JP7471767B2 - Method for joining concrete members and joined concrete - Google Patents

Description

The present invention relates to a method for joining concrete members and to joined concrete.

Conventionally, when joining concrete members together, as shown in, for example, Patent Document 1 below, a method has been adopted in which a chipping treatment is performed on the joint surface of one (existing) concrete member, a primer is applied to the joint surface, and concrete is then poured into the gap to join it to the other concrete member.

JP 2005-002558 A

However, with conventional methods for joining concrete members, if the adhesion between the joint surface of the existing concrete member and the fill concrete is insufficient, there is a risk that the boundary between the joint surface and the fill concrete will peel off due to drying shrinkage and repeated loads after construction. As a result, there is a risk that deterioration factors such as water will penetrate, accelerating deterioration such as rebar corrosion and reducing the durability of the concrete structure. Therefore, there is room for improvement in the joint strength between existing concrete and newly constructed concrete.

The present invention has been made in consideration of the above, and aims to provide a method for joining concrete members and joined concrete that can ensure sufficient joint strength.

In order to achieve the above-mentioned object, the method of joining concrete members of the present invention comprises a chipping process for applying a chipping treatment to the joint surface of an existing concrete member, a base agent application process for applying only a base agent to the joint surface without applying an adhesive after the chipping process, and a joining process for joining newly installed latex-modified fast-hardening concrete to the joint surface after the base agent application process, wherein the base agent is a water absorption adjusting material.

In the present invention, latex-modified quick-hardening concrete, which has high adhesive strength, is used for the new concrete, so sufficient bond strength can be ensured.

In the present invention, since the base agent is a water absorption regulator , it is possible to prevent deterioration factors such as water from penetrating into the joint surface, and it is possible to more effectively ensure the joint strength.

In order to achieve the above-mentioned object, the joint concrete of the present invention comprises existing concrete members, a base agent placed on the joint surface of the existing concrete members, and newly constructed latex-modified rapid-hardening concrete joined to the existing concrete members via the base agent, and is characterized in that the base agent is a water absorption adjusting material.

In the present invention, the joined concrete is joined using the joining method for concrete members described above, so sufficient joint strength can be ensured.

The concrete member joining method of the present invention ensures sufficient joining strength.

(a) Schematic diagram showing the state of concrete being poured in one piece, (b) Schematic diagram showing the state of ordinary concrete being poured in situ and joined to existing lightweight concrete, (c) Schematic diagram showing joined concrete according to Example 1 of the present invention, and (d) Schematic diagram showing joined concrete according to Example 2 of the present invention. FIG. 2 is a schematic diagram showing the state of a test sample in an evaluation test.

The method for joining concrete members in this embodiment will be described below.
As shown in Fig. 1, the method for joining concrete members in this embodiment includes a chipping process for performing a chipping treatment on a joint surface 10A of an existing concrete member (lightweight concrete) 10. In the chipping process, minute irregularities are formed on the joint surface 10A to improve the adhesive strength of a base agent 30 (described in detail later) on the joint surface 10A.
The existing concrete member 10 may be cast-in-place concrete, or may be precast concrete that has been cast in advance at another location.

In addition, the method of joining concrete members in this embodiment includes a base agent application process of applying a base agent 30 to the joint surface 10A after the chipping process.
For example, a water absorption regulator , an epoxy adhesive, a dedicated primer, etc. can be used as the base agent 30. The material of the base agent 30 is not limited to these, and can be selected arbitrarily based on the function to be imparted to the joint surface 10A.

The concrete joining method of the present embodiment includes, after the base agent application step, a joining step of joining newly laid latex modified rapid hardening concrete (hereinafter referred to as LMFC concrete) 20 to the joint surface 10A. The LMFC concrete 20 may be cast-in-place concrete or may be precast concrete formed in advance at another location.
This allows the existing concrete member 10 and the newly constructed LMFC concrete member 20 to be joined together, thereby obtaining joined concrete 40.

(Verification test)
Next, a verification test for verifying the effect of this embodiment will be described.
In this verification test, four types of concrete members (test pieces) were used and their bending strengths were measured.
First, as Comparative Example 1, a structure in which lightweight concrete was cast in one piece was adopted, as shown in FIG. 1(a).
As a comparative example 2, as shown in Fig. 1(b), a joint concrete was used in which ordinary concrete 50 was poured on-site to a pre-cast lightweight concrete (or precast concrete) 10 as an existing concrete member 10. A water absorption regulator 31 was applied as a base agent 30 to the joint surface 10A of the comparative example 2.

As Example 1 of this embodiment, as shown in Fig. 1(c), a joint concrete 40 was adopted in which a newly constructed precast concrete LMFC concrete 20 was joined to an existing lightweight concrete 10. A water absorption regulator 31 was applied as a base agent 30 to a joint surface 10A of Example 1.
Finally, as a second embodiment of the present invention, as shown in FIG. 1(d), instead of the configuration of the first embodiment, a joint concrete 45 having an epoxy adhesive 32 and a special primer 33 applied to the joint surface 10A is adopted.

Six of these test specimens were evaluated for each of two ages, indicating the curing period after the new concrete was poured: one week (7 days) and four weeks (28 days). Details of each test specimen are shown in Table 1.

As shown in Figure 2, both lateral ends of the underside of each test piece were supported at two points, and two points in the approximate center of the upper surface in the lateral direction were pressed downward to apply a bending load to each test piece, thereby evaluating its bending strength. In this evaluation, the bending strength ratio of each test piece was calculated, assuming the bending strength of Comparative Example 1 to be 100. The results are shown in Table 2.

As a result, it was confirmed that the strength of Comparative Example 2 (Case 2) was significantly reduced at both 1 week and 4 weeks compared to Comparative Example 1 (Case 1). Specifically, it was confirmed that the strength of the material at 1 week was reduced by about 35%, and that the strength of the material at 4 weeks was reduced by about 20%.
On the other hand, it was confirmed that the strength of Example 1 (Case 3) was increased compared to Comparative Example 1. Specifically, it was confirmed that the strength increased by about 2% for the material aged one week, and by about 10% for the material aged four weeks.
Finally, it was confirmed that in Example 2 (Case 4), the strength was slightly decreased compared to Comparative Example 1. Specifically, it was confirmed that the strength was decreased by about 7% for the material aged for one week, and by about 3% for the material aged for four weeks. However, it was confirmed that the bending strength of Example 2 was higher than that of Comparative Example 2, and that the bending strength was increased by about 28% for the material aged for one week, and by about 18% for the material aged for four weeks, compared to Comparative Example 2.

The above results confirm that the concrete joining methods of Examples 1 and 2 ensure strength greater than or equal to that of lightweight concrete cast in one piece. This confirms that the concrete joining method of this embodiment can ensure sufficient joining strength.

As described above, the method for joining concrete members according to this embodiment ensures sufficient joining strength by joining latex-modified rapid hardening concrete (LMFC concrete) 20, which has high adhesive strength as a new concrete. Furthermore, this embodiment can simplify construction because it is only necessary to apply the water absorption adjuster 31 to the existing lightweight concrete 10 and then join the new LMFC concrete 20.

Furthermore, when the base agent 30 is a water absorption adjusting material , it is possible to prevent deterioration factors such as water from penetrating into the joint surface 10A, and the joint strength can be ensured more effectively.
Furthermore, since the joint concrete members 40, 45 are joined by the joining method for concrete members described above, sufficient joint strength can be ensured.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and can be modified as appropriate without departing from the spirit of the invention.

For example, in the above verification test, a configuration was shown in which lightweight concrete was used as the existing concrete member 10, but this is not limited to this configuration. A general concrete member that is not lightweight may also be used as the existing concrete member 10.

In addition, the components in the above-described embodiments may be replaced with well-known components as appropriate without departing from the spirit of the present invention.

10 Existing concrete member 20 New latex-modified quick-hardening concrete 30 Base material 31 Water absorption regulator
40, 45 Bonded concrete

Claims (2)

A chipping process for performing a chipping treatment on the joint surface of an existing concrete member;
After the chipping step, a base agent application step of applying only a base agent to the joint surface without applying an adhesive ;
After the base agent application step, a joining step of joining newly installed latex-modified rapid hardening concrete to the joint surface is provided.
2. A method for joining concrete members, comprising the steps of: (a) applying a pressure to the concrete member to form a joint; Existing concrete members and
A base agent disposed on a joint surface of the existing concrete member;
and a newly constructed latex-modified rapid-hardening concrete bonded to the existing concrete member via the base agent.
The above-mentioned base agent is a water absorption adjusting agent.

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