The feasibility of utilizing sifted desert sand (

Abstract

To deal with the shortage of the raw materials, like cement, gravel, and sand in the construction and building materials (CBM) industry, the feasibility of utilizing the desert sand (DS) was investigated. In this research, the DS sourced from Maowusu desert was applied. As inspired by that the smaller the particles, the more reactive of the powder, the particles smaller than 75 μm (which is called sifted desert sand, SDS) was sieved with its physical properties and chemical compositions being evaluated and compared with the original DS. It showed that compared with DS powder, the SDS particles have much smaller size (median diameter = 52 μm) and smoother surfaces, with lower SiO2 content, and much higher contents of alkaline oxide, Al2O3 and CaO in particular, which indicated a higher activity of the SDS. Then, the SDS was used to partly replace the cement clinