Polyurethane Crack Injection Waterproofing: How to Mix, Inject, and Test OPU-600 at 20°C (Foam Ratio, Cream Time, Tack-Free Time)

This guide explains polyurethane (PU) crack injection waterproofing and leak sealing, and provides a repeatable 20°C bench test for Adoration Polyurethane OPU-600. It also references Adoration Injection Pump and Adoration Injection Packer as core hardware in professional injection setups.

Why This Test Matters

Polyurethane (PU) chemical grouting is widely used for crack injection waterproofing and active leak sealing because it reacts with water, foams, expands, and blocks water pathways.

In real jobs, failures are often caused by inconsistent mixing, unknown reaction timing, uncontrolled temperature, or poor injection hardware setup—not by the material itself.

This post provides a repeatable, video-friendly test at 20°C to measure foam expansion, initiation time (cream time), and tack-free time for Adoration Polyurethane OPU-600, while also outlining a practical injection workflow.

Tools & Hardware 

·         Adoration Injection Pump: Delivers controlled pressure and flow so the grout reaches the crack network within the usable reaction window.

·         Adoration Injection Packer: Creates a sealed, pressure-capable injection port so the grout goes into the structure instead of leaking out at the surface.

·         Tip: Many ‘it won’t take material’ or ‘it leaked everywhere’ problems are packer seal/anchoring problems, not pump power problems.

Test Goal at 20°C (Standard Conditions)

At 20°C (68°F), run two scaled batches at the same 10:1 grout-to-water mass ratio to verify consistency:

·         Batch A: 20 g Adoration Polyurethane OPU-600 + 2 g water

·         Batch B: 40 g Adoration Polyurethane OPU-600 + 4 g water

Record three metrics:

1.       Initiation time (cream time): From the moment mixing starts to visible foaming/expansion

2.       Foam expansion ratio: Peak foam volume divided by initial mixed liquid volume (or height ratio in the same cup)

3.       Tack-free time: Time until the foam surface is no longer sticky to a light touch (with gloves)

Safety & Setup

·         Work in a ventilated area and wear gloves and eye protection. PU reactions can be exothermic and can expand quickly.

·         Stabilize the environment at 20°C. Temperature swings can significantly change reaction timing.

·         Use a digital scale (0.1 g resolution recommended), a transparent graduated cup (or clear container with markings), a mixing stick, a timer, and a phone/camera for continuous video.

·         Use clean, dry containers. Any leftover moisture in the cup can alter results.

Step-by-Step Test Procedure 

4.       Prepare the measuring cup: Use a clear graduated cup or mark reference lines on the cup wall with a marker.

5.       Weigh the polyurethane: Measure 20.0 g (Batch A) or 40.0 g (Batch B) of Adoration Polyurethane OPU-600 into the cup.

6.       Weigh the water: Measure 2.0 g (Batch A) or 4.0 g (Batch B). Do not estimate by volume—use mass.

7.       Start video first: Frame the cup and markings clearly. Define time zero (t=0) as the moment you start mixing after adding water.

8.       Add water and mix consistently: Pour in the water and mix immediately for ~10–15 seconds with consistent intensity. Scrape the sides so the mix is uniform.

9.       Stop mixing and observe: After the mixing window, stop agitation and allow the reaction to proceed naturally while recording.

10.   Record initiation time: Note the timestamp when clear foaming/expansion begins (cream time / initiation time).

11.   Record peak foam volume (or height): When the foam reaches its maximum, pause the video and read the cup’s volume marking or measure foam height.

12.   Calculate foam expansion ratio: Use volume ratio (peak foam volume ÷ initial mixed liquid volume) or height ratio in the same cup.

13.   Measure tack-free time: Every 30 seconds, lightly touch the foam surface edge (with gloves). Record the time when it is no longer tacky/sticky.

How to Interpret Results (20 g/2 g vs 40 g/4 g)

Because both batches use the same 10:1 mass ratio at the same temperature, initiation time, foam ratio, and tack-free time should be broadly consistent (within normal variability).

If the two batches differ strongly, common causes include:

·         Mixing time/intensity not consistent between batches

·         Cup contamination (residual moisture or residue)

·         Temperature drift away from 20°C

·         Water measurement error (not weighed)

·         Material condition or batch variation

Practical ‘How to Inject’ Workflow

Once you know your reaction window from the test, apply it to injection work:

14.   Identify the water pathway: Prioritize where the water is traveling, not just visible surface cracking.

15.   Plan drilling and spacing: Set injection points that can communicate through the crack/void network.

16.   Install and tighten Adoration Injection Packer units properly: A reliable seal is critical.

17.   Use Adoration Injection Pump with controlled pressure: Start low and watch for response at adjacent packers.

18.   Inject in stages: Overfilling early points can cause near-surface reaction and prevent deeper penetration.

19.   Re-inject strategically if needed: After initial reaction, return to points that did not take material or were bypassed.

Today’s Test Data 

Use the table below to record your measurements at 20°C. Keeping this data in the post increases credibility and helps readers understand the reaction window.

A short, standardized test at 20°C turns polyurethane grouting from guesswork into a measurable process. If you can document initiation time, foam expansion, and tack-free time on video, you can inject with better timing, explain results to customers more clearly, and reduce failure rates.