How To Repair Cracks In Terrazzo Floor
PITTING ON POLISHED CONCRETE
Question:
My company was the contractor on a retail remodeling project that had an existing physical floor requiring a grind and polish stop. Nosotros had to sawcut and remove portions of the floor for new hole-and-corner mechanicals and so cascade these sections back. Our task was to then grind and polish the entire floor to the level of gloss required. On the existing concrete areas, we had no problems. However we experienced problems from the start with the new concrete areas. The engineer involved with the projection gave us a method of grinding that allowed us to achieve the right sheen on gloss tests. Now less than half-dozen months after, these areas have failed miserably and the surface is visibly porous and is trapping dirt to the point where floor looks black in areas. The polishing contractor is challenge that this is a concrete finishing issue and the only manner to take out the highs and lows of the concrete surface is to grind deep and expose the aggregate, but this would not be acceptable to the owner.
Part of me agrees with the polishing contractor, but during a preconstruction meeting with the polishing company and project engineer, concrete finishing was a non-issue, and the stop did pass initial gloss testing. There accept also been some comments about how the store has maintained the flooring and their utilise of chemicals to clean it, which may have caused the concrete finish to fail. Any input y'all could give us would be great. We are a large general contractor in the Midwest, merely our experience in grinding and polishing physical is limited and we are hoping that this is not going to plough into an expensive lesson.
Polished concrete with a poor mix design or inadequate curing will suffer from premature pitting.
Respond:
Concrete, polished or not, should not pit and exist weak on the surface. This ordinarily indicates a mix pattern or curing issue. With situations like this involving many players, I like to go back to the start and focus on the key issue. In this case, the main issue seems to be that the replaced concrete sections are not holding gloss and polish considering of surface deterioration that occurred before long after the floor was put into service - within the outset six months.
From the details y'all have provided, it appears that the replacement sections of concrete are failing and soft, either due to substandard mix design and concrete placement or post-applied chemicals. Polished concrete needs to be properly chemically hardened during the polishing process. This increases the surface hardness and provides meliorate gloss. Lithium or sodium silicate hardeners are well-nigh unremarkably used. If applied properly, these should harden the concrete to a bespeak where soft pitting does non occur, unless the concrete was and so substandard that it was really soft and weak to outset with.
To zero in on what'due south causing the flooring deterioration, the post-obit questions demand to be addressed:
- Is there anything different about the replacement areas in regard to mix design and how the concrete was placed and finished? Did the concrete freeze after placement? What you need to look for is anything that might have created a weak surface.
- What is the store using to clean the concrete? If a harsh cleaner is pitting the concrete, information technology would do it to some extent on all the concrete, non just the replacement sections.
In regard to the finish, information technology is probably i of the most critical parts of preparing the concrete when polishing. The concrete mix pattern, placement, finish, flatness, and curing are all critical. If you get a soft slab, you lot end upwardly with what you are experiencing. As for the repair, you can regrind to go deeper and become rid of the pitting, but this ignores the existent problem in hopes of a quick ready. If the concrete is weak, the new grind volition last another six months and so yous're right back to where y'all started. I suggest taking a cadre sample or performing a surface hardness test. Likewise, practise some research on the hardener that was used and make sure it was applied correctly and at the right coverage charge per unit.
EFFLORESCENCE ON A STAINED Flooring SLAB
White efflorescence acquired by high water motility pushing salts out of a physical flooring slab.
Question:
Nosotros accept a stained physical floor slab on course in our Houston habitation. We accept salts that our escaping and clouding the flooring. During the three years nosotros have lived in the house, our builder has tried various things to fix the floor. First, he tried redoing the stain and sealer, but the same discoloration happened. About six months agone, the builder removed the sealer and waxed the floor to allow information technology to breathe and the salts to ascent through the floor. The salts are now easily wiped abroad, only the wax is wearing off, onto our socks, shoes, the dog's paws, etc. Can anything be done to relieve the flooring? We have thought virtually tiling over it, but are any special preparations necessary, such as applying a thin-set mortar or a moisture bulwark?
Respond:
It sounds like you lot have a chronic efflorescence problem. Efflorescence is a process where salts leach out of the concrete, carried by water, and end up on the surface equally a white dusty balance. Since you have had this issue since yous've lived in the home, it seems to be chronic and ongoing. Since water is the trigger, do you take a high water table, overflowing plain, or other situation that's causing h2o to get under your concrete foundation? Anything you lot can practise to minimize water migration under your concrete will help. This would include installing French drains or mayhap regrading the slope of your property.
