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- Air entrained mix. For exterior slabs, sidewalks, and patios, use air-entrained concrete that meets the ACI requirements. …
- Don’t overwork over-wet concrete. Another contributor to scaling can be overworking of over-wet concrete. …
- Spraying Curing Compound. …
- Terrain should slope away from slab.
Damage will show up when the concrete is exposed to ice or snow which then melts and penetrates into the concrete and freezes. … Frozen water expands about 10%, pushing the thin, weak top layer upwards causing the layer to peel off (known as spalling).
Spalling concrete can look like round or oval depressions along surfaces or joints. Spalling tends to be most common in cold climates when de-icing chemicals are applied or when seasonal freeze-thaw cycles damage the concrete.
REPAIR SPALLED CONCRETE To address the problem after it has occurred requires covering the entire affected area with a polymer-modified cementitious overlay in a color matching the existing driveway. Once the overlay cures, apply a waterproofing sealer to prevent the problem from reoccurring.
Sealing is the best way to prevent moisture-related spalling. For new concrete, apply a penetrating waterproofing sealer 28 days after concrete placement and every few years thereafter. The correct concrete mix can also help prevent spalling.
Crumbling concrete can be repaired before crazing occurs. Crumbling concrete is not just unsightly, it may also be a sign of serious damage beneath the structure. Address the problem as soon as possible to prevent it from spreading or causing other damage, such as crazing, in which a network of random cracks occurs.
Repair Spalled Concrete Driveway Spalling occurs due to cold weather conditions and direct exposure to damaging road salts. Concrete resurfacing resolves spalling issues and costs an average of $2.50 to $4.00 per square foot with a range of $250 to $400 for a 100 square foot area.
For early detection of potential spalling concrete slabs, look out for any flaking, chipping, or missing large chunks from the concrete surface, and exposed coarse rocky concrete aggregate.
There are two main types of concrete sealers: film-forming sealers and penetrating sealers. Film-forming sealers include acrylics, epoxies, and urethanes that form a coating on the surface of the concrete. Film-forming sealers, especially acrylics, are more susceptible to wear and will need to be reapplied frequently.
- Bleeding. Bleeding refers to excess moisture and water leaching to the surface of poured concrete while the heavier deposits settle to the bottom. …
- Delamination. …
- Honeycombing. …
- Cracking. …
Crazing is the development of a network of fine ran- dom cracks or fissures on the surface of concrete or mortar caused by shrinkage of the surface layer. … Crazing cracks are sometimes referred to as shallow map or pattern cracking.
If your driveway surface has spalling concrete, the most likely cause is an installation mistake. Common mistakes include adding too much water to the mix, to make it easier to pour; sprinkling the surface of the concrete with water, to extend finishing time; and not curing the concrete properly after installation.
It is not a cosmetic problem as it can cause severe structural damage or even bring down the entire building so it should be taken seriously. Spalling can occur after an extended period of heavy rains where the floods take a long time to dry up or in basements where moisture and salt are not controlled.
This bumpy condition is often referred to as concrete honeycombing and causes broken bits of rock and stone on the edges of a concrete slab. While it’s not always common, it’s usually a result of voids in concrete due to the mortar not filling the spaces between coarse particles.
The cause of a popout due to a chemical reaction is often related to alkali-silica reaction (ASR). Alkalis from cement or another source cause an environment of high pH — high concentrations of OH ions — causing the breakdown of silica and formation of an ASR gel.
In most cases, a poor concrete job cannot be saved; the slab should be removed and a new one poured in its place. If the visible finishing was done poorly then you can assume there are other hidden problems that will soon appear.
Spalling is a physical process of the breakdown of surface layers of masonry (typically concrete) which crumble into small pebble-like pieces in response to high temperatures and/or mechanical pressure. … These processes break the bond that holds the solids together and thus cause the concrete to crumble.
Once the surface begins to pit, filling the divots with concrete is usually a temporary fix that loosens over time. You can fill pits with a bonding concrete repair material, which is similar to caulk. Restoring the porch to a more original appearance requires dressing it with a special resurfacing concrete mixture.
Nationally, the average cost for concrete resurfacing is $3 to $10 per square foot, depending on the condition of the original concrete and local labor costs. For smaller projects, some contractors charge a flat fee of at least $500 to $1,000. The new concrete must also be sealed, which costs $20 to $80 per gallon.
Fortunately, filling cracks in a concrete driveway is a simple and relatively inexpensive DIY project. … A cracking driveway looks unsightly to potential buyers. Cracks can usually be filled and repaired if the rest of the driveway is in good shape and it was installed properly in the first place.
Carbonation of concrete is the chemical reaction between carbon dioxide in the air and calcium hydroxide and hydrated calcium silicate in the concrete to give mainly carbonates. … Carbonation reduces the pH-value of concrete. A high pH is needed to protect the reinforcement against corrosion.
Efflorescence is a crystalline deposit of salts that can form when water is present in or on brick, concrete, stone, stucco or other building surfaces. It has a white or greyish tint and consists of salt deposits that remain on the surface after water evaporates.
Spalling is similar to scaling, except the expansion occurs from deeper within the concrete, causing the surface to disintegrate into larger fragments.
The Thompson’s WaterSeal Clear Waterproofer is a multipurpose product that can be used on wood, brick and concrete. The same formula has been around for years without any new or innovative efforts to improve the performance.
When to seal concrete Allow new concrete to cure completely (at least 28 days or as recommended). Most sealers must be applied under dry conditions. Applying to damp concrete could cause haziness or loss of adhesion. Air temperatures should be above 50°F during sealer application and for at least 24 hours after.
A: Yes! Old concrete can be sealed for the first time or resealed if it has been previously sealed with a concrete sealer. … You want to make sure all mold, mildew, efflorescence, rust, grease and oil are removed from the concrete before sealing as you do not want to seal these elements into the concrete.
Problems with concrete include construction errors, disintegration, scaling, cracking, efflorescence, erosion, spalling, and popouts.
The end of the cylinder is exposed to heat for an hour. If spalling occurs, it is usually accompanied by a sound, the time of which is recorded. After the exposure, the area of spalling is measured and the spalled material collected and weighed.
If water has a high iron or mineral content, or if the water is carrying leaves or dirt, it can leave behind iron or rust colored stains, or dark spots on the concrete. The most common way to remove discoloration caused by water is to use a heated pressure washer, or acid rinse.
The process is fairly simple and involves grinding off the top layer of concrete to leave a smooth, unblemished surface. The top is then sealed, protecting the slab. Once the process is complete, your concrete slab will be restored to its original look without losing any of its durability and strength.
Although crazing is considered a glaze defect, it can also be corrected by adjusting the clay body. A glaze adjustment might not be possible if it is under so much tension that there is no room in the recipe for correction.
Concrete contractors can minimize or prevent craze cracks by starting to cure as soon as possible after final finishing, especially on a hard-troweled floor. Moist curing is best, although a spray-on monomolecular curing compound also can be effective. Using a drier, stiffer mix can reduce crazing as well.