December 19, 2022

Geopolymer: WSAA-listed mortar leading the fight against corrosion

A geopolymer structural mortar is a key weapon against corrosion, helping to rehabilitate and protect assets from deterioration, extending their life and reducing long-term costs. This is particularly important for water and wastewater infrastructure across Australia, with concrete pipes constantly exposed to harsh conditions that can cause significant downtime due to costly rehabilitation or maintenance works. The technology is now listed in WSA 201 Manual for Selection and Application of Protective Coatings.

GeoCast Geopolymer technology

GeoCast Geopolymer technology offers a unique and sustainable solution to corrosion that delivers high levels of strength and durability. 

A green technology product made from over 90 per cent recycled Australian raw materials, the high performance geopolymer mortar with densified micro silica powder, flyash, pozzolanic materials and other select admixtures, has a unique formulation and a low carbon footprint. 

GeoCast is specifically designed for horizontal, vertical and overhead surface repairs in new and existing reinforced concrete and brick pipes, corrugated metal pipe inverts (CMP) and arches, sewer manholes and (water) wastewater structures. 

The superior physical properties from geopolymer allow the material to be used as a standalone structural lining. It can be cast in place in much less thickness than traditional cement-based products like shotcrete, therefore pipe diameter is not drastically changed.

It is designed for quick turnaround with an initial curing time of 4.5 hours and the asset can return to service within 18 hours. Accelerators can also be used to speed up this process. This is ideal to reduce disruption to the community, ensuring the asset up and running again in the shortest time possible.

The product originates from the Reliner MSP® Cement co-patent technology being used in gunned shotcrete coating applications, existing construction rehabilitation, low-pressure spraying renewal and centrifugally [spin] cast applications. 

Boasting diverse applications that includes structural repairs in large diameter sewer pipes, stormwater culverts, manholes and pump stations, the product’s unique formula can be wet sprayed, dry gunite sprayed or hand applied. It can also be spray applied using automatic techniques from centrifugal spinning equipment.

Trusted formula 

GeoCast builds on a formula that has been used for many years and has been used in key structures (including both concrete and metal pipes) for major authorities throughout Australia.

Formulated with freeze thaw durability advantages on demand, GeoCast provides long-term performance, tenacious bond and lower permeability as well as higher compressive, flexural and tensile strength. 

It was used in the national trials for the CRC-P smart linings project which has been used as a benchmark for WSA 201. Following the trials, geopolymer was added as a product category in WSA 201 manual (GEO), with the subclass for geopolymer detailed in the WSSA 161 document. 

Protection levels 

GeoCast can be applied to 100mm thicknesses overhead, preventing water infiltration in pipes, tunnels, manholes, wet wells, raw water filtration, bridges, dams, and treatment plant structures. 

It protects against corrosion, [MIC] hydrogen sulfide gas (H2S), sulfates, salt water, chlorides, water vapor, grease and acids to pH 2.0 (ASTM C267).

GeoCast differs significantly from ordinary Portland cement and will not corrode or attack reinforcing steel. The geopolymer mortar contains microsilica powder admixture, polymer modifiers, polypropylene fibers and flyash that work together to produce a silica rich paste with increased abrasion resistance and reduced cracking. 

This allows GeoCast Geopolymer structural linings to reduce service downtime and rehabilitate existing structures with a design life of over 50 years.

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