High-strength chemical bolt construction technology!

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Construction Technology of High-Strength Chemical Bolts I. Introduction Chemical bolt anchoring technology belongs to the category of post-reinforcement techniques. In recent years, in areas such as building renovation, changes in building use, or the expansion and modification of existing buildings, chemical bolt anchoring has been widely used in construction as a new, simple, and effective post-fixing method. 　　1. Composition of chemical bolts Chemical bolts consist of a chemical adhesive tube, screw rod, washer, and nut. 　　Screws, washers, and hex nuts are generally available in either galvanized steel or stainless steel (hot-dip galvanizing is also possible upon request). 　　Chemical hoses (or agent tubes packaged in plastic) contain reactive resin, a curing agent, and quartz particles. 　　2. Relevant parameters of chemical bolts Drilling depth: The required drilling depth is determined by the type and size of the anchor bolt; with a few exceptions, it is generally greater than the anchoring depth. When drilling holes, controlling the drilling depth is particularly important. If a drill machine designed to automatically ensure the correct hole depth is used in conjunction with the corresponding manufacturer’s anchor bolts (for example, German Hilti anchor bolts come with a high-tech column-cone universal drill bit called FZUB), drilling becomes very convenient. 　　Anchoring depth: The distance from the surface of the anchoring foundation structure to the bottom end of the screw; it is an important parameter that affects its load-bearing capacity, as shown in Figure 2. Anchoring thickness: The anchoring thickness is equal to the thickness of the object being anchored. If the anchoring foundation is covered with at least plaster or tiles, as well as an insulating layer, then the thickness of the anchor fixation shall be at least equal to the thickness of the plaster or tiles, the insulating layer, plus the thickness of the object being anchored, as shown in Figure 2. Margin: refers to the distance from the axis of the anchor bolt to the free edge of the component. 　　Spacing: refers to the distance between the axes of adjacent anchor bolts. 　　Component thickness: refers to the thickness of the anchoring foundation. 　　To achieve the maximum load-bearing capacity of an anchor bolt, it is necessary to maintain certain spacing, margins, and component thicknesses; the relevant values are generally based on the technical parameters provided by the manufacturer. 　　II. Scope of Application 1. Applicable to ordinary concrete with a strength grade of C15 or higher (crack-free concrete) and dense natural stones. 　　2. Used to fix ordinary steel structures, bases, guide rails, column caps, column feet, brackets, fences, stairs, curtain walls, flat steel and shaped steel, embedded rebar, buried formwork, etc. 　　III. Characteristics: 1. The construction temperature range is wide, from 15°C to 40°C. 　　2. It features non-expansive anchoring, which does not generate compressive stress on the concrete; it is suitable for various substrate types and performs even better on concrete with lower strength. 　　3. Safe and convenient (for example, the special inverted shape of the Hilti bolt chemical tube ensures it does not fall during vertical suspension construction). 　　4. Small spacing and margins, suitable for tight spaces. 　　5. It is easy to install, can solidify quickly after installation, and possesses high load-bearing capacity. 　　6. Suitable for heavy loads and various vibrating loads. 　　7. The anchorage thickness is large. 　　IV. Process Principle: The anchor rods and the wall of the hole are bonded together using synthetic resin mortar, thereby forming a single unit with the anchor rods, the anchoring foundation, and the structure to be anchored. This approach achieves the purpose of fixing components or enhancing their load-bearing capacity. 　　V. Process flow:
Installation procedure: Drilling – Hole cleaning – Inserting the chemical tube – Driving in bolts – Gelation process – Hardening process – Fixing the object
1. Drilling: First, according to the design requirements, mark the positions based on the spacing and margins specified in the drawings, and then drill holes in the base layer. The diameter and depth of these holes must meet the design specifications. 　　2. Hole cleaning: Use tools such as air-pressure blowers to remove floating dust and debris from within the hole, keeping it clean. 　　3. Insert the medicament tube: Insert the tube into the clean hole; the rubber tube can be used only when the resin flows like honey at body temperature. 　　4. Drive in the bolt: Use a drill to screw in the screw until the liquid comes out. Electric drills generally use impact drills or hand drills, with a drilling speed of 750 revolutions per minute. At this point, the bolt is screwed in, causing the resin tube to break; the resin, curing agent, and quartz particles mix together and fill the gap between the anchor bolt and the wall of the hole. At the same time, anchor bolts can also be inserted into wet holes, but the water must be drained from the drill hole, and the waiting time for the gelation and curing processes must be doubled. 　　5. Gelation process: Keep the mounting tool in place; the chemical reaction time is as specified in Table 1. 6. Hardening process: Remove the mounting tool and wait for the agent to harden; the chemical reaction time is as specified in Table 1. 7. Fixing the object: Once the agent has fully hardened, attach washers and hex nuts to fix the object in place. 　　VI. Quality Requirements and Control 　　1. It is advisable to use drills that are compatible with the anchor bolts when drilling, and the steel rebar must not be damaged. 　　2. Before construction, mechanical property tests must be conducted on the anchor bolts; they can be used on site only after passing these tests. 　　3. On-site construction should include tests to determine the applicable conditions for anchor bolts, in order to fully assess their load-bearing capacity. Tests should be conducted not only in low-strength concrete but also in high-strength concrete. During testing, it allows the load capacity, appropriate spacing, and thickness of the edge members to be determined based on the manufacturer’s instructions for installing the anchor bolts. The test employed axial tension, shear force, and combined tension-shear forces in order to determine the effect of loading direction on bearing capacity. 　　4. When cleaning the hole, it is necessary to remove all dust and debris from within it. 　　5. When using the resin tube in winter applications, it should be pre-treated to maintain its warmth, so as to ensure sufficient fluidity when it is inserted into the drill hole (at body temperature, the resin flows like honey). 　　6. The screw must be screwed in using a drill; it is not allowed to be driven in by hitting it directly. 　　7. There must be no water accumulation inside the drill hole. 　　VII. Construction Examples and Application Effects: In the seismic reinforcement project of the National Culture Palace, for the application of steel bonding to the exterior wall edge beams on the 12th floor in Section III, as well as for the fixation of components in the exhibition halls of Section IV and the walkways in the auditorium of Section I, a method combining the use of YJ structural adhesive with chemical bolt anchoring was employed. The reinforcement of section III beams involves unilateral reinforcement using chemical bolts, which ensures an optimal overall reinforcement effect and meets the requirements of design and seismic reinforcement