Anchors are available in the following types:
(1) Expansion anchor bolts
Expansion anchor bolt, referred to as expansion bolt, is a component that uses the relative movement of the cone and the expansion plate (or expansion sleeve) to promote the expansion of the expansion sheet, generate expansion and extrusion force with the concrete of the hole wall, and generate the pull-out force through shear friction to realize the anchorage of the connected parts. Expansion anchors are divided into torque control type and displacement control type according to the different expansion force control methods during installation. The former is controlled by torsional force and the latter by displacement.
(2) Reaming anchors
Reaming anchor, referred to as reaming bolt or grooving bolt, is a component that realizes the anchoring of the connected piece by using the mechanical interlock between the concrete bearing surface formed after reaming and the expansion head of the anchor bolt by using the re-slotting and reaming of the concrete at the bottom of the borehole. According to the different reaming methods, the reaming anchor bolt is divided into pre-reaming and self-reaming. The former is pre-cut and reamed with a special drilling tool, while the latter has its own cutter for anchor bolts, which can be grooved and reamed by itself during installation, and the grooving installation is completed at one time.
(3) Bonded anchors
Bonded anchor bolt, also known as chemical anchor bolt, referred to as chemical bolt or adhesive bolt, is a component that uses a special chemical adhesive (anchoring glue) to cement and fix the screw and internal threaded pipe in the concrete substrate drilling, and realizes the anchoring of the connected parts through the bonding and locking key of the binder and the screw and the binder and the concrete hole wall.
(4) Chemical reinforcement planting
Chemical reinforcement includes threaded steel bars and long screws, which is a post-anchor connection technology widely used in China's engineering circles. The anchorage principle of chemical reinforcement is the same as that of bonded anchor bolts, but the anchorage of chemical reinforcement and long screws is similar to cast-in-place concrete reinforcement due to the length is not limited, and the failure mode is easy to control, and can generally be controlled as the failure of anchor reinforcement steel, so it is suitable for the anchoring connection of structural components or non-structural components with a static and seismic fortification intensity of ≤8.
(5) Concrete screws
The structure and anchoring mechanism of concrete screws are similar to those of wood screws, which are hard and sharp knife-edge threaded screws by rolling and quenching by special process, and the straight holes with smaller hole diameters are pre-drilled during installation, and then the screws are screwed in, and the occlusion of the thread and the concrete of the hole wall is used to produce pull-out resistance, so as to realize a kind of component that anchors the connected parts.
(6) Nail shooting
Nail is a kind of gunpowder power, high hardness steel nails, including screws, into concrete, using its high temperature (900 °C) to make the steel nail and concrete due to chemical fusion and clamping action as a whole, to achieve the anchorage of the connected parts.
(7) Anchoring glue
The anchoring performance of chemical reinforcement and bonded anchor bolts mainly depends on the anchoring glue (also known as adhesive, binder) and construction method, and the most widely used anchoring glue in China is epoxy-based anchoring glue.