Types and properties of concrete waterproofing agents

(Types and properties of concrete waterproofing agents)

Concrete waterproofing agent and flocculant

The waterproofing agent is a kind of admixture that can reduce the water permeability of mortar and concrete under hydrostatic pressure.

It is a unique admixture used to improve the impermeability of concrete and to improve the watertightness and water quality of concrete.

In the process of mixing concrete, after adding powder, liquid, or emulsion waterproofing agent, the water permeability and water absorption of the material can be reduced, and the waterproof or water-increasing effect can be strengthened.

Types and properties of concrete waterproofing agents

According to its chemical composition, waterproofing agents can be divided into three categories: inorganic waterproofing agents, organic waterproofing agents, and compound waterproofing agents.

(1) Inorganic waterproofing agents, such as chloride (ferric chloride, calcium chloride, etc.), siliceous powder (fly ash, pozzolanic ash, silica ash, diatomite, etc.), wrong compounds, etc.

(2) Organic waterproofing agents: such as water reducers, air entraining agents, fatty acids and their salts (potassium stearate, stearic amine, sodium stearate, oleate, etc.), paraffin and asphalt (paraffin emulsion), water-soluble resins (polyvinyl alcohol, methylcellulose, etc.), organosilicon (sodium methyl silicone, sodium ethyl silicone, etc.).

(3) compound waterproofing agents, such as inorganic compounds, organic compounds, and organic-inorganic compounds.

 

According to the principle of waterproofing, waterproofing agents can also be divided into three categories

1. Anti-seepage waterproofing agent: its function is to reduce the pores of concrete and fill the capillary channel so as to reduce the water permeability of concrete.

These kinds of waterproofing agents are chloride, siliceous powder, wrong compound, water reducer, air entraining agents, and so on.

Among them, ferric chloride waterproofing agent produces calcium chloroaluminate, ferric hydroxide, and aluminum hydroxide colloids in the process of cement hydration, which improves the compactness of cement stone and blocks and cuts off the capillary channel.

The siliceous powder waterproofing agent is excellent and reacts with calcium hydroxide in the process of cement hydration to form colloidal hydrated silicate, which improves the compactness of cement stone.

Water reducer and air entraining agent, first, reduce water consumption and improve the compactness of cement stone; second, refine the pores; and third, introduce a large number of micro-sealed bubbles, cutting off the capillary channel, thus improving the impermeability.

2. Monk water waterproofing agents: such as silicone waterproofing agents, metal soap waterproofing agents (potassium stearate, stearic acid discouraged, sodium stearate), etc., their function is to make the concrete surface and its capillary wall becomes a hydrophobic surface, so as to reduce the water passing capacity caused by capillary action.

3Multifunctional waterproofing agent: this kind of waterproofing agent can not only improve the compactness of concrete but also cut off the capillary channel and make the concrete surface and its capillary wall become a monk water surface, which can plasticize and improve the freeze-thaw resistance.

Inorganic waterproofing agents mainly include chloride waterproofing agents (ferric chloride, calcium chloride), water glass waterproofing agents (sodium silicate), aluminum salt waterproofing agents, and siliceous powder (fly ash, pozzolanic ash, silica fume, diatomite, etc.).

(1) Chloride waterproofing agent. 

It is mainly prepared by calcium chloride, aluminum chloride, and water according to a certain proportion and mixed into concrete. In the process of hydration and hardening of cement, it can interact with cement and water to form double salt, fill the gap between concrete and mortar, and improve the compactness and impermeability of concrete so as to play the role of waterproof and impervious.

Chloride waterproofing agent has the properties of rapid setting, early strength, pressure resistance, waterproofing, impermeability, frost resistance, and so on.

It can be used for roofs, basements, warehouses, underground moistureproof layers, swimming pools, water tanks, etc., waterproof and impervious, and the amount of cement is about 5%.

(2) Ferric chloride waterproofing agent

Ferric chloride waterproofing agent is a strongly acidic liquid formed by a chemical reaction of iron oxide scale (mixture of FeO, Fe2O3, and Fe3O4), iron powder, hydrochloric acid, aluminum sulfate, and industrial hydrochloric acid in a particular order at room temperature.

A ferric chloride waterproofing agent can be used to prepare waterproof mortar and waterproof concrete, as well as other underground and humid concrete, reinforced concrete engineering, and waterproof leakage plugging.

Because a large amount of ferric hydroxide colloid is generated in ferric chloride waterproof concrete, the iron hydroxide colloid film formed around the steel bar can also protect the steel bar from rust.

The amount of ferric chloride waterproofing agent is about 3% of the amount of cement.

(3) Sodium silicate

Water glass series (sodium silicate) waterproofing agent is an oily liquid made of water glass as base material supplemented with copper sulfate, aluminum potassium sulfate, and potassium ferrous sulfate.

Mainly, sodium silicate and cement hydration product calcium hydroxide are used to form insoluble calcium silicate, blocking the path of water so as to improve water tightness.

Other sulfates play the role of promoting cement to produce gel substances to enhance the water tightness of water glass and have the functions of rapid setting, waterproofing, anti-seepage, and anti-leakage. It can be used for waterproofing and leakage plugging of building roofs, basements, pools, water towers, oil depots, and water diversion channels.

(4) Inorganic aluminum salt waterproofing agent

The inorganic aluminum salt waterproofing agent is a yellow liquid formed by a chemical reaction with aluminum salt and calcium carbonate as the primary raw materials and a variety of inorganic salts as ingredients.

It has complete functions of anti-leakage, anti-freezing, heat resistance, pressure resistance, early strength, and quick setting.

It is non-toxic, tasteless, and pollution-free.

The content is 3% to 5% of the amount of cement.

When inorganic aluminum salt is mixed into concrete, it reacts with Ca (OH) 2 formed after cement hydration to form cementitious substances such as aluminum hydroxide and ferric hydroxide. At the same time, it reacts with hydrated calcium aluminate in cement to form double salt calcium sulphoaluminate crystal with certain expansibility.

These colloidal materials and crystals are filled in the pores and voids of cement mortar or concrete structure, which block the channel of water migration and improve the compactness, waterproofing, and impermeability of concrete.

Inorganic aluminum salt is suitable for rigid, self-waterproof, and surface-waterproof layers of concrete and reinforced concrete structures.

It can be used for newly built and constructed waterproofing projects such as roof planes, toilet rooms, building seam, basements, grain depot roof floors, tunnels, sewer, water towers, bridges, water storage tanks, dam grouting, well facilities, and wall moistureproof, etc.

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(Types and properties of concrete waterproofing agents)