GRM by CTS
Rubber modification of road construction bitumen and asphalt

What is "GRM by CTS"?

A lot of knowledge on the topic of “rubber modification of bitumen and asphalt” and years of patient tests were needed to develop the concentrated rubber-modified bitumen granulates “GRM by CTS”. GRM stands for Granulate Rubber Modified. GRM by CTS is produced from buffing dusts with additivation specially manufactured for CTS, bitumen and bulking agents with specific properties in a complex and controlled manufacturing process. Due to the fact that the polymers from the buffing dust used are optimally decomposed and combined with the bitumen matrix, the asphalts manufactured with GRM by CTS can be installed immediately after production. Today, GRM by CTS safely fulfils all the requirements set by the “Technical conditions of delivery for rubber-modified bitumen, TL RmB-StB, By; 2010 Edition” and “E GmBA – Recommendations on rubber-modified bitumen and asphalt; 2012 Edition”.

At the asphalt mixing plant, GRM by CTS is added directly to the mixing process along with aggregates and road construction bitumen. The asphalt pavements designed in this way show the greatest advantage: a long useful life. In the event of proper application and corresponding dosage, it can increase by 40 – 50% on average (compared to asphalt pavements with conventional formulae) e.g. in the case of porous asphalt. Evaluations of existing roads confirm this.
The GRM by CTS rubber-modified bitumen granulates are demixing-stable. They are delivered by lorry and can be stored long-term at the asphalt mixing plant without concern in the event of an appropriate environment. The dosage takes place directly into the asphalt mixer. Usually, no changes are required to the usual asphalt production.

Use of GRM by CTS in the Flüster-Asphalt®

The high efficiency of GRM by CTS 40/20 impresses particularly in the production of Flüster-Asphalt®. (Porous asphalt, PA).

More information

Advantages of rubber modification with GRM by CTS

  • Significantly increased viscosity
  • Expanded plasticity span (use temperature range)
  • High resistance towards hardening (minimised ageing due to oxidation)
  • Improved resistance towards climatic influences (UV radiation, high and low temperatures)
  • Very good elastic properties
  • Increased adhesive force (also on adhesion-critical aggregates)
  • Problem-free storage and handling at the asphalt mixing plant
  • Highly flexible application. Only by varying the dosage quantity and selecting a corresponding basic binding agent are nearly all conceivable elastomer-modified asphalts reproducibly presentable.
  • GRM by CTS is a tried-and-tested product. So far, it has been used on nearly 14 m square metres of asphalt worldwide.
  • Demonstrably clear increase in the durability of the asphalt pavements thanks to the favourable properties of GRM by CTS
  • This results in long-term savings due to extended use intervals. 15-year useful life e.g. in porous asphalts is no exception
  • Tenders can take place according to TL RmB-StB, By; 2010 Edition or E GmBA – Recommendations on rubber-modified bitumen and asphalt; 2012 Edition (reference to rubber-modified bitumen granulate is required)
  • GRM by CTS is a “finished product”. Since no so-called longer maturation or swelling times are required for usual mixed goods temperatures in the pre-fabricated silo of the asphalt mixing plant, temperature-reduced asphalts can also be tendered and manufactured without any problem with suitable basic binding agents
  • GRM by CTS is a tried-and-tested product. Polymer-modified binding agents (type: PmB A) can be substituted without any problem. See also foreword to TL RmB StB, By
  • GRM by CTS is nearly unlimited in terms of storability at the asphalt mixing plant. Therefore, the product can be stored at any time. Thus, small and very small asphalt quantities can be tendered and also manufactured at any time.
  • GRM by CTS is a tried-and-tested product. Polymer-modified binding agents (type: PmB A) can be substituted without any problem. See also foreword to TL RmB StB, By
  • GRM by CTS is nearly unlimited in terms of storability at the asphalt mixing plant. Therefore, the product can be stored at any time. Thus, small and very small asphalt quantities can be tendered and also manufactured at any time.

Advantages for installers

  • No special measures are required for installing asphalts designed with GRM by CTS.
  • The use of GRM by CTS is absolutely process-reliable.
  • Additionally, GRM by CTS is equipped with an “odour inhibitor”. Annoying vapours are successfully avoided
  • GRM by CTS is a tried-and-tested, safe product
  • If the processing instructions are complied with, no substances hazardous to health are released at any time
  • Like asphalts with usual polymer-modified binding agents, all asphalt varieties manufactured with GRM by CTS can be installed and condensed. Special measures, also during transportation, are not required. Water in small quantities has proved to be an outstanding separating agent

