Chapter 17

Construction Process Standardization: One Scrape, Two Apply, Three Press, Four Level

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

Key Points

• Flexible stone construction is fundamentally different from ceramic tile construction: different material characteristics, different construction tools, and different acceptance standards. Using ceramic tile construction experience to apply flexible stone is the number one cause of project failure.
• Construction preparation must focus on four tasks: technical preparation, material preparation, tool preparation, and personnel preparation. The more thorough the preparation, the smoother the construction.
• Substrate treatment and bonding agent are the two life-or-death barriers of flexible stone construction. If the substrate is not firm, everything later is wasted; if the bonding agent is wrong, even the best flexible stone is useless.
• The core process of flexible stone application is “one scrape, two apply, three press, four level”; construction at special parts is a technical difficulty and also a key control point for project quality.
• Standardized construction is the key for a project to move from “can do” to “can do in batches.” Whoever standardizes construction can replicate projects.

17.1 The “Three Differences” of Flexible Stone Construction

17.1.1 Different Material Characteristics

Ceramic tiles are “hard and brittle”: relatively heavy, and the bonding agent needs to provide sufficient bonding strength; ceramic tiles themselves cannot bend, so corners and curved parts require cutting or special accessories.

Flexible stone is “light and flexible”: self-weight is only about 1/3 of ceramic tiles, so bonding difficulty is relatively lower; flexible stone can bend, so corners and curved parts can be directly wrapped, but the construction process at bent parts requires special attention.

Coatings are “thin and soft”: coatings are applied as liquids and form a coating film; coatings have extremely high requirements for substrate flatness and cannot cover substrate defects.

Flexible stone is “thin and tough”: flexible stone is installed as panels and adhered with bonding agents; flexible stone has a certain tolerance for substrate flatness, but the tolerance is limited.

Table 17-5 Comparison of Material Characteristics of Flexible Stone, Ceramic Tiles, and Coatings

A failure scene of “using ceramic tile experience to apply flexible stone”:

A construction team applied flexible stone for the first time and followed the ceramic tile process: after leveling the substrate, they scraped the bonding agent with a notched trowel, then applied the flexible stone and tapped it with a rubber hammer. As a result, after tapping, the surface was full of hammer marks—flexible stone is too thin, and one tap with a rubber hammer makes a dent. The construction team leader said: “Tapping ceramic tiles like this is fine, why does flexible stone dent with one tap?” The technician said: “Ceramic tiles are stone, flexible stone is ‘skin.’ Using the force for tapping stone to tap skin—how can it not dent?” Later, a pressing plate was used for compaction, and the problem was solved. This scene shows that flexible stone is “skin,” not “stone.” Using the force for tapping stone to tap “skin” naturally dents the skin.

17.1.2 Different Construction Tools

The core tools for ceramic tile construction are notched trowels, rubber hammers, and ceramic tile cutters. The core tools for flexible stone construction are notched trowels, pressing plates, and woodworking table saws.

Table 17-6 Comparison of Construction Tools for Flexible Stone and Ceramic Tiles

A site story of “using the wrong cutting tool”:

A construction team used a ceramic tile cutter to cut flexible stone, and the cut edges were all burrs, making the joints look very rough. The construction team leader said: “This material is too brittle.” The technician cut a piece on site with a utility knife, and the edge was smooth and flat. The construction team leader was stunned: “It turns out it’s not the material that is brittle, but the tool that is wrong.” Wrong tool, material takes the blame. Flexible stone should use a utility knife or special cutting knife, not a ceramic tile cutter.

17.1.3 Different Quality Acceptance Standards

The acceptance standards for ceramic tiles focus on flatness, verticality, hollowing rate, and joint uniformity. The acceptance standards for flexible stone, in addition to the above indicators, also require surface integrity (no scratches, no pressure marks, no contamination), curved part fit, and edge treatment quality.

Table 17-7 Comparison of Acceptance Standards for Flexible Stone and Ceramic Tiles

In a project acceptance, the client’s supervisor accepted according to ceramic tile standards and said “hollowing rate exceeds standards.” The construction team leader said: “Flexible stone is different from ceramic tiles; the hollowing rate standard for flexible stone is more lenient than ceramic tiles.” The supervisor said: “I don’t care; hollowing is not acceptable.” Later, the technician intervened, produced the flexible stone product standards, and explained the hollowing rate acceptance standards for flexible stone to the supervisor. The supervisor recognized it but required that “hollowing parts must be repaired.” The construction team leader later sighed: “Different standards lead to disputes at acceptance. Aligning standards with the supervisor in advance can save half the dispute time.” Aligning acceptance standards with the supervisor before construction is more important than anything else.

17.2 Construction Preparation

17.2.1 Technical Preparation

Drawing review and detailed design: organize drawing review before construction, check design drawings against actual site conditions; carry out detailed design based on on-site measured data, determine the joint layout scheme; prepare construction plans, clarifying construction processes, quality requirements, and safety measures.

Technical briefing: conduct technical briefings for construction teams, explaining key construction process points; clarify quality acceptance standards so workers know “what counts as qualified”; sample first—make sample walls first, and after confirmation by the client and supervisor, carry out large-area construction.

Table 17-8 Technical Preparation Content

17.2.2 Material Preparation

Material entry acceptance: flexible stone panels—check specifications, thickness, texture, color, and verify factory certificate; bonding agent—check model, production date, shelf life, and verify test reports; auxiliary materials—check corner beads, joint strips, sealant, and other supporting materials.

Material storage: flexible stone panels should be stored flat in a dry and ventilated place, with the bottom raised to avoid moisture deformation; bonding agent should be stored in a cool and dry place, protected from moisture and sunlight; auxiliary materials should be stored by category with clear labels to avoid confusion.

Material re-inspection: flexible stone panels should be sampled and re-inspected by batch, testing tensile strength, flexibility, and other indicators; bonding agent should be sampled and re-inspected by batch, testing bonding strength, water resistance, and other indicators. Materials that fail re-inspection must not be used.

Table 17-9 Material Preparation Content

17.2.3 Tool Preparation

Table 17-10 Flexible Stone Construction Tool List

Tool inspection: check whether all tools are in good condition before construction; whether the cutting machine blade is sharp to avoid chipping; whether the mixer speed is normal to avoid uneven mixing.

In terms of construction tools, the enterprise’s independently developed flexible stone cutting device integrates cutting, fixing, pushing, and dust removal. Through the coordinated cooperation of the positioning base, folding assembly, cutting assembly, pushing assembly, and dust removal assembly, the cutting process is more precise, efficient, and environmentally friendly, solving the problems of large dust and easy material damage in traditional cutting. It is particularly suitable for the “retrofit while occupied” construction environment of facade retrofit projects and can effectively reduce the impact of cutting dust and noise on residents’ lives.

17.2.4 Personnel Preparation

Table 17-11 Flexible Stone Construction Personnel Configuration

Personnel training: conduct technical training for all workers before construction; training content includes construction processes, operation points, quality standards, and safety specifications; workers can only work after passing assessment; those who fail must not participate in construction.

Table 17-12 Personnel Training Content

17.3 Substrate Treatment: The “First Life-or-Death Barrier” of Flexible Stone Construction

Substrate treatment is the first process of flexible stone construction and the key process determining project quality. If substrate treatment is not in place, all subsequent processes are wasted.

Note: For analysis of substrate disease types and causes, see Chapter 2; for on-site investigation methods, see Chapter 14; for substrate treatment system solutions, see Chapter 15.

17.3.1 Substrate Inspection and “Four Checks”

Table 17-13 Substrate Inspection Items and Standards

Before construction, the substrate must undergo “four checks”:

First check strength: whether the substrate is firm, whether there is dusting, powder falling, or hollowing. Use a pull-off tester to test substrate strength, which should not be less than 0.3 MPa.

Second check flatness: whether the substrate is flat. Use a 2 m straightedge to check; flatness deviation should not exceed 4 mm, depending on product requirements.

Third check moisture content: whether the substrate is dry. Moisture content should not exceed 10%. If moisture content is too high, the bonding agent cannot fully cure, and bonding strength is greatly reduced.

Fourth check contamination: whether the substrate has floating dust, oil, release agent, old coating, or other contamination. These contaminants will block bonding between the bonding agent and the substrate.

Table 17-14 Substrate Four-Check List

A practical checklist of “substrate four checks”:

When training construction teams, we often emphasize “substrate four checks, none can be omitted.” A construction team found it troublesome and only checked strength and flatness, not moisture content. As a result, after applying flexible stone, local hollowing appeared. Investigation found that substrate moisture content exceeded standards, and the bonding agent did not fully cure. The construction team leader later wrote the “four checks” into the pre-shift meeting process, checking once before work every day. Miss one check, repair one more wall later.

17.3.2 Treatment of Substrate Defects

Table 17-15 Substrate Defect Treatment Scheme

Dusting and powder-falling substrate: treat with primer to enhance substrate surface strength. For severe dusting, remove and re-level.

Hollowing substrate: hollowing parts need to be removed and re-leveled.

Flatness-exceeding substrate: re-level with leveling mortar, controlling flatness deviation within 4 mm.

Moisture content-exceeding substrate: wait for substrate to dry, or use drying measures, and construct after moisture content drops below 10%.

Contaminated substrate: remove floating dust, oil, release agent, and other contaminants; high-pressure water washing if necessary.

A failure case of “substrate dusting not treated”:

In a project, the substrate had severe dusting, and the construction team found it troublesome and applied directly. As a result, less than half a year after application, local flexible stone began to detach. Pull-off test showed bonding strength was only 0.1 MPa—the bonding agent did not bond to the substrate at all, but adhered to a layer of floating dust. Later, it was removed and redone, with primer applied to the substrate first, then flexible stone applied. It took half a month longer, but the wall was stable. If substrate dusting is not treated, the applied flexible stone is a “borrowed wall” that will be returned when the wind blows.

17.3.3 Substrate Acceptance

Table 17-16 Substrate Acceptance Standards

Acceptance process: construction team self-inspection → technician re-inspection → report to supervisor/client for acceptance → after acceptance passes, handle concealed works acceptance records → after acceptance passes, flexible stone application construction can proceed.

17.4 Bonding Agent: The “Second Life-or-Death Barrier” of Flexible Stone Construction

The bonding agent is the “bridge” between flexible stone and substrate. If the bonding agent is selected or used incorrectly, even the best flexible stone is useless.

17.4.1 Selection of Bonding Agent

Flexible stone must use a special bonding agent and must not be mixed with ceramic tile bonding agent or ordinary cement mortar. The reasons are: flexible stone is relatively thin, and ordinary ceramic tile bonding agents have large shrinkage stress and can easily “pull and crack” flexible stone; flexible stone is flexible, and the bonding agent needs corresponding flexibility to match the deformation of flexible stone; flexible stone has medium water absorption, about 10%, and the bonding agent needs good water retention and bonding strength to ensure full bonding.

A site accident of “using the wrong bonding agent”:

To save effort, a construction team used ceramic tile bonding agent to apply flexible stone. One month after application, fine cracks appeared on the surface of some flexible stone. The construction team said “the material is too brittle.” The technician went to the site and saw that the ceramic tile bonding agent had too much shrinkage stress and “pulled and cracked” the flexible stone. Later, they switched to special flexible stone bonding agent, and the problem was solved. The construction team leader later sighed: “It turns out bonding agents also have ‘special’ ones.” The bonding agent is the “other half” of flexible stone; choosing the wrong other half means the project quality cannot have a good life.

17.4.2 Construction Points of Bonding Agent

Mixing: the bonding agent must be mixed evenly with an electric mixer, not manually. If not mixed evenly, bonding agent performance is inconsistent, and local bonding strength is insufficient.

Resting: after mixing, let it rest for 5–10 minutes to allow the bonding agent to fully mature, then mix again before use.

Application: apply with a notched trowel; the notch specification is selected according to flexible stone specifications and substrate flatness. Application should be uniform and full, with no omissions or thin spots.

Open time: after the bonding agent is applied, flexible stone application should be completed within the open time. If the open time is exceeded, the bonding agent surface skins, and bonding strength is greatly reduced.

