Some admire it, others hate it: latex for the modification of bitumen emulsions is at the center of heated debates in the road sector. Although the benefits of having latex in finished pavements are widely known, this polymer also brings its share of challenges, especially when it comes to producing the emulsions. In this article, we review the main advantages of this polymer for the modification of emulsions as well as points of vigilance to keep in mind in order to avoid unpleasant surprises.
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I want to modify my emulsions : should I use latex ?
You produce spraying and/or mixing emulsions? You consider that modifying your emulsions with polymers is of economic and technical interest? Then you have several options: PMB-based emulsions or latex-modified emulsions.
The preparation of modified bitumens is done using dedicated production units. A wide range of compatible solid polymers can be used, and the PMBs produced can be used for both cold and hot applications. Let’s face it : some jobs require Polymer Modified Bitumen (PMB) to maximize cohesion and improve durability under harsh temperature and traffic conditions. However, latex modification makes absolute sense in the following situations:
- Latex is compatible with your applications and performance spcifications ?
- In this case, it is easier to modify your latex emulsions than to modify your bitumens, for which compatibility with polymers is an issue.
- You want to cut energy consumption and costs ?
- Latex is easily dispersed in the emulsion with a good homogenizer, and no need to increase the heating to improve the mixing. These mild conditions make the solution particularly interesting when compared to the production and/or emulsification of modified bitumens, both in terms of energy and economics.
- You already have an emulsion production unit ?
- A latex line is easily added to your existing installation. Latex is available in IBC, so no need for an additional storage tank.
Emulsions modified with latex, whether natural or synthetic, are therefore ideal solutions from a technical, practical and economic point of view, while offering good performance on construction sites. Too good to be true ?
The dark side of latex
Nothing to be afraid of. Latex certainly has some wild traits, however they can easily managed with adapted measures and equipment:
- Not all mills are compatible
- Indeed, homogenizers are not all equal when it comes to latex. While the ATOMIX® allows it to be incorporated into the emulsion without any issue, some colloid mills can have difficulties with latex, which limits productivity and increases maintenance costs.
- Latex has an expiration date
- Don’t confuse it with your day-to-day milk. Just like the latter, latex is also a dispersion. Generally composed of 60 to 65% dry matter, latex is a suspension of polymer in an aqueous phase, the whole being stabilized by emulsifying molecules. This implies that latex, whether natural or synthetic, is susceptible to evaporation and destabilization. It is therefore essential to follow the storage conditions recommended by your supplier of choice.
- « Latex sticks everywhere »
- Some may have lukewarm memories of their attempts with latex. Indeed, this polymer has a tendency to clog the filters as well as to adhere to most surfaces. However, the previous advice in combination with a high-performing unit will allow you to avoid these inconveniences.
In short, latex is of major interest for the modification of bitumen emulsions from a technical, energy and financial point of view. The only conditions: mastering the process and taking care of the raw material, both during storage and production.
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