What is the difference in the effect of polypropylene fiber and expansion agent?

Adding expansion agents and fibers to concrete can achieve the goal of crack resistance and seepage prevention. But there are certain differences in the principle of action and efficacy.

1. Principle: Expansion agents generate ettringite or calcium hydroxide crystals through chemical reactions, causing concrete to expand to compensate for its shrinkage, thereby reducing or preventing the occurrence of concrete cracks. Fibers reduce the occurrence of concrete cracks through physical action.

2. Effect: Expansion agents can only achieve good crack resistance and anti-seepage effects in humid environments. If in a dry environment, it may not be effective or even have the opposite effect; And fibers can achieve good crack resistance and anti-seepage effects in both humid and dry environments.

3. Construction conditions: The expansion agent has very strict maintenance conditions, requiring water storage and maintenance for more than 14 days. There are no special requirements for fiber maintenance.