By combining Green Terramesh and ParaDrain geogrid products, an environmentally friendly noise barrier was constructed at a housing development owned by Bellway Homes
Maccaferri products, including Green Terramesh and ParaDrain, were used to build an environmentally friendly noise barrier
To protect a new housing development in Banbury, Oxfordshire from the noise of the M40 Motorway close to it, the developer Bellway Homes, deemed that an acoustic barrier was necessary. The bund would run immediately adjacent to the motorway.
Made with Maccaferri’s Green Terramesh and ParaDrain systems, the structure is formed of a soil reinforced slope which re-uses the poor and marginal site won fill material. The total structure is 1,300-metres long with a maximum height of 7 meters. The first stage of the works started in April 2016 and finished in September 2016, for a total length of 550 metres.
Being developed by contractor M Lambe Construction, the acoustic barrier designed by our engineers is the result of an innovative design methodology and approach for reinforced slopes and walls with low-permeability fills. Drainage geocomposites (including MacDrain W) have been used too in place of a traditional drainage solutions using mineral media (gravels, sands), which consistently resulted in large cost reductions as well as representing a more environmental-friendly approach.
Most geotechnical engineers, especially Maccaferri’s, nowadays pay the utmost attention to the protection of the environment. By reusing the soil material as structural backfill within the acoustic bund, it did not have to be removed from site, not only saving the costs of transportation and disposal, but also reducing the vehicle movements on the local roads and their commensurate emissions.
Maccaferri firmly believes that engineers should be able to design reinforced soil structures using marginal, poorly drained fills, without the need to import granular material, which has both cost and environmental implications. As many of us know, marginal fill typically carries high silt and/or clay content which, when loaded, generates pore water pressure in the backfill. This reduces the soil’s effective strength and the bond between it and the soil reinforcement.
Thus, marginal fill can only be used in reinforced soil structures if adequate drainage is provided. These more sustainable and environmentally friendly slopes and walls can be achieved using a geogrid that has the dual function of reinforcement and drainage geogrid; known as a “drainage geogrid”. The ParaDrain geogrid was used as the primary geogrid with Green Terramesh which provided secondary reinforcement with its integral pre-fabricated fascia units to speed up construction.
Unlike a traditional planar drainage geocomposite (such as our MacDrain), ParaDrain is a true geogrid. Each of the longitudinal strength elements features a drainage trough protected with a geotextile filter to prevent clogging with fine materials; ParaDrain introduces into the soil a multitude of small drainage channels which reduce the pore water pressure in the soil backfill.
At the Bellway Homes site, investigations were conducted with some specific testing for the Maccaferri design. Moreover, as part of the construction quality control process, insitu testing of soil compaction have been performed following the Specification for Highway Works.
For further information do not hesitate to contact us.