Overview
Expansive mortar is a specialized chemical demolition agent primarily composed of calcium oxide (quicklime) with proprietary additives. When mixed with water, it undergoes a hydration reaction that produces substantial expansive force—up to 50 MPa—capable of fracturing rock or concrete without vibration, noise, or flying debris. Developed as an eco-friendly alternative to explosives, it revolutionized demolition in sensitive environments like urban areas and heritage sites. First commercialized in Japan during the 1970s, modern formulations achieve controlled expansion rates through calibrated particle sizes and retarders. The material is particularly valued for precision work in marble quarries, tunnel engineering, and infrastructure decommissioning where traditional blasting is prohibited.
Physical and Chemical Properties
The active ingredient (CaO) reacts with water via CaO + H₂O → Ca(OH)₂ + heat, generating calcium hydroxide with a theoretical volume increase of 212%. Commercial products achieve 100-120% practical expansion within 10-24 hours, depending on ambient temperature and water-to-powder ratios (typically 25-35% by weight). Key performance metrics include expansion onset time (adjustable from 30 mins to 2 hrs via retarders) and peak pressure duration (usually 6-12 hrs). The exothermic reaction reaches 80-100°C, requiring careful handling. Unlike explosives, the pressure develops gradually, allowing predictable fracture patterns along pre-drilled holes (30-50mm diameter, spaced at 15-20cm intervals).
Main Applications
In quarrying, expansive mortar enables block extraction with minimal waste—critical for high-value materials like granite and marble where saw cuts would reduce usable volume. Operators drill hole patterns, pour the slurry, and achieve clean fractures within 24 hours, preserving stone integrity. Construction demolition projects utilize sequential cracking for structural control, especially in confined spaces. A notable case is the Tokyo Metro renovation, where SCA removed 12,000m³ of concrete within 2m of operational tunnels. Emerging applications include underwater demolition (with waterproof sleeves) and archaeological site preparation, where shock-free operation preserves adjacent artifacts.
Safety and Storage
Though non-explosive, improper handling can cause chemical burns from the exothermic reaction or dust inhalation. Suppliers provide MSDS sheets detailing: (1) mandatory PPE (nitrile gloves, dust masks, and face shields), (2) first aid measures (copious water flushing for skin contact), and (3) spill control (absorb with inert material like sand). Storage requires airtight containers in dry warehouses (<40% RH). Bulk bags should be palletized and covered with moisture barriers. Shelf life degrades upon exposure to humid air—test batches with 10% water before large-scale use if storage exceeds 6 months. Never mix with acids or organic compounds, which may trigger violent reactions.
B2B Procurement Guide
Industrial buyers should evaluate: (1) expansion pressure certification (ISO 9001 manufacturers provide lab test reports), (2) temperature stability (high-grade products work from 5°C to 40°C), and (3) packaging options (25kg bags with inner liners for humid climates). Leading manufacturers like Denka (Japan) and NCT (China) offer technical support for hole pattern design. Sample testing is advised—typical parameters are 3kg/m³ consumption for medium-hard rock. Logistics require waterproof transport; sea shipments need desiccant packs. Contract terms often include MOQs of 20 tons, with spot prices fluctuating with lime market trends. Consider blended procurement with retarder additives for winter operations.
Related Manufacturers
- 主营：高效无声破碎剂、静态破碎剂、无声膨胀剂、岩石膨胀剂、岩石破碎剂、混凝土破碎剂、矿山开石剂