1. Viscosity is a parameter that reflects whether the mortar is easy to use.
Mortar with normal viscosity can be applied smoothly and will not fall off easily when applied to the wall.
2. When the viscosity is not good, the mortar looks loose and is difficult to construct.
When the viscosity is too high, it will be difficult for the mortar to dry on the wall, and the scraper will easily stick to the scraper when workers rub it, making construction difficult.
3. Another way to adjust the viscosity is to add admixtures.
The viscosity of the mortar will decrease as the sand in the mortar becomes coarser. The dosage of admixture should be increased. When the sand is fine, the viscosity of the mortar will increase, and the amount of admixture should be reduced. Generally, the fineness modulus of controlled sand is optimal within the range of 2.4~2.6. Outside this range. The fineness modulus of sand increases or decreases by 0.1. The dosage of the additive formula should be increased or decreased by about 1Kg/m 3 .
4. Seasons also affect viscosity.
The viscosity of mortar will increase in winter, and the amount of admixture used to adjust the viscosity should be reduced accordingly. When the temperature is high in summer, the viscosity of the mortar will decrease, and the dosage of admixtures will increase accordingly. Generally, for every 5-degree increase or decrease in temperature, the amount of admixture should also increase or decrease by about 1Kg/m 3 accordingly.
5. Materials that have a greater impact on the viscosity of mortar include stone powder.
Too many impurities in stone powder will cause low whiteness. When used in mortar, phenomena such as mortar viscosity difference and mortar bleeding may occur. It is better to control the whiteness of stone powder above 40 degrees. Low whiteness indicates too many impurities. It has a great impact on the quality of mortar.
The drying time of plastering mortar on the wall
1. The drying time of the wall
That is, the time from when the mortar is scraped onto the wall until it reaches a certain degree of water absorption and is slightly hardened so that it can be smoothed.
2. The drying time of the wall is related to four aspects:
the degree of water absorption of the wall, the humidity of the environment, the water retention of the mortar, and the setting time of the mortar.
3. The working principle of wet mortar is:
the water reducing agent provides the smoothness and water retention of the mortar.
The conditioner prevents the hydration of the cement in the mortar, and when the mortar absorbs a little water, it quickly loses its effectiveness in preventing hydration, and the mortar will immediately hydrate and harden. If the mortar cannot absorb water, the mortar can only hydrate normally when the initial setting time is reached.
4. In actual construction, there are several situations:
(1) The wall humidity is normal and the air humidity is normal and the construction thickness is within 2cm.
In this case, the drying time of the mortar on the wall is normal, which is the same as that of the mortar mixed on site. The mortar opening time is adjusted to 20 p.m., which can meet the usage requirements of most construction sites and will not cause long drying time problems.
(2) The wall humidity is very high or the air humidity is very high or the construction thickness exceeds 2cm.
In this case, the drying time of the mortar on the wall will be slightly longer, one to three hours longer than that of mortar mixed on site. The mortar opening time is adjusted to 20 p.m., which can meet the requirements of most construction sites and will not cause the problem of too long drying time.
(3) The wall humidity is very high and the air humidity is very high and the construction thickness exceeds 2cm.
The drying time of mortar on the wall will be very long, and the mortar will not start to collect water and dry until it reaches the setting time. The following measures can be taken to deal with it:
First, it is suggested that the watering time on the construction site wall should be one to two days in advance to increase the water absorption of the mortar on the wall. This method is more direct and effective.
Second, it is suggested that the thick parts should be slurred in advance to a certain thickness to an altitude of about 1~2cm, and can be leveled at once the next day. This method requires two days of construction to complete.
The third is to reduce the amount of water reducing agent to reduce the water retention of the mortar. However, this method will lose the workability of the mortar on the wall.
The fourth is to shorten the opening time of the mortar and allow the mortar to quickly reach the setting time to shorten the drying time.
However, this method can easily cause the mortar to quickly solidify and harden, causing losses. Because the actual environment and temperature changes at the construction site cannot be predicted by humans.