PR204 Solves Lignite Issues for South Thamesmead Residential Project
Project Overview:
Blade Flooring were tasked with preparing a calcium sulphate subfloor in a large-scale residential development in South Thamesmead. During laitance removal, heavy concentrations of lignite were exposed. This posed a significant challenge, as lignite within calcium sulphate screeds is a common cause of instability, resulting in weak points, surface friability, and potential debonding of subsequent floor finishes if not treated correctly.
Challenge:
Lignite, a lightweight organic material often found in calcium sulphate screeds, can create problematic areas of weakness. When exposed, it compromises the structural integrity of the screed surface and hinders adhesion of primers, smoothing compounds, and floor coverings. Without the correct treatment, this can lead to premature failure of the floor system. Blade Flooring needed a proven solution to stabilise the screed, isolate the lignite, and provide a robust, reliable base for the installation of a smoothing compound.
PROBOND® Solutions Chosen:
PROBOND attended site to assess the substrate and recommended the use of PROBOND® PR204 Substrate Binding Primer.
PR204 is a two-part, solvent free, low viscosity hybrid resin specifically designed to consolidate the surface fines and aggregates of dense substrates. It penetrates the screed to produce a sealed and hardened surface, increasing tensile pull-off strengths to around 1.2/1.3 MPa. Crucially, it also isolates lignite inclusions, preventing them from causing surface weakness.
- The ground subfloor was treated with PR204, applied by squeegee and roller to ensure optimum penetration and coverage.
- Once cured (typically between 5–16 hours depending on site conditions), the surface was neat primed with PROBOND® PR200, optimising adhesion for the next layer.
- A 3–5mm application of PROBOND® FL307 Smoothing Compound was then installed, providing a durable, level surface ready to receive the final floor coverings.
Benefits, Delivered:
After 5 days, pull-off tests were carried out to confirm the performance of the PR204 in solidifying and isolating the lignite-affected areas. The results were excellent, showing bond strengths above expectation and a stable, consolidated substrate.
By deploying PR204 alongside PR200 and FL307, Blade Flooring successfully overcame the lignite challenge and ensured the long-term integrity of the flooring system. This safeguarded the project against potential failures and provided the client with confidence in both the method and the finished installation.