Advantages for producers

  • GRM by CTS is a concentrated rubber-modified bitumen granulate. Due to its nature, it can be stored at the asphalt mixing plant on an unlimited basis without special requirements. No special silo units, binding agent tanks with mixing system or other tank capacities are required.
  • Since there is no minimum order quantity, exactly the required quantity can be allotted in advance of the measure. Costly residual quantities are unerringly avoided. Also possible waiting or idle times in the binding agent delivery
  • Depending on the configuration of the asphalt mixing plant, the required quantity of GRM by CTS can be delivered flexibly packaged:
    • in big bags (700kg)
    • or on pallets in fusible PE bags. To the gram up to a packaging size of 20 kg; tailored exactly to customer wishes (respective intended use and an expedient batch size)
  • The dosage of GRM by CTS is simple. Directly into the mixer of the asphalt mixing plant onto the hot aggregates.
  • Since the strong increase in viscosity takes place only in the asphalt mixer of the asphalt mixing plant, the pumps and the binding agent conveying system are sustainably protected, as only usual road construction bitumen is conveyed and dosed
  • GRM by CTS is a “finished product”. No so-called longer maturation or swelling times are required in the case of usual mixed good temperatures in the pre-fabricated silo of the asphalt mixing plant
  • Due to the flexible use possibilities of the CTS rubber-modified bitumen granulate, nearly all possible asphalt conceptions are implementable, in accordance with the modular design principle – different concentrations and road construction bitumen of different gradation. Thus, additional tank capacities no longer need to be stored (e.g.: PmB, PmB RC, PmB RC plus, PmB with a higher degree of modification)

Origin and success of GRM by CTS

Until 2005, rubber-modified bitumen was available only as a “liquid product”. From an asphalt technology perspective, this “liquid product” brought very good results. However, this positive impression was clouded by a series of negative accompanying circumstances:

  • It was storable only to a limited extent,
  • available in complete TTFs only and,
  • therefore usable in a limited radius of production
  • and sensibly as of a certain size of construction measure.

Since 2005, the product GRM by CTS has now been available in granulate form. Thus, it is now possible to expand the transportation radius around the whole world and to increase storability considerably.

Additionally, even the first tests showed that the new granulate possessed even better properties than the liquid variant. This led to the production department at CTS Bitumen GmbH focusing heavily on GRM by CTS. The success of the new product resulted in a huge increase in the marketed quantity of rubber-modified bitumen of CTS Bitumen GmbH:

Further information

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Use of GRM by CTS in the Flüster-Asphalt®

Flüster-Asphalt® is the concept for noise-reducing asphalt construction methods. CTS Bitumen has trademarked the name and it stands for noise-optimised porous asphalts designed with rubber-modified CTS bitumen.

Thanks to many years of experience and a great deal of practical knowledge (since the beginning of the 1980s, CTS has occupied itself intensively with the problems related to porous asphalt) as well as the high quality level of CTS’s rubber-modified binding agents, a significantly extended useful life was achieved as a result. With the background of more than 4,000,000 m² installed PA in Germany, an average useful life of approximately 14 years was determined. You will find more information on this on our reference page. In the case of comparable roads formulated with traditional, higher-modified PmB A 40/100-65, an average useful life of only 9-10 years lay time was established.

Long-term, effective noise reduction is dependent on many factors: hollow content, structure of the asphalt, flatness and retention of the surface texture. Noise-reducing asphalts manufactured with CTS Bitumen also show better noise-technical results over a longer period. On the laboratory scale, this statement can be proved by the results of the Cantabro test. Here, the effectively measures grain loss provides a good starting point regarding the permanence of hollow-rich asphalt.

In the Cantabro test, asphalt test bodies are stressed on a defined basis and the grain loss determined. Test bodies manufactured with GRM by CTS 40/20 shine with a typical grain loss of approximately 10 M %. In comparison, the PmB, type PmB A 40/100-65, also show small average grain losses in the scale of 10 – 15 M %. Currently, hot-liquid rubber-modified bitumens show significantly higher grain losses (> 30 M %). The reason is simple. For occupational health and safety reasons, production must take place at a low temperature level. As a consequence, this results in a non-optimal decomposition of the polymers of the buffing dusts used.

In the Cantabro test, the PmB A (PmB A 40/100-65) and GRM by CTS 40/20 show low to very low grain losses. The question arises: are these products equivalent? No, as the documented useful lives speak in favour of rubber-modified bitumens from CTS. Here, too, a simple answer is possible: ageing, oxidation by oxygen, the influence of the climate and UV light afflicts PmB A considerably more quickly and intensively than comparable rubber-modified binding agents. (e.g.: RmB G)

CTS Blog

CTS, based in Buch am Erlbach, Bavaria (Germany), has been involved in the development and improvement of rubber-modified bitumen for road construction since 1985. Among other things, we developed porous asphalt into "Flüsterasphalt®". As one of the first market participants in the field of rubber modification, we claim to be the technology leader today. After many years of research and continuous development, CTS Bitumen was able to present an absolutely innovative new development: rubber-modified bitumen granulates. This achievement sets new standards and is characterised worldwide by unproblematic handling, transport and above-average performance.

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