change along the entire length of the wall, stakes should be driven to the proper height as determined by a transit to indicate the proper bottom elevation of the wall. These stakes should also show where base step-ups are located. Bear in mind that each step-up causes the leveling pad location to step back by one inch due to the integral setback of ReCon “Series 50” units.
Fill the trench and any over-excavated areas with the specified base material. Unless specified otherwise, this material should generally consist of a well-draining material that also contains enough fines that the leveling pad will hold its shape after compaction. Depending on the region, this material may be referred to as road base, ¾” minus, crush and run or Class 5. Fully compact the base material and add or remove material as necessary to keep the leveling pad as close to the final level grade as possible. Where step-ups are located, base material should taper up at roughly a 45° angle.
At times a concrete leveling pad may be required or desirable in lieu of a compacted granular base material. Unless the leveling pad is designed as a true “footing” and extends below frost depth, the concrete should not contain steel reinforcing and should consist of a relatively weak mix capable of breaking up under frost pressures. This allows for resettlement as the frost dissipates. Also, when using a concrete leveling pad take extra care to keep the pad level and any step-ups at their proper height to avoid difficulty in maintaining height tolerances.
Base Course Installation
The first (base) course of a ReCon wall requires the use of a Base Block. This unit does not have the special groove on the bottom. This makes for easier leveling of the base course and also provides greater shear resistance at the interface between the leveling pad and ReCon base block.
Walls should generally be built starting at the lowest point in the wall. Make sure to properly place the edge of the first unit at an even 2 foot increment from any fixed wall features such as a 90° corner, a control joint or building structure. This helps to avoid unnecessary cutting or trimming of the ReCon units and improves wall aesthetics.
Depending on the type of material used for the leveling pad and how level the pad is to start with, base course leveling may be easier if the leveling pad is topped and screed with up to ½” of clean sand. On long straight sections of wall, it may be helpful to set units with a canter or tip-back of up to ½”. This increases the ability to maintain a positive wall batter and minimize rotation during soil compaction when robust compaction equipment is used.
As base units are laid, ensure that the units are in full contact with the leveling pad and check to ascertain that the units are level both front-to- back and left-to-right. Use a jig if necessary to maintain a consistent leveling plane from unit-to- unit. Lay units end-to-end and avoid gaps between units. The use of a string line will help ensure proper wall alignment along straight sections of wall. After the base units have been placed and before compacting the backfill material behind the wall, compaction to the specified embedment depth should be done in front of the wall.