In terms of interface stability, the enterprise’s independently developed non-migratory flexible stone emulsion technology uses reactive emulsifiers, bonding emulsifier molecules to polymer particle surfaces through covalent bonds, fundamentally avoiding surface skinning, mold sticking, and water resistance degradation caused by emulsifier migration. This technology improves the stability of flexible stone emulsion from the perspective of interface engineering, allowing the bonding agent to maintain more stable bonding performance within the open time, reducing the risk of bonding strength reduction caused by bonding agent skinning.

Table 17-17 Bonding Agent Construction Points

A site problem of “exceeding open time”:

Some workers applied the bonding agent but did not immediately apply the panel, but went to answer a phone call. When they came back, the panel had exceeded the open time. The technician arrived at the site, touched the bonding agent surface with his hand, and it had already skinned. He said: “This panel will be a false application even if applied; bonding strength will be directly discounted.” The open time of the bonding agent is its “shelf life”; applying after the shelf life is false application. During construction, the habit of “apply one panel, apply one panel” must be developed.

17.4.3 Bonding Agent Dosage Control

The more bonding agent, the better is not true. If the dosage is too much, the bonding agent is too thick, shrinkage stress increases, and it is more likely to cause hollowing and cracking. The bonding agent dosage should be determined according to flexible stone specifications and substrate flatness. Generally, the bonding agent thickness should be controlled at 3–5 mm.

A site problem of “scraping bonding agent too thick”:

A construction team thought “the thicker the bonding agent, the stronger the bond,” and scraped nearly 1 cm thick. After applying flexible stone, the surface was uneven—flexible stone is too thin, the bonding agent is too thick, and during compaction, the flexible stone undulates with the thickness of the bonding agent. Later, rework was done, controlling the bonding agent thickness at 3–5 mm, and the surface became flat. The bonding agent is not “the thicker the stronger,” but “the thicker the more uneven.” 3–5 mm is just right.

17.5 Flexible Stone Application Construction

17.5.1 Line Snapping and Layout

According to the detailed design drawings, determine the joint layout scheme. Snap horizontal lines, vertical lines, and joint lines on the substrate surface. Horizontal lines are snapped with a spirit level or leveling instrument to ensure horizontality; vertical lines are snapped with a plumb bob or theodolite to ensure verticality; joint lines are snapped according to design joint dimensions to ensure uniformity.

Joint principles: joint dimensions are determined according to flexible stone specifications and design effect, commonly 600 mm × 600 mm, 600 mm × 900 mm, 600 mm × 1200 mm. Joint width is determined according to design, commonly 8–10 mm. Joint positions should avoid the edges of doors and windows to avoid narrow strips.

Table 17-18 Line Snapping and Layout Requirements

17.5.2 Bonding Agent Mixing

Use an electric mixer, with speed controlled at 400–600 rpm. Add water according to the product manual ratio; do not increase or decrease at will. Mixing time is 3–5 minutes, mixing until uniform and free of lumps. Mixed bonding agent should be used within 2 hours; do not use after the time limit.

17.5.3 Flexible Stone Application: One Scrape, Two Apply, Three Press, Four Level

The core action of flexible stone application can be summarized as “one scrape, two apply, three press, four level.”

One scrape: apply bonding agent. Use a notched trowel to apply bonding agent evenly on the substrate; the notch specification is selected according to flexible stone specifications and substrate flatness. Application should be uniform and full, with no omissions or thin spots.

Two apply: apply flexible stone. Align the flexible stone to the position and gently apply. Flexible stone is light and easy to position, but care should be taken not to apply it crooked.

Three press: compact and expel air. Use a pressing plate to compact from the middle toward the surroundings, expelling air in the bonding agent, ensuring full contact between the bonding agent and flexible stone. The compaction force should be uniform, not excessive, to avoid damaging the flexible stone surface.

A hollowing case of “insufficient compaction”:

In a project, after applying flexible stone, the local hollowing rate was relatively high. Investigation found that the construction team did not compact sufficiently, and air existed between the bonding agent and flexible stone. Later, a pressing plate was used to compact from the middle toward the surroundings, and the hollowing rate significantly decreased. Compaction is the “air release valve” for expelling air; without compaction, air remains inside, and hollowing comes.

