Chemical bolts rely on the joint action of the gripping force and mechanical bite force between the concrete to resist pulling and the bolt itself to resist shear, mainly used in the connection of the new and old structures, the mechanical indicators you can find the manufacturer is the product introduction, the calculation should be based on the information provided by the manufacturer, because the chemical adhesives produced by various manufacturers are different, so the bonding ability is different. Chemical bolt is a kind of embedded parts, which is used in the leakage of embedded parts or post-construction projects. Chemical bolt anchoring technology belongs to post-reinforcement technology. In recent years, as a new, simple and effective post-fixing method, chemical bolt anchoring has been widely used in construction in the aspects of building renovation, building use change, or existing building reconstruction and expansion.
1. Composition of chemical bolts
Chemical bolts are composed of chemical hoses, screws, washers and nuts. Screws, washers, and nuts (hexagonal) are generally available in galvanized steel and stainless steel (can also be hot-dip galvanized upon request). Chemical hoses (or pharmaceutical tubes packaged in plastic) contain reactive resin, 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, control of drilling depth is particularly important. If you use anchor bolts from the corresponding manufacturer, there will be a matching drilling rig that automatically guarantees the hole depth.
Fixing depth: The distance from the surface of the fixing basic structure to the bottom of the screw is an important parameter that affects its bearing capacity.
Anchor thickness: The anchor thickness is equal to the thickness of the anchored object. If the foundation to be fixed is at least covered with plaster or tiles or insulation, the thickness of the fixing is equal to the thickness of the plaster or tiles or insulation layer, which is the thickness of the object to be fixed.
Margin: refers to the distance from the anchor axis to the free edge of the component.
Spacing: refers to the distance between adjacent anchor bolt axes.
Component thickness: refers to the thickness of the anchor foundation. In order to exert the maximum load-bearing capacity of an anchor bolt, a certain spacing, edge distance, and component thickness must be guaranteed. The data is generally based on the technical parameters provided by the manufacturer.
3. Scope of application
(1) Applicable to ordinary concrete strength grade greater than or equal to C15 (uncracked concrete), dense natural stone.
(2) Used to fix ordinary steel structures, bottoms, guide rails, column caps, column feet, corbels, fences, stairs, curtain walls, flat steel and section steel, embedded steel bars, embedded formwork, etc.
(1) The construction temperature range is wide, from 15℃–40℃
(2) No expansion force anchoring, no extrusion stress on concrete, suitable for various base materials, and performs better on concrete with poor strength.
(3) Safe and convenient
(4) The spacing and margins are small, suitable for small spaces.
(5) It is easy to install and operate, can be quickly consolidated after installation, and has a high bearing capacity.
(6) Suitable for heavy loads and various vibration loads.
(7) The anchoring thickness is large.
5. Working principle
The working principle of the chemical anchor bolts is also very simple, first of all, according to the engineering requirements, in the substrate (rock, concrete, etc.) in the corresponding position of the hole, and then use a special air cylinder, brush or compressed air machine to clean the dust in the drilling hole, the chemical bottle into the drilled hole, which is also the biggest difference with the ordinary anchor bolt, and finally screw into the hole to mash the internal agent, make it expand, and then fill the entire hole, so that the agent, the anchor bolt and the substrate are all mixed together to become a whole, to achieve the effect of anchoring.
6. Process flow
Installation procedure: Drilling – clearing the holes – inserting the chemical tube – drilling the bolts – gelling process – hardening process – fixing the object
(1) Drilling: First, according to the design requirements, determine the position according to the spacing and margin of the drawing, and drill holes on the base layer. The hole diameter and hole depth must meet the design requirements.
(2) Clean the hole: Use air pressure blowpipe and other tools to remove floating dust and dust in the hole to keep the hole clean.
(3) Insert the medicine tube: Insert the medicine tube into a clean hole. The hose can only be used when the resin can flow like honey under hand temperature during insertion.
(4) Drill the bolt: Use an electric drill to screw in the screw until the agent flows out. Electric drills generally use impact drills or hand drills with a drilling speed of 750 rpm. At this time, the bolt is screwed in, the agent tube will be broken, the resin, curing agent and quartz particles are mixed, and the gap between the anchor bolt and the hole wall is filled. At the same time, anchor bolts can also be inserted into wet holes, but the water must be drained out of the drill hole, and the waiting time for the gelling process and hardening process must be doubled.
(5) Gel process: Keep the installation tool still.
(6) Hardening process: Remove the installation tools and wait for the agent to harden.
(7) Fix the object: After the agent is completely hardened, add washers and hexagonal nuts to fix the object.
7. Quality requirements and control
(1) When drilling, it is best to use a drill bit that matches the wrong bolt and do not damage the steel bar.
(2) Before construction, the material mechanical properties of the anchor bolts must be tested. After passing the test, they can be used on site.
(3) During on-site construction, tests to determine the on-site application conditions of wrong bolts should be conducted to fully test the bearing capacity. The tests are carried out not only in low-strength concrete, but also in high-strength concrete. During the test, the allowable load, corresponding spacing, and thickness of edge components were used to embed the anchor bolts according to the manufacturer’s instructions. The test uses axial tensile force, shear force and combined tensile and shear force to determine the effect of load direction on bearing capacity.
(4) When cleaning the hole, the dust and floating ash in the hole must be cleaned up.
(5) When the drug tube is applied in winter, it should be insulated in advance to ensure that the drug tube has sufficient fluidity when inserted into the drill hole.
(6) The screw must be screwed in with an electric drill and is not allowed to be knocked in directly.
(7) There should be no accumulation of water in the borehole.
The working principle of chemical bolts is to use a special chemical adhesive to glue the screws into the drilled holes in the concrete base material to achieve composite parts that anchor the fixings.
The chemical bolts provided by GloryRail are also mostly used in the construction of rail systems, as well as steel structure systems, supporting rail system processing parts, and providing customers with one-stop procurement of rail materials, which is our important purpose.