# Asphalt Additives

Asphalt additives are any of a number of substances that can be added to the asphalt binder to alter the characteristics of the final blend of HMA.

- Canonical URL: https://pavementinteractive.org/reference-desk/materials/asphalt/asphalt-additives/
- Last updated: 2026-11-01
- Review: reviewed by licensed professional engineers on the previous Pavement Interactive site, where reviewers were not recorded by name

## Additives

[Asphalt](https://pavementinteractive.org/reference-desk/materials/asphalt/introduction/) additives are any of a number of substances that can be added to the asphalt [binder](https://pavementinteractive.org/reference-desk/testing/binder-tests/asphalt-binder-and-characterization/) to alter the characteristics of the final blend of HMA.

### Sasol

Sasol production meets about 30% of South Africa’s transportation fuel needs. There are two major plants in South Africa, one at Sasolburg, which is a natural gas raw feed, (formerly coal) and one at Secunda, which is a coal raw feed.

#### Production at Sasolburg

1. Step 1: Natural gas is reformed into CO and H₂.
2. Step 2: CO and H₂ is processed through two F-T plants which produce hydrocarbon compounds that require further processing.
3. Step 3: Hydrocarbon compounds from the F-T processing are further refined through various distillation processes.
4. Step 4: Various waxes produced by Sasol are processed for shipping.

#### Sasol wax and paving applications

Paving oriented wax products include:

- Sasobit : Compaction aid and WMA
- Sasolwax Flex: SBS-Sasobit co-modifier for bitumen
- Sasolwax Link TX: A cross linking agent for bitumen which aids SBS additives.
- Sasolwax BituGlide: Reduces or eliminates asphalt sticking to truck beds and roller wheels.

#### Sasobit

Sasobit is a Sasol wax, with a 102°C melting point. It is notable for its low viscosity: [dynamic viscosity](https://pavementinteractive.org/glossary/dynamic-viscosity/) at 135°C is 12cP (ASTM D4402). Sasobit wax is 100% soluble in bitumen, and is used in small amounts (typically 1 to 1.5% of the binder is replaced with Sasobit) for [WMA](https://pavementinteractive.org/glossary/warm-mix-asphalt-wma/) and as a compaction aid.