WO2019071704A1 - Low-plasticity composite base concrete and roller-compacted concrete dam impervious layer produced therefrom - Google Patents

Abstract

A low-plasticity composite base concrete and a roller-compacted concrete dam impervious layer prepared therefrom, the concrete being produced from water, cement, fly ash, medium sands, broken stones having a diameter between 5-20 mm, broken stones having a diameter between 20-40 mm, polypropylene fibers, a water reducer, an air entraining agent and a shrinkage reducer. The roller-compacted concrete dam impervious layer is prepared by means of the following construction method: 1) mixing the low-plasticity composite base concrete; and 2) simultaneously paving using the low-plasticity composite base concrete and ordinary roller-compacted concrete, performing vertical and inclined mixed vibration on the low-plasticity composite base concrete, condensing the low-plasticity composite base concrete to obtain an impervious layer, and condensing the ordinary roller-compacted concrete to obtain a dam main body. The low-plasticity composite base concrete has excellent performance such as in self-generated volume deformation, impermeability and tensile resistance, and the roller-compacted concrete dam impervious layer prepared therefrom has the advantages of good crack resistance, good impervious effect, remarkably reduced thickness, and facilitation of temperature control and crack prevention.

Description

Low-plastic composite concrete and anti-seepage layer of RCC dam prepared therefrom Technical field

The invention relates to a low plastic composite foundation concrete and an anti-seepage layer of a roller compacted concrete dam prepared therefrom.

Background technique

Roller compacted concrete is a dry hard cement-depleted concrete, which is made of Portland cement, pozzolanic admixture, water, admixture, sand and graded coarse aggregate. Transportation and paving equipment and earth and stone. The dam is the same. The RCC dam is a dam type often used in water conservancy and hydropower projects. It has the characteristics of small volume, high strength, good anti-seepage performance, overflow of the dam body, and simple, fast and economical construction procedures. The RCC dam is generally composed of three parts: the water-repellent surface anti-seepage layer, the rich slurry RCC anti-seepage area and the RCC main body area. At present, the anti-seepage layer on the water surface generally adopts the metamorphic concrete process of rolling concrete on-site grouting, the quality fluctuation is large, the quality defects and leakage often occur, and the thickness of the anti-seepage zone of the rich RCC is required to reach 4~ 6m can meet the anti-seepage requirements, it is not economical, it will lead to the difficulty of temperature control of the dam and the increase of the probability of cracks, and the safety hazard will increase.

Therefore, it is necessary to develop a more excellent performance concrete and an anti-seepage layer of a RCC dam which is superior in anti-seepage performance.

Summary of the invention

The object of the present invention is to provide a low-plastic composite-based concrete and an anti-seepage layer for a RCC dam prepared therefrom.

The technical solution adopted by the present invention is:

A low-plastic composite-based concrete composed of the following raw materials:

Water: 100 parts;

Cement: 138-175 parts;

Fly ash: 75 to 112 parts;

Medium sand: 536~551 parts;

Crushed stone with a diameter of 5 to 20 mm: 391 to 397 parts;

Crushed stone with a diameter of 20 to 40 mm: 588 to 597 parts;

Polypropylene fiber: 2.0 to 2.5 parts;

Water reducing agent: 2.0 to 2.5 parts;

Air entraining agent: 0.05 to 0.10 parts;

Shrinkage reducing agent: 2.5 to 5.0 parts.

The cement is P.O42.5 ordinary Portland cement.

The sand is at least one of natural river sand and artificial sand.

The crushed stone is at least one of granite and limestone.

The polypropylene fiber has a diameter of 30 to 40 μm, a length of 15 to 20 mm, and a tensile strength of 500 to 700 MPa.

The water reducing agent is a polycarboxylic acid type water reducing agent.

The shrinkage reducing agent is a polyether shrinkage reducing agent.

An anti-seepage layer of a roller compacted concrete dam is prepared by the following construction methods:

1) Mixing the above low-plastic composite concrete with a mixing plant;

2) Simultaneously pave the low-plastic composite foundation concrete and ordinary RCC according to the design area, and then vertically and obliquely mix and vibrate the low-plastic composite foundation concrete, and the low-plastic composite concrete will be coagulated to obtain the anti-seepage layer. Concrete condenses to get the dam body.

The invention has the beneficial effects that the low-plastic composite-based concrete of the invention has excellent self-generated volume deformation, impermeability, tensile strength and the like, and the anti-seepage and anti-seepage effect of the anti-seepage layer of the RCC dam prepared therefrom is good. The thickness of the anti-seepage layer is significantly reduced, which is favorable for temperature control and crack prevention.

1) The low-plastic composite-based concrete of the invention adopts a mixing building for centralized mixing, and can accurately control the mixing ratio parameter of the concrete, and the quality is better than that of the grouted metamorphic concrete;

2) The thickness of the anti-seepage layer of the RCC dam of the present invention only needs 25 to 35 cm to meet the actual demand, which is far lower than the 50-60 cm of the anti-seepage layer of the conventional RCC dam, which is favorable for temperature control and crack prevention;

3) The anti-seepage performance of the anti-seepage layer of the RCC dam of the invention is excellent, and the thickness of the anti-seepage zone of the rich RCC can be reduced from the conventional 4-6m to 2~3m, which saves materials and reduces the cost.

DRAWINGS

Figure 1 is a schematic view of the structure of a roller compacted concrete dam.

The description of the reference numerals: 10, the anti-seepage layer on the water surface; 20, the anti-seepage area of the rich RCC concrete; 30, the main area of the RCC dam.

Detailed ways

A low-plastic composite-based concrete composed of the following raw materials:

Water: 100 parts;

Cement: 138-175 parts;

Fly ash: 75 to 112 parts;

Medium sand: 536~551 parts;

Crushed stone with a diameter of 5 to 20 mm: 391 to 397 parts;

Crushed stone with a diameter of 20 to 40 mm: 588 to 597 parts;

Polypropylene fiber: 2.0 to 2.5 parts;

Water reducing agent: 2.0 to 2.5 parts;

Air entraining agent: 0.05 to 0.10 parts;

Shrinkage reducing agent: 2.5 to 5.0 parts.

Preferably, the cement is P.O42.5 ordinary Portland cement.

Preferably, the sand is at least one of natural river sand and artificial sand.

Preferably, the crushed stone is at least one of granite and limestone.

Preferably, the polypropylene fiber has a diameter of 30 to 40 μm, a length of 15 to 20 mm, and a tensile strength of 500 to 700 MPa.

Preferably, the water reducing agent is a polycarboxylic acid type water reducing agent.

Preferably, the shrinkage reducing agent is a polyether shrinkage reducing agent.

An anti-seepage layer of a roller compacted concrete dam is prepared by the following construction methods:

1) Mixing the above low-plastic composite concrete with a mixing plant;

2) Simultaneously pave the low-plastic composite foundation concrete and ordinary RCC according to the design area, and then vertically and obliquely mix and vibrate the low-plastic composite foundation concrete, and the low-plastic composite concrete will be coagulated to obtain the anti-seepage layer. Concrete condenses to get the dam body.

The invention will be further explained and illustrated below in conjunction with specific embodiments.

The structural schematic diagram of the RCC dam is shown in Figure 1, including the water-repellent surface impermeable layer 10, the rich RCC anti-seepage zone 20 and the RCC dam main body zone 30.

Example 1:

A low-plastic composite-based concrete whose raw material composition is as follows:

Table 1 Table of raw material composition of a low-plastic composite-based concrete

raw material	Parts by mass
water	100
P.O42.5 ordinary Portland cement	138
Fly ash	112
Sand	551
Crushed stone (diameter 5 ~ 20mm)	391
Crushed stone (20~40mm in diameter)	588
Polypropylene fibers	2.5
Polycarboxylic acid water reducing agent	2.5

Air entraining agent	0.1
Polyether shrinkage reducing agent	5

Example 2:

A low-plastic composite-based concrete whose raw material composition is as follows:

Table 2 Table of raw material composition of a low-plastic composite-based concrete

raw material	Parts by mass
water	100
P.O42.5 ordinary Portland cement	175
Fly ash	75
Sand	536
Crushed stone (diameter 5 ~ 20mm)	397
Crushed stone (20~40mm in diameter)	597
Polypropylene fibers	2.3
Polycarboxylic acid water reducing agent	2.3
Air entraining agent	0.05
Polyether shrinkage reducing agent	3.7

Example 3:

A low-plastic composite-based concrete whose raw material composition is as follows:

Table 3 Table of raw material composition of a low plastic composite concrete

raw material	Parts by mass
water	100
P.O42.5 ordinary Portland cement	150
Fly ash	100
Sand	545
Crushed stone (diameter 5 ~ 20mm)	393
Crushed stone (20~40mm in diameter)	593
Polypropylene fibers	2.0
Polycarboxylic acid water reducing agent	2.0
Air entraining agent	0.07

Polyether shrinkage reducing agent

2.5

Comparative example:

An ordinary roller compacted concrete whose raw material composition is as follows:

Table 4 Table of raw materials for a common RCC

raw material	Parts by mass
water	100
P.O42.5 ordinary Portland cement	175
Fly ash	75
Sand	551
Crushed stone (diameter 5 ~ 20mm)	391
Crushed stone (20~40mm in diameter)	588
Polycarboxylic acid water reducing agent	2.3

Test case:

The performance tests were carried out on the concrete of Examples 1 to 3 and the comparative examples. The test results are shown in the following table:

Table 5 Performance test results of concrete of Examples 1 to 3 and Comparative Example (90 d age)

It can be seen from Table 5 that the impermeability, autogenous volume deformation and tensile strength of the low-plastic composite-based concrete of the present invention are obviously superior to ordinary RCC of the same grade, and the effect of improving the crack resistance and seepage prevention performance of the dam is remarkable. It laid the foundation for further optimizing the concrete material division of the RCC dam.

The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and combinations thereof may be made without departing from the spirit and scope of the invention. Simplifications should all be equivalent replacements and are included in the scope of the present invention.

Claims (8)

1. A low-plastic composite-based concrete characterized by: consisting of the following raw materials:

   Water: 100 parts;

   Cement: 138-175 parts;

   Fly ash: 75 to 112 parts;

   Medium sand: 536~551 parts;

   Crushed stone with a diameter of 5 to 20 mm: 391 to 397 parts;

   Crushed stone with a diameter of 20 to 40 mm: 588 to 597 parts;

   Polypropylene fiber: 2.0 to 2.5 parts;

   Water reducing agent: 2.0 to 2.5 parts;

   Air entraining agent: 0.05 to 0.10 parts;

   Shrinkage reducing agent: 2.5 to 5.0 parts.
2. The low-plastic composite-based concrete according to claim 1, wherein the cement is P.O42.5 ordinary Portland cement.
3. The low-plastic composite-based concrete according to claim 1, wherein the sand is at least one of natural river sand and artificial sand.
4. The low-plastic composite-based concrete according to claim 1, wherein the crushed stone is at least one of granite and limestone.
5. The low-plastic composite-based concrete according to claim 1, wherein the polypropylene fiber has a diameter of 30 to 40 μm, a length of 15 to 20 mm, and a tensile strength of 500 to 700 MPa.
6. The low-plastic composite-based concrete according to claim 1, wherein the water reducing agent is a polycarboxylic acid-based water reducing agent.
7. The low-plastic composite-based concrete according to claim 1, wherein the shrinkage reducing agent is a polyether shrinkage reducing agent.
8. An anti-seepage layer for a roller compacted concrete dam, which is characterized by: the following construction method:

   1) mixing the low-plastic composite-based concrete according to claim 1 with a mixing plant;

   2) Simultaneously pave the low-plastic composite foundation concrete and ordinary RCC according to the design area, and then vertically and obliquely mix and vibrate the low-plastic composite foundation concrete, and the low-plastic composite concrete will be coagulated to obtain the anti-seepage layer. Concrete condenses to get the dam body.

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