JPS5818342B2 - Poor mix concrete for pumping - Google Patents

Description

[Detailed Description of the Invention] Concrete pumps have rapidly become popular in recent years, and their proportion in the amount of concrete placed is increasing year by year.
concrete pumps account for more than 65% of civil engineering work, and improvements have been made to concrete pump models to improve their performance.

However, there are various restrictions when placing concrete using a concrete pump, and among these, the lower limit of the amount of cement per unit is generally said to be 260 kg/l, and 300 to 350 kg/l for concrete for normal pumping.
kg/m'.

In the case of poorly mixed concrete, the frictional resistance inside the pipe increases, the amount of cement particles decreases, and the unit water volume increases, so water flows in advance in the pipe, causing water separation and clogging. Pumping is difficult;
Therefore, in reality, the amount of cement increases, forcing uneconomical construction.

If it becomes possible to pump poorly mixed concrete, it will be possible to save labor in the construction of concrete pumps.

The present invention was proposed in view of these circumstances, and was proposed for the purpose of providing a low-mix concrete that can be pumped with a unit weight of 1.20 to 200 kg/rrl. The unit cement amount is 120 to 200 kg/m, and the blending ratio of cement, fine aggregate, and coarse aggregate with a diameter of 40 mm or less is 1 by weight.
: 4 to 11 (surface dry) = 4 to 11 (surface dry), and a foaming agent is mixed therein to introduce an air amount of 5 to 12 parts.

Concrete pumping involves pumping the mortar paste of fresh concrete itself as a lubricant, and sand or gravel cannot be pumped through pipes either individually or collectively.

Therefore, concrete suitable for pumping must contain an appropriate amount of high-quality mortar paste, and must have gravel that is suitable for the size of the concrete pump piping.

As in the present invention, the unit cement amount is 120 to 200 kg/
In the case of m', fluidity cannot be maintained unless the blending ratio of cement, fine aggregate, and coarse aggregate is in the range of 1 = 4 to 11 (surface dry): 4 to 11 (surface dry) in terms of weight ratio. Confirmed by experiment.

Furthermore, depending on the concrete placement thickness, the presence or absence of reinforcing bars, etc., the maximum grain size of coarse aggregate in general concrete is 40 mm.

Also, the capacity and limitations of concrete pump trucks! Taking into account the fact that the larger the surface area of the coarse aggregate is, the more paste is required to cover the aggregate, that is, the larger the amount of cement, in the present invention, the coarse aggregate is The particle size is 40 vanJJ or less.

1. Also, in the present invention, water separation can be prevented by adding a foaming agent as described above.

Also, if the concrete has a poor mix, it will lose its fluidity.
As mentioned above, by adding a foaming agent, the fluidity can be improved by supplementing the mortar paste content.

As mentioned above, the amount of air in a concrete mix suitable for pumping while maintaining improved water retention and fluidity is 5.
~12φ.

If the ratio is less than 5, the foaming agent will not be effective and water retention and fluidity will not improve.

Moreover, if it exceeds 12%, water retention and fluidity will be improved, but pumping will not be possible.

This is because the concrete causes a cushioning effect like a rubber material, which causes blockage in the concrete pouring pipe and makes it impossible to pump the concrete.In addition, in the present invention, a high viscosity cellulose derivative solution is added to the concrete with the above composition. This is characterized by the fact that the air bubbles are stabilized and the frictional resistance within the concrete pouring pipe is further reduced.

3 The cement used in the present invention may be any of ordinary Portland cement, early strength cement, fly ash cement, or blast furnace cement.

Foaming agents used as admixtures include resinous soaps, saponins, synthetic surfactants (alkyl, allyl sulfonates, alkylnaphthalene sulfonates, etc.)
, hydrolyzed protein, etc. are known, but as the foaming agent in the present invention, maleic acid obtained by adding maleic anhydride to abietic acid shown in Japanese Patent Publication No. 38-21624, It is preferable to use a homogeneous emulsion containing a saponified resin as the main component, to which a synthetic emulsion is added as a bubble stabilizer.

The structural formula of the maleated resin is as shown below.

Therefore, in the present invention, the cement, fine aggregate, and coarse aggregate are blended in the above-mentioned mixing ratio, and the foaming agent is added to this in an amount of 0.02 to 0.3 fb (cement weight %). It is also possible to add 0.5 to 3.0% (cement weight %) of a high viscosity cellulose derivative as a water-soluble polymer material to further improve the bubble stabilizing effect. The required amount of air can be introduced by the mix-forming method using a tilting type or forced mixing bowl mixer.

