Bradstone Woburn Rumbled Infilta Permeable Block Paving Graphite
Concrete Block Permeable Paving (CBPP) differs from conventional block paving because it allows rainwater to filter through gaps between the blocks into a stone sub-base below.
Bradstone Woburn Rumbled Infilta Permeable Block Paving Graphite
The sub-base should have enough space to store the water for a short period of time to allow it to soak into the ground naturally, discharge in a controlled manner to a surface water drainage system or connect to a rainwater harvesting system to collect the water for re-use.
The installation of Bradstone’s Infilta range varies from standard block paving and here we are looking to offer basic guidance and advice on the differences.
Design Consideration
When assessing the design of a permeable paved driveway, considerations should be given to levels, soil permeability and soil strength.
Sub-base
Conventional MOT Type 1 is not used for the sub-base as it is not free draining, the open graded Bradstone 20mm Drainage Aggregate is used instead.
In free draining applications, a suitable geotextile should be placed at formation level (overlapping joints by 300mm), below the 20mm Drainage Aggregate sub-base. When the sub-base is designed to hold water an impermeable membrane lining should be used.
Laying geotextile.
Laying sub-base with Bradstone 20mm Drainage Aggregate.
The depth of the sub-base will be governed by the strength and type of the underlying ground, but typically you will need to be around 200mm deep on soils of good strength and 500mm in areas of poor soil strength.
It is best to prevent vehicles running on the sub-base during construction if possible, as they will cause rutting in the loose surface. The blocks are restrained in the conventional way with a kerb or edging and provide more than adequate support to traffic.
Laying Course
The laying course uses Bradstone Bedding Aggregate, a 6mm angular, open graded material.
Levelling the laying course of Bradstone 6mm Bedding Aggregate.
Laying blocks.
Unlike normal bedding sand, it is free draining and therefore it does not require any control on moisture content.
The laying course should be 50mm thick, rather than 30mm for conventional paving and it is not compacted before the blocks are laid. Once laid, and prior to jointing, a light pass over with a whacker plate with a rubber mat is required.
The preparation and levelling of the bedding surface is critical as an aggregate bedding layer will not be compacted as with conventional block paving.
Jointing
Brushing in the Bradstone 3mm Jointing Aggregate.
Bradstone Infilta blocks have a nominal joint width of 5mm which is greater than a normal block paving. Therefore, the Bradstone 3mm Jointing Aggregate should be used for joint filling.
Brush in and after ensuring there is not loose aggregate on the surface that could mark the blocks, another pass with the whacker is required. Finally, brush in more aggregate to fill voids as required.
Compacting blocks with a whacker plate.
If you require any help, please give the Simply Paving office a call on 0800 032 6306 and we will try to assist you in all aspects of your landscaping project.
I think I will leave it to the experts!