Road construction experts deny talk of too little asphalt layer on roads: it is hard to imagine

“Quality control in the road sector is really very strict and it is mostly invisible and unknown to us, the residents. We can hear that such ignorance sometimes causes people to have doubts about the quality, questions about why a small pothole can already be seen on a new road or similar. We want to have as few doubts as possible. To that end, it is important to reveal the behind-the-scenes of the works, which are truly extraordinary – in order for the road to be built, every centimeter of its layer is checked,” comments Šarūnas Frolenko, head of the “Lietuvos keliai” association.

Irmantas Karalevičius, technical director of the road and bridge construction company “Alkesta”, says that road construction consists of many layers, and each of them has its own specifics.

“The construction of the road begins with the embankment, or in other words, the foundation. After that, a frost-resistant layer, crushed stone or gravel layers are poured, and everything is finished with an asphalt base. Each of these layers must meet strict specifications to ensure durability and safety,” the specialist teaches.

He says that any material used must be tested to confirm its suitability.

“It’s not like we went, dug the gravel we needed in the quarry and that’s it, we use it. Absolutely not – first you need to evaluate its granulometry, contamination, water conductivity. We perform these and other suitability tests in our company’s accredited laboratory. We have to make sure that the materials we use meet the quality parameters set for them, because in the following processes, the customer will test repeatedly and will still see if the materials used are unsuitable”, says I. Karalevičius.

Mindaugas Petrauskas, technical director of the road and street construction company “Kerista”, agrees that road construction processes require careful planning and maintenance – there is simply no other choice.

“For each material and layer we will find very specific requirements for how it must be installed and how it must be measured and tested in the laboratory. All these test standards are international, not our own invention. Each tier is essentially given a green or red light by the technical supervisor – until the material is tested in the lab and satisfactory test results are obtained, the higher tier cannot even begin. That’s how the road “sandwich” grows little by little, says M. Petrauskas.

The expert mentions that the contractors themselves usually have and use equipment that monitors more than one quality parameter, and part of the self-control takes place automatically, without human intervention, thus reducing the probability of error.

M. Petrauskas states that in road construction, three stages of control are applied to each part of the road construction and their materials: suitability, internal control and control performed by the customer.

“Work starts long before you see it on the road. Even before purchasing materials, suppliers must provide a declaration of product performance, which ensures that the product will always be the same, and there will be no “surprises” in the next batch. During the works, we usually check it again with self-control tests to make sure of everything, and then we can calmly hand over the works”, says M. Petrauskas.

Next, once the work has begun, a series of internal quality control tests are carried out to ensure that all processes are carried out correctly.

“Finally, control tests are carried out by the customer, by which he determines whether the properties of the materials used and the road construction work performed meet the requirements of the project and regulatory documents. For example, you can pay attention to the small cylindrical holes drilled in the newly laid roads – these are the samples that are analyzed in the laboratory chosen by the customer”, says I. Karalevičius.

According to him, discrepancies do occur during these essential tests, although not often.

“For example, the compaction of the asphalt layer must be at least 98 percent. Up to 95.6 percent it is still possible to accept the project, but the contractor receives a monetary deduction. If it is still below the limit, the work is not accepted, it would have to be redone. Believe me, it would really cost such money, due to which deviations are carefully monitored throughout the process,” says the specialist.

The interlocutor adds that some tests could be carried out without destroying the road surface in a random way, and using destructive methods only where there are suspicions.

“Software systems that help to identify potentially unsuitable places for asphalt laying are not yet so widespread in Lithuania, but in Scandinavia.” This allows for faster, more efficient and cheaper inspection of the paved asphalt layer without destroying it. The customer can even see exactly where and how many times the so-called roller passed, what its temperature was during compaction. It is possible to determine more precisely where the compaction could have been of poor quality”, I. Karalevičius shares his foreign experience.

Žilvinas Smalskys, head of the technical maintenance department of the state company Viamatika, which performs laboratory tests of materials used in road construction, says that the road is not only streets, but also bridges, viaducts, culverts, overpasses, animal crossings and more, so it is really important to check there is something

“Our technical maintenance experts perform construction supervision so that the users of bridges, roads, water and airports – that is us, all residents – use safe and high-quality infrastructure,” says Ž. Smalsky

According to the spokesman, these technical supervisors must evaluate and determine whether the contractor can be allowed to proceed with the work at all. For example, during the formation of the bedrock, the supervisors have to see it themselves, make various measurements with special devices, and send the samples to the laboratory, where their strength and other properties are tested, and only then are they allowed to start pouring other layers. And the fact that contractors are looking for ways to do the work cheaper, he calls it a myth.

“I don’t believe that there can be intentional savings in materials or deviations from the design in order for the contractor to save. It’s very risky and can cost the same contractor a lot of money later on – it’s easy to check. In the laboratory, we have all the layers in the palm of our hands, we evaluate them according to a large number of parameters that are forwarded to the contractor, and he usually sees everything on the computer the very next day after the tests,” says Ž. Smalsky

According to the data provided by the company “Via Lietuva”, which is responsible for the construction and maintenance of roads of state importance, according to the statistics of the last three years, an average of 267 objects are inspected per year.

“Despite strict initial testing and construction standards, surface defects are still detected during initial inspections of new projects in recent years, although most of them are minor. This shows that quality control is necessary and it works – even the smallest inconsistencies noticed in time are corrected before the roads are used”, says Martynas Gedaminskas, Head of the Infrastructure and Support Group of Via Lietuva.

“Via Lietuva” tests are carried out by a mobile research laboratory, which allows for a faster, more accurate and more objective assessment of the condition of the roads and the quality of the work performed.

“Research conducted by the mobile road laboratory minimizes human influence in assessing the condition of the road surface. After we have conducted the research, the objects are repeatedly checked by accredited and independent research laboratories, applying double control”, says M. Gedaminskas.

All stages of road surface construction installation are monitored by a hired independent certified technical supervisor. He accepts the work after having previously ordered the necessary control studies and tests for quality assurance depending on the part of the road surface structure installed.