1. the magnesium oxide content in the expansion agent shall not exceed 5% (except for the magnesium-containing expansion agents currently on trial). the later expansion of magnesium will cause the hardened concrete structure to crack. the most important physical properties are that the expansion at 7 days of age should not be less than 0.025% and the shrinkage rate (i.e. negative expansion) of 7 days in water + 21 days of curing in air should not be large, so that it is a high-quality expansion agent.
2. expansion agents are mainly used to prepare shrinkage-compensating concrete, expansion concrete for filling and expansion mortar for grouting.
concrete mixed with expansion agent is suitable for reinforced concrete projects and filled concrete projects.
the expansion-compensating shrinkage concrete rigid roof is suitable for use in southern areas.
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