Frequently Asked Questions - Homeowner

 

Paving Stones
Keystone Products

 

 

 
  Paving Stone Questions
 
Q1: Why do Anchor Paving Stones make a better pavement than asphalt or concrete?
Q2: Are all paving stones interlocking?
Q3: Does the color fade over time?
Q4: How much quarry process and sand do I need for my project?
Q5: Why should I use sand for the setting bed and sweeping into the joints between the paving stones?
Q6: Should I mix some Portland cement into the sand I am going to sweep into the paving stones and the setting bed sand?
Q7: How do paving stones compare in performance to stamped concrete?
Q8: Should I seal my concrete paving stones? Are there any advantages to doing this?
Q9: Will weeds grow up from my paving stones?
Q10: What can I do if my paving stones become damaged or badly stained?
Q11: How do I remove snow from my paving stone driveway or walkway?
Q12: Can I lay my new paving stones over my existing concrete driveway and patio?
Q13: Can I use Anchor paving stones around my new pool?
 
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  Keystone Product Questions
 
Q1: How high can Keystone walls be built without the use of geogid?
Q2: Are concrete footings ever necessary or required?
Q3: Can I use sand to help level the units?
Q4: Can adjustments be made on a concrete leveling pad?
Q5: How many Keystone units should be buried?
Q6: Is there a way to figure how much setback there will be per course before construction of the wall begins?
Q7: Should I always begin construction at one end of the wall or is it o.k. to start in the middle?
Q8: What size rock is best suited for filling in and around the Keystone units in the drainage zone?
Q9: How much rock do I need to use?
Q10: What advantages are there to using a pinned system?
Q11: How high can Keystone units be stacked before placing unit corefill and backfill?
Q12: What type of material should be used to backfill?
Q13: How often do I need to compact the fill soils?
Q14: How often should the wall's alignment be checked?
Q15: How can I fix units that are out of level?
Q16: How can units that are out of alignment be fixed?
Q17: When building gravity walls with terraces, what is the recommended distance between the terraced walls where the upper wall does not affect the loading condition on the lower wall?
   
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  Paving Stone Questions & Answers
 
Q1: Why do Anchor Paving Stones make a better pavement than asphalt or concrete?
A1: Properly installed Anchor Concrete paving stones provide a superior pavement to asphalt and concrete in a freeze/thaw environment. Paving stones provide a rigid yet flexible pavement that will expand and contract with the freeze/thaw cycles. Each paving stone provides an expansion joint to allow for this movement, unlike concrete slabs that have expansion joints formed and cut into them. Paving stones can also be easily dismantled to make repairs to utilities that may be underneath the surface, and then repaired without a patch quilt look to the pavement.
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Q2: Are all paving stones interlocking?
A2: Some paving stones interlock based on their shape. Others achieve interlock by the laying pattern. When installed on a proper base with one inch of sand as a setting bed, and proper joint sand placed between the paving stones, all paving stones achieve interlock.
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Q3: Does the color fade over time?
A3: No. Color in concrete paving stones does not fade. Dirt, dust and other inert matter can mask the color in the paving stones. Anchor Concrete also uses the Anchor Guard process that will provide a higher concentration of color at the surface of the paving stone. This process will also provide a longer, more durable wearing surface than other types of paving stones available in the marketplace today.
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Q4:  How much quarry process and sand do I need for my project?
A4: This will depend on the type of installation that you are doing. For a patio or sidewalk, the ICPI recommends that 4 to 6 inches of quarry process on a compacted sub base, with 1 inch of course concrete sand as the setting bed for the paving stones. For a driveway, you should use 8-12 inches of quarry process with 1 inch of course concrete sand as the setting bed. Usually 1 ton of quarry process or sand will cover 100 square feet 2 inches thick. So for a 100 square foot patio, you would need 2 tons of quarry process (4 inches thick) and Vi ton of concrete sand (1 inch thick). You will also need to have about 3 to 5% more sand for sweeping into the joints between the paving stones.
