installation, reducing on-site construction schedule and labor, and also reducing construction waste and noise generated by on-site construction.

25.3.2 Matching with Prefabricated Interior Wall Panels

Prefabricated interior wall panels (such as ALC panels and lightweight partition panels) have flat surfaces and precise dimensions, making them ideal substrates for flexible stone. Flexible stone can be directly applied to factory-prefabricated interior wall panels, realizing “prefabricated decoration” of interior wall facing.

Prefabricated decoration requires dry construction, and traditional wet work (plastering, tile adhesion) is gradually being replaced. Flexible stone uses special bonding agents for thin-set adhesion, belonging to dry or semi-dry construction, consistent with the dry concept of prefabricated decoration. Flexible stone can be used in combination with plastering-free prefabricated partitions, ceilings, floors, integrated kitchens and bathrooms, and other component materials, forming a complete prefabricated decoration system.

25.3.3 Matching with Modular Coordination

The core design principle of prefabricated construction is modular coordination. The specifications of facing materials should adapt to building modules, reducing on-site cutting and waste.

Flexible stone can be customized in dimensions according to modules, with conventional specifications such as 600×300 mm, 600×600 mm, and 600×1200 mm, matching the common modules of prefabricated construction (300 mm basic module). In the factory post-adhesion process, flexible stone is pre-cut in the factory according to the layout drawing, requiring no secondary processing on site.

The Technical Standard for Prefabricated Concrete Buildings requires that for prefabricated components with facing, the facing materials should be pre-drawn with positioning drawings according to the layout drawing, and the factory should cut, plate-make, and process the facing materials according to the drawing requirements. The customization capability of flexible stone is highly compatible with this requirement. The enterprise’s independently developed flexible stone cutting device integrates cutting, fixing, pushing, and dust removal, making the cutting process more precise, efficient, and environmentally friendly, providing equipment support for factory prefabricated cutting, and meeting the dimensional precision requirements of modular coordination in prefabricated construction.

25.3.4 Matching with Prefabrication Rate Evaluation

In the prefabricated building evaluation system, “integration of enclosure wall with insulation, heat preservation, and decoration” is an important scoring item. Standard for Assessment of Prefabricated Building GB/T 51129—2017 establishes the “prefabrication rate” evaluation indicator system. Prefabricated buildings need to meet four basic conditions: the evaluation score of the main structure part is not less than 20 points; the evaluation score of the enclosure wall and interior partition part is not less than 10 points; full decoration is adopted; and the prefabrication rate is not less than 50%.

In the evaluation of enclosure walls and interior partitions, the scoring item of “integration of enclosure wall with insulation, heat preservation, and decoration” is fully applicable to the factory post-adhesion scheme of flexible stone. Some regions require a prefabrication rate of not less than 50% for prefabricated buildings, which can be implemented using the national standard GB/T 51129—2017 or the Guangdong provincial standard DBJ/T 15—163—2019. As a factory post-adhered facing material, flexible stone’s application path of “integration of facing and structure” directly corresponds to the “integration” requirement in the prefabrication rate evaluation.

25.4 Three Typical Application Schemes

25.4.1 Facing Scheme for Prefabricated Renovation of Existing Buildings

Applicable conditions: exterior wall renovation of existing buildings, original facing is coatings or old ceramic tiles, structural form is cast-in-place or masonry.

Scheme content: substrate crack resistance treatment + direct flexible stone application + joint sealing.

Typical effect: In a renovation project of a senior apartment, the original building facade was ordinary coating facing. In the renovation, flexible flexible stone was selected and directly applied to the wall surface after crack resistance treatment. The flexible stone thickness is 2.5–3 mm, suitable for different substrates and curved walls, with low comprehensive cost. The project adopted a mix of two different red tones, and the 60×240 mm size gave the building complex an elegant and warm texture. This case reflects the prefabricated thinking of flexible stone in existing building renovation: factory-prefabricated materials, rapid on-site installation.

Selection recommendations: Existing building renovation should prioritize the on-site dry fast installation path, and substrate treatment and primer application should be treated as special quality control points.

25.4.2 Facing Scheme for Historic District Character Renewal

Applicable conditions: facade renewal of historic districts and character protection areas, requiring preservation of traditional texture and shortening of on-site construction period.

Scheme content: prefabricated antique brick texture flexible stone panels + modular installation system + laser positioning.

Typical effect: A historic district renovation project adopted prefabricated antique brick texture flexible stone panels, with modular installation through snap-fit splicing combined with laser positioning instruments. The technical path of standardized prefabrication, modular installation, and dry construction is consistent with the core logic of prefabricated construction. The on-site application period was controlled at about 9 days, effectively reducing the impact of traditional wet work on the normal operation of the district.

Selection recommendations: Historic district renewal should adopt customized texture products such as antique brick texture and terracotta color series. On-site fixing methods can use a combination of bonding and mechanical snap-fit, balancing durability and replaceability.