No matter what y'all do, the efflorescence problem will need to be mitigated. Efflorescence will non only cause problems with a stained concrete floor, it can as well delaminate tile and warp forest floors. The best approach would exist to strip all the sealer and wax off the concrete. Once the sealer and wax are removed, a wet examination should be conducted and so y'all tin can get an idea of how much h2o is moving through the slab. The exam results will dictate your adjacent pace. If the water motion is low, a penetrating sealer designed to terminate or irksome efflorescence can exist used. After the sealer is applied, y'all tin reapply a stain or dye to the flooring. If the h2o motion is high, a more drastic and aggressive topical waterproof blanket may have to be used. If you then want to restain the flooring, a cement and polymer topping would need to applied to create a new sail on which to utilize the stain. If you want to tile over the flooring, the aforementioned water mitigation procedures would have to be completed.
Acceptable NUMBER OF CRACKS IN CONCRETE FLOOR
Question:
I am involved with the belongings committee of Saint Matthew Lutheran Church in Bel Air, Md. Since 2005, before long afterward the stamped concrete floors of our new 750-seat sanctuary and 500-square-foot narthex were poured, there has been an ever increasing quantity of deep floor cracks. All of the floors are slab pours without expansion joints, merely accept saw cuts for alleged crack control. The cracks run both perpendicular and parallel to the saw cuts. There are likewise cracks running up to the audio and electrical boxes in the floor. No expansion joint cloth was wrapped around these metal boxes earlier the physical was poured. In many areas, the cream is popping off of underlying big aggregate, and in other areas, pieces of the floor are starting to come out, which is causing a hazard for women wearing high heals. Unfortunately, the contractor went out of business before long after project completion, and the full general contractor has been less than sympathetic about the problem. Our committee has the following questions:
- What is an acceptable quantity of cracks, and should pieces of the floor come out?
- Is there any mode to halt the seemingly never-catastrophe growth of the cracks?
- What can we use to make full the cracks to minimize the dark moisture staining that is taking identify along the surfaces adjacent to the cracks?
This concrete floor in Saint Matthew Lutheran Church is riddled with an unholy number of cracks,running both parallel and perpendicular to the joints. The likely causes are poor subbase preparation and joint location.
Respond:
All concrete cracks to some extent. While nifty is unavoidable, you can control where and how those cracks develop. This is where joints come into play. Both expansion joints and control joints are critical to physical flatwork, simply each type serves a different purpose. Expansion joints are designed to let an entire slab to aggrandize and contract without coming into contact with an side by side slab, wall or structure. As you noted, a good identify for an expansion joint or expansion material would have been around the electrical boxes and betwixt slabs. Control joints are used to salve the stress within a concrete slab. These joints, which may exist formed with a jointer before the concrete sets or cut with a saw later the physical hardens, are designed to "control" where the scissure will occur by inducing the concrete to scissure in the location of the articulation. The placement and number of these joints are disquisitional. (See Be Active in Deciding Where Control Joints Will Be Placed). It appears from your photos that the floors are saw cut in a square or tile grid pattern. If and then, there seem to exist plenty of command joints present, meaning the issue is not a lack of control joints, but rather their location in the slab.
Regarding your question of what number of cracks is considered adequate, there are no difficult-and-fast standards that I'm aware of. In all the cases I've been involved with, information technology comes down to flooring size, perception and safety. On a floor comprised of thousands or tens of thousands of square feet of concrete flatwork, a few cracks are to be expected and are generally deemed adequate. When the number becomes unacceptable is the gray area. Non-structural surface cracks are not as critical and pose only an aesthetic issue, then they are usually tolerated in larger numbers than structural cracks. The cracks in your floor appear to be structural, running through the depth of the slab and starting to come apart in certain areas. Aside from the number of cracks, their severity leads me to believe they are beyond what I would consider acceptable for a floor of this blazon.
Methods for stopping the formation of additional cracks are express. If the subbase is jeopardized or was non prepared properly, no number of control joints will limit the nifty. It will keep to occur until the slab has come into equilibrium with the base on which information technology rests and the stress causing the cracks has been alleviated. Sawing additional control joints in places where in that location may non be plenty of them is about the only solution. Consider having a concrete engineer audit the floor and determine if additional joints are warranted and where they should be placed.