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Q5: Why should I use sand for the setting bed and sweeping into the joints between the paving stones?
A5: The sand used for the setting bed should always be of a course sand type. Concrete sand is the optimum type and gradation for this part of the project. This is a national uniform specification set forth by the Interlocking Concrete Paving Institute (ICPI). Some people like to use stone dust, and in some areas, stone dust can be an effective setting bed. The reason stone dust is not recommended is because it will not allow for drainage under the paving stone. It is also harder to get the paving stones to "seat" properly in a setting bed of stone dust.
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Q6: Should I mix some Portland cement into the sand I am going to sweep into the paving stones and the setting bed sand?
A6: No. Never mix Portland with the sweeping sand. This will cause a stain that will be permanent. As far as the setting sand is concerned, you will be defeating the purpose of a flexible system.
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Q7: How do paving stones compare in performance to stamped concrete?
A7: Stamped concrete is merely concrete slabs with a pattern stamped into the surface. They are susceptible to the same problems of a concrete slab sidewalk or patio. Cracking due to freeze/thaw cycles may happen with a stamped concrete patio. Paving stones can be dismantled and repaired with the same product being used on the surface. How do you repair a utility, such as a pool filter, that may break under a concrete slab? You would need to cut out and remove the concrete and repair it, and pour new concrete and stamp it. It will never match.
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Q8: Should I seal my concrete paving stones? Are there any advantages to doing this?
A9: There are several advantages to sealing concrete paving stones. Sealing paving stones will help them to resist staining. Sealing will also help to bind the sand in place and prevent germination of weed seeds that may collect at the surface of joint sand. In New Jersey and New York, only water-based sealers are available. One disadvantage to sealing paving stones is that it would need to be sealed every couple of years, thus increasing the maintenance of the project.
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Q9: Will weeds grow up from my paving stones?
A9: The growth of weeds or grass results from seeds blowing into, and then lodging in the joint sand. Weeds do not grow up from the bottom through the quarry process. Controlling these weeds is a simple solution. Mix a pre-emergent weed killer into the joint sand. Should weeds germinate over time, the use of a post emergence weed killer, such as Round-up, can be spot sprayed to control the problem.
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Q10: What can I do if my paving stones become damaged or badly stained?
A10: You can easily remove a paving stone and replace it. Sometimes, oil stains can be so bad that they cannot be removed with an oil stain remover. Simply remove the paving stones and replace them with clean stones.
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Q11: How do I remove snow from my paving stone driveway or walkway?
A11: Paving stones can be shoveled and plowed the same as a concrete or asphalt pavement. The chamfered edges around the paving stones help to prevent the edges of the plow from hitting the comers of the stones. A plow with a rubber edge is preferred. Rock salt and calcium chloride will melt snow and ice, but they can also harm the paving stones.
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Q12: Can I lay my new paving stones over my existing concrete driveway and patio?
A12: Yes, provided you have ample room to allow for the additional 3 inches that will be above the concrete. If this is going into a doorway, you may have a problem with clearance. Also, the concrete should be free of any major cracks. Remember, any movement in the concrete slabs that you are going over will show themselves in the surface of the paving stones.
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Q13: Can I use Anchor paving stones around my new pool?
A13: Can I use Anchor paving stones around my new pool? A: Yes. Paving stones make an attractive pool deck and provide a slip resistant walking surface. Paving stones also take on moisture, leaving a pavement cooler underfoot than the traditional poured concrete surface. Anchor Concrete Products, Inc. also has a bullnose paving stone that will make an attractive pool coping that will match the paving stones around your pool deck.
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  Keystone Product Questions & Answers
 
Q1: How high can Keystone walls be built without the use of geogid?
A1: Keystone walls can be constructed between 2' (.6m) and 6' (1.8m) high depending on the type of unit, soil conditions, amount of batter used, and surcharge on top of wall.
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Q2: Are concrete footings ever necessary or required?
A2: Most Keystone walls can be built directly on 4-6" (100-150mm) of well compacted granular base. However, there may be occasion to consider the use of a concrete leveling pad. EXAMPLE: Applications in or near water, a taller wall built on soft sub-soils, or a wall that is very long and by using a concrete footing, the contractor can speed up the installation process.
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Q3: Can I use sand to help level the units?
A3: Yes. After the road base material has been leveled and compacted, a '/2" (13mm) to 1" (25mm) of sand may be used to help speed up the leveling process.
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Q4: Can adjustments be made on a concrete leveling pad?
A4: Minor inconsistencies on a concrete leveling pad will not usually create much of a problem. However, if there are noticeable differences in block height as the units are placed due to low spots in the leveling pad, a thin layer of sand or mortar may be used to help the leveling process. High point inconsistencies may require some grinding. Make all adjustments as gradual as possible. Before you begin laying the base course, be sure to check that the leveling pad is level front to back. Make corrections as needed, especially if the back of the footing is higher than the front. It is important to note, that taking the time to accurately level and finish off the concrete leveling pad will allow for minimal adjustment time and greatly speed up the installation process.
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Q5: How many Keystone units should be buried?
A5: Typically, 1" (25mm) is buried for every 8" (200mm) of wall height with a minimum of 6" (150mm) below finished grade. In most cases, other than where the grade slopes away from the wall at the base, 3 to 4 units are the maximum to be buried on tall walls. More than that does not create an added benefit. Unit burial is not a function of building below frost depth in cold climate areas like rigid wall systems, but is meant to provide resistance to base exposure from erosion to grade in front of the wall.
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Q6: Is there a way to figure how much setback there will be per course before construction of the wall begins?
A6: Yes. Level three units side by side and install the pins in the preferred set of pin holes. Set the next course of Keystone units on the three you just leveled and slide them forward toward the wall face so they are in full contact with the pins. Measure the distance the second course tails are overhanging the units below. This will give you your true setback per course.
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Q7: Should I always begin construction at one end of the wall or is it o.k. to start in the middle?
A7: Construction of the wall should begin at your lowest point whenever possible. If the wall is going to tie into a building or structure, measure the distance from the comer of the Keystone unit to the edge of the building and make sure the distance is in an increment of 18" (457mm). (Full, unit width).
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Q8: What size rock is best suited for filling in and around the Keystone units in the drainage zone?
A8: A clean, angular W (20mm) rock is best for corefill if available. Otherwise, use a clean rock material that is '/2 - 1 '/2" (15-40mm) in diameter. Avoid aggregates that are round in nature. Angular material will provide the best interlocking strength. Also, avoid material that contains a lot of fine grains in that these fines can flow with water through the wall and possibly stain the wall face.
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Q9: How much rock do I need to use?
A9: Adequately fill all open cores and 12" (305mm) behind the unit when using a Keystone Compac unit. The additional rock behind the unit provides better drainage and eliminates the need for compaction equipment directly behind the wall. For Keystone Standard units, core filling needs only to be placed in all open cores to the back of the tail.
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Q10: What advantages are there to using a pinned system?
A10: Unlike other retaining wall products. Keystone's pinned system offers the choice of near vertical or one inch setback options. It allows you to achieve tight comers and radii automatically without having to cut units while maintaining the running bond pattern. The Keystone fiberglass pins also provide additional shear strength at the wall face and positive connection with geogrid which allows proper pre-tensioning and resistance to bulging during construction.
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Q11: How high can Keystone units be stacked before placing unit corefill and backfill?
A11: Keystone recommends adding corefill and backfill after each consecutive course for the Compac units. This insures that all voids are properly filled with rock providing maximum interlocking strength. It also aids in keeping the wall straight and reduces the amount ofwaisted rock. NOTE: Because of the depth and size of open core areas on the Keystone Standard units, Keystone recommends that the standard units can be stacked up to a maximum of 3 units before placing unit corefill and backfill.
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Q12: What type of material should be used to backfill?
A12: Granular materials such as rock and sand are best if available. These types of materials compact fairly easy and won't hold moisture than can increase the weight of the soil behind the wall. Keystone walls can be effectively built with silty material and lean clays, but these types of soils require more compaction and care should be taken not to place these materials when they are wet. High clay soils that shrink and swell rapidly as well as organic soils should be avoided.
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Q13: How often do I need to compact the fill soils?
A13: Compacting backfill material in 8" to 12" (200mm-300mm) lifts allows you to effectively compact the entire area behind the wall without putting unnecessary pressure on the units. Thick lifts of soil require more compaction effort and create a greater force at the back of the wall which may cause potential alignment and rotation problems. Consult with a geotechnical engineer for further compaction criteria based on specific site soil.
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Q14: How often should the wall's alignment be checked?
A14: Wall alignment should be checked at least every third course by visually looking down the wall or using a string line along the pin holes or tall positions. The wall should also be checked every 15-20' (4.6m-6.1m) to make sure the units are level from front to back. If the bubble on the level is high to the back, this means the wall is building to negative batter (leaning forward) and needs corrective measures.
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Q15: How can I fix units that are out of level?
A15: If the units are leaning back toward the embankment, due to geogrid thickness or units being thicker in front than back, this is generally not a problem in that the batter is increased. However, if space is limited on top of the wall, this could be a problem because the wall is setting back faster than expected. To correct this problem, you may uniformly insert shims under the tails to bring the units back to level. The best material for this would be excess geogrid, pieces of asphalt shingles or other appropriate non-deteriorating materials. Avoid using wood or materials that will deteriorate over time. Care should be taken to make adjustment in small increments. If the units are rotating outward and higher toward the back of the unit, the problem should be addressed immediately. If the tails are higher than the fronts by more than Vi" (20mm), disassembling and portion of the wall should be considered. The same guidelines and materials for shimming the back of units may be used for the fronts as well. For minor adjustment, tapping down the back of the units with a maul or dead blow hammer may also help.
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Q16: How can units that are out of alignment be fixed?
A16: To determine which units are out of alignment, run a string line across the pin holes before the pins are placed. Adjust the misaligned units by sliding back and forth until the pin holes are in alignment with the string line. If when looking down at the kidney shaped holes, you see that these units are not in full contact with the pins below due to the adjustment, don't be alarmed. The gravel fill should adequately fill in around this area to secure the unit against the pin. If the unit type you are using has the dual pin option, either position may be used if it helps the alignment process.
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Q17: When building gravity walls with terraces, what is the recommended distance between the terraced walls where the upper wall does not affect the loading condition on the lower wall?
A17: The distance between terraces (face of wall to face of wall) should be greater than or equal to two times the lower wall height. Typically this can also work for lower height soil reinforced walls. With higher reinforced walls or walls built on a slope, the issue of global stability must be considered by a qualified engineer in analyzing the terrace situation.
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