25.4.3 Exterior Wall Facing Scheme for New Prefabricated Residential Buildings

Applicable conditions: new prefabricated residential and public building projects, prefabricated exterior wall panels using factory post-adhesion process.

Scheme content: prefabricated exterior wall panels with flexible stone adhesion completed in the factory + on-site hoisting installation + joint sealing.

Typical effect: A prefabricated residential project adopted prefabricated concrete exterior wall panels, with prefabricated-purpose flexible stone for facing. After casting and curing in the factory, the prefabricated exterior wall panels completed flexible stone adhesion in the factory, and were directly hoisted and installed after arriving on site. The project advantages are manifested in three aspects: first, on-site facing-free construction, shortening the schedule by about 30%; second, component weight reduction of about 200 kg per panel, lowering hoisting equipment requirements; third, controllable factory environment, stable adhesion quality, and 100% pass rate of factory pull-off tests. This case verified the feasibility of the factory post-adhesion path.

Selection recommendations: New prefabricated projects should prioritize the factory post-adhesion path, and the flexible stone layout drawing and cutting drawing should be completed simultaneously in the component detailed design stage, reserving sufficient time for factory production.

25.5 The “Three Boundaries” of Flexible Stone in Prefabricated Construction

25.5.1 Not Suitable for Reverse-Casting Process

The reverse-casting process involves laying facing materials face-down at the bottom of the mold, then pouring concrete and vibrating for forming. The reason ceramic tiles and stone can withstand this process is that they are rigid, do not deform during vibration, and do not tear during demolding.

Flexible stone is a flexible thin-sheet material (thickness only 3–5 mm). Applying the reverse-casting process is prone to three types of problems: first, grout leakage contamination, where concrete slurry penetrates from the gap between flexible stone and the formwork, contaminating the flexible stone decorative surface; second, vibration displacement, where vibration impact causes flexible stone displacement; third, demolding damage, where flexible stone is torn or scratched during demolding. Therefore, the reverse-casting process is not suitable as the main path for combining flexible stone with prefabricated construction. The application of flexible stone in prefabricated construction should be mainly through factory post-adhesion and on-site dry fast installation.

25.5.2 Flexible Design of Structural Joints

There are joints between exterior wall panels of prefabricated construction, and the joints need to adapt to inter-story displacement and temperature deformation. The Technical Standard for Prefabricated Concrete Buildings stipulates that joints should adopt a waterproof and drainage design combining structural waterproofing and material waterproofing according to local climate conditions, and joint materials should meet the requirements of waterproofing, durability, and deformation adaptation.

The enterprise’s independently developed high-flexibility flexible stone emulsion technology gives flexible stone -30°C low-temperature flexibility and 100 freeze-thaw cycle tolerance, capable of adapting to the slight deformation of both sides of structural joints caused by temperature changes and structural displacement. However, it should be clarified: flexible stone should not be applied across structural joints; structural joints should be disconnected and sealed with elastic sealant, coordinated with the joint sealing system design.

25.5.3 Cost Balance

The initial procurement cost of flexible stone facing is generally higher than coatings but lower than ceramic tiles and stone. In prefabricated construction, evaluating the economics of flexible stone should be comprehensively weighed from a full life cycle perspective, rather than只看单方材料价格.

Compared with coatings, flexible stone has three cost advantages in prefabricated construction: first, factory post-adhesion realizes on-site facing-free construction, shortening the schedule by about 30% and reducing on-site labor and measure costs; second, lightweighting reduces component hoisting and transportation costs, with each panel reduced in weight by 200–360 kg; third, durability is superior to coatings, with flexible stone weather resistance reaching 3500h, which can be extended to more than 20 years with regular maintenance, far superior to the 5–8 years of coatings, reducing the number of renovations in the full life cycle.

Compared with ceramic tiles and stone, although the unit price of flexible stone may not necessarily be lower, its self-weight is only about 1/6, which can significantly reduce component loads and hoisting equipment requirements. In existing building renovation, flexible stone can be directly applied to the original facing substrate or after local leveling, reducing substrate demolition and modification costs.

At the same time, it should also be recognized that flexible stone is not the optimal solution in all projects: in special areas with extremely high impact resistance and wear resistance requirements, ceramic tiles and stone still have advantages; in temporary buildings with extremely cost-sensitive and low durability requirements, coatings may be more economical. Therefore, technical and economic comparison should be conducted in the scheme stage, and the facing scheme should be comprehensively determined based on component type, construction conditions, and maintenance cycle.

Acceptance and Delivery

I. Material Entry Acceptance

When flexible stone products enter the site, the product certificate, factory inspection report, and type inspection report should be verified. The type inspection report should include key performance indicators such as bonding strength, weather resistance, freeze-thaw resistance, and salt spray resistance. Prefabricated-purpose flexible stone should be checked against the design specifications and layout drawing for dimensional tolerances, and dimensional deviations should meet design requirements.

II. Process Quality Control

Factory post-adhesion process: Prefabricated components should be cured to the specified age after demolding, and the surface moisture content should be ≤10% before adhesion; pull-off test sampling should be conducted before the component leaves the factory, and the adhesion area and hollowing condition should be inspected piece by piece, with non-conforming products not allowed to leave the factory.

