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Density and fluidization rate factors of clay pebbles/ leca blocks

Concrete is generally used instead of gravel and pebbles. The solid waste of leca blocks, varies in color, usually black, and the matte surface is smooth. The internal structure is fine honeycomb.

Leca blocks 3 types

According to the density, they are divided into three types: general density type, ultra-light density type, and optical density type. It has high strength and is used for insulating concrete or reinforced concrete structures. The price is more reasonable. 

Leca bolcks is economic

High-quality leca blocks cost affects project investment and operating costs. Although cheap natural materials are used for filter media, investment can be saved, but the properties such as density and fluidization rate are not suitable for backwashing, which may increase energy consumption and affect operating costs.

Some synthetic filter materials have good performance but are costly, price is too high. Therefore, the choice should take into account both performance and price. 

The nitrification function of the biological aerated filter is the best when the particle size is 2-4mm.

At present, the particle size of the filter material commonly used in the biological aerated filter is 3-6mm, and the thickness of the filter layer is 3-4mm.

Leca blocks benefits

 The clay pebbles/ leca is a kind of light artificial particle with unique performance, which is widely used in the preparation of high-rise building structure concrete, roof slope finding, thermal insulation, sewage treatment, landscaping, soilless cultivation and other fields.

It has a proper packing density of the filter material, and the layer voids are evenly distributed, making backwashing easy, with low backwashing consumption, small water consumption, small water head loss, and no material leakage during backwashing.

The high-quality have overcome the shortcomings of backwashing being difficult to control and running out of materials. It adopts good particle size distribution, strong dirt holding capacity and high utilization rate of filter material. The water head increases slowly, the operation period is long, and the water production is large. The concrete of clay pebbles/ leca blocks is better than ordinary concrete in acid, alkali corrosion and frost resistance.

Concrete of clay pebbles/ leca blocks is an excellent building material

For the concrete of No. 250 fly ash clay pebbles/ leca block, the strength loss of 15 freeze-thaw cycles is not more than 2%. In 1976, relevant departments conducted actual measurements on the concrete projects of leca blocks built since 1985. The results showed that no matter whether it was prefabricated or cast-in-place, indoor or outdoor, the steel bars contained in them were not corroded. The depth of carbonization is generally not more than 30 mm, and the strength can continue to grow in the later stage. It can be seen that the concrete of clay pebbles/ leca blocks is an excellent building material and should be vigorously promoted.

Except construction, other applications of clay aggregates?

  1. For the preparation of lightweight aggregate concrete:

Lightweight clay aggregates can be used to prepare CL2.5-CL30Mpa lightweight aggregate concrete with a density less than 1600 kg/m3.

  1. For the production of lightweight blocks:

The lightweight blocks produced with lightweight clay aggregates have excellent properties such as energy saving and environmental protection, light weight and high strength, sound insulation and heat insulation, fire resistance and moisture resistance.

  1. For the production of lightweight wall panels:

The lightweight wallboard produced by lightweight clay aggregates has excellent properties such as light weight, high strength, heat preservation, heat insulation, sound insulation, fire resistance, good moisture resistance, earthquake resistance, impact resistance, and small shrinkage.

  1. Used for roof insulation and slope finding clay aggregates:

It has heat insulation effect when used for roof insulation and slope finding; good integrity, easy construction; high compressive strength; it can be used for a long time, the roof can bear load, and the reinforced concrete structure does not need to find slope, and drainage slope can be laid according to the requirements of use. Greatly facilitate design and construction.

  1. For floor cushion and moisture-proof layer:

The use of clay aggregates in the cushion can improve the thermal insulation, heat insulation, sound insulation and bearing capacity between floors; it can facilitate the layout and installation of pipelines in the ground. Used as a moisture-proof layer, it can also prevent the floor from regaining moisture and keep it dry. It is very beneficial to protect various wooden floors and plastic panels from deformation and fading, and to prevent moisture and water in the basement.

  1. Used for roof garden greening:

The use of clay aggregates in the roof garden can reduce the load of the floor, protect the soil from being lost with water, quickly dredge the accumulated water, and maintain the supply of soil moisture and fertilizer when it is hot and dry.

  1. For soilless cultivation/ hydroponics:

Ceramic materials are used in soilless cultivation/ hydroponics of potted flowers and gardening, which can not only retain water and fertilizer, keep the soil loose for a long time, prevent soil compaction, but also be clean, hygienic and beautiful.

