From Quarry By-Product to Concrete Resource: Investigating the Beneficial Use of Alternative Fines
September Technical Insight
By: Matthew Carson BEng. Civil
In 2020, as part of my Civil Engineering dissertation at the University of Southern Queensland, I investigated a question that remains highly relevant to both the quarry and concrete industries:
Can materials that accumulate as quarry and recycling by-products be converted into useful constituents of concrete?
The research was developed around two practical industry challenges: the environmental impact associated with conventional concrete production, and the accumulation of low-value or waste materials generated by quarries and recycling operations. The project investigated whether selected quarry dusts and recycled glass products could be incorporated into concrete as partial replacements for conventional cementitious or fine aggregate materials.
Six years later, the results are still useful, but perhaps the more important lesson is how we should approach alternative materials before trying to introduce them into routine production.
From waste stream to potential resource
Aggregate production inevitably generates fine material.
Depending on the geology, crushing circuit, washing process and final products being manufactured, these fines may accumulate as crusher dust, filter cake, silt, fine manufactured sand or other low-value by-products.
The original research recognised that some of these materials may have greater value than their existing application suggests. Rather than treating them solely as waste, the project investigated whether they could become inputs into concrete production. The original objective was to assess their feasibility as either cementitious supplements or aggregate supplements.
The materials investigated included:
andesite quarry dust;
marble quarry dust;
sandstone quarry dust;
limestone dust;
recycled glass dust; and
recycled glass fine sand.
Figure 1 — Materials investigated - Conventional and alternative fine materials investigated during the 2020 research program.
The dissertation contained photographs comparing the conventional cementitious materials and alternative fines, as well as natural fine sand and recycled glass fine sand.
The first lesson: characterise the material before testing the concrete
One of the most important aspects of the study was that the materials were not treated simply as generic “crusher dust”.
Before the concrete trials, the alternative materials were investigated using methods including particle size distribution, petrographic analysis, chemical analysis and particle density. The research methodology then moved through concrete mix trials, assessment of fresh and hardened properties and, finally, consideration of economic and environmental performance.
That basic approach remains important today.
Two materials may both be described commercially as quarry fines while having very different:
particle size distributions;
particle shapes and surface textures;
mineralogy;
chemical composition;
density;
water demand; and
variability between production runs.
Those characteristics can substantially change the way the material behaves once incorporated into concrete.
Have a quarry fine or by-product you think may have potential?
CGE can help characterise the material, review its likely behaviour in concrete and develop a structured testing pathway.
Figure 2 — Research approach
Not all fines behave the same
The initial program investigated five alternative fine materials as partial cement replacements at 5%, 10%, 15% and 20% by mass.
Recycled glass fine sand was treated differently and investigated as a replacement for natural fine sand at 25%, 50%, 75% and 100%.
The results quickly showed that there was no universal replacement level that could be applied across all materials.
Andesite quarry dust and marble quarry dust achieved the target strength at replacement levels up to 20% in the initial trials. Sandstone dust and recycled glass dust achieved the target at lower replacement levels, while the limestone dust investigated did not achieve the target strength at the tested replacement rates. A 50% replacement of natural fine sand with recycled glass fine sand was selected for the subsequent detailed trial program.
This is an important result for both quarry operators and concrete producers.
Calling something quarry dust, crusher fines or even identifying its parent rock type is not sufficient to predict how it will perform in concrete.
Figure 3 — Particle-size distribution
Strength was only part of the story
It is tempting to assess an alternative concrete material primarily by asking:
Did it achieve the required compressive strength?
That is necessary, but it is not enough.
Once practical replacement levels were selected, the second-stage trials investigated a much broader range of concrete properties, including:
slump;
entrapped air;
setting time;
bleeding;
compressive strength;
hardened density;
flexural strength;
shrinkage; and
sulphate and chloride content.
The results demonstrated substantially different behaviour between materials.
For example, the 20% andesite trial produced a slump of 70 mm, 1.4% entrapped air and a setting time of 6 hours 25 minutes. Its corresponding 20% fly ash control produced a 65 mm slump, 1.4% air and a setting time of 5 hours 20 minutes.
The 10% sandstone trial produced only a 40 mm slump, while the 10% recycled glass dust trial produced 70 mm slump but 4.0% entrapped air. The 50% recycled glass fine sand trial achieved the same 65 mm slump as its control but recorded greater bleeding.
These differences matter in real concrete production.
A material may achieve compressive strength while simultaneously changing:
water demand;
admixture demand;
finishing characteristics;
pumping behaviour;
setting time;
bleeding;
early-age stability; or
long-term dimensional behaviour.
Figure 4 — Compressive strength
Some results were genuinely promising
Several materials showed sufficient performance to justify further investigation.