Four level: adjust flatness. After compaction, check whether the flexible stone surface is flat. If not, gently adjust. Adjustment should be completed within the bonding agent open time; after the open time, the bonding agent begins to cure, and adjustment will damage the bonding layer.

Table 17-19 Operation Points of One Scrape, Two Apply, Three Press, Four Level

17.5.4 Application Quality Standards

Table 17-20 Flexible Stone Application Quality Standards

17.5.5 Joint Filling and Sealing

Joint lines use special joint filler or weather-resistant sealant. Expansion joints use elastic sealant to adapt to deformation.

Joint filling steps: clean the joint → fill backing material → joint filling construction → scrape flat and compact.

Joint filling standards: full, dense, and flat; uniform joint width, smooth surface; sealant firmly bonded to flexible stone, no debonding.

Table 17-21 Joint Filling and Sealing Requirements

17.6 Construction at Special Parts: The “Technical Difficulty” of Flexible Stone Construction

Construction at special parts is the technical difficulty of flexible stone construction and also a key control point for project quality.

17.6.1 Internal and External Corner Construction

External corner: when wrapping an external corner with flexible stone, use a whole piece of flexible stone to wrap, avoiding splicing. When wrapping, the flexible stone bending radius should not be less than 20 mm, and compaction should be sufficient.

Internal corner: flexible stone should fit naturally at internal corners, avoiding stretching. If there are wrinkles, cut and splice.

A quality problem of “external corner splicing”:

In a project, two pieces of flexible stone were spliced at an external corner, and cracks appeared at the joint. The technician went to the site and saw that the flexible stone bending radius at the external corner was too small, edge stress was concentrated, and cracking occurred. Later, it was changed to whole-piece wrapping, and the problem was solved. External corners use whole pieces, internal corners use splicing; splicing when it should be whole-piece, cracks will find their way in.

17.6.2 Door and Window Opening Construction

Door and window openings are difficult parts of flexible stone construction, prone to water seepage, cracking, and detachment.

Construction points: the periphery of the opening should be wrapped with whole-piece flexible stone, avoiding splicing; windowsills should be waterproofed to prevent rainwater infiltration; drip lines should be set to prevent rainwater from flowing down the wall.

A rework case of “windowsill water seepage”:

In a project, the windowsill part was not waterproofed. During the rainy season, rainwater infiltrated, causing hollowing and detachment of flexible stone below the windowsill. Later, rework was done: waterproofing the windowsill first, then applying flexible stone, and the problem was solved. If the windowsill is not waterproofed, rainwater will “enter the house”; parts that should be waterproofed cannot be omitted.

17.6.3 Curved Surface Construction

Curved surface construction is flexible stone’s “advantage project,” but also a construction difficulty.

Construction points: bending radius not less than 20 mm; bonding agent on curved parts should be applied more fully, and compaction more sufficient; when cutting is needed on curved parts, use a utility knife, and the cut edges should be smooth.

In curved surface construction, the enterprise’s independently developed high-flexibility flexible stone emulsion technology, from the perspective of molecular structure regulation, through the introduction of modified additives, regulates the glass transition temperature and crosslinking degree of the core-shell structure, giving flexible stone excellent flexibility at -30°C, withstanding 100 freeze-thaw cycles without cracking or peeling, and weather resistance of 3500h. This technology fundamentally improves the flexibility and wide-temperature-range performance of flexible stone, providing better material adaptability for curved surface construction. At the same time, the enterprise’s independently developed flexible stone cutting device integrates cutting, fixing, pushing, and dust removal, providing equipment assurance for precise cutting of curved and irregular parts.

A practical experience of “curved surface construction”:

A commercial complex’s curved exterior wall had curvature radii ranging from 200 mm to 500 mm. Before construction, a sample was made to determine the construction process under different radii, and then the construction team received half a day of training, focusing on bonding agent application and compaction on curved parts. The final construction was completed smoothly, and the client specifically praised the appearance quality of the curved parts during acceptance. For curved surface construction, make samples first before large-area work; the sample is the construction team’s “coach.”

