Landcel introduces you to the possible problems when using construction mortar.

1. What are the reasons for the constructional hollowing of mortar?

Answer: The hollowing of mortar construction refers to the phenomenon of peeling between the mortar layer and the interface agent layer.
The reasons for this phenomenon are uneven interface treatment and insufficient roughness. The mortar is rubbed and pressed before the water is collected, and the mortar adhesion is poor.

2. How to prevent construction hollowing of mortar?

Answer: Improve the uniformity and roughness of the interface mortar during interface treatment. It is recommended that workers rub and press the surface after collecting water to avoid excessive water dissipation, and at the same time improve the adhesion of plastering mortar.

3. How to define the mortar entering the winter construction period?

Answer: When the construction site (the average outdoor temperature measured at 6:00, 14:00, and 21:00 every day) is lower than +5°C or the lowest temperature is lower than -3°C, and the average day and night temperature is lower than 5°C for five consecutive days, it is considered Entering the winter construction period.

4. Can antifreeze be added to the mortar for antifreeze?

Answer: At present, ordinary plastering mortar belongs to thin layer plastering, and the thickness of plastering is about 1.5cm-2cm. During the construction period in winter, if there is no good heat preservation treatment, antifreeze cannot be carried out.

5. How to control the thickness of mortar aggregate?

Answer: It is ideal to control the fineness modulus of sand between 2.3 and 2.7. If there is enough sand site, fine sand and coarse sand can be used in combination to adjust the fineness modulus of the sand. The fineness modulus of masonry mortar is relatively large, 2.8-3.0 is enough.

6. What is the control range of mortar bulk density?

Answer: If natural sand is used, mortar can be divided into masonry, plaster, and ground mortar according to different construction sites. The masonry mortar is controlled at 1800±30g/L. Plastering mortar is controlled according to 1750±50g/L. The ground mortar should not be lower than 2000g/L. (If machine-made sand or tailing sand is used, it needs to be adjusted according to the actual situation)

7. In what range should the consistency of the plastering mortar be controlled?

The discharge control is within the range of 85mm-95mm, which is suitable for workers’ construction requirements. If the consistency problem cannot be reasonably controlled, it is recommended that the consistency is rather dry than thin. If the temperature is high in summer and the water evaporates quickly, the consistency of the mortar should be controlled to be larger, preferably about 100mm.

8. How long can the surface be finished after the mortar is applied to the wall?

Generally, it is more appropriate to close the surface about 30-40 minutes after the wall is completed.

9. What is the mixing time for wet-mixed mortar?

The mixing time of the wet-mixed mortar should be determined through experiments with reference to the technical parameters of the mixer, the mortar mix ratio, the type and amount of admixtures and additives, and the amount of feed. The mortar mixture should be stirred evenly, and the stirring time should not be less than 30 seconds after all the materials are cast.

Mortar is made by mixing a variety of different components. During the mixing process, a series of complex physical and chemical effects will occur between the components, which will take a certain amount of time.
Only after a certain period of time and strong external stirring can the components of the mortar be homogenized, and the role of each component material can be fully exerted, so that the mortar can achieve the required performance. Therefore, it is required that the minimum mixing time of wet-mixed mortar should not be less than 90s, generally 120s.

10. Is the higher the strength of the plastering mortar, the better?

Different substrates of plastering mortar require different mortar strength grades. The greater the mortar strength grade, the greater the amount of cement, and the greater the amount of cement, the greater the shrinkage of the mortar when the cement is hydrated. For the wall substrate, its shrinkage rate is tens of times or hundreds of times different from that of mortar
The greater the shrinkage, the greater the stress between the mortar and the substrate, and the greater the risk of mortar cracking.