Further, the base concrete is transported to the unloading location using a truck mixer, and before being poured into the concrete pump, a predetermined amount of the above-mentioned foaming agent and high viscosity cellulose derivative are added, and the required amount of air is introduced by stirring with the truck mixer. You can also do it.

The concrete according to the present invention can be used for foundation concrete, waste concrete, artificial rock, which does not require much strength.
Used for backfilling concrete in subways, shield tunnels, retaining walls, etc.

Next, examples of the present invention will be described.

Concrete was pumped through piping as shown in Figure 1 using a concrete pump truck shown in Table 1 below.

In the figure, a is a pump truck, b and c are flexible hoses connected to the base and tip of the concrete-casting pipe d,
e is the concrete placement surface, f is the pump pressure transducer, A,
B, C, D and E are pressure measurement points in the pipe d.

As a result, the internal pressure of concrete casting pipes in Examples 1 to 3, which will be described later, was the same as or lower than that of ordinary concrete, and the concrete could be pumped smoothly.

In Examples 1 to 3, the aggregates shown in Table 2 were used.

Example 1 Concrete having the composition shown in Table 3 below was pumped.

The concrete has a maleated resin foaming agent added to it.

Table 4 below shows the theoretical discharge amount, main oil pressure and pipe internal pressure measurement results of the concrete pump, and Table 5 below shows the quality test results.

From this result, the normal unit cement amount is 300 to 350 kg.
/m' of concrete, or lower pipe pressure was obtained, and the concrete could be pumped extremely smoothly.

C---Asano Ordinary Portland Cement S, FU---
River sand GFU produced by Ichifuji Corporation River gravel B---Maleated resin foaming agent CXWT% Example 2 Concrete having the composition shown in Table 6 below was pumped.

The concrete contains a maleated resin foaming agent and a high viscosity derivative.

Table-7 and Table-8 show the test results, and in this case also Example 1
The pump was able to pump smoothly as well.

C---To Asano ordinary Portland cement FU---River sand G produced for Ichifuji, FU-1-ll River gravel A---High viscosity cellulose derivative CXWT%B---Maleated resin foaming agent 〃 Implementation Example 3 Concrete having the composition shown in Table 9 below was pumped.

The concrete is made by adding a commercially available lignin sulfonate to a maleic J resin foaming agent, a high viscosity derivative, and a high viscosity derivative.

Tables 10 and 11 show the test results, and in this case as well, smooth pumping was possible as in Examples 1 and 2.

C-11 Asano Ordinary Portland Cement 51KI-11 Kinu-produced river sand G, KI--1 〃 River gravel P ---IJ Kuninsulfonate cxwr %A-
-- High viscosity cellulose derivative // B --- Maleated resin foaming agent 〃 Figures 2 and 3 show construction examples using the concrete of the present invention, 1 is a subway roadway, 2 is a backside The poured concrete 3 is a pipe roof with a diameter of 800 mrtt, and a pump truck 4 pumps back-filled concrete to an average depth of 7 m.

In this case, if ordinary concrete is used as the backing material, the unit volume capacity will be 2.5 t/rrt, and the overburden 2 loads (
Concrete must have a unit volume weight of 2.1t/rrl or less due to the slab thickness.

In this case, construction by pumping cannot be carried out unless the concrete for pumping of the present invention is used.

Concrete IJ for pumping used in the construction:
Concrete having the composition shown in Table 9 of Example 3 is suitable.

During construction, under normal piping conditions, the capacity of the concrete pump is approximately 300 to 350 kg of cement per unit.
It can be pumped in the same way as g/m' concrete.

In addition, there are two methods for adding an admixture: one is to add it in a plant, and the other is to transport it in a truck mixer, add it on-site, and knead it again.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the piping and the measurement position of the internal pressure in the concrete pumping test, and FIGS. 2 and 3 are longitudinal sections showing an example of a construction site using concrete of the present invention. FIG. 1...Subway Rondo, 2...Concrete backing, 3...Vibe Roof, 4...
pump car.

Claims (1)

[Claims] 1. The unit cement amount is 120 to 200 kg/m, and the weight ratio of cement, fine aggregate, and coarse aggregate with a diameter of 40 mm or less is 1:4 to 11 (surface dry):4 to 11 (surface dry) and a foaming agent is mixed therein to introduce an air content of 5 to 12%. 2 Unit cement amount 120-200kg/77+3,
The weight ratio of cement, fine aggregate, and coarse aggregate with a diameter of 40 mm or less is 1:4 to 11 (surface dry): 4 to 11 (surface dry)
Then, a foaming agent is mixed with this and an air amount of 5 to 12 $r is introduced into the concrete, and a high viscosity cellulose derivative solution is added as a water-soluble polymer substance. Poor mix concrete.