What are the factors that affect the strength of mortar?

The strength of mortar is mainly based on compressive ultimate strength. According to its compressive strength, the strength grade of mortar can be divided into ml.0, M2.5, M5.0, M7.5, M 10.0, among which m2.5, M5.0 and M7.5 are commonly used. There are many factors that affect the strength of mortar, mainly in the following two aspects: (1. Brick is a water-absorbing material. Although the amount of water applied to the mortar is slightly different, the water retained in the mortar is almost the same after the brick surface absorbs water, so the strength of the mortar mainly depends on the cement grade and cement dosage, and has nothing to do with the water-cement ratio. (2) Mixing time in mortar tank: Mixing time in mortar tank has great influence on mortar strength. Mortar shall be stirred in a mortar tank for at least 1.5 min. Mortar mixed with micro foaming agent should be stirred in mortar tank for not less than 4 minutes and not more than 6 minutes. Mortar should be used with mixing, and cement mortar and cement mixed mortar must be used within 3h and 4h after mixing. If the maximum temperature exceeds 33 degrees Celsius during construction, it must be used within 2 hours and 3 hours respectively. Overnight mortar is strictly prohibited. According to the test, the M5.0 overnight mortar mashed and mixed with water can only reach 3N/mm2 after 28d. M2.5 overnight mortar can only reach 1.4N/mm2. Therefore, the use of overnight mortar will seriously affect the strength of masonry.