JPS5855354A - Pile surface friction power developing grout material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a grout material that produces a frictional force between a pile and surrounding earth and sand when a ready-made pile is buried underground. Methods for burying prefabricated piles include direct driving, embedding, and tunneling, but the direct driving method is disappearing because it causes noise and vibration pollution. As for the recent technology of embedding method and medium excavation method, burying method is still typified by cement method (Lukue method), but among the medium excavation method, the method of enlarging advance excavation has been attracting attention in recent years. Whether it is the deep-in construction method or the medium-cut construction method, emphasis has been placed on how to increase the supporting capacity at the tip, and it can be said that consideration has been lacking in the method of expressing the friction force on the pile circumferential surface. Various methods have been devised.In the cement milk method, a hardening solution was used to fix the pile circumference as a friction force generating material for the pile circumference, and in the medium excavation method, a method was developed due to the use of the 117 riction cutter. Various methods have been used to inject grout into the voids created between the antibody and the surface earth and sand, but in all cases, the grout used is cement or its mixture, and none of them are yet satisfactory. This means that a large amount of water is required to create pourable fluidity, which may cause material separation, water in the cement paste may be absorbed by the surrounding soil, and even more ice formation may occur. , several additional injections may be required, which is complicated and requires a great deal of effort.Furthermore, in areas where underground water exists, there is a risk that all the grout material will be washed away. Underflow water resistance is also a serious problem that cannot be taken lightly. With such grout materials, it cannot be expected that they will adhere uniformly and firmly to the antibody, and the designed values cannot be satisfied.

The present invention prevents material separation and floating water phenomenon in the presence of a large amount of water as in the past, and even in the presence of underground water, the grout material adheres uniformly and firmly to the antibody without being washed away, and is inexpensive. As a result of repeated research to develop a grout material that exerts friction force on the circumferential surface of piles, we found that by mixing powder mainly composed of calcium silicate hydrate into cement, various types of grout material can be developed, even in the presence of a large amount of water as in conventional methods. We found that it shows the features of this technology and completed it.

Commercially available cement may be used in the present invention. Calcium silicate hydrate is nx(C'aO)・n
It has a composition of z("io) .n5(H2O) and can be obtained by thermal synthesis or high-temperature, high-pressure steam curing.

Examples of the products thus obtained include lightweight aerated concrete, silica bricks, and calcium silicate plates, which are ground into powder using a rod mill, ball mill, or the like. At this time, the particle size is pulverized to 2 to 6 microns below 5fl, but if the particle size exceeds 5H, injection performance will deteriorate and long-distance injection will be impossible.
The more fine particles with a particle size of 2 to 3 microns, the better.The specific surface area as a whole should be 2,000σ2/9 or more, and the amount should be 10 to 5001 parts by weight per 100 parts by weight of cement.

The fine powder, which is mainly composed of calcium silicate hydrate, swells in water and has excellent water retention properties, which prevents water from leaching into the soil. Such a grouting material is a very effective grouting material that increases viscosity and prevents the phenomenon of floating ice, material separation, and water loss into underground water, and adheres uniformly and firmly after hardening. If the amount is less than 10 parts by weight, floating ice phenomenon, material separation and loss to underground water will occur, and if it is less than 500 parts by weight, the compressive strength of the hardened grout material will decrease, and the adhesion force with antibodies and surrounding earth and sand will also decrease. . As a result, the intended purpose cannot be achieved. An effective grout material as described above can be obtained by mixing only cement, a powder mainly composed of calcium silicate hydrate, and water.

However, even if the particle size of the powder mainly composed of calcium silicate hydrate is 2 to 3 microns below 5 fl, the large particle size accounts for a large proportion, and the total specific surface area is 2.0 μm.
00 tML"/9 or less, water retention performance and viscosity will decrease if only cement and water are mixed, resulting in floating ice phenomenon and the grout being washed away into the soil. In such cases, basic magnesium carbonate should be added to the cement by weight. It has been found that by adding 0.5 to 5 parts by weight to the sum of parts by weight and parts by weight of powder mainly composed of calcium silicate hydrate and kneading with water, the same effects as in the first invention can be obtained. %2,000 ctu as a total specific surface area with a particle size of 2 to 3 microns or less
The amount of powder mainly composed of calcium silicate hydrate of 2/g or less is 10 to 500 parts by weight per 100 parts by weight of cement. The amount of basic magnesium carbonate added differs depending on the temperature at which the grout rises and the temperature of the outside air, but the amount is 0.
If less than 5 parts by weight is added, it is not effective in preventing the floating ice phenomenon, loss of water to underground water, and material separation, and even if more than 5 parts by weight is added, the effect does not improve significantly, and the material becomes jelly-like, causing the injection This is because it would be impossible.

