Outside Curve With Gravity Extenders

Curves, Gravity, Outside Curve

Outside Curve With Gravity Extenders

Key Considerations for Gravity Outside Curves

Gravity retaining walls taller than 4 ft. (1.22 m.) must be reinforced with gravity extender units.
MagnumStone outside curves have a minimum convex curve of approximately 12 ft. (3.66 m.)
Measure the radius of the curve appropriately to match its approved engineered design.
Convex (outside) curves have a slight increase in batter or setback to the standard 1”/ft. (25 mm per block).
The taller the wall, the larger the convex curve’s first course needs to be. The radius of each additional course will be slightly smaller than the course below.
The MagnumStone blocks should begin at a fixed point in the retaining wall. This should be the lowest point of elevation, or if it’s a flat surface begin at the 90-degree corner, curve or an abutment to another structure.
For effective time management and efficiency, if gravity extenders are part of the approved engineering design, it’s recommended to place the block then attach its extender unit(s), before moving on to the next block.

STEP

First Course of MagnumStone outside Curve units

Quick Steps

When possible, start building a curve from the center and work outward to the left and right, through the curve.
Use PVC Flex Pipes along the base leveling pad to create a smooth and accurate Convex (outside) curve. For alignment purposes, the PVC flex pipe will be positioned along the back of where the base blocks will be placed.
Properly measure the convex curve and place the first MagnumStone base block on the leveling pad where the center of the convex curve will be located.
The back of the MagnumStone base block should be tight to, but not touching, the PVC Flex Pipe to provide an accurate, consistent alignment.
The blocks should be tight together, level and the back of the blocks should be aligned along the PVC Flex Pipe.
Continue to lay the MagnumStone base course on either side of the convex curve until the first course of blocks is complete.
Each block should be placed in direct contact with adjacent blocks, pressed as tightly together as possible to ensure there are no gaps between the blocks.
Once the convex curve’s base course is confirmed to be the correct radius and position outlined in the approved engineering design, the PVC Flex Pipe used for alignment can be removed from behind the wall.
At the discretion of the project engineer, impermeable materials can be placed and compacted at the toe of the wall. If this is specified, the amount of impermeable material should reach the desired height of the perforated drainpipe.
If no gravity extender units are required, proceed to install adequate drainage, fill the hollow core blocks with clear crush drainage gravel, then add and compact layers of backfill behind the blocks as outlined here in these steps of the MagnumStone Unit Installation section.
Sweep any excess stones off the top of the blocks before beginning to place the next course of retaining wall blocks.

STEP

Gravity Extenders Units for First Course of Outside Curve

Quick Steps

If MagnumStone gravity extender units are part of the approved engineering design, they can be added once the first course of MagnumStone base blocks are properly installed.
The size of gravity extender units required will vary depending on the retaining wall design.
Similar to the beginning of the first course, begin placing gravity extender units at the center of the curve, and work outward along retaining wall.
Follow the retaining wall’s approved design to install 2 ft. (0.61 m.) or 4 ft. (1.22 m.) gravity extender units to the next MagnumStone base blocks along the rest of the first course.
At the discretion of the project engineer, impermeable materials can be placed and compacted at the toe of the wall. If this is specified, the amount of impermeable material should reach the desired height of the perforated drainpipe.
Once gravity extender units are installed, proceed to install adequate drainage, fill the hollow core blocks and surround the gravity extenders with clear crush drainage gravel, then add and compact layers of backfill behind the blocks as outlined here in these steps of the MagnumStone Unit Installation section.
Sweep any excess stones off the top of the blocks and gravity extenders before beginning to place the next course of retaining wall blocks.

STEP

Laying Second Course of Outside Curve

Quick Steps

Similar to the first course, begin the second course at the center of the convex curve.
Maintain the running bond pattern by centering the block so it overlaps above the two blocks below (with SecureLugs in the hollow cores of the blocks beneath it).
The second course will naturally have a setback of 1”/ft. (25 mm. per block).
Continue to place MagnumStone standard blocks along the second course, on both sides of the convex curve until second course is complete.
Each block should be placed in direct contact with adjacent blocks, pressed as tightly together as possible to ensure there are no gaps between the blocks.
If no gravity extender units are required, proceed to install adequate drainage, fill the hollow core blocks with clear crush drainage gravel, then add and compact layers of backfill behind the blocks as outlined here in these steps of the MagnumStone Unit Installation section.
Sweep any excess stones off the top of the blocks before beginning to place the next course of retaining wall blocks.

STEP

Gravity Extender Units for Second Course of Outside Curve

Quick Steps

Similar to the gravity extenders of the first course’s convex curve, attach gravity extender units according to the approved engineering design.
Continue placing 2 ft. (0.61 m.) or 4 ft. (1.22 m.) gravity extender units as required by the retaining wall’s design plans for the remainder of the second course.
Once gravity extender units are installed, proceed to install adequate drainage, fill and compact the hollow core blocks and surround the gravity extenders with clear crush drainage gravel, then add and compact layers of backfill behind the blocks as outlined here in these steps of the MagnumStone Unit Installation section.
Sweep any excess stones off the top of the blocks and gravity extenders before beginning to place the next course of retaining wall blocks.

STEP

Higher and Top Courses of Outside Curves

Quick Steps

Properly install layers of clear crush gravel and approved backfill materials for each course as outlined in the previous steps.
Sweep any excess stones off the top of the blocks.
For the final course of the retaining wall, install MagnumStone top blocks for a clean finish and more versatility for top of wall details.
Add and compact gravel in the hollow core’s top block and install approved backfill materials behind the wall, until both are level with the back of the top block.
Lay soil separation fabric from the back of the top block’s facing over the block and approximately 12” (0.3 m.) over the backfill area.
Atop the remaining 8” (0.2 m.) behind the block facing, install planting soil to cover the soil separation fabric and backfill zone.