Crystallizing Admixture For Waterproof Concrete From Mapei

feature-top Fig.1: Crystallization Process

Concrete is one of the most commonly used building and construction materials. However, due to its composition, is often susceptible to damage and deterioration from water and chemical penetration. The durability of concrete as a construction material and the durability of reinforced concrete structures under different environmental conditions are probably the least understood attributes of concrete. No simple theory applies and only incremental advancement based on experiences gained through practice can be achieved.
Concrete can be considered as a micro porous and permeable material. Porosity refers to the number of voids left in concrete and how well the voids are connected. Even though concrete is a durable material requiring a little or no maintenance in normal environment, but when subjected to highly aggressive or hostile environments, it has been found to deteriorate resulting in premature failure of structures or reach state requiring costly repairs. If this is not waterproofed it can absorb water and aggressive chemicals. To avoid this, Crystalline waterproofing admixture can be used to block the movement of water. The basic idea behind crystalline waterproofing is to prevent the movement of water through the concrete by plugging or blocking the pores, capillaries and micro cracks found in all concrete. This stands in contrast to more conventional means of waterproofing, which usually involves applying a coating or membrane to the concrete surfaces, but is sometimes also attempted through densification of the concrete.
When added to concrete, crystalline admixture creates a reaction that causes long, narrow crystals to form and fill the pores, capillaries and hairline cracks of the concrete mass. As long as moisture remains present, crystals continue to grow throughout the concrete. Once the concrete has cured and dried, the crystalline admixture sits dormant until another dose of water (such as through a new crack) causes the chemical reaction to begin again and grow crystals to shut off the water. This self seals the concrete there by avoiding minor cracks and helps to reduce the long term maintenance and repair costs of a concrete structure. Crystalline Waterproofing admixtures contributes many beneficial properties to a given project, including:
- Protection – Ability to improve the self-sealing ability of concrete. Due to the potency of the crystalline chemicals, only a small portion is required to facilitate a large amount of crystal growth. The chemicals lay dormant so when future cracks occur, triggering new crystal growth that seals the crack;
- Easy To Apply – Crystalline waterproofing admixtures comes in a powder form and is conveniently and easily added to new concrete at the time of batching, either in a ready-mix truck or at the plant. The chemicals create a powerful water barrier, which leaves no need for any surface applied product at the jobsite;
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Mapei Construction Products India Pvt. Ltd.,
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- Sustainable & Reliable – Crystalline Waterproofing admixtures is a permanent solution to concrete waterproofing needs. It is impervious to physical damage or deterioration, and can reduce shrinkage cracking. It’s non-toxic, safe for use in portable water and contains no volatile organic compounds (VOCs); and
- Saves time & Money – The use of crystalline admixtures can accelerate a project’s schedule by eliminating the need for a traditional surface applied membrane. Backfilling can begin right after concrete has set, lowering the cost of labour and materials. Crystalline waterproofing admixture can also be used with structural shotcrete.
Mapei’s Idrocrete KR1000 is a powder admixture made from special hydrophilic components which, when added to a concrete mix, reduces the permeability of hardened concrete. Idrocrete KR1000, when mixed with water reacts with the Calcium hydroxide and other products that form during the hydration process of the cement to form compounds of calcium silicate and other non-soluble salts. The crystalline compounds and calcium silicate hydrate are deposited in the voids of the cement matrix and reduce its total porosity, thereby increasing the resistance of the concrete to the penetration of water under pressure. Idrocrete KR1000 may be used with any type of concrete when a reduction of permeability is required. Once Idrocrete KR1000 is added to the mix, it reacts with water reducing the entire service life of the concrete. Idrocrete KR1000 is used to produce concrete for the following applications:
- Dams
- Bridges
- Car parks
- Storage tanks
- Pipes and piles
- Retaining walls
- Tunnels
- Marine structures
- Basement and foundations
- Swimming pools
- Precast elements
Idrocrete KR1000 reduces the permeability characteristics of concrete. Laboratory tests have shown that adding Idrocrete KR1000 to concrete reduces its level of capillary absorption and makes it more resistant to the hydrostatic pressure. The crack bridging ability of Idrocrete KR1000 allows to close micro cracks up to 0.4mm. Idrocrete KR1000 is compatible with all Mapei admixtures used in the production of high quality concrete, particularly:
- WR and HRWR admixtures from Mapeplast, Mapefluid and Dynamon ranges
- Set retarding admixtures from the Mapetard range to extend and maintain the workability of concrete
- Chloride-free, hardening-accelerator admixtures from the Mapefast range to achieve very high mechanical strength after short curing cycles, even in cold climates
- Viscosity modifying admixtures from the Viscostar and Viscofluid range used to make self-compacting concrete
- Expancrete expanding agent used in the production of shrinkage compensated concrete
- Air entraining admixtures from the Mapeiair AE range used in the production of concrete resistant to freeze/thaw cycles
- Alkali-free accelerator for shotcrete from the Mapequick AF range
- Form-releasing agents from the Mapeform, Mapeform Eco range and DMA range for stripping formwork from concrete
- Curing agents from the Mapecure range used to reduce the risk of plastic shrinkage cracks in concrete
Idrocrete KR1000 is a versatile crystalline waterproofing product that provides enhanced benefits of reducing porosity and permeability of concrete. The crystals grow relatively fast and minimises pore volume and become integral part of the concrete structure.