On-site dry fast installation process: After prefabricated components are installed, the substrate surface should be cleaned and primed; after each inspection lot is completed, pull-off tests and hollowing inspections should be conducted; the disconnection and sealing treatment of flexible stone at structural joints should be specially inspected.

III. Acceptance Standards

The acceptance indicators in this chapter are consistent with the unified standards in Chapter 19:

• Bonding strength ≥0.4 MPa
• Hollowing rate ≤5%
• Flatness ≤3 mm
• Appearance free of contamination and obvious color difference, with straight joint lines;
• Structural joints disconnected, with continuous and full sealant.

Decision Reference for Facade Retrofit Offices

I. Applicable Object Determination: This chapter applies to three types of projects—facing engineering of new prefabricated buildings (prefabricated exterior wall panels, prefabricated interior wall panels, light steel and modular buildings), prefabricated renovation of existing buildings, and projects where the prefabrication rate evaluation needs to include the “integration of facing and structure” score. Before decision-making, first determine the project type: new projects prioritize factory post-adhesion, renovation projects prioritize on-site dry fast installation, and light steel and modular projects adopt flexible adaptation schemes.

II. Key Decision Indicators: New prefabricated projects should focus on verifying the factory adaptability of flexible stone products—self-weight (3–5 kg/m²), dimensional tolerance (≤±1 mm), and factory post-adhesion curing conditions; renovation projects should focus on verifying substrate conditions—substrate strength, flatness, and moisture content ≤10%; prefabrication rate evaluation projects should verify the correspondence between the flexible stone factory post-adhesion scheme and the “integration of enclosure wall with insulation, heat preservation, and decoration” scoring item in GB/T 51129—2017. In full life cycle decision-making, the comprehensive differences between flexible stone and coatings, ceramic tiles/stone in component weight reduction, maintenance cycle, and renovation cost should be compared.

III. Scheme Comparison Recommendations: Prefabricated concrete components prioritize the factory post-adhesion path; existing building renovation and projects with limited on-site conditions choose on-site dry fast installation; light steel, modular, and integrated houses choose flexible adaptation schemes. Three boundaries should be noted: do not use the reverse-casting process; disconnect flexible stone at structural joints and use elastic sealing; cost evaluation should be compared on a full life cycle basis, not using unit material price as the sole decision basis.

IV. Cost and Schedule Reference: The cost of the factory post-adhesion path includes flexible stone material costs, factory adhesion labor costs, component transportation protection, and finished product protection costs, with comprehensive costs lower than on-site wet-work facing; the labor cost of the on-site dry fast installation path is lower than traditional ceramic tile application. In terms of schedule, factory post-adhesion transfers the facing process from the site to the factory, with on-site facing-free construction, and the total project schedule can be shortened by about 30%; on-site dry fast installation construction efficiency is 30–50 m²/person·day, 2–3 times that of ceramic tile application. Component transportation and hoisting protection costs should be included in the cost and should not be omitted.

V. Implementation Risk Warnings: The three major risks are loss of control of factory adhesion quality, facing damage during transportation and hoisting, and cracking and detachment at structural joints. Factory quality risk is controlled through piece-by-piece factory inspection and pull-off sampling; transportation and hoisting risk is controlled through facing finished product protection and special hoisting schemes; structural joint risk is controlled through flexible stone disconnection and elastic sealing. Acceptance should be executed according to the unified standards in Chapter 19: bonding strength ≥0.4 MPa, hollowing rate ≤5%, flatness ≤3 mm, with additional prefabricated-specific inspections: factory inspection data of factory post-adhered components, on-site pull-off test records, and structural joint sealing inspection records.

Reflections on Stone, Insights on Fortune

Prefabricated construction solves “how to build structures faster and better,” while flexible stone solves “how to deliver facing synchronously with structure.” Moving facing construction from the site to the factory, and then extending the factory’s precision to the site—this is the core logic this chapter aims to clarify. But we should also clearly understand the boundaries: flexible stone is not a material for the reverse-casting process, cannot cross structural joints, and does not have economic advantages in all projects. Knowing what a material can do, and even more knowing what it cannot do—the maturity of engineering technology is precisely reflected in respect for boundaries. Using it well where it should be used, and explaining clearly where it should not be used—this is the engineering attitude this chapter wants to convey.

References

[1] GB/T 51129—2017, Standard for Assessment of Prefabricated Building[S].

[2] GB/T 51231—2016, Technical Standard for Prefabricated Concrete Buildings[S].

[3] JGJ/T 491—2021, Technical Standard for Prefabricated Interior Decoration[S].

[4] DBJ/T 15—163—2019, Standard for Assessment of Prefabricated Building (Guangdong Provincial Standard)[S].

[5] GB 50210—2018, Standard for Construction Quality Acceptance of Building Decoration[S].

[6] Related general clauses in Chapters 10, 12, 15, 17, 18, and 19 of this book.