High Temperature Behaviour of Concrete Produced with Desert Sand

There has always been some issues with the use of desert sand as a construction material due to the fact that it is too rounded and uniformly graded to be suitable for construction purposes. Concrete produced from desert sand can exhibit lower strength, poor cohesion, poor slump, and poor workability when compared with River Sand. However, researchers from the College of Civil and Hydraulic Engineering, Ningxia University, China have evaluated the behaviour of concrete produced with desert sand when subjected to high temperature. The study was published in Springer – International Journal of Concrete Structures and Materials.


There have been speculations and researches on the application of desert sand in the production of ‘low carbon concrete‘, but the researchers from Ningxia suggests that desert sand has been successfully used for construction in China, citing some publications.

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Desert Sand

At higher temperature, the properties of concrete are usually altered. Therefore, the knowledge of the mechanical properties and behaviour of concrete at elevated temperature is important due to fire events that can occur in buildings. In previous research works, the compressive strength of ordinary and high-performance concrete have been observed to generally declined with temperature. However, the strength reduction of ordinary concrete was higher than that of high-performance concrete.

To carry out the experiment, the researchers used desert sand from Mu Us Sandy land in Yanchi Country as the fine aggregate, grade 42.5R cement, and 10-20 mm diamater crushed rock coarse aggregate.. They went ahead to study the effects of desert sand replacement rate (DSRR), temperature, and cooling regime on the elasticity modulus under static compression, cubic compressive strength and prismatic compressive strength of concrete. The influence of temperature on the microstructure of concrete produced with desert sand was also analyzed using X-ray diffraction (XRD) and Scanning Electron Microscope (SEM). After curing the samples for 28 days, CSL-26-17 heating furnace with a ultimate temperature of 1600 °C was used to carry out elevated temperature test. Target temperatures were 100 °C, 300 °C, 500 °C and 700 °C.

The results showed that the cubic compressive strength of concrete produced with desert sand increased firstly, and then declined with temperature. Whereas, the prismatic compressive strength and elasticity modulus of concrete produced with desert sand under static compression declined with temperature.

Furthermore, it was observed that the elasticity modulus under static compression, cubic compressive strength and prismatic compressive strength of concrete produced with desert sand after elevated temperature increased firstly, and then declined with DSRR. When DSRR was equal to 40%, the elasticity modulus under static compression, cubic compressive strength and prismatic compressive strength of concrete produced with desert sand reached the maximum value.


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SEM of desert sand concrete at different temperatures (Liu et al,, 2020)

From microscopic observations, concrete produced with desert sand at room temperature was structurally-complete and had good compactness. The interface between coarse aggregate and cement mortar became more distinct after 300 °C. After 500 °C, the dimension of intact layered CH decreased and Many small pores were produced. After 700 °C, cement matrix became more shriveled and white large crystals CH were scarce.

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Reference
Haifeng Liu, Xiaolong Chen, Jialing Che, Ning Liu and Minghu Zhang (2020): Mechanical Performances of Concrete Produced with Desert Sand After Elevated Temperature. International Journal of Concrete Structures and Materials. (2020) 14:26 https://doi.org/10.1186/s40069-020-00402-3

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