In that location are a number of remedies for repairing cracks in concrete floors. The technology has come a long way in terms of scissure repair polymers and injection systems. Today, you can inject cracks with a resin (epoxy, polyurethane or polyurea) that will really attain a strength greater than nigh typical concrete slabs (encounter Epoxies vs. Polyurethanes for Scissure Repair). This ways that the repaired crack will actually be stronger than the surrounding surface area. These repair systems are usually injected into the scissure afterward cleaning and crack chasing (routing out the scissure with a saw or angle grinder), and they cure in 12 to 24 hours. Some colour choices are available, but aesthetics are usually not the most important factor. Another option is to fill the cracks with a physical caulk, which is usually made of a softer resin cloth. These products are applied to the fissure or articulation with a caulk gun and are available in a wide range of colors. Because this type of repair is more visible than crack injection, aesthetics are very important. (For sources, visit Concrete Repair Products.)
I suggest that you start monitoring some of the cracks in the floors to see if they proceed to move or remain static. If they are nevertheless moving or growing in length or width, cleft injection may be the all-time solution. If they are static, a crevice filler is all-time. The crumbling pieces of concrete may need to exist removed, or they can be glued back into identify with either system, depending on the size and depth of the pieces.
In the areas of the flooring where you say "the cream is popping off," this is likely to be spalling or scaling. On interior concrete slabs, this is usually caused past overfinishing or backlog water in the concrete, resulting in a weak surface. The keen is probably causing an already weak surface to come up off.
I believe that the cracks in your flooring are acquired by poor subbase preparation or some major move or deficiency under the slab. If the proper corporeality of reinforcement was used, the physical should agree together, despite the cracks, and not dissever or heave. Ask your builder to provide documents showing how the subbase was prepared, the type of concrete poured, slab thickness, and the amount and type of metallic reinforcement. I remember y'all have a pretty strong example that installation deficiencies caused the problems with your floors. The fact that the contractor who installed the physical is out of concern also does non give me a lot of conviction in the quality of the work.
TERRAZZO Physical FLOOR CONTROL JOINTS
Question:
Does the physical slab for a terrazzo floor require command joints? Typically we cascade a monolithic concrete floor, but then we become modest alligator dandy. Nosotros commonly encompass this with a bridging membrane and finish material.
Answer:
Control joints (as well called contraction joints) are ever recommended in concrete slabs to reduce random neat. (Encounter Joints in Concrete Slabs.)The bridging membrane is good, but if the slab develops major cracks down the route, they might telegraph through to the surface. I ever wait at control joints every bit cheap insurance.
TAPE MARKS ON Concrete FLOORS
Question:
I take a question near an integrally colored concrete floor that a subcontractor poured for me. The pigment was added to the concrete at the ready-mix plant, and the contractor added no boosted water to the concrete at the jobsite or while finishing the slab. About 2 months after the floor was installed, nosotros had the interior of the house painted, and the painting contractor covered the concrete flooring with sheets of newspaper, using painter'southward tape to concord them in identify. When he pulled up the tape a week later, later he finished his painting, it took off the top surface of the concrete downwards to sand and stone. What caused the surface to come up off with the record, and tin can anything be done to fix the flooring? The tape marks are nearly an inch wide.
Answer:
The reason the record pulled the surface upward is because of plasticizer migration. Plasticizers are polymers that make glue, plastic and rubber flexible. In the case of record, plasticizers are used to allow the glue to migrate into annihilation porous, like concrete. Almost often I come across situations where the tape pulls up the concrete sealer and stain, but every then often it tin pull up the concrete surface also. When painter's tape pulls off physical, information technology's typically because the concrete mix contained besides much water or the concrete was overfinished. Concrete strength is directly related to the water content when placed and finished. The more water you have, the weaker the concrete surface. Since the water was added at the ready-mix institute nether controlled atmospheric condition, it's more likely that your concrete was overfinished. If concrete is worked too much with a trowel, likewise much water and cement paste are brought to the surface, producing a weak tiptop layer that is often soft and dusty. Try performing a cross-hatch exam to run across how the surface holds. This test is oft used to exam sealers for adhesion to concrete, but it will also work on the concrete surface itself. (See How to Test Sealers for Adhesion.)
To treat concrete with a weak or soft surface, employ a concrete densifier or hardener. These types of sealers contain sodium or lithium salts that chemically reinforce the concrete surface and farther solidify the crystalline network that makes up the "gum" in physical. In the areas where the tape removed the surface paste, yous tin utilise a microtopping (see Concrete Overlays) or a patch textile colored to match the existing finish.
WAX FINISH SCRATCHES Hands
Scratches on a soft wax coating
Question:
Our contractor and decorative concrete subcontractor accept installed a cute physical flooring colored with a brown stain and protected by a water-based epoxy sealer and a wax finish. We are having issues with the wax scratching and need to know how to maintain the look. From the first day we were able to walk on the floor, we've been getting marks and scratches from shoes (heel marks, not scuffs), foot and dog prints (from blank feet and canis familiaris paws -- not boom scratches), empty boxes that were attack the floor and scooted a few feet, and a soft push broom. We take tried several floor cleaners (most recommended by the installer) and soap and water. The dirt comes correct up, simply the tracks and scratches from any object that comes in contact with the floor remain.
I know the wax is a Johnson production, and the floors were not buffed. Our contractors have tried both a matte and high-gloss finish. The high-gloss wax makes the scratches more apparent. We were told we should rewax yearly, just have not been able to remove the scratches or prints since the flooring was waxed the starting time fourth dimension a month or so agone so again a few weeks later. Recently, 1 area was covered with a high-gloss wax. Nosotros waited two days to walk on it, and inside minutes scratches and prints that will not come up up were nowadays. I've been told that information technology is too late to have the physical polished because of the colour awarding. I likewise empathise that the terminate is a sacrificial coating to avoid scratching the sealer. All the same, the wax scratches so easily on the night color that the flooring always looks like it needs to be cleaned, even afterward it is freshly mopped.
The floor is gorgeous, except for the scratches and prints. Tin can we apply a durable urethane that will not scratch or testify prints and then easily? We are so frustrated that we are considering a dissimilar floor material altogether.
Reply:
Floor wax is actually a generic term for a special blazon of stop coating that is a blend of acrylic and wax. Every bit a general rule, these finishes should not scratch nether normal daily use, but they are non immune to article of clothing over fourth dimension. The questions then become:
- What type of daily wear are the floors seeing?
- How long before the scratches appear?
- What type of wax product are y'all using?
- How are you maintaining the wax?
Y'all mention getting both scratches and scuffs. These are two very different issues. A scratch is a concrete indentation in the coating surface, and a scuff is where some other material is left behind on the blanket surface (such as a black marking from a shoe). From your description, it sounds similar you have a wax hardness issue. Waxes are softer than coatings, simply they are designed to handle the traffic y'all draw.
Is the Johnson production specifically designed to get over a coating on a concrete floor? Does it state that it needs to be burnished? The heat generated past loftier-speed burnishing is sometimes needed to harden the wax. Check the instructions on the product to see if they mention the need to burnish or buff the wax to terminate it off. Also, endeavour buffing a minor surface area of the floor with an angle grinder and a buffing pad, like you would use to wax a car. If this solves the issue, you know you need to take the floor burnished.
Not all waxes are akin. Y'all may desire to attempt a higher-class finish, such as a commercial grade of wax designed to go over concrete coatings. You can purchase this at a janitorial supply store, and you want something that would be used over a polyurethane coating in a school or hospital. You should be able to apply the wax right over the existing wax. It may take three to five coats, just in the end you should become a dainty shine, hard finish. Test in a small area first.
Lastly, you tin can strip off the wax and but alive with the epoxy sealer as your walking surface. Not a groovy approach, simply ameliorate so what you have now. I feel confident you tin can solve this by using the right wax. Commercial-course products designed for concrete floors are pretty fool-proof.
REPAIR TIPS FOR PEELING CONCRETE PAINT
Question:
I painted the concrete floors in my kitchen with a physical paint purchased from a local hardware store. I primed the concrete before painting. The problem is the paint won't stay and it chips very hands. Would applying a topcoat to seal the paint aid? Also, I'd like to paint some designs on the concrete floor considering it seems a little plain.
Answer:
Your trouble indicates that the concrete was not porous enough to have the primer or paint - a very common consequence when painting physical. Sealing the painted surface may help, but information technology does nix to set up the real problem, which is poor adhesion between the paint and the concrete. Because a kitchen is a loftier-traffic expanse, the paint will proceed to fail in short order, even with a sealer.
I recommend stripping off all the pigment, and preparing the physical properly. (See Concrete Surface Training.) And then you lot tin apply a stain, tint or dye that penetrates into the physical. You can utilise stencils or faux terminate techniques to create designs. Finally, seal your piece of work with a skillful sealer, followed by a finish wax designed for stained concrete floors.
View all decorative physical Q&A topics
Source: https://www.concretenetwork.com/fix-concrete-floor/
Posted by: wrightwhistless.blogspot.com
0 Response to "How To Repair Cracks In Terrazzo Floor"
Post a Comment