Basic magnesium carbonate may be added to powder mainly composed of calcium silicate hydrate with a particle size of 5H or less 2 to 3 microns and a specific surface area of 2,000 crrL2/9 or more.
There is no need to add it since there is no significant improvement in the effect compared to no addition. The grout material obtained by the above two inventions not only prevents inconveniences such as material separation, floating ice phenomenon, and being washed away by underground water, but also adheres uniformly and firmly to the antibody, and can be used to the same extent as the conventional direct pouring method. It is an inexpensive grout material that exhibits a greater frictional force on the pile circumferential surface than the pile construction method and the hollow excavation method.

The present invention will be explained below with reference to Examples.

Example 1. Comparative Example 1 Ordinary Portland cement, powder mainly composed of calcium silicate hydrate, and basic magnesium carbonate were used as the first
Regarding the grout material obtained by mixing and kneading 130 parts by weight of water to 100 parts by weight of the grout material in the proportions shown in the table, the amount of floating water, the residual ratio to underground water, and the age of 28
The compressive strength of each day was measured. Experiments A6-47 as examples
．． 412-AI6 as a comparative example, Experiment AI, 2,48
-11 and AI7-19 are shown in Table 1. In the Examples and Comparative Examples, the amount of floating water was 6.
minutes later, it is poured into a polyethylene bag and expressed as the ratio of the upper floating ice volume that occurs 6 hours after standing to the volume at that time. It is expressed as the ratio of the weight remaining after 5 minutes to the weight, and the compressive strength was measured according to A1108 on the 51st. In order to exhibit a satisfactory function as a grout material for expressing frictional force on the circumferential surface of a pile, it is necessary to have a floating water amount of 2.0% or less, an underground water residual rate of 80% or more, and a compressive strength of 2Q Kfl/an2 or more. As can be seen from Table 1, Comparative Example AI, 2° & 8
~11. Examples A6 to A7 did not satisfy all conditions in terms of floating water amount, subsurface water residual rate, and compressive strength. AI 2-Ya 16 exhibited a remarkable effect of satisfying all the necessary conditions for a grout material that exhibits friction force on the circumferential surface of a pile. In particular, significant differences in effectiveness were observed in the amount of floating water and the residual rate of underground water.

Example 2 In order to confirm the interfacial adhesion between the antibody and the surrounding soil, the length was 90 mm.
cIIL1 A concrete model with an effective diameter of 15 cWL was buried in saturated sand, and at the same time, Comparative Example AI,
2.8.9.10 and 17, Example A3.4.7.1
After injecting grout materials No. 2.13 and No. 15 to a thickness of 2 crrL, a loaded push-out test was conducted when the materials were 7 days old. In the grout materials of Comparative Examples A1.2.9 and 10, a floating water amount of 20 to 30% was confirmed during the test. The results of the loaded push-out test are shown in Table-2. The reason why the grout material of the comparative example was not effective was that (1) a large amount of floating ice was formed, so the actual adhesion area became small. ■The compressive strength of the grout material is low. etc., and the example grout material shows remarkable effects. Furthermore, all of the grout materials of the examples adhered uniformly and firmly to the antibodies and were cured.

Example 3 To confirm the interfacial adhesion between the antibody and the grout material. Using the grout material and model made by the same laboratory as in Example 2, a 5 cWL grout was injected onto the peripheral surface of the pile and a push-out test was conducted.

The results are shown in Table 2, and as in Example 2, the Example grout material showed a remarkable effect compared to the Comparative Example grout material, confirming that the grout material firmly adhered to the antibody.

(hereinafter referred to as Order b)

Claims (1)

[Claims] 1. A grout for expressing frictional force on the circumferential surface of a pile, characterized in that 10 to 500 parts by weight of powder mainly composed of calcium silicate hydrate is mixed with water in the presence of 100 parts by weight of cement. Material 2, 10 to 500 parts by weight of powder based on calcium silicate hydrate per 100 parts by weight of cement, and 0. 5 to 5 parts by weight of basic magnesium carbonate with water