The focus points we will be covering in this article is on the importance of the Iron Works reinstatement system. This is the third article in the series. So currently, there is an issue or ongoing challenge around the country regarding this. Many, many local authorities are reporting challenges with failing ironworks.
So it's crucial we take a step back and understand the reason for those failures. Leading of the back of part 1 and 2 we discuss all the other elements of this completely cold applied ironwork.
Coming onto the backfill concrete, we recommend using a flowable system. The objective is to ensure that the concrete then flows down around the ironwork covering the bedding mortar and surrounding the frame, flange, and locking it in with the substrates around it. This then gives you a very strong ring beam effect, which sits directly above the chamber itself and comes up through the carriageway to the underside of the wearing coarse.
For this application, we would recommend the use of our Magma HardMaster, W615. This is going to achieve the required 20 newtons per millimetre squared compressive strength within 90 minutes, and 50 newtons per millimetre squared after 28 days. The end result is that it compensates for the strength of the bedding, mortar and the structures below.
Last but not least, we review the top wearing course. With this, we're looking at the top 40mm down from the top of the ironwork rime. One of the key points we need to emphasise is the stability of the ironwork structure. So whether it be on a deep dig storm drain chamber where it could be up to 5 plus metres down into the ground, or it could be a small gully pot that's maybe 400 to 600m deep, all of the structures are designed as a solid structure. They have concrete foundations. They're not designed to move, so the ironwork structure is there as a solid structure.
The road carriageway surface is designed to move. Highways engineers have spent many years developing and engineering asphalt to ensure the asphalt flexes as heavy goods vehicles pass across it.
So we have a stress point where you've got the ironworks structure meets the top of the road carriageway. This is where you will find carriageway movement adjacent to what is designed to be a solid structure. It is therefore critical that we have a movement joint at that junction. That's why we've got here another cold applied system, which is Magma Bituseal, H561 joint strip. This is a self-adhesive poly modified bitumen strip which is applied to the vertically cut surface or wearing course. The Bituseal is 40mm deep and 8 mm thick poly modified bitumen provides a watertight seal and also enables movement between the newly finished surface and surrounding substrates.
For the top wearing course would recommend using the Meon Magma PermaFyx MMA wearing course. This is a 2 component system mixed in with 6mm or 10mm aggregate and placed as a backfill to the wearing course around the ironworks.
The advantage of using a PermaFyx L271 or an MMA cured backfill system is that you've got a very good placement adhesion. You got extremely high tensile strength, and you've got a guaranteed SRV greater than 45. The product is mixed cold, placed around ironworks and then trowelled level with the surrounding carriageway. There's no requirement for any compaction, and the whole system can be delivered without any need for hot works.
If you want to know more on how Meon can help with your failed ironworks then get in touch today on 02392 200 606 or email us at mail@meonuk.com.
