Polymer water-based release agents for concrete are widely used in the construction industry due to their environmental friendliness, ease of cleaning, and protective effect on concrete surfaces. However, different formwork materials have different performance requirements for release agents, necessitating comprehensive adjustments based on formwork characteristics, release agent formulation, and construction techniques.
Wooden formwork, due to its porous structure and water absorption, is prone to excessive release agent penetration and rapid consumption, and residual moisture may cause expansion or cracking. To address this issue, the film-forming properties of the release agent need to be optimized by adding high-molecular polymers (such as acrylates or polyvinyl alcohol) to enhance film density, reduce penetration, and extend the protection period. Furthermore, an appropriate amount of wetting agent can be introduced into the formulation to balance the formwork's water absorption and the release agent's adhesion, preventing film embrittlement due to excessively rapid drying. During construction, ensure the formwork surface is clean and dry, and allow sufficient drying time after application to allow the film to fully cure and resist concrete adhesion.
Plastic formwork (such as polypropylene or polyvinyl chloride) has a smooth and highly hydrophobic surface. Conventional release agents often suffer from insufficient adhesion, leading to difficulties in demolding or film peeling. To improve compatibility, the surfactant type of the release agent needs to be adjusted, using nonionic or siloxane surfactants to reduce the surface tension of the solution and enhance wettability. Simultaneously, nano-sized silica or organosilicon modifiers can be added to the formulation to create micro-nano structural roughness, increasing mechanical adhesion without affecting the surface smoothness of the formwork. During construction, a spraying process is recommended to ensure uniform coverage of the release agent and avoid repeated brushing that results in an excessively thick film.
Aluminum alloy formwork, due to its high thermal conductivity and easy surface oxidation, places higher demands on the temperature resistance and rust prevention of the release agent. Under high-temperature environments, ordinary water-based release agents may cause the film to soften and stick to the formwork, while the oxide layer may cause rust spots on the concrete surface. Optimization directions include: introducing high-temperature resistant polymers (such as fluorocarbon resins or silicone resins) to improve the thermal stability of the release agent film; adding phosphate ester rust inhibitors to form a passivation film on the formwork surface to isolate moisture and oxygen. In addition, residual concrete on the formwork surface must be cleaned promptly after construction to prevent long-term corrosion and damage to the release agent film.
The compatibility optimization of steel formwork needs to balance both rust prevention and release. Traditional oil-based release agents, while effective in rust prevention, easily contaminate the concrete surface; water-based release agents require formulation improvements to achieve a functional balance. For example, using a mixture of water-based epoxy resin and rust-inhibiting pigments can form a dense isolation film while also inhibiting electrochemical corrosion through corrosion inhibitors. During construction, the coating thickness must be controlled to avoid excessive thickness leading to pores on the concrete surface, and regular recoating is necessary to repair worn areas.
Composite material formwork (such as fiberglass or wood-plastic composite boards) has significant surface energy differences, requiring adjustment of the release agent's polarity for compatibility. Low surface energy formwork (such as polyethylene) requires the use of fluorinated surfactants or siloxane additives to enhance wettability; high surface energy formwork (such as fiberglass) can improve film adhesion by adding water-based polyurethane. Small-scale tests are necessary before construction to verify release performance and formwork compatibility.
Optimizing construction processes is equally crucial for improving adaptability. For example, wooden formwork requires sealing treatment (such as applying varnish or waterproofing agent) before applying release agent to reduce water absorption; plastic formwork requires increasing surface roughness through plasma treatment or sanding; metal formwork requires thorough rust removal and application of anti-rust primer before applying release agent. Furthermore, controlling ambient temperature and humidity (such as avoiding high temperature and high humidity conditions) and managing drying time (such as extending the drying cycle until the film is fully cured) can significantly improve release performance.
Optimizing the compatibility of concrete polymer water-based release agents with different formwork materials requires a formwork-oriented approach, achieving a functional balance through formulation adjustments (such as polymer type and additive selection) and process improvements (such as surface treatment and construction parameter control). In the future, with the development of nanotechnology and smart responsive materials, release agents are expected to achieve more precise material adaptation and adaptive adjustment, further promoting green and efficient construction in the building industry.
