John Graham (Alicon Limited)
Allan McKerchar (Civil Engineering Central Limited)
Griffiths Street, Putaruru
Tucked away in Putaruru a small residential property features two beautiful Allan Block walls. The client wanted to provide an aesthetically pleasing and structurally sound improvement to their driveway and garden, both features the Allan Block system boasts. The wall was designed featuring curves and step-up/downs both complimented by the Iron Sand coloured blocks providing a stunning result.
This project required a retaining wall at the back of the house to be cantilevered off the lower level where there was a driveway. A masonry application using Allan Block was offered to the client due to limited space and the surrounding area being rock making it uneconomical to excavate.
Cirtex provided a concept detail and the confidence that the Allan Block built as a masonry application was in essence equivalent (the same for design purposes) to a masonry wall using 20 series concrete blocks. In fact, from a design point of view, the Allan Block offers a better solution as the concrete units are more substantial and stronger than the 20 series blocks. The AB Classic provides a more natural look, and its setback helps to reduce the amount of soil needed to be retained, reducing the pressure on the structure.
This project required knowledge and experience, a task that only an Allan Block master wall builder was able to do smoothly from start to finish. The Alicon team used all their creativity to overcome the multiple challenges a masonry application represents. One of the main problems was the proper rebar placement along the curve part of the wall as the radius on an Allan Block inside curve grows with height, complicating the positioning of subsequent courses of blocks. Ensuring the vertical rebars had the same inclination as the retaining wall while avoiding the cutting of any block cells was a critical part of installing this wall correctly. The final challenge Alicon successfully overcame was providing a line and level for the remaining Allan Block courses, the first layer of blocks was mortared to the top of the concrete footing
The Allan Block Retaining Wall System provided the following benefits to the project: