Terrazzo is a commonly used building decoration material. Because of its abundant sources of raw materials, low price, good decorative effect, and simple construction technology, it has been widely used. Terrazzo is also a kind of artificial stone. It uses cement as cement and mixed with marble or granite gravel of different colors and particle sizes. After mixing, shaping, curing, grinding and other processes, an artificial stone with a certain decorative effect is made.
1. The construction operation procedures are as follows
Leveling layer construction - fixed grid strips - plastering - polishing - waxing
2. Operation points
(1) Leveling layer construction
The cement mortar leveling layer construction technology mainly controls the following issues.
A. Grassroots cleanup. Holes on the terrazzo floor and weak bonding are often caused by insufficient cleaning of the base layer and debris that affects the bonding. Therefore, in terms of process arrangement, cleaning the base layer should be completed as a process. In other words, the next process cannot be carried out without cleaning the base layer.
B. The consistency of the cement mortar should be appropriate and the mixing should be uniform. On-site mixing in piles, manual mixing, and on-site sharing should not be advocated. If there are drainage slope requirements, special attention should be paid to the direction of flooding and the location and elevation of floor drains, which should be completed accurately during the construction of the leveling layer. It is inappropriate to do the leveling layer carelessly and then find the slope for the surface layer. In order to better control the drainage slope, if an inspection process can be added after the leveling layer is completed, if any defects are found and dealt with in time, the slope problem can be better solved. At the same time, it should also be noted that while strengthening the construction of civil works, It is also necessary to cooperate with the equipment work types to solve the problems of construction period, progress, elevation and protection of the two types of work.
C. Pay attention to check the quality of the structure, such as cracks in the floor slab. If cracks are found, the attention of the relevant units should be brought to the attention, and judgment and treatment opinions should be made. In recent years, terrazzo floors have often been affected by cracks in the floor slab (other surface layers will also encounter similar situations). It is best to deal with the cracks that need to be treated before the construction of the leveling layer. If you deal with it after the surface layer is completed, it will inevitably affect the integrity of the color of the surface layer and cause traces of joints. For floors where water often flows, such as bathrooms, kitchens, etc., you also need to pay attention to the work of wiping the floor drain and plugging the holes through the floor, because once water penetrates these parts, they must be repaired. Renovation will destroy part of the surface layer. Although it can be repaired, the connection between the previous and later constructions is relatively obvious. Before making the leveling layer, special attention should be paid to these issues. After the construction of the leveling layer is completed, water should be sprayed and cured 24 hours later. After curing for 2 to 3 days, the surface layer can be constructed.
(2) Fixed grid strips
The existing terrazzo floor is inlaid with grid strips, which not only increases the beauty of the ground, but also facilitates construction. Therefore, the existing terrazzo floors are all equipped with grid strips. To inlay the grid strips, you must first snap the line and pop the location of the grid strips onto the leveling layer. The elastic lines are mainly based on the design requirements for the divisions and combined with the plane dimensions of the construction site to be accurate and fully reflect the design intention. Some designs do not specify the size and direction of the partitions. When determining the partition size, 1 to 1m is generally used. It is advisable to divide the partitions from the middle to both sides, and drive the non-whole pieces to the corners. Sometimes it is also necessary to consider the position of the door and the pattern and division of the ceiling, so that the divisions of the ground and the divisions of the ceiling echo.
Use plain cement slurry to fix the partition strips. Within a partition, first use plain cement slurry to partially fix it, and then pull through the upper part for inspection. After passing the inspection, all the parts will be plastered into a figure-eight shape of cement. Pulp. The height of cement slurry generally accounts for about 70% of the height of the partition strips. Generally, 3 to 4 mm should be left on the upper part, which is not suitable for applying cement slurry. As shown in the picture. This will allow the stone ballast to be spread evenly on both sides of the grid strips.
At the vertical and horizontal intersections of the grid strips, leave 4~5cm free of plain slurry to avoid sparse stone ballast there. The dividing strips should be selected before use. If the corners are damaged, pay attention to the direction of use, so that the damaged side faces downwards. Straighten copper and aluminum strips that are not bent straight before use. Glass partitions are easily broken and damaged, so be careful to keep them. For grid strips made of various materials, attention should be paid to the neat corners at the ends to avoid obvious joints at the splicing joints.
After the grid strips are fixed, attention should be paid to protection and proper watering and maintenance. Misplaced grid strips should be replaced in time. The grid bars are fixed as shown in the figure below.
(3) Plastering the surface
The dividing strips are fixed for about three days. When the dividing strips are stable, the surface can be plastered, commonly known as plastering.
First of all, the leveling layer should be cleaned, and any floating dust or broken gratings should be cleaned up. In order to make the surface mortar and the leveling layer bond firmly, wet the leveling layer before plastering the surface layer, and then apply a layer of plain mortar. The surface layer should be applied from the inside out. After installing a piece, tap it gently with an iron trowel and then smooth it out. Finally, use a small ruler to place on the grid strips on both sides to check the flatness and elevation, and finally roll it with a roller.
If the area is too high, use an iron trowel to dig out the excess part, and then tap and smooth the dug-out part. Do not use a scraper to scrape it flat, as this can easily lead to uneven distribution of stone ballast, or a small amount of local stone ballast, resulting in overall non-uniformity. Use a trowel to tap with moderate force, so that the surface is flat and the stone ballast is stable.
The surface plastering should be 1 to 2 mm higher than the grating. After polishing, the surface layer and the grid strips can remain consistent.
If artistic terrazzo is used, it is advisable to apply the surface mortar of the same color first before making another color to avoid confusion or color differences. Use surface layers of different shades on the same ground. When spreading ash, it is better to lay the dark part first and then the light part. The mixing and dosage of surface pigments, as well as the dosage of different specifications and colors of stone ballast, should be handled by dedicated personnel. In particular, the amount of pigment added should be strictly measured. Mix the pigment into the cement, dry mix it evenly first, and then mix the washed stone ballast with the cement. The consistency of cement ballast slurry is about 6cm. Before large-scale construction, it is advisable to make a small prototype first. After the design is confirmed, it can be expanded to a large area.
The proportion of surface cement ballast slurry varies slightly depending on the particle size of the ballast, and may also vary due to different requirements for decorative effects. The commonly used ratio is: cement: ballast = 1:1.5~2 (volume ratio). If you want to obtain denser stone ballast on the surface layer and increase the beauty, you can also spread a layer of stone ballast on the surface after patting it flat during construction, and then pat it flat and steady. But it should be noted that the ballast should be spread evenly and in an appropriate amount.
(4) Polishing
Polishing is an important process for the effect of terrazzo. The main purpose of polishing is to remove the cement slurry on the surface layer and smooth the stone ballast on the surface.
There are two types of polishing: mechanical polishing and manual polishing. If construction conditions permit, mechanical polishing should be used as much as possible, which not only results in faster work, but also reduces labor intensity. If you choose to use a polishing machine for polishing, you will generally use abrasive tools. The structure of abrasive tools generally includes abrasive grains, binders, pores and fillers.
Abrasive grains are the main body of the grinding tool, and the edges and corners exposed on the surface of the grinding tool are used as cutting edges to cut terrazzo. Abrasives are made of various materials, such as quartz sand, corundum, natural diamond, carbide, etc. According to different uses, the abrasives are processed into particles of different diameters. According to the Chinese standard GB2477-81, the particle size of abrasives is divided into four categories and 31 numbers according to the size of the particles. The specific classifications are detailed in the table below.
Grinding grains, grinding powder, micro powder, fine powder
12#, 14#, 16#24#, 36#, 46#60#, 70#, 80#?100#,120#,150#180#,240#,280#?W63,W50,W40W28,W20,W14W10,W7,W5?W3.5,W2.5W1.0,W0.5
Binder is the bonding material of abrasive tools, which serves to consolidate the abrasive grains and make them into abrasive tools with a certain shape and strength.
The pores are the gaps inside the grinding tool. During grinding, they have the function of excluding grinding and containing cooling water. Due to the large amount of chips generated during rough grinding of terrazzo, if the grinding tool structure is tight and the space for holding grinding chips and cooling water is small, it will not only burn the board, but also affect the gloss of the board surface. Therefore, in order to overcome this phenomenon, some soft materials, such as aerated concrete or perlite particles, are generally added inside the grinding tool structure.
There are two main points to control when polishing. One is to control the polishing time; the other is to master the number of polishing passes. If the grinding time is not properly controlled, work efficiency and quality will be affected. If the cement ballast slurry is ground too early and the strength of the cement ballast slurry is too low, the ballast will loosen or even fall off. If the grinding time is late, the strength of the cement ballast slurry will be high, which will make polishing difficult. To achieve the same effect, the time spent will be correspondingly longer.
Different cement grades, different proportions, and different temperatures all have an impact on the hardening and strength growth of cement ballast slurry. To obtain the appropriate grinding time, the best way is to determine it through trial grinding. The general principle is to grind without removing stone particles. The following table is the reference time for grinding time under different temperatures.
Method? Temperature (℃)
5～10?10～20?20～30
Mechanical polishing (d) Manual polishing (d) ?5～62～3?3～41.5～2.5?2～31～2
Note: The number of days is calculated from the completion of terrazzo compaction and troweling.
The number of polishing passes is different for different grades of terrazzo floors. The current ordinary terrazzo generally needs to go through no less than "two slurries and three grindings" to achieve the desired effect. For high-end art terrazzo, the number of polishing passes should be appropriately increased and the fineness of the oilstone should be increased. Normally, a coarser grinding wheel should be used for the first polishing, usually No. 60 to No. 80. This time requires smoothing and grinding so that all the stones and grid strips are clearly exposed. After the first pass of polishing, drain off the turbid slurry, rinse the surface with clean water, and then use a ruler to check the surface flatness. In the first pass, because the grinding wheel is thicker, the surface has a certain degree of wear marks. In addition, grinding off a layer of cement slurry exposes surface defects, such as blisters, small holes, bubbles, etc. These surface defects should be repaired with cement slurry of the same color as the surface layer, commonly known as grouting. After curing for 2 to 3 days, the second polishing can be performed.
For the second polishing, use a finer grinding wheel than the first time, and use the same grinding method as the first time.
This time it is required to remove the wear marks and polish the surface. For local pitting and small defects, repair them with cement slurry of the same color. After curing for 2 to 3 days, the third polishing can be carried out.
For the third time, use a fine grinding stone of No. 180 to No. 240. This time, the surface should be smooth and flat, without blisters or pores, and the stones should be exposed evenly. Since the machine is not easy to control, the corners should be re-grinded by hand and finally rinsed with water.
(5) Waxing
The purpose of waxing is to make the terrazzo floor brighter, smoother and more beautiful. At the same time, it is easy to maintain and clean because of the thin layer of wax on the surface. Waxing can only begin after the surface layer is completely dry. Before waxing, in order to make the wax liquid better adhere to the surface layer, the surface layer should be scrubbed with oxalic acid. The main function of oxalic acid is to clean the residual cement slurry and fine stone powder on the surface layer, so that a small amount of suspended slurry and powder substances deposited on the surface can be eliminated through the action of oxalic acid. Oxalic acid is oxalic acid, with the chemical formula (COOH)2, and is the simplest dicarboxylic acid. Colorless crystal, easily soluble in water. Oxalic acid is prone to chemical reactions with calcium hydroxide in cement, and has slight corrosion and surface decontamination effects on the layer. Therefore, scrubbing with oxalic acid before waxing can ensure the bonding between the wax liquid and the surface layer and improve the wax-finding effect.
When using oxalic acid, first dissolve it with water into a 10% oxalic acid solution, sprinkle it evenly on the surface, then grind it lightly with a whetstone, and then rinse it with water. After the ground is dry, you can wax it. .
Waxing is also called rubbing wax. Floor wax is generally used. It is a wax product that protects and decorates the floor. It is made of natural wax or solid paraffin wax extracted from petroleum and solvent. You can also use 1 pound of Sichuan insect wax and 4 pounds of kerosene, boil it in an iron bucket at 130°C (white smoke is emitted), add six ounces of pine perfume (No. 200 solvent gasoline), and one ounce of fish oil to prepare it.
The following two methods are commonly used for waxing. One is to use cotton gauze (or thin cloth) dipped in finished wax and rub a layer on the surface. After drying, use a stone grinder to tie a sack (or hemp) roll, and rub it several times until it is smooth and bright. Another method of waxing is to apply the finished wax on the surface, bake it with a blowtorch to allow the melted wax liquid to penetrate into the pores, and then polish it.
The waxed floor should be bright and smooth, with a flat and delicate surface, clear and beautiful stones, and uniform color. If there is dust locally, you can use a mop dipped in a small amount of kerosene to gently wipe it off.
3. Common quality defects and prevention in projects
(1) Hollowing on the ground
Hollowing on the existing terrazzo floor is more serious than other types of floors. The main reason for this is that the terrazzo floor has many layers. Different time, different material processes, and improper handling may affect the bonding and cause hollowing. The main manifestations of hollow drum are: A. The bond between the surface layer and the base layer is not strong, causing hollowing. B． The bond between the surface layer and the leveling layer is not strong, causing hollowing.
The main reason is that the base layer is not cleaned enough, such as ash, debris and other additional materials, which will affect the bonding between the two layers. In addition, the slurry bonding layer is not swept carefully, which is also the cause of hollowing. It can be seen that the cleaning of the base layer is a key factor affecting the bonding.
The hollow drums on the surface layer need to be dealt with, especially the hollow drums with large areas of cracks, the service life will be greatly affected. However, when dealing with existing terrazzo floors, when dealing with hollowing problems, attention should be paid to keeping the repaired color as consistent as possible with the original floor color. When repairing, try to make the size of the piece to be repaired regular. If the whole piece can be repaired within a grid, the effect will be better.
(2) Uneven exposure of stones
Essentially reflects the problem of ground flatness. Especially when there are footprints on the surface, if not dealt with in time, the footprints will sink slightly. In addition, if your feet step on a softer surface, the stones at the footprints will sink and the upper part of the cement slurry will increase. When polishing, the slight sinking of the footprint affects the polish. Therefore, it seems that the stones on the surface are not uniform and clear enough.
The main reason for this phenomenon is that the operator should arrange the construction procedures well and try to avoid a large number of penetrations on the smoothed surface. In addition, you should try to wear flat-soled rubber shoes during construction, and do not wear high-heeled shoes or rubber shoes with obvious convex soles.
(3) The lattice strips are unevenly exposed
The lattice strips have a certain decorative effect. If the lattice strips are intermittent, the decorative effect of the ground will be affected. The main reason for the uneven exposure of the grid strips is the uneven surface layer. Since the cement slurry of the surface layer covers the dividing strips, it may not be polished during polishing, causing obstruction. It is also possible that the cement slurry is too thick and cannot be removed during polishing, so there is still a small amount of cement slurry covering the dividing strips to block them.
In addition, the height of the dividing strips is inconsistent and fluctuates between high and low. Then, when installing dust, it will inevitably cause the dividing strips in certain parts to be covered too much. For this kind of problem, the main thing is to control the elevation of the upper part of the grid strips, check the lines when installing the grid strips, and correct the errors in a timely manner if any errors are found.
(4) Terrazzo has uneven color
Commonly known as "big painted face", there are two main reasons for this defect. First, the paint is not stirred evenly. The second surface layer is contaminated by other colored liquids.
The mixing of pigments should be done by a dedicated person and the measurement must be accurate. Don't judge by heart and eye. In addition, you can't add water and pour paint at the same time. Doing so will cause the paint to clump together and make the color heavier in some areas. The method of dry mixing the pigment and cement before adding water and gravel should be adhered to so that the pigment is evenly dispersed.
If the surface layer is contaminated, it should be cleaned up in time. The most fundamental way is to strengthen management. If the ground fence work is completed and other projects are still intersecting, it is best to lay a layer of protective material on the top of the surface layer to avoid contamination and damage. For high-end art terrazzo, special attention should be paid to this aspect.
4. Repair and polishing of old terrazzo floors
Repairing and polishing terrazzo floors is a relatively simple construction method, but it is not easy to make the repaired and polished terrazzo floors look brand new. .
According to our experience in the construction practice of modern protected buildings, the key to terrazzo floor renovation is not polishing, but repairing, that is, no cracks can be seen on the floor, and the cracked surface after repair must There is no or very little color difference from the surrounding floor.
(1) Operating procedures
Crack repair--mechanical polishing--complementary color treatment--coating protective agent
(2) Operating points
Crack repair
A. Analyze the cement, cement grade and stone particle size range of the original terrazzo floor.
B. Choose the same type of cement and gravel with a particle size that is very close to the original floor.
C. Expand the cracks according to their natural direction.
D. Mix the selected cement, stones and grading into proportions.
E. Caulking the mixed terrazzo raw materials. The gaps should be cleaned, and after cleaning, apply a concrete interface agent to ensure that the new material is firmly bonded to the original floor.
Mechanical polishing
A. Before mechanical grinding, it must be confirmed that all cracks have been treated and the newly embedded terrazzo has solidified and has considerable strength.
B. The grinding disc is first polished layer by layer with a 600-mesh high-grade oilstone.
C. After grinding once, check the grinding effect, and then replace it with a higher-grit oil stone for finer grinding according to the situation.
D. When repairing cracks, grind carefully and carefully check whether the interface is flat. Stop grinding only after it is flat.
E. In the inner corners, a small portable grinder must be used for grinding.
Complementary color processing
A. After mechanical polishing, clean with oxalic acid.
B. Carefully check the crack repair areas, mainly observing the color difference of the floor finish.
C. If the color difference is large, ask a professional to tinker and repair it to reduce the degree of color difference.
Apply protective agent
A. The floor must be free of dust before applying protective agent.
B. The stone protective agent should be applied evenly without any leakage