Can I use untreated river sand for concrete?

It's not recommended, it can contain clays, salts, and organic matter that reduce strength; a certified washed sand should be used.

Does silica sand work for construction mortar?

It's mainly for pool filtration and decorative uses; for mortar it's better to use fine sand or washed construction sand.

Construction Sand: A Guide to Choosing by Use and Particle Size

Q: What's the difference between fine sand and soft fine sand?

Both are fine, but soft fine sand offers greater workability and finer finishes than standard fine sand.

Quick answer: there's no such thing as a single "construction sand": every job needs a different particle size. For concrete, coarse washed sand (0-6 mm) is used; for masonry mortars and rendering, fine sand (0-2 mm); for very fine joints between blocks or pavers, 0-1 mm sand; and for special uses (insulation, blasting, mineral fillers) there are specific sands that aren't conventional aggregates.

Sands for Concrete and Structural Mortars

Product	Particle Size	Main Use
Washed Construction Sand	0-6 mm	High-quality concrete and mortars; free of clays and salts
Fine Construction Sand	0-2 mm	Masonry mortar, structural concrete, gardening, and leveling
Soft Fine Sand	Fine, highly workable	Finer finishes than standard fine sand; easy to handle

Sand for Joints and Precision Finishes

Yellow Jointing Sand 0-1 mm has an intense yellow tone designed for joints between concrete blocks of the same color (such as those from Prefabricados Adybor): its fineness allows for very tight joints and a uniform finish matching the block's tone.

Sands for Special Uses

Product	What It's For
Silica Sand	Pool filtration, construction, and landscaping; high purity and durability
White Marble Sand	Mineral filler for polymer concretes and white concrete with white cement (0-1 mm, 100% natural marble)
Crushed Expanded Clay Sand	Lightweight concrete and mortars with thermal and acoustic insulation; Euroclass A-1 fire resistance (1-5 mm)
Blasting Sand	Silica abrasive for cleaning and preparing metal surfaces (removing paint, rust)

How to Choose for Your Project

You're mixing concrete on site: Washed Sand 0-6 mm, or directly the Sand and Gravel Mix, to which you only need to add cement and water.
You're building a wall or rendering: Fine Sand or Soft Fine Sand, depending on the finish level you're after.
You're jointing colored blocks or pavers: Yellow Sand 0-1 mm if the block is yellow, or look for a sand that matches your material's tone.
You need insulation in a lightweight mortar or slab: crushed expanded clay.
You need to clean metal or prepare a surface: Blasting Sand, not a conventional construction sand.

Frequently Asked Questions

Can I use river sand straight from the field to make concrete?

It's not recommended: unwashed sand can contain clays, salts, and organic matter that reduce the concrete's strength. A certified washed sand like Washed Construction Sand guarantees a clean, consistent material.

What's the difference between fine sand and soft fine sand?

Both are fine and suitable for mortars, but soft fine sand offers even greater workability and allows for finer finishes, while standard fine sand is the more common choice for masonry mortar and structural concrete.

Does silica sand work for making mortar?

It's mainly for pool filtration and decorative or industrial uses; for construction mortar it's better to use fine sand or washed construction sand, formulated specifically for that purpose.

See also: cement, concrete, and premixes.