Why Saudi Arabia imports sand despite its vast desert

Saudi Arabia has no shortage of sand, yet it still imports the material needed to make concrete. The reason lies in the shape and texture of the grains covering its deserts.

The Rub al-Khali desert stretches across about 650,000 square kilometers in the south of the Arabian Peninsula. Some dunes rise more than 250 meters, higher than many of the skyscrapers Saudi Arabia plans to build. Even with large construction projects near major cities such as Riyadh, the kingdom imported $1.22 million worth of sand in 2023. Much of it came from Australia.

Construction sand generally comes from rivers and quarries. It forms from large rocks and has irregular, angular grains with sharp edges. Desert sand is the opposite. After thousands of years of rolling and bouncing across dunes, its grains become smooth and almost spherical.

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To make it, you need sand, and not just any sand: it must have the right size and shape.

Ren Wei of the Norwegian University of Science and Technology explained that concrete requires sand with the right size and shape. Smooth desert grains slide over one another like bearings instead of locking together. That can leave microscopic gaps and weak joints in the finished concrete. Wind also sorts dune sand by weight, producing huge fields dominated by grains that are nearly identical, a pattern engineers call monomodal gradation.

A study from the university says desert sand is too fine to act as a binding component, leaving concrete without enough hardness for many construction projects. One alternative has already been used in Dubai. Palm Jumeirah was built in 2006 with about 94 million cubic meters of sand and rock. The sand came not from nearby desert dunes, but from specific areas of the Persian Gulf where the grains were the right size. GPS-guided ships deposited it using a technique called rainbowing.

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after thousands of years of rolling and bouncing over the dunes, it wears down into a smooth, almost spherical pebble