Hydrate in asphalt

Hydrat in asphalt

Roads should be durable, load and weather resistant. Lime hydrate in asphalt extends the service life and increases resistance to abrasion, ruts and premature aging.

Fels hydrated lime is a natural product which, as an additive in asphalt, significantly extends the service life of asphalt layers:

  1. Increases the adhesion between rock and bitumen
  2. Increases resistance to surface deformation
  3. Delays age embrittlement


Operating principle

The addition of Fels lime hydrate causes the following effects through calcium ion exchange between the rock and the bituminous mortar improves adhesion and reduces oxidative embrittlement. This has positive effects on the most common types of damage:

  1. Ruts: The increasing traffic load increasingly overtaxes the elasticity of the asphalt and leads to permanent deformations. Rock hydrated lime has been shown to improve elasticity and significantly reduce swelling.
  2. Cracking: High traffic loads and stresses due to temperature fluctuations lead to cracking. Lime hydrate inhibits the aging of the mortar, reduces the increase in viscosity and reduces oxidative embrittlement.
  3. Ceiling detachments: Loss of adhesion and breakouts due to moisture cause the road surface to come off. Lime hydrate increases the adhesion and tensile strength of the asphalt - especially in the case of adhesive-critical rocks.

Adhesion between rock and bitumen through reaction of calcium
hydroxide with the rock surface is detected. Adhesion improvement is even achieved with adhesive-critical rock and the formation of insoluble calcium soaps with polar bitumen components. The asphalt mix becomes more durable and resilient.


With bitumen coated stones after 60 min. of cooking in the laboratory


Quarzporphyr unbehandelt mit Bitumen 50-70

Quartz porphyry untreated
with bitumen 50-70

Quarzporphyr unbehandelt mit PmB 25/55-55A

Quartz porphyry untreated
with PmB 25 / 55-55A

Quarzporphyr behandelt mit Fels Weißkalkhydrat und Bitumen 50-70

Quartz porphyry treated
with Fels hydrated lime
and bitumen 50-70


The use of Fels hydrated lime provides the best arguments for decision-makers in road construction, as it prolongs the service life of the roads in the long term:

  1. Increase of deformation resistance - leads to a reduction of rut formation
  2. Reduces swelling - prevents damage from moisture
  3. Increased adhesive tensile strength - prevents break-outs and ceiling delamination
  4. Delays age embrittlement - reduces the tendency to crack formation


Hazard classification

  1. Irritating effect on the skin Cat. 2
  2. Severe eye damage Cat. 1
  3. Specific target organ toxicity (single exposure) Cat. 3