The semi grouting sleeve processes one end of the steel bar according to the technical requirements and screws it into the threaded end of the grouting sleeve. After binding and forming, it is placed in the component mold. A corrugated pipe is fitted on the grouting and exhaust ports, and a magnetic suction cup positioning fixture is used to position the corrugated pipe. The concrete is poured and formed. When installing the component, the open end of the grouting sleeve is aligned with the steel bar extending from the lower wall panel, and the matching grouting material is injected from the grouting port after sealing or seat grouting. When the exhaust hole overflows, the exhaust hole and grouting hole are sealed. After the grouting material reaches a certain strength, the longitudinal steel bars are connected as a whole.

Schematic diagram of semi grouted sleeve product

Compared with full sleeve grouting connection, half sleeve grouting connection has the following characteristics:

(1) 50% of the connection can be completed through threads in the factory, which makes it easy to control the connection quality and facilitates the installation and fixation of the sleeve in the mold, maximizing the advantages of prefabrication;

(2) Compared to full sleeve grouting connection, it can reduce the number of reinforcement bars in the densification zone;

(3) Compared with full grouting, it can significantly reduce the amount of grouting material used. When connecting steel bars of the same type, the grouting height can be reduced by half, which greatly reduces the grouting pressure and the difficulty of compartment separation, making it easier to ensure grouting quality. In addition, once the phenomenon of insufficient grouting occurs, the semi grouted connection appears at the end of the steel bar, which has a relatively small impact on the stress of the connection, while the fully grouted connection happens precisely at the location where the steel bar is subjected to the maximum stress, which has a significant impact on the quality of the connection;

(4) The semi grouted sleeve material is of good quality and has high processing accuracy. When applied to shear wall structures, it can maximize the H-value of double row steel bars while meeting the thickness of the protective layer.

The function and installation position of grouting sleeve

The obvious difference between prefabricated concrete structures and cast-in-place concrete structures in terms of form is the discontinuity of concrete at the joints and the cutting of steel bars caused by component segmentation and prefabrication. The reliability of steel bar connections has become a key technical issue in order to achieve an assembled integral concrete structure that is equivalent to cast-in-place. Sleeve grouting connection is the most commonly used technical means.

Sleeve grouting connection is the process of connecting steel bars that have been disconnected from prefabricated components through a specially designed steel sleeve. The space between the steel bars and the inner cavity of the sleeve is filled with non shrink, high-strength grouting material to form a steel bar sleeve grouting connection. Sleeve, as a steel connector, plays a particularly important role in prefabricated buildings. After the sleeve is installed in place, the grouting hole and discharge hole of the sleeve should be located above the sleeve. A single sleeve grouting special tool or equipment should be used for pressure grouting. The grouting material is injected into the grouting hole from one end of the sleeve, and after flowing out from the other end, the grouting surface of the grouting material in the joint of the inlet and outlet holes should be higher than the highest point on the outer surface of the sleeve.

The following two pictures can vividly demonstrate the position and installation method of grouting sleeves in prefabricated components of prefabricated buildings.

Construction process of sleeve grouting

The entire process of grouting can be divided into the following steps in detail: vertical component hoisting in place → base treatment → grouting chamber sealing → grouting construction preparation → preparation of joint slurry → inspection of joint slurry → injection of grout → overflow of grout → stopping grouting → plugging of rubber plug grouting slurry → removal of grouting discharge pipe blockage on the component → final inspection → sleeve connection test. Among them, the grouting process is the most important and difficult to understand in the entire process. Because the grouting sleeve is inside the prefabricated component, we cannot see the entire grouting process. In order to demonstrate the entire grouting process in detail, we will use the following animation to illustrate it in detail.

Diagram of grouting sleeve grouting

Half grouted sleeves are used for connecting longitudinal load-bearing steel bars in wall panels. Prefabricated wall panels are lifted and aligned with sleeves, and wall panel sleeves are grouted. Prefabricated column longitudinal steel bar sleeves are grouted and connected, and prefabricated column lifting is aligned with sleeves, and prefabricated column sleeves are grouted.