17.6.4 Expansion Joint Construction

Expansion joints are the “respiratory tract” of exterior walls and require special attention during construction.

Construction points: flexible stone should be disconnected at expansion joints and must not cross expansion joints; expansion joint sealing should use elastic sealant to ensure the normal expansion function of the expansion joint; if the design requires expansion joint cover plates, they should be installed after flexible stone construction is completed.

A construction error of “crossing expansion joints”:

A construction team applied flexible stone directly across the expansion joint without disconnecting it. As a result, with thermal expansion and contraction of the building, the flexible stone at the expansion joint was squeezed, bulging and cracking. Later, rework was done: cutting the flexible stone at the expansion joint and re-treating it. Expansion joints are the “joints” of the wall; if joints are not treated, the wall gets “arthritis.”

17.6.5 Parapet and Coping Treatment

Flexible stone is applied on the inner side of the parapet, consistent with the exterior wall flexible stone. A coping is set at the top of the parapet, covered with metal or flexible stone. The coping slopes outward to prevent rainwater retention. Sealant is applied at the junction between the coping and the wall.

Quality standards: parapet flexible stone firmly applied, no hollowing; coping flat and straight, no lifting; junctions tightly sealed, no leakage.

17.7 Quality Acceptance

17.7.1 Acceptance Standards

Table 17-22 Main Control Item Acceptance Standards

Table 17-23 General Item Acceptance Standards

17.7.2 Common Quality Problems and Prevention

Note: For cause analysis and prevention measures of common quality problems, see Chapter 18. This section focuses on identification of common problems at the acceptance stage.

Table 17-24 Common Quality Problems and Prevention

17.8 Finished Product Protection: The “Last Process” of Flexible Stone Construction

Finished product protection is the last process of flexible stone construction and also a process that is easily overlooked.

17.8.1 Finished Product Protection During Construction

Set warning signs in uncured areas, prohibiting stepping and collision. Cover completed areas with protective film to prevent contamination and scratches. Material storage: flexible stone should be stored flat or upright, avoiding compression and deformation.

A site accident of “inadequate finished product protection”:

In a project, after flexible stone application, the construction team directly stacked steel pipes near the wall. As a result, the steel pipes fell and cracked a piece of flexible stone. Rework was needed, and the schedule was delayed. The construction team leader later included “finished product protection” in the safety briefing and checked once before leaving work every day. If finished product protection is not in place, all previous work is wasted.

17.8.2 Finished Product Protection Before Delivery

Cleaning: remove stains and adhesive marks left during construction.

Inspection: check whether the surface has scratches, pressure marks, or contamination.

Repair: repair defects in time if any.

Protection: if there are subsequent processes, cover with protective film.

A practical experience of “pre-delivery cleaning”:

Before delivery of a project, the client found adhesive marks on the wall and requested cleaning. The construction team tried cleaning with water, but it did not work; trying solvent cleaning, they were afraid of damaging the surface. Later, a special cleaner was recommended, and it cleaned easily. The client’s project manager said: “It turns out cleaning also has special tools.” Using the right cleaning tool, adhesive marks come off easily; using the wrong tool, the surface comes off too.

17.9 On-Site Management: The “Invisible Quality” of Flexible Stone Construction

On-site management is the “invisible quality” of flexible stone construction—invisible, but determining the visible project quality.

17.9.1 Technical Briefing

Before construction, a technical briefing must be conducted. The briefing content includes: material characteristics, construction process, quality control points, and acceptance standards.

A practical template for “technical briefing”:

Technical briefing is usually divided into three steps: first, talk about materials—what flexible stone is, what characteristics it has, and how it differs from ceramic tiles. Second, talk about process—substrate treatment, bonding agent, application, compaction, special part construction. Third, talk about standards—acceptance standards, testing methods, common problems. A construction team leader said: “Your briefing is more detailed than our company’s own briefing.” The more detailed the briefing, the less rework; the less rework, the more worry-free for everyone.

17.9.2 Sample First

Before large-area construction, a sample must be made first. The role of the sample is to verify the process, confirm the effect, and train workers.

