Cracks Self-Heal and Pourable Even in Rain...Special Concrete Market Expands

Special concrete that can self-repair cracks and be poured even in the rain is expanding the market. According to the ready-mixed concrete industry on the 31st, major companies are developing and commercializing special concrete using their patented technologies.

Special concrete is being poured at a construction site in downtown Seoul.
[Photo by Asia Economy DB]

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Yujin Corporation has commercialized and is actively using self-healing concrete made from smart materials containing an expansion agent, cement reaction accelerators, and carbonate compounds. Self-healing concrete fills cracks with a width of 0.3 mm or less by itself. The smart materials mixed inside the concrete react with water during rainfall to form crystals that expand and seal the cracks.

This concrete was mainly used for water treatment structures directly exposed to water, such as water purification plants, sewage treatment plants, underground tunnels, and waterways. It prevents loss of structural function due to leakage caused by cracks through self-healing. Since last year, Yujin Corporation has also been using this concrete on the exterior walls of general residential buildings. Since its commercialization in 2022, shipments of self-healing concrete have increased by 300% through the first half of this year.

Sampyo Industry’s main special concrete product is the 'Bluecon' series, which uses admixtures with high fluidity and increased viscosity. Last month, they developed 'Bluecon Rain OK,' which allows concrete pouring even during rain. By adding water-soluble polymers to the concrete to increase viscosity, the compressive strength when water penetrates the concrete is higher than when dry. When rainfall is less than 4 mm per hour, the compressive strength is 33% higher compared to regular concrete.

The 'Bluecon Self,' a self-compacting concrete that can spread and fill densely without separate compaction work and is also noted as a solution for inter-floor noise, is also popular. It can reduce concrete pouring work speed by about 50%, minimize on-site labor, and allow pouring without vibrators, which are the cause of noise and vibration complaints.

Sampyo Industry launched special concrete in 2018, and sales of special concrete increased by 121% the following year. Sales in 2023 are ten times higher than in 2019, and the company expects a 166% sales increase this year as well.

Ajoo Industry is targeting the special concrete market with 'medium-thickness concrete,' a type of low-carbon concrete. When vertically and horizontally extending and remodeling over 30-year-old apartment complexes in first-generation new towns in the metropolitan area, new concrete is applied over existing concrete. However, general concrete has unstable adhesion, causing gaps and finishing issues. Medium-thickness concrete completely fills the gaps without resistance between materials.

Ajoo Industry also widely uses ultra-high-performance concrete (UHPC), which has six times the compressive strength of general concrete while maintaining excellent flexibility, allowing various shapes and coloring. The UHPC applied at The Hyundai Seoul in Yeouido, Seoul, produces a luxurious color different from conventional concrete. Ajoo Industry’s UHPC sales are expected to increase from 424 million KRW last year to 1.7 billion KRW this year.

An industry insider said, "Using special concrete shortens pouring time, resulting in cost savings," adding, "Although it is about 1.5 times more expensive than regular concrete, demand is increasing due to its various advantages."

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