Pioneering Engineered Sand

As part of our commitment to long-term reliability and innovation, Allied Concrete has been working closely with Brookby Quarry in Auckland to pioneer the use of a fully engineered manufactured sand, now a key component in a majority of our Auckland concrete mixes supplied from our Penrose plant. While traditionally much of Auckland’s sand supply came from marine sources, disruptions in the past prompted us to explore more resilient alternatives. This journey began in 2022 and was driven by a clear goal: to ensure a stable, local supply of high-quality sand that would meet the technical expectations of our customers.

Partnership and Purpose

Our journey with Brookby Quarry began in 2022 when trials were initiated to develop a high-quality manufactured sand from greywacke rock.

Working closely with the quarry team to refine grading, shape, and performance characteristics, the goal was to produce a sand that would perform across a wide range of concrete applications, ensuring reliability for both residential and commercial use.

Rigorous Testing Across Applications

The development process involved not only internal trials but also significant testing with industry contractors. The engineered sand has been rigorously tested across a wide range of applications, using familiar mix designs and performance benchmarks. From residential slabs to commercial floors and infrastructure, this sand has been trialled and refined alongside trusted contractors, pump operators, and engineers.

A comparative trial was carried out in March 2023 at Brookby Quarry, where two slabs were poured using mix designs, differing only in their sand component. One used our traditional blend of PAP7 (Crushed Fines) and fine marine sand and the other used 100 percent of the newly developed manufactured sand. Performance was indistinguishable during placement and finishing, while the engineered sand achieved higher strength values and provided an opportunity for significant reductions in water and therefore, cement demand.

Allied Concrete then ran a full series of mix trials using various admixtures and cement substitutions including SCM’s (Supplementary Cement Materials) such as, Ground Granulated Blast-Furnace Slag (GGBFS) and Fly Ash (FA). Mixes for infrastructure (in tremie and piling applications), spray concrete, and both residential and commercial flooring applications, were tested. These trials involved pump operators and contractors, and considered placeability, set times, bleed rate and characteristics to ensure that concrete made with this sand performed effectively in both pumped and non-pumped applications.

Importantly, the characteristic of the mix designs our customers know, remain fundamentally unchanged, the only variation has been in the sand source. Extensive testing was undertaken to ensure that placing, finishing, and strength performance remain consistent with existing expectations.

Operational Transition

By October 2024, Allied Concrete Penrose had commercially introduced the new sand into production. This was not a sudden shift, but a carefully phased rollout to ensure alignment with customer expectations and industry standards. This process confirmed earlier findings and the manufactured sand mixes met performance expectations across the full range of applications.

This represents a practical, scalable solution to industry challenges and not one which is only for specified projects. Allied Concrete has incorporated this material into mainstream supply at a high-volume, operational scale, which is backed by a resilience in supply chain and an innovative approach to sourcing local materials.

A Sustainable and Scalable Resource

Brookby Quarry’s investment in a purpose-built manufactured sand processing plant and new power infrastructure underpins this shift. Their site now has a production capacity of 300,000 tonnes per annum of this material, with an expansion capability of up to 600,000 tonnes if required. The use of local materials not only strengthens supply chain resilience but also supports broader sustainability goals by having alternatives to both marine extraction and long-haul transport.

Looking Ahead

Allied Concrete remains committed to innovation, product performance, and sustainable practices. Our work with Brookby Quarry reflects a shared focus on developing fit-for-purpose materials that meet the needs of today’s construction sector, without compromise; This milestone marks a significant advance in material performance, consistency, and sustainability, and sets a new standard for concrete production in the region.

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