Permeable Resin Bound Paving & The Heatwave….Friend or Foe? 

The weather this year has gone from one extreme to another. The “beast of the east” earlier in the year to now one of the hottest spells since the 70’s. Whilst many love the sun, many also face challenges. So how does the permeable resin bound paving industry fair?

What does it mean for resin bound contractors?

Well, first of all it means no doubt the shirts will be off. You will need to reach for your hats and slap on the factor 50. (I hear some of you sniggering that it’s too high and heading straight to slap on factor 8 oil. The sun is strong guys. It’s not worth it. Red is not the new black). Keep hydrated. The days are long and at times unbearingly warm.

What does it mean for the resin install?

Positives

On the plus side, the weather is less unpredictable than usual. We know that it’s going to be clear blue skies for the next couple of weeks. This allows for maximum productivity due to the early starts and late finishes. A permeable resin bound paving project that may normally take a couple of days will certainly have shorter lead times because of this.

Using UV stable resin means its ‘winner winner chicken dinner’, as there is certainly no need to purchase any catalyst at all, reducing your resin kit costs. A catalyst is usually required to speed up the reaction of the particles in the resin. Because it’s so warm, a faster chemical reaction occurs naturally and so there is no catalyst requirement.

Negatives

Who would have thought there would be a flip side to lovely hot summers days? Well, in the resin bound industry there is. The main reason being, the chemical reactions in the resin happen much faster, halving the trowel time of the resin bound aggregates. Once the outside temperature reaches above a certain level, it will be very tricky, if not impossible to successfully lay a resin surface. This is because the resin will begin to set. Once it starts setting, you will be unable to compress and trowel it in to the smooth, seamless surface that resin surfacing is well known for.

UV stable resin is more forgiving than non-uv stable resin. Please remember however even with that, installing in temperatures above 28°c, is pushing it. For every 10°c rise in temperature, the reaction times speed up x2. In ‘ideal’ conditions when using UV stable resin, you can usually expect to have a trowel time of around 35-40minutes. When the weather is hot however, things change. At the maximum installation temperature, you can look at having a maximum trowel time of 10-12 minutes.

Please remember however, that resin laying is a chemistry and the dynamics can change depending on the different variables of the installation. For instance: When installing on to hot tarmac with resin and aggregates that have been left out in the sun, the trowel time will be increasingly lower in comparison to where the resin and aggregates have been kept cool in the shade and installed on to concrete.

Non UV stable resin is not recommended for installations in the heat. This is because it can only be installed in temperatures up to 25°c. The maximum trowel time is really pushing it too, around 5 minutes, again dependant on the other variables in the installation.

How will the heat affect the longevity of resin gravel surfacing?

In short, it doesn’t. Permeable resin bound paving has a melting point of 220°c. You could be stood in the middle of Death Valley and the structure and the durability of a UV stable resin surface would not be affected by the heat.

A look to the future…

The current situation

Infrastructure, such as roads, take a huge hit when we receive long spells of hot weather. This is because the majority are made of tarmac. Just like the roads, there is large percentage of driveways also made of tarmac. Tarmac softens like chocolate; melting when it is hot and turning brittle and hard when it is cold. It does not hold the same strength and durability all the year round, acting differently in different temperatures. When it’s sunny, because tarmac is black, it absorbs the heat, becoming much hotter than the actual outside air temperature. When temperatures start rising in to the mid 30°c’s, the tarmac can reach anywhere up to and way above 80°c. Tarmac will start softening at 50°c, so when it reaches heights of 80°c it will begin to melt. This causes severe damage. According to the Met Office, heat damage to road surfaces in Oxfordshire in 2006 cost an estimated £3.6m of taxpayers money to repair. Re-surfacing and repairs from the heat alone can therefore become extremely expensive.

Image: courtesy of Thames Valley Police

Images: courtesy of the BBC

An increase in humidity, coupled with warm temperatures, creates warm and moist air, that will rise in to the atmosphere. When these hot particles rise, they cause an unstable atmosphere. They collide with ice and colder particles suspended higher in the air as clouds, to the short of it, causing a thunderstorm. Heavy showers from thunderstorms are not ideal for traditional methods of paving. This is because the water sits on the top of the surface, causing a) inconveniences, and b) in more severe cases, flash flooding.

Permeable resin bound paving does not have this issue because the surface is porous, allowing water to drain through and follow its natural water course.

To conclude

Heat is a friend of resin gravel systems in one sense but a foe in another. Permeable resin bound paving is a great solution for surfacing in hot temperatures and countries with warmer climates, as it maintains its durability. However, from an installation perspective, you need to ensure that the temperatures are practical, with consistent variables and working conditions to ensure the right working time to trowel it. In order to have a stunning and stable resin bound surface, you need to be able to install it in the first place.

Due to its durability and resistance to different weather conditions, it could even be argued that resin bound systems could possibly provide a wide spread, long term solution for infrastructure and countries with unpredictable weather.

Permeable resin bound paving is exceptionally functional, as it sits both sides of the weather spectrum. In times of rain, its allows water to drain through, is SuDS compliant and doesn’t require planning permission. When it is hot resin bound systems are hardwearing and withstand the heat, they just cant be installed in the heat.