JP3075713B2 - Dam concrete production - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the process for the preparation of dam concrete had use <br/> unwashed gravel.

[0002]

2. Description of the Related Art Conventionally, fine and coarse aggregates used for dam concrete production have been washed and classified from crushed stones and gravel collected from rocky mountains and riverbeds, and have been confirmed to meet JIS standard quality. Used above. In other words, conventional dam concrete production presupposes the use of fine and coarse aggregate that has been washed and classified, and based on this, the mix design, production method, transport method, and construction method are determined. ing.

[0003] Washing and classification of the collected sand and gravel requires a large amount of cost for managing a large machine and its work process, and there is also a problem of river pollution. For this reason, as one of the rationalization works for concrete dams, if the gravel collected from the riverbed is to be used as aggregate for dam concrete without cleaning, use the conventionally cleaned and classified concrete. It is difficult to secure the required quality with the composition design, manufacturing method, transportation method and construction method based on the premise of the above.

[0004] At present, there is no case in which gravel on a riverbed is used as aggregate for dam concrete without being washed. Therefore, there is no clue whether such a thing can be realized.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is to develop a concrete dam capable of using riverbed gravel as an aggregate without washing, regardless of whether it is internal concrete or external concrete. is there.

[0006]

According to the present invention SUMMARY OF], under the dam concrete equivalent cement content of normal and water-cement ratio, using a riverbed gravel unwashed as aggregate dam
To Rusai kneading the concrete, JIS A 110
Perform the test according to the slump test method for concrete 1
It was after (to the slump value and S _1), further Seraing
30 times natural by setting the push bar vertically from the height of 15 cm to the plate
When performing a slump impact test to drop
The amplifier value and _{S 3), (S 3 -S} 1) / value according to formula of S ₁ is 2.0 or more inside the concrete dam
Above, the concrete outside the dam still has a value of 3.5 or more.
Vibrating superplasticizer so that unmixed concrete is obtained
Damp concrete characterized by mixing and kneading
Provide a manufacturing method for

[0007]

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The composition of dam concrete differs between internal concrete and external concrete. For internal concrete, the water-cement ratio (W / C) is usually 60-90%,
The unit cement amount is about 110 to 180 kg / m ³ , and the external concrete usually has a water / cement ratio (W / C) of 50 to 60%, and the unit cement amount is 180 to 260 kg / m ^3.
m ³ . The present invention is also intended to produce not only the internal concrete having such a low cement content and the high ratio of water cement but also the external concrete using unwashed gravel as an aggregate.

[0009] In concrete in which the gravel on the riverbed is used as aggregate without being washed, mud attached to the gravel affects its properties. In particular, in the case of dam concrete with a low cement content, even if such adhering mud is present, it is necessary to obtain a required slump value without increasing the unit water amount more than necessary. In other words, even when unwashed gravel is used as aggregate, workability must be secured with the same unit water volume as when washed gravel is used.

The present inventors have found that this problem can be solved by using a suitable vibrating fluidizer. The "vibration fluidizing agent" referred to in the present specification is an admixture that can impart the property of improving the fluidity while maintaining the properties of plastic to the concrete that has not yet solidified by applying vibration. Conventional general water reducing agent, A
E water reducer, high performance water reducer, etc. from this point of view,
It has more or less such properties. However,
According to tests by the present inventors, it has been found that there are few dam concretes that can solve the above-described problems in the case of unwashed gravel.

As a result of a number of tests, it is clear that as a vibration fluidizing agent that can be used for the construction of the concrete dam of the present invention, a material having a water-soluble vinyl copolymer composed of a carboxyl group-containing polyether as a main component is suitable. It became.

When such a vibration fluidizing agent is blended with dam concrete using unwashed gravel as an aggregate under the same cement amount and water cement ratio as ordinary dam concrete, JIS A 1101 after tested according slump test method of the concrete (the slump value and S _1), further against the slump plate rod height 15
When subjected to slump hitting test to 30 times free fall vertically from cm (its slump value and S _3), the value according to equation _{(S 3 -S 1) / S} 1 ·· (1), It is important to select and mix the type and amount of the vibration fluidizer so that concrete not yet set with a value of 2.0 or more for the concrete inside the dam and 3.5 or more for the concrete outside the dam can be obtained. is there.

If the value according to the above equation (1) is 2.0 or more for internal concrete and 3.5 or more for external concrete, even if it is a dam concrete using unwashed gravel, it has good workability and strength. Construction of a concrete dam comparable in quality is possible. Although the reason is not always clear, if such a value is satisfied, the mud adhering to the unwashed gravel will be well dispersed during the compaction by vibration, and concrete with low cement content will not be used. It is presumed that even if there is an appropriate viscosity, an appropriate flow state can be obtained while adding an appropriate viscosity. Therefore, it is indispensable that the dam concrete of the present invention be compacted by vibration after casting, and the real value of the dam concrete of the present invention is exhibited at the time of compaction by vibration.

