Reference
Technical information
How our sands are made, how to specify them, and what the common tests and terms mean.
A Queensland TMR-approved producer.
One deposit, three processes
Everything we supply comes from one quartz sand deposit at Talgai, Queensland, and is processed on site. Raw sand is washed to remove silt and clay, screened to a grading, and — where a dry or sized product is needed — kiln-dried and screened again. Thermal bedding sand is the exception. It is screened and graded but not washed, because the fines are what let it compact. The deposit and the plant do not change, so the product does not change between deliveries.
Grading and sieve analysis
A sand is described by its particle size distribution: how much of it passes each sieve in a standard set. Plotted, that is the grading curve. Two sands can have the same largest grain and behave completely differently, depending on how much of each size is in them. A well-graded sand has a spread of sizes and packs densely. A single-sized sand has most of its mass in one fraction, packs loosely and drains freely. Which one you want depends on the job. Thermal backfill wants the first. Filter media wants the second.
Fines
Fines in natural sand means silt and clay — material finer than 75 micrometres. In concrete they raise water demand and weaken the bond, so fine aggregate is commonly specified against AS 2758.1, which limits them. Washing is how a natural sand is brought within those limits. In thermal backfill and controlled fill the same fines are an asset. They fill the gaps between larger grains and let the material compact. That is why we wash some products and deliberately do not wash others.
Filter media: effective size and uniformity coefficient
Filter sand is specified by two numbers read off the grading curve. Effective size (D10) is the sieve size that 10% of the sand passes. It sets how fine a particle the bed captures and how fast it clogs. Uniformity coefficient (D60/D10) is the 60% passing size divided by the effective size. A low number means a narrow, even grading that filters and backwashes evenly. Meeting a spec like this needs a sand that has been washed, dried so it can be screened accurately, and screened to a narrow fraction. That is what the kiln-dried range is for.
Moisture
Washed sand is supplied moist from the wash plant. Kiln-dried sand is supplied dry from the kiln. Moisture matters in two places: dry-mix and pre-blended products, where water in the sand would start setting off the cement in the bag; and anything that has to flow through a spreader or into a joint. If a formulation sets a maximum moisture content, tell us when you enquire.
Controlled fill and compaction
Fill is specified by the density it must reach when compacted — usually a percentage of a laboratory maximum for that material — with field density testing of each layer. The tests are done on site by the project's geotechnical testing contractor. What the fill supplier controls is consistency: a screened, uniform material compacts the same way every time, so the target density is reachable with a known number of passes. Select Fill is supplied on that basis.
Thermal resistivity
Backfill around a power cable is specified by its thermal resistivity — how much it resists heat flowing away from the cable. It is measured on a compacted sample at a set density and moisture using a thermal needle probe. The project spec sets the maximum allowed, often at both placed moisture and fully dry. What drives the result is density: a well-graded sand with its fines kept in compacts with few air voids, and air is what blocks heat. Thermal Bedding Sand is graded for that. If a spec needs a measured value, tell us when you enquire.
Test results and documentation
MRP Sand Quarry is a Queensland Department of Transport and Main Roads approved producer. If a project needs grading results, test certificates or source registration, say so when you enquire and it will be handled for that product and quantity. Standards named on this site are the ones customers commonly work to. They are not claims of certification.