Water-Based Bitumen Primer for Waterproofing Membranes

What it is

This is a polymer-modified emulsified bitumen with water as its base, made by Hubei Juyons Waterproof Materials Technology Co., Ltd. The label on the bucket reads “Bitumen Membrane Primer” with the code JY-JCCLJ, and the certificate printed on it gives a net weight of 20 kg and the maker’s enterprise standard Q/JY 0716-2021. In the JUYONS online listing the product appears as model B101.

Its purpose, in the words of the JUYONS product sheet, is substrate treatment before bitumen waterproof membranes are laid: it “improves adhesion between membrane and substrate while helping resist moisture penetration”. The listing calls it non-flammable and non-explosive, with a shelf life of 6 months.

The JUYONS instructions for its bitumen membrane call for 0.3 kg of primer per square metre, rolled or brushed on. At that rate a 20 kg bucket treats 66.7 m², which is our calculation (20 ÷ 0.3) rather than a maker’s figure. Neither the colour of the liquid nor whether it can be thinned with water is stated. The bitumen primer page covers primers in general, and waterproofing membranes the rolls laid over them.

How it is used

The method below follows the JUYONS listing for this primer.

1. Treat the corners, joints and the roots of pipes first, then coat the rest of the concrete or screed evenly.
2. Apply by brush, roller or spray; the listing names spraying as the preferred way. The JUYONS membrane instructions set the dose at 0.3 kg/m² by roller or brush.
3. Leave the primer to dry fully before the membrane goes down: 2–3 hours at normal temperature, according to the listing.

Between jobs, JUYONS asks for the buckets to be kept in a dry, cool and ventilated place at 5–35°C, out of rain and direct sun, and protected from frost, pressure and knocks. Mind the 6-month shelf life stated in the listing and check the production date on each bucket. The documents give no figure for how long a dried coat can stay open before membrane laying in hot weather.