How a fraction is written: the d/D notation
Aggregates are designated by the smallest and largest sieve sizes between which most of the material falls, written d/D in millimetres. A 0/3 is a sand whose grains pass a 3 mm sieve; a 3/8 is a fine gravel (gravillon) retained on 3 mm and passing 8 mm; a 0/31.5 is an all-in graded material from fines to 31.5 mm. The notation does not promise that every grain is inside the range: the standards allow a defined percentage of oversize and undersize, which is why a grading curve, not the name alone, is what a laboratory checks.
In Algeria the fractions most often requested for building and road works are, in general, sands in the 0/3 to 0/5 range, gravels such as 3/8, 8/15 and 15/25 for concrete, and all-in graded materials such as 0/20 and 0/31.5 for unbound pavement layers. Asphalt mixes use their own set of fractions, typically a 0/2 or 0/3 crushed sand combined with 2/6, 6/10 and 10/14 gravels. The exact sizes are fixed by the project specification (the CCTP), not by the supplier.
Which standards Algerian contracts refer to
Most Algerian project specifications describe aggregates with the vocabulary of the European standards, either directly or through the Algerian NA standards published by IANOR, which are largely aligned with them. Three texts cover the three main uses: EN 12620 for aggregates for concrete, EN 13242 for unbound and hydraulically bound materials used in road layers, and EN 13043 for aggregates for bituminous mixtures. The French complement NF P 18-545, which groups the requirements into codes (A, B, C, D) per use, is also widely cited, and older specifications may still refer to the former French P 18 series.
For a buyer, the practical consequence is simple: the specification will name a category for each property (for example a grading category, a fines category, a resistance category), and the supplier’s test certificates should state the result for each one. When a contract cites a standard without categories, it is worth asking the engineer which values apply before ordering, so that both sides test against the same thresholds.
The tests you will see on a certificate
The names below are those used in Algerian laboratories and specifications; the European test standards are given for reference.
| Test | What it measures | Why it matters |
|---|---|---|
| Grading (granulométrie, EN 933-1) | The sieve curve of the material | Workability of concrete, compaction of road layers, asphalt mix design |
| Sand equivalent (équivalent de sable, EN 933-8) | Cleanliness of a sand: proportion of clay-like fines | Clayey fines weaken concrete and asphalt; values in the 60–70 range are typically required for concrete sand |
| Methylene blue (bleu de méthylène, EN 933-9) | The activity of the clay in the fines | Complements the sand equivalent for crushed sands with many fines |
| Los Angeles (EN 1097-2) | Resistance to fragmentation by impact | Base layers, asphalt surfacing and concrete under heavy traffic |
| Micro-Deval (EN 1097-1) | Resistance to wear in the presence of water | Surface courses, unbound layers exposed to traffic and moisture |
| Flakiness (coefficient d’aplatissement, EN 933-3) | Proportion of flat grains | Flat grains compact badly and break in asphalt |
| Density and water absorption (EN 1097-6) | Particle density and open porosity | Mix design, water demand of concrete and asphalt |
| Fineness modulus | A single number summarizing the sand curve | Sands around 2.2–2.8 are generally preferred for concrete; dune sand is far finer |
Crushed, alluvial or dune sand
Northern Algeria has little natural sand left to extract: the dredging of wadis has been restricted for years, and the dune sands of the south are very fine, which gives them a low fineness modulus and a high water demand in concrete. Crushed sand, produced from quarried limestone or other hard rock in a crushing and screening plant, has therefore become the common answer. It is angular, which helps the strength of the mix, and its fines content is controlled at the plant rather than left to the river.
Algerian research on conventional concretes and mortars with crushed limestone sand generally finds an optimum around 10 to 15 percent clean limestone fines, with acceptable results up to about 20 percent in some series; specifications nevertheless cap the fines of a concrete sand at a category fixed by the standard, so the plant must deliver to that figure. This is also why the methylene blue test matters as much as the sand equivalent for this material. Blending crushed and dune sand to correct the curve is also well documented. In practice, the project laboratory decides the mix; the supplier’s job is to deliver a sand whose curve and cleanliness stay stable from one truck to the next.
Reading a supplier’s answer
A credible answer names the quarry and plant the material comes from, attaches recent test results for the fractions offered, and says how production and stock are organized to hold the delivery rate. It also states what is not covered: a supplier cannot promise that a sand will suit a concrete formula before the project laboratory has run its trial mixes, and it should say so. Test requirements, sampling frequency and the method of acceptance are best written into the supply agreement before the first delivery.
Ask also about haulage. Aggregates are heavy and cheap per tonne, so transport distance often weighs more than the price at the plant. A supplier with its own trucks and semi-trailers can give a delivered price per tonne for your location and commit to a rhythm; one who depends on third-party hauliers may not.
Frequently asked questions
What does 0/3 or 3/8 mean for aggregates?
A 0/3 is a sand whose grains pass a 3 mm sieve, and a 3/8 is a fine gravel retained on a 3 mm sieve and passing an 8 mm sieve. The two numbers are the lower and upper sieve sizes of the fraction in millimetres, with a tolerance for oversize and undersize defined by the standard.
Which standard applies to aggregates for concrete in Algeria?
Algerian specifications generally use EN 12620 for concrete aggregates, either directly, through the aligned Algerian NA standards of IANOR, or alongside the French NF P 18-545, and name categories for grading, fines and resistance. The contract specification (CCTP) for each project states which text and which categories apply.
What is a good sand equivalent value?
A sand equivalent above about 60 generally indicates a clean sand, and concrete specifications in Algeria typically require values in the 60–70 range depending on the exposure class. For crushed sands with a high fines content, the methylene blue test is used in addition to judge whether the fines are harmful.
Can crushed sand be used in concrete?
Yes. Crushed sand (manufactured sand) is widely used in concrete in Algeria because natural sand is scarce, and Algerian research on crushed limestone sands generally finds fines contents of about 10 to 15 percent optimal, and up to roughly 20 percent acceptable in some studies, when the fines are limestone dust rather than clay; the specification fixes the category to deliver. The project laboratory confirms the formula with trial mixes.
Who tests the aggregates, the supplier or the client?
In general both: the producer tests at the plant to control production, and the client’s laboratory tests on delivery against the categories in the specification. Sampling frequency and acceptance rules are typically written into the supply agreement before deliveries start.
How ETAHG can help
SARL ETAHG produces high-quality fine aggregates at its own quarry and stone crushing plant, Carrière Djellal El Gharbi at Oued Sdeur near Aïn El Ibel, in the wilaya of Djelfa, with crushing and grinding machines suited to projects that require high production rates. Test requirements are agreed with the client before supply, and the company hauls with its own trucks and tipper semi-trailers. See the fine aggregate production page for the uses and the way supply is organized, or the road construction page for how the same material goes into pavement layers.