  1. For sewage treatment:

clay aggregates can be used as a biological carrier in sewage treatment, and can filter impurities in sewage, and can absorb oil and harmful substances.

clay aggregates concrete has been widely used in various types of prefabricated and cast-in-place concrete projects in industrial and civil buildings (such as prestressed and non-prestressed, load-bearing structure or enclosure, heat insulation or impermeability, static load or dynamic loaded). clay aggregates can also be used in other building materials such as pipeline insulation, furnace insulation, cold insulation, sound insulation and sound absorption; it can also be used as soilless foundation bed materials and water filtration materials in agriculture and gardens.

The super adaptability of building materials clay aggregate

It has been a long time since the appearance of building material clay aggregate, and now its application is very extensive. It has been proved by decades of production practice at home and abroad that according to different resource conditions in various places, clay, shale, fly ash or other solid materials can be used respectively. Waste production of clay aggregate.

According to different uses and market needs, clay aggregate products with different bulk densities and particle sizes can be produced (ultra-light clay aggregate, clay aggregate for structural insulation, clay aggregate for structure), and clay aggregate for special purposes, such as high temperature resistant clay aggregate. Granules, acid-resistant clay aggregate and flower clay aggregate, etc.

Utilizing these excellent properties of clay aggregate, it can be widely used in building materials, horticulture, food and beverage, refractory and thermal insulation materials, chemical industry, petroleum and other departments. The application fields are becoming wider and wider, and are still expanding.

Construct the dream of green building, new building clay aggregate concrete attracts attention

The history of human civilization changes includes numerous changes in building materials, and every progress embodies human wisdom.

It is precisely because of people’s complex of Qin bricks, Han tiles and tiles for thousands of years that this vast land is riddled with holes, reduced cultivated land, soil erosion, and ecological environment damage. “But save a square inch of land and leave it to your descendants to cultivate.” This is a helpless cry.

We clearly see that with the rapid development of cities, various types of construction waste are also increasing, and “garbage siege” has become an unbearable burden on the development road of many cities. In order to change this situation, during the “Twelfth Five-Year Plan” period, the state promulgated a mandatory standard for building energy efficiency to reach 65% nationwide, but very few lightweight wall materials on the market meet this indicator.

Therefore, we took the lead in starting the resource utilization of construction waste. Scientific and technological research, departmental linkage, and pilot projects first, use urban domestic sludge and river and lake sludge, construction waste, factory pulverized coal powder and other materials to obtain a low-cost, low-density, high-strength, low thermal conductivity, and corrosion-resistant material through expansion.

Strong sludge clay aggregate is used as aggregate, and the traditional chemical foaming method is improved to a physical foaming method to develop a self-insulating masonry material for green building energy saving. The block combines the advantages of clay aggregate and reinforced foam concrete, which makes it have light density, high strength, excellent heat insulation performance, small shrinkage, low water absorption and impermeability compared with general foam concrete self-insulation blocks. Strong, good frost resistance, excellent fire resistance and durability, good sound insulation and sound absorption effect, and has good shock absorption and shock resistance.

In the production process, a fully automatic frequency conversion numerical control cutting system is used to ensure the accurate size of the product, which indirectly improves the quality of the wall, so that the wall made of this kind of clay aggregate reinforced foam concrete self-insulating block has high later strength and the same service life of the building. Significant advantages. The green building using this product has huge economic and social effects, the building load is greatly reduced compared with ordinary buildings, and there is no need for internal and external wall insulation and waterproofing, reducing thermal bridges and cold bridges. Especially suitable for use in hot summer and cold winter regions.

Clay Aggregate Concrete Mixing and Construction Technology

1. Concrete mixing

(1) When mixing high-performance clay aggregate light aggregate concrete, the mixing personnel are required to feed materials strictly according to the mix ratio.

(2) Timely measure the water content of the sand, adjust the water consumption of concrete mixing, and change the slump of self-compacting concrete must be carried out by on-site technicians, and it is strictly forbidden to increase the water consumption at will;

When mixing clay aggregate concrete, the optimal watering time is also closely related to the order of feeding materials. If a self-falling mixer is used for mixing, the hopper is raised and the water is released in time when the material is just fed, so that the mixing time can be shortened, the mixing is easier, and it is easy to mix evenly. If you add water first or later, it is not easy to stir evenly. Therefore, it is very important to choose the best time to add water. Because clay aggregate has strong water absorption performance, when preparing concrete, the total amount of water added is larger than that of ordinary concrete, and the water absorption of clay aggregate for 15 minutes is generally increased.

(3) Concrete mixing time The mixing time of clay aggregate concrete should be longer than that of ordinary concrete. If a forced mixer is used for mixing, the concrete mixing time should be strictly controlled at 120~160s. If a self-falling mixer is used, the mixing time can be controlled at 160~240s to ensure that the concrete mixture is evenly mixed and the work-ability of the mixture meets the aforementioned quality requirements.

(4) Requirements for concrete mixture Control the concrete slump to (160+-20)mm. In order to ensure the pouring quality, strength and durability of concrete, it is required that the concrete mixture does not bleed and has good work-ability.

(5) Selection of clay aggregate concrete mixer Since clay aggregate is light and easy to float, it is not easy to mix evenly, so it is best to choose equipment with better mixing performance, such as forced mixer.

(6) When mixing clay aggregate concrete, there are currently two ways to add water.

a. Pre-sprinkle the clay aggregate with water until it is almost saturated, then mix the ingredients and mix, and only add the effective amount of water during the formal mixing. The advantage of this method is that the combination is relatively stable; the disadvantage is that the concrete is prepared after the clay aggregate absorbs water, and the strength of the concrete decreases. .

b. The clay aggregate in the natural dry state is directly used for batching and stirring, and the total water consumption is added to the formal stirring. The advantage of this method is that the strength of the prepared concrete is high, and the disadvantage is that the quality of the mix is not easy to stabilize.

Light weight expanded clay aggregate.

As a new type of environmentally friendly material, clay pebbles (LECA) was mainly used in the construction industry at the beginning. It is a porous and lightweight particle formed by high temperature expansion of clay. It has a series of functions such as heat preservation, heat insulation, fire prevention, and earthquake resistance. Because of its cheap price, with good adsorption and air permeability, it is now widely used in gardening and water treatment and other related fields. It is divided into various models, not only the size of the particles, but also the natural color and color. Colored clay pebbles (LECA) is mainly used for in the decoration industry, it can also be used to fix the root system of hydroponic plants and increase the ornamental value.

clay pebbles (LECA) has the following characteristics:
clay pebbles (LECA) is a light particle after high temperature expansion. Although it contains a small amount of mineral trace elements, it does not contain organic matter and belongs to a sterile matrix. It has a light weight and a porous honeycomb structure inside, which has certain adsorption and air permeability. 80% of its uses are used in the construction industry. In the gardening field, it is generally used to cushion the bottom of flowerpots, act as paving stones, and fix the roots of hydroponic plants, or used to purify and stabilize water quality in fish tanks and aquariums. It is rarely used for soil preparation because it does not contain organic matter and is not easy to decompose. The effect of soil preparation is not as good as medical stone, vermiculite, red jade soil and other mineral particle substrates.

The main role of clay pebbles (LECA) in gardening and home furnishing:
① Act as a paving stone:
The particle size of clay pebbles (LECA) is relatively uniform, the material is light, and the price is very cheap. It can be used as a paving stone to prevent the soil from splashing around when watering, to avoid the floating of light substrates such as coconut peat and perlite, and to prevent the soil from being directly exposed to water. In the natural environment, it can also isolate the peculiar smell of the soil, prevent the breeding of mosquitoes in summer, and increase the ornamental value of potted plants.

② Cushion the bottom of the flowerpot:
Using clay pebbles (LECA) to cushion the bottom of the flowerpot can play the role of a hydrophobic layer, which saves soil and breathes air. When potting or changing potted plants, you can first spread a layer of clay pebbles (LECA) on the bottom of the pot, which can not only save nutrient soil, but also prevent the soil from losing from the bottom hole of the pot when watering, and at the same time protect It can prevent water accumulation in the pot and increase the air permeability of the root system.

â‘Ē Hydroponic flowers:
When growing hydroponic plants or carrying out soilless cultivation (hydroponics), spread a layer of colored clay pebbles (LECA) on the bottom of the hydroponic container, which can not only fix the root system, increase the oxygen content of the root system, but also purify the water quality, and at the same time let the single water Cultivated plants look more aesthetically pleasing.

â‘ĢPurification of water quality in fish tanks and grass tanks:
The porous structure of clay pebbles (LECA) honeycomb has a certain degree of adsorption, so it has the function of purifying and stabilizing water quality and can be used as the bottom sand of fish tanks and grass tanks. However, it should be noted that the clay pebbles (LECA) used in the aquarium belongs to clay pebbles (LECA) sand, the particles are relatively small, and the material is heavier than ordinary clay pebbles (LECA), and it will not float on the water surface, but it needs to be cleaned many times before use. of dust.

As a high-quality granular matrix, clay pebbles (LECA) not only exerts its unique advantages in the construction field, but also exerts its waste heat for the gardening family. You can choose the specific particle size and color according to your actual needs.
Suggestion: Use 3-5 mm small particles for paving, 5-8 mm large particles for the bottom of the flowerpot, colored clay pebbles (LECA) for hydroponics, and special clay pebbles (LECA) sand for aquariums. As for growing flowers with soil, it is better to use peat, perlite, and coconut peat. These three most commonly used substrates can be mixed together, so that most of the potted plants can be used universally.