The andesite dust was particularly interesting. In the dissertation's cost and benefits assessment, the 20% andesite mix was slightly cheaper than the corresponding fly ash control and was considered one of the more promising alternative materials investigated.
The recycled glass fine sand also produced several encouraging results.
At the selected 50% natural sand replacement level, the mix achieved its design compressive strength at 28 days and continued to gain strength through to 56 days. Its flexural strength also exceeded the corresponding fly ash control in the detailed trial program.
However, it also demonstrated why an alternative material cannot be evaluated on strength alone. The glass fine sand recorded the greatest bleeding of the mixes tested, consistent with its very low water absorption.
The sandstone, marble and glass dust trials similarly demonstrated combinations of positive and negative properties.
That is perhaps the most important technical conclusion from the entire study:
There was no single “best” alternative fine across every concrete property. Each material changed the behaviour of the concrete differently.
Figure 5 — Performance comparison
The unexpected observations also matter
Laboratory trials are valuable partly because they reveal behaviours that may not be obvious from specification data.
During the recycled glass dust trials, for example, unusual foaming was observed during washout. The dissertation documented this as a specific experimental observation.
Figure 6 — Laboratory trial photograph
Alternative materials should be observed, not just tested.
Changes in mixing response, cohesion, bleeding, foaming, finishing or washout behaviour can identify issues that may not be obvious from a 28-day compressive-strength result.
What I would look at differently in 2026
Looking back at the research six years later, I would place even greater emphasis on variability and production control.
The original thesis itself identified variability in some of the materials, particularly the marble dust, and recognised that further optimisation and testing would be required before commercial implementation.
Today, I would treat the question slightly differently.
Rather than asking only:
Can this quarry fine work in concrete?
I would ask:
Can this source consistently produce a material that a concrete producer can design and control a mix around?
That means investigating not just one laboratory sample, but the likely production envelope.
A commercial assessment should consider:
variability between quarry faces or geological units;
variability through time;
changes associated with crusher configuration;
stockpile segregation;
moisture variation;
mineralogical consistency;
particle-size consistency;
chemical and durability risks;
interaction with cementitious materials and admixtures; and
the practicality of maintaining specification compliance in routine production.
This distinction is critical.
A successful laboratory mix demonstrates technical potential.
A viable construction material requires repeatability and production control.
A by-product has to become a product
For quarry operators, this is where the commercial opportunity lies.
A material does not become a useful concrete constituent simply because laboratory testing shows that one sample can perform.
The material needs to move through a process such as:
Figure 7 — From quarry by-product to controlled construction product
A successful trial is only the beginning.
CGE can assist with material characterisation, mix optimisation, validation and the pathway from laboratory potential to a controlled construction product.
What does this mean for concrete producers?
Alternative fines potentially provide another tool for mix optimisation, particularly where suitable local materials are available.
But substitution should not be approached as a simple percentage replacement exercise.
The concrete producer needs to understand how the material affects the complete mix system, including:
water demand + admixture response + workability + setting + bleeding + strength development + durability + consistency.
The cheapest or strongest trial mix is not necessarily the most practical production mix.
What does this mean for quarry operators?
For quarries, fine materials can represent either a liability or an underutilised resource.
The difference is often characterisation and control.
Understanding the material allows potential markets to be investigated rationally rather than treating every fine stream as generic crusher dust.
Depending on its properties, a fine quarry material may have potential as:
a concrete fine aggregate component;
a manufactured sand component;
a mineral filler;
a supplementary fine;
an engineered blended product; or
a raw material for another construction application.
Not every material will be suitable.
The value comes from identifying the ones that are.
Six years later
My 2020 dissertation was necessarily a preliminary investigation.
It demonstrated that selected quarry and recycled fines could be incorporated into concrete at meaningful replacement levels and still produce workable concrete with acceptable engineering properties. It also demonstrated that different materials could behave very differently once incorporated into the mix.
Six years later, I think the most useful conclusion is broader than whether a particular andesite, marble, sandstone or glass product performed well in one series of trials.
It is this:
A quarry by-product should not be dismissed as waste simply because it does not currently have a market. But neither should it be considered a construction product until its properties, variability and performance are properly understood.
There is potentially considerable value sitting in material streams that already exist within Australian quarry operations.
Finding that value requires collaboration between quarry operators, concrete technologists, laboratories and materials engineers — starting with proper characterisation and progressing through controlled testing and full-scale validation.
That was the question behind the research in 2020.
It remains a worthwhile question in 2026.
Have a material stream you’re not sure what to do with?
It may be worth a closer look. Talk to CGE about whether it has potential for concrete or another construction application.
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