Sample production points: the sample location should be representative, including flat surfaces, internal and external corners, doors and windows, etc.; the sample area is generally not less than 10 m²; after the sample is completed, it should be jointly accepted by the client, supervisor, and construction party to confirm the process and effect.

A practical value of “sample first”:

Before construction of a project, a 20 m² sample was made first. After viewing the sample, the client was very satisfied with the color and texture, but raised opinions on the joint treatment. The joint process was adjusted according to the client’s opinions, and a new sample was made. After the client confirmed, large-area construction began. Because of sample first, large-scale rework was avoided. The sample is the “trial-and-error device” of construction; try first, then large-area work, and there will be fewer mistakes.

17.9.3 Process Inspection

During construction, process inspection should be carried out. Inspection content includes: substrate treatment, bonding agent use, application process, special part construction, and finished product protection.

A practical experience of “process inspection”:

A large project was inspected once a week. During one inspection, it was found that the construction team mixed the bonding agent unevenly, with dry powder lumps. Work was stopped on the spot, and re-mixing was required. The construction team leader said: “Just a little dry powder, it doesn’t affect anything, right?” The technician said: “Dry powder lumps in the bonding layer are ‘time bombs.’ If not treated now, hollowing later will be more troublesome.” After re-mixing, the problem was solved. Process inspection is “finding faults,” but finding faults is to avoid rework; stopping now is better than reworking later.

17.9.4 Acceptance Management

After construction is completed, acceptance should be carried out. Acceptance content includes: appearance quality, bonding strength, hollowing rate, flatness, and special part quality.

A practical checklist of “acceptance management”:

The acceptance checklist provided to the client usually includes: appearance—consistent color, clear texture, no scratches, no pressure marks, no contamination; bonding—pull-off test ≥0.3 MPa, failure surface inside flexible stone or bonding layer; hollowing—hollowing rate ≤5%, single hollowing area ≤10%; flatness—2 m straightedge deviation ≤4 mm. A client said: “Your checklist is more detailed than the supervisor’s.” The more detailed the acceptance checklist, the fewer disputes at acceptance; written in black and white, acceptance has a basis.

17.10 Safety and Civilized Construction

17.10.1 Safe Construction

Establish and improve safety management systems and clarify safety responsibilities. Conduct safety technical briefings before construction. Conduct regular safety inspections and eliminate safety hazards in time.

Working at height: wear safety belts, set up safety nets.

Scaffolding work: check scaffolding stability, lay scaffolding boards.

Temporary electricity: use qualified distribution boxes, overhead cables.

Mechanical operation: cutting machines and other machinery operated by dedicated personnel, wearing protective equipment.

Table 17-25 Safe Construction Points

17.10.2 Civilized Construction

Materials stored by category with clear labels. Construction waste cleaned up in time, achieving “work completed, site clean.” Site kept tidy, roads unobstructed. Control construction noise, avoid disturbing residents. Dust operations take dust reduction measures. Waste sorted and disposed of, not discarded at will.

Table 17-26 Civilized Construction Points

Decision Reference for Facade Retrofit Offices

Key Decision Points of This Chapter

• Flexible stone construction is fundamentally different from ceramic tile construction. Using ceramic tile construction experience to apply flexible stone is the number one cause of project failure. Before entering the site, the “three differences” briefing on material characteristics, construction tools, and acceptance standards must be completed.
• Construction preparation must focus on four preparations: technical, material, tool, and personnel. Sample first must be implemented; large-area construction must not proceed without confirmation of the sample by the client and supervisor.
• Substrate treatment and bonding agent are the two life-or-death barriers of flexible stone construction. Substrate “four checks” cannot omit any; bonding agent must use special products, control thickness at 3–5 mm, and complete application within the open time.
• “One scrape, two apply, three press, four level” is the core process and must form standard actions. Special part construction must have special briefings; make samples first before large-area construction.

Compliance Check Items

• Verify whether drawing review, technical briefing, and sample first are completed before construction, and whether technical briefing records are complete.
• Verify whether material entry acceptance records, re-inspection reports, and factory certificates are complete, and whether the bonding agent is a special flexible stone product.
• Verify substrate “four checks” records, and whether the four indicators of substrate strength, flatness, moisture content, and contamination all meet standards before entering the application process.
• Verify whether quality acceptance is executed according to main control items and general items, and whether the frequency of pull-off tests, full coverage rate inspection, and hollowing inspection meets requirements.
• Verify whether safety briefings, safety inspection records, and special operation personnel certificates are complete.

Cost Reference Range

• Construction preparation stage costs account for about 1%–2% of total cost, including drawing review, detailed design, sample wall production, technical briefing, and personnel training.
• Substrate treatment costs depend on substrate conditions, accounting for about 15%–30% of total cost, including removal of old facing, repair, leveling, and primer treatment. Specific costs are based on project investigation results.
• Bonding agent and auxiliary material costs account for about 8%–15% of total cost; special flexible stone bonding agent must be used, and ceramic tile bonding agent must not be mixed to reduce costs.
• Finished product protection and pre-delivery cleaning costs account for about 1%–2% of total cost, including protective film, warning signs, cleaner, and labor. The above costs are based on local market prices.

Risk Warnings

• Risk of using ceramic tile construction experience to apply flexible stone: wrong tools, wrong process, mismatched acceptance standards, leading to rework and disputes.
• Risk of missing items in substrate “four checks”: missing moisture content or strength checks, leading to hollowing and detachment after application; rework cost far greater than testing cost.
• Risk of wrong bonding agent or exceeding open time: false application, pulling and cracking, hollowing; quality hazards are hidden and difficult to repair.
• Risk of inadequate construction at special parts: external corner cracking, windowsill water seepage, expansion joint bulging; later maintenance costs are high.
• Risk of missing finished product protection: applied flexible stone is cracked, contaminated, or scratched, and all previous engineering work is lost.

Replicability Judgment

• The framework of “three differences, four preparations, two life-or-death barriers, one scrape two apply three press four level” is highly replicable and can be compiled into a standard flexible stone construction process card.
• Tools such as the substrate four-check list, technical briefing template, sample-first system, and process inspection form are highly replicable and suitable for implementation in all flexible stone facade retrofit projects.
• It is recommended to solidify “sample first, then large-area work,” “substrate four checks cannot omit any,” and “bonding agent open time is shelf life” as mandatory construction management systems to improve the overall construction quality of facade retrofit flexible stone projects.

Reflections on Stone, Insights on Fortune

No matter how good the material is, if construction is not good, the effect is zero. Flexible stone is “skin,” not “stone”; you cannot use the force for tapping stone to tap skin. The substrate is the “foundation” of flexible stone, and the bonding agent is the “other half” of flexible stone; miss one of the four checks, and you repair one more wall later; choose the wrong “other half,” and the days will not last long. “One scrape, two apply, three press, four level” is not simple to do well: every scrape full, every application aligned, every press expelling air, every level checked. Sample first is the trial-and-error device, process inspection is the mine detector, and finished product protection is the last line of defense. Engrave standard actions into habits, implement quality control in processes, and flexible stone engineering can move from “can do” to “can do in batches.”

References

[1] GB 50210—2018, Standard for Construction Quality Acceptance of Building Decoration[S]. Beijing: China Architecture & Building Press, 2018.

[2] JGJ/T 427—2018, Technical Specification for Construction of Wood Flooring in Building Decoration Engineering[S]. Beijing: China Architecture & Building Press, 2018.

[3] JGJ 80—2016, Technical Code for Safety of Working at Height in Building Construction[S]. Beijing: China Architecture & Building Press, 2016.

[4] JGJ 46—2005, Technical Code for Safety of Temporary Electricity on Construction Site[S]. Beijing: China Architecture & Building Press, 2005.

[5] JGJ 110—2017, Standard for Testing Bonding Strength of Facing Tiles in Building Engineering[S]. Beijing: China Architecture & Building Press, 2017.

[6] JC/T 2219—2014, Modified Inorganic Powder Composite Building Facing Sheet[S]. Beijing: China Building Materials Industry Press, 2014.