How to perfectly control the water consumption of lightweight gypsum mortar

The amount of water directly affects the water-binder ratio, which in turn affects the strength. Problems such as cracks, honeycombs, and pitting caused by excessive water consumption will reduce the durability of lightweight gypsum mortar. As we all know, reducing water consumption can improve the strength and durability of lightweight gypsum mortar while saving some costs, so it should be strictly controlled during the production process.

Factors affecting water consumption

1. Influence of raw materials

(1) The amount of cement and admixtures increases, the storage temperature (sometimes the storage temperature Excessive temperature will lead to rapid collapse and a significant increase in water consumption). The larger the specific surface area, the greater the water consumption of light gypsum mortar. The amount of water used for the standard consistency of cement directly results in the amount of water used. Poor adaptability of cement and admixtures will lead to changes in the proportion of water used.

(2) The higher the mud and powder content of sand and stone, the worse the continuity of particle gradation, and the greater the water consumption. The accuracy of moisture content detection directly affects the amount of water consumption. The moisture content of newly entered sand and gravel often varies greatly from the top to the bottom of the pile. It should be measured multiple times during use, otherwise the slump will be greatly affected during production.

(3) The type of admixture, the water reduction rate of the admixture, the amount of air-entraining agent, and the difference in adaptability to cement.

(4) Various properties such as loss on ignition, fineness, water demand ratio, etc. of fly ash and mineral powder, as well as the amount of cement replaced.

(5) The use of other materials, expansion agents, fibers, synergists, etc. has greatly increased or reduced water consumption.

(6) Different levels of sewage have different effects on the performance of lightweight gypsum mortar, which should be verified before being determined.

The dosage and performance of each material may directly affect the amount of water consumption. All materials should be tested and verified one by one before actual production to determine the reasonable water consumption. .

2. The impact of measurement and machinery on water consumption

(1) All material scales used in the production of building mixers and all testing equipment in the laboratory should be self-calibrated regularly and relevant testing departments should be entrusted regularly. Perform accurate verification. As the saying goes, "a slight mistake can lead to a thousand miles of misunderstanding."

(2) You should also regularly check whether the position of the sensor has changed, whether there is a backlog of dust on the scale, whether the dust bag will cause overweighing or underweighing, and whether there is any dripping of additives and water on the scale. , automatic detection of moisture content, regular detection of whether it is accurate, etc.

(3) In addition, the order of blending first and then adding additives also has an impact. Generally, the post-mixing method has a higher utilization rate of additives, and the machine can be modified appropriately.

(4) The mixing uniformity of different machines is different. Regular maintenance should be carried out to ensure that the blades and bearings of the mixer are not worn too much and that the belt is not spilled. Sometimes there is a unified proportion and the water consumption of different mixers for the same material varies greatly.

(5) The use of waste materials under the belt should be eliminated or must be processed and verified before use. Prevent site cleanup workers from using cleanup debris in lightweight gypsum mortar. Some small stations, in order to save trouble, believe that a small amount of garbage has no impact, which sometimes leads to an increase in water consumption and even the phenomenon of light gypsum mortar not setting for several days.

3. Slump requirements

Different construction parts have different requirements for slump. When high-rise lightweight gypsum mortar, underwater cast-in-place piles, bored piles, and steel bars are denser, the slump requirements are generally larger, and the workability is also required to be better. However, the requirements for the cap platform, floor, foundation, post-casting belt, etc. should not be too large. Therefore, the proportion of water consumption should be adjusted in advance according to different construction parts.

4. Personnel aspects

The technical level, experience and sense of responsibility of the personnel directly affect the accuracy of water consumption. The operator can directly determine whether the material is normal or not based on basic control standards such as slump and gravel consumption. The operator can make a preliminary judgment based on the size of the ammeter and intuitive judgment on the display. Production control personnel will then conduct sampling testing for confirmation and maintain a certain frequency.

5. Influence of weather and temperature

Due to the high temperature in summer, the temperature of raw materials such as sand and stone will rise, and even complete water loss in the air will cause water absorption. The slump loss in summer is also faster than in other seasons. The slump-preserving and retarding components of the admixture should be appropriately adjusted. In the high wind season in autumn, because the weather is too dry, attention should be paid to the moisturizing of the lightweight gypsum mortar, and the water consumption of the lightweight gypsum mortar should not be increased to increase the slump. Control all transportation links to avoid the mixer truck waiting too long at the construction site, plan the driving route to avoid traffic jams on the road, and prevent drivers and construction workers from adding water to the lightweight gypsum mortar in pursuit of construction speed. During the low temperature season in winter, water consumption should be reduced to avoid excessive free water, which may cause the lightweight gypsum mortar to freeze.

How to achieve low water consumption

(1) Strictly test the performance of each material and control the above factors to reduce water consumption.

(2) Increase the dosage of admixtures or use admixtures with high efficiency and high water reduction rate, and select admixtures and cement varieties with better adaptability.

(3) Improve the sand and gravel gradation and find out the sand and gravel gradation for each mix ratio to improve it.� Workability, thereby reducing water consumption.

(4) Improve workability by using high dosage of cementitious materials.

(5) Even if the silo is covered, the moisture content of the sand and gravel should be tested multiple times, and the sense of responsibility should be strengthened to ensure that the slump of each plate of light gypsum mortar is within the control range.

(6) It is very important to communicate with the construction side of the construction site. To obtain the understanding of the construction personnel, cooperate with the construction side's technical personnel to avoid excessive slump. Correct understanding: It is not that the greater the slump, the easier the pumping will be, but the workability and the amount of gravel should be adjusted

(7) Usually the actual water consumption in production and the trial water consumption Amounts will vary greatly. Therefore, it is necessary to strictly select materials that are superior to or close to the content of the trial fit. The water-to-cement ratio should be controlled more strictly than the trial fit to ensure that there is sufficient excess strength and that the final materials entering the construction site are qualified. Maintain the principle of production over trial fitting.

Methods for determining water consumption

(1) Through a large amount of test data analysis, accumulate a large amount of test data to make accurate judgments.

(2) Confirm the water consumption by collecting materials on site and conducting a small-volume trial mix (1~2L) before pre-production.

(3) Carry out more sampling and do more opening appraisals to confirm adjustments.

(4) The first car and the first plate of materials must be sampled for testing before starting work.

(5) The first vehicle will go to the construction site to confirm the slump and workability, etc., and provide timely feedback to the production control personnel through phone calls, WeChat videos, etc. Maintain timely communication with construction personnel on the construction site to ensure quality fluctuations.

(6) All information must be prepared in advance. Generally, night shift workers summarize all materials, production, and construction site information in advance before starting work in the morning, and conduct unified discussions in the form of group meetings. Confirm the adjustment of water consumption and mix ratio, and avoid many detailed problems.

Strict control of process water consumption to avoid errors and mistakes. It is necessary to formulate a rigorous work process, strictly check every detail and every key link, and improve everyone's sense of responsibility. Science is rigorous and there is no room for sloppiness. Don't neglect quality control at work due to temporary greed or irresponsibility. </p