The dam concrete of the present invention can of course be kneaded and mixed using a batcher plant or a normal mixer, but it is kneaded using an agitator wheel for transporting the ready-mixed concrete to a casting site. Can be mixed. In this case, an agitator truck will be dispatched near the riverbed and gravel collection site, and the riverbed and gravel, excluding coarse gravel of approximately 80 mm or more, and cement, water, admixture, etc. will be properly measured with a measuring device, and then these will be agitated. It is convenient to put it in a car and mix it. In this measurement, the amount and composition of the vibration fluidizer are determined so that the value of equation (1) becomes 2.0 or more for internal concrete and 3.5 or more for external concrete as described above. In the case of mixing, higher workability can be obtained by mixing the unwashed gravel, cement, and mixing water, and then adding and adding a vibration fluidizer separately from the mixing water.

[0015]

[Example] Riverbed gravel as-collected with a size of 80 mm or more removed was used as a mixer input material without washing, and was mixed with concrete mixes A, B and C (kg / m ³ ) shown in Table 1. Kneaded. Table 2 shows the volume conversion value (L / m ³ ) of each material for each formulation. Formulations A and B are intended for the concrete inside the dam, and formulation C is for the concrete outside the dam. In the table, those indicated as fine aggregate and coarse aggregate were separately classified for riverbed and gravel used for each formulation.
The weight ratio of those with m or more was determined, and the sum of the input riverbed and gravel multiplied by the former ratio was defined as fine aggregate and the latter multiplied by the ratio was defined as coarse aggregate. The additive amount of the admixture was set to unit cement amount × 0.25%.

[0016]

[Table 1]

[0017]

[Table 2]

In each of Formulations A, B and C, as an admixture, a vibration fluidizer containing a carbosyl group-containing polyether-based water-soluble vinyl copolymer compound as a main component and lignin, a typical AE water reducing agent, were used. A sulphonic acid compound polyol complex system (Pozoris No. 70, manufactured by NMB Co., Ltd.) was used, and the slump value and the impact slump value when 0.25% of these were added to the unit cement amount were measured. Table 3 shows the results. Impact slump value after tested according slump test method Concrete JIS A 1101 (the slump value and S _1), further with a plunger slump plate from a height 15cm vertically 15 times and 30 times The slump value at the time of natural fall was measured, and displayed as after 15 hits (S ₂ ) and after 30 hits (S ₃ ). Table 4 shows the strength test results for Formulations A and B.

[0019]

[Table 3]

[0020]

[Table 4]

As is evident from the results in Table 3, even when the same unwashed gravel is used as an aggregate and the concrete is kneaded with the same composition, when the carbosyl group-containing polyether admixture is used, As compared with the case of the ligninsulfonic acid-based admixture, the initial slump value is almost the same, but the fluidization is remarkably fluidized by vibration. This effect is particularly significant when the amount of water is low, and (S ₃ -S ₁ ) / S ₁ is more than 2.0 in the composition A and B of the internal concrete, and 3.5 or more in the composition C of the external concrete. I have. Therefore, even with concrete that uses unwashed sand and gravel, by adding a carbosyl group-containing polyether-based admixture, it is possible to obtain dam concrete that exhibits good fluidity during compaction by vibration and that is comparable in strength. It can be seen that it can be obtained.

[0022]

As described above, according to the present invention,
Even if the collected gravel is used as aggregate without washing, the construction of concrete dams is possible, which can greatly contribute to the rationalization of concrete dams. Also, the problem of river pollution during washing of aggregates is avoided.

────────────────────────────────────────────────── (5) Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI C04B 18:12 24:26) (56) References JP-A-6-305579 (JP, A) JP-A-11-28719 (JP) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C04B 28/02 B28C 7/00 C04B 18/12

Claims (2)

(57) [Claims] 1. Cement equivalent to ordinary dam concrete
Unwashed riverbed as aggregate under the amount of water and water-cement ratio
When mixing dam concrete with sand and gravel, slump test method of JIS A 1101 concrete
After performing the test in accordance with the law (to the slump value and S ₁
), And then hang a stick from a height of 15cm on the slump plate.
Perform a slump impact test of dropping 30 times naturally.
(Its slump value and _{S 3), (S 3 -S} 1) / value according to formula of S ₁ is 2.0 or more inside the concrete dam when the
Above, the concrete outside the dam still has a value of 3.5 or more.
Vibrating superplasticizer so that unmixed concrete is obtained
Damp concrete characterized by mixing and kneading
Production method. 2. The concrete inside the dam is water-cement ratio
(W / C) 60-90%, unit cement amount 110-
180 kg / m ³ and concrete outside the dam is water
Cement ratio (W / C) 50-60%, unit cement amount
Co according to claim 1 but is 180~260Kg / m ³
Manufacturing method of concrete dam .