Installation Requirements and Key Technical Points for Pre-Embedded Counterbore Sockets

In the construction and installation of new architectural decorative materials such as UHPC/GRC/GRG/GRP, embedded countersunk bolts serve as key nodes connecting the structure and decorative components, and their installation quality directly affects the safety and durability of the entire project. Qinglong Group, with 28 years of experience in detailed design, manufacturing, and construction, has always regarded embedded countersunk bolt installation technology as a core control point for project quality. This article will systematically analyze the installation specifications and technical essentials of embedded countersunk bolts in the application of new decorative materials.

### I. Technical Requirements for Selection and Compatibility of Embedded Countersunk Bolts

The selection of embedded countersunk bolts requires comprehensive judgment based on the material properties of UHPC/GRC/GRG/GRP and the engineering scenario. For load-bearing components such as UHPC exterior wall panels, high-strength bolts with tensile strength ≥800MPa should be selected, together with chemical anchors with a diameter ≥12mm; non-load-bearing components such as GRC decorative moldings may use stainless steel expansion bolts, but the embedding depth must be no less than 2/3 of the component thickness. Qinglong Group has a dedicated testing laboratory at its Nanning production base, capable of conducting full-item testing on indicators such as the mechanical properties of bolt materials and the adhesion of anti-corrosion coatings, ensuring selection compatibility.

### II. Precise Positioning and Detailed Design Before Construction

Precise positioning is the primary step in embedded countersunk bolt installation. Qinglong uses BIM technology combined with 3D laser scanning to control positioning errors within ±3mm. For complex curved installation scenarios such as GRG ceilings, bolt positioning coordinates are generated through parametric design software, combined with customized molds to ensure multi-angle inclined installation accuracy. In the translucent concrete project at Century Plaza on Nanjing East Road, this technology successfully solved the bolt positioning challenge for hyperbolic curved components, winning the AALBORG WHITE Cup UHPC Engineering Innovation Award.

### III. Key Quality Control Points in the Installation Process

Drilling depth and hole-cleaning quality directly affect anchoring force. Qinglong's construction specifications require the drilling depth to be 10-15mm deeper than the bolt length, using a high-pressure air blowing + brush two-way hole-cleaning process to ensure dust residue in the hole ≤0.5g. For applications in humid environments such as GRP daylighting roofs, a polyurea anti-corrosion coating with a dry film thickness ≥200μm must be applied to the bolt surface. In an airport project in Malaysia, this process improved the bolt's salt spray resistance to over 5,000 hours.

### IV. Acceptance Standards and Full Life-Cycle Assurance

Qinglong has established a three-level acceptance system: initial inspection verifies the exposed length of the bolt (specification value 5-10mm), re-inspection uses pull-out tests (tensile bearing capacity ≥1.2 times the design value), and final inspection performs visual verification through the BIM model. As a national high-tech enterprise, Qinglong has incorporated embedded countersunk bolts into its after-sales maintenance system, providing rust monitoring services for up to 15 years. Its patented anti-rust technology (Patent No. ZL2023XXXXXX) has been applied in over 300 projects nationwide.

Although embedded countersunk bolts are concealed works, they are the "lifeline" for the safe implementation of new decorative materials. With 28 years of full-chain experience, Qinglong Group deeply integrates material properties with installation technology, ensuring the reliability of every node through refined management and control. From detailed design to after-sales maintenance, Qinglong has always honored its commitment of "meticulousness and the pursuit of excellence," providing designers and owners with full-process technical support from concept to completion, helping to create safe and durable architectural masterpieces.