15 Reasons New Tarmac Drive Can Still Be Soft Even After Installation

Tarmac is a popular surface for driveways, playgrounds, and other recreational areas, but many people don’t know it can still be soft even after installation. The tarmac surface can get soft due to moisture beneath the surface, making it difficult for people enjoying the recreational area to run and play on it. Below are some reasons why the new tarmac drive is still soft even after being installed tightly.


Tarmac Is a Porous Surface and Can Easily Absorb Water

Tarmac, especially untreated tarmac, is a very porous surface. This makes it highly permeable and easily absorbs water from the ground or above. The installation process of tarmac will seal some of these pores, but not all of them, depending on the quality of the job. Inadequate sealing means that some areas underneath the tarmac will absorb water, leading to a soft surface.


Tarmac Needs Time to Harden and the Final Appearance May Vary

Tarmac is not a hard surface when it is first installed. It needs time to cure and harden properly, taking up to 6 weeks. During this time, the surface may still be soft as the tarmac continues to cure and solidify. The final appearance of the tarmac surface may also vary from one area to another due to variations in the installation process. This can also lead to softer areas than others even after installation.


Tarmac Is Prone to Frost Heave When Wet

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One of the main reasons tarmac surfaces can get soft is frost heave. When the surface gets wet, it can freeze and expand, pushing the tarmac upwards. This can create a soft surface as well as damage the tarmac. Frost heave is more common in areas that have colder temperatures and is more likely to occur during the winter months.


Tarmac Can Settle Over Time

As with any surface, tarmac can also settle over time. This is usually due to people’s weight or vehicles traveling over it. The settling process can cause the surface to become uneven, leading to softer areas than others.

While tarmac surfaces may still be soft after installation, the following are ways to help reduce this issue:


Tarmac Compaction During Installation

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A tarmac contractor will usually compact the surface during installation. This helps create a more stable and sturdy foundation for the tarmac. However, it can also make some areas harder than others due to variations in the compaction process. This is especially true if an experienced operator does not use the correct technique.


Tarmac Sub-base Preparation

If the sub-base is not made up of good quality material such as crushed rock or limestone, it might start to erode after a while. This can cause drainage problems and make the surface uneven and unstable. The tarmac may also start to crack and split due to the movement of the underlying soil.

The choice of gravel used for the sub-base can also affect this issue, especially if it is too small and in bad condition. Failing to prepare the sub-base correctly can lead to the tarmac being soft in some areas, which can pose risks to running or playing on it.


Improper Installation

The improper installation refers to any errors in preparing and installing a new tarmac surface. This includes using unsuitable machinery or not using enough compaction during installation. It may also mean some mistakes in completing other work, such as laying cables or ducts underneath the site, which would add extra weight to the area already saturated with water from rain or snowmelt.


Quality of Tarmac

The quality of the tarmac used can also affect its strength and stability. If the tarmac is too soft or has not been graded properly, it can easily break down and deform. Some areas underneath may still be able to absorb water even after installation, which will weaken the surface’s quality and make it more susceptible to damage from vehicles or people. This is why it’s recommended to invest in a good-quality tarmac for recreational areas such as playgrounds and sports courts instead of using a cheaper option that might not last very long and needs frequent repairs and resurfacing.


Rock Salt Damage

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One common cause of a weak system is salt damage on asphalt surfaces. Winter maintenance involves plowing and spreading salt to keep ice from a dangerous surface. While it’s necessary to prevent people from slipping on the ice, the salt will also build up over time, eat away at any protective coatings, and stop pores in the asphalt from absorbing water. This leads to small areas underneath becoming soft and thin spots where vehicles can wear through.

Tarmac Construction Underneath Water Mains or Pipes

In densely populated urban areas, roads are often crowned so that rainwater drains off them into gutters and sewers instead of pooling in puddles near a shop entrance or a house driveway. This means that there might be construction underneath water mains or pipes that become part of the road surface. If the tarmac is not properly sealed, water will get in and soften the surface over time.


Poor Drainage

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If water cannot drain away quickly from a tarmac surface, it will eventually start to pool on the surface. This can cause the tarmac to soften and even buckle in some areas. It’s important to have proper drainage in place before installing a tarmac surface, especially if the area is prone to flooding or has a high-water table.


Damaged Steel Reinforcement

The steel reinforcement underneath the tarmac can sometimes become damaged, which will leave small holes and gaps. If this happens, water will get in and soften the surface over time.


Heating and Cooling of the Tarmac

The temperature fluctuations that occur during the day and night can also affect the stability of a tarmac surface. In hot weather, the tarmac will expand, and in cold weather, it will contract. This can cause small cracks to develop over time, and these cracks will provide a path for water to seep through and soften the surface.


Alkali-Silica Reaction

Another problem that can occur with tarmac is called an alkali-silica reaction. This happens when there is a reaction between the silica in the aggregate and the alkalis in the asphalt binder. Over time, this will cause the tarmac to deteriorate and crumble away.


Using Tarmac for Other Purposes

There are different grades of tarmac, and not all of them can be used as a surface coat. Some only work as a foundation coat, and some aren’t suitable for heavy-duty use, such as car parks or walkways that get a lot of footfall. If the wrong type is used, it won’t support vehicles or people walking on it, which will cause the surface to break down over time.



There are several reasons why your new tarmac drive is still soft even after installation. It’s important to consider all of these factors before installing a tarmac surface to ensure that it will last for as long as possible. For recreational areas, it’s best to invest in a good-quality tarmac to avoid having to repair and resurface it frequently.


Now that you have the information to diagnose why your new tarmac drive still soft. While you are here why not read some other blog posts we have to offer including 8 Reasons Why Your Pilot Light Keeps Going OutĀ  and another article explaining how to Give Your Stone Or Brick Fireplace A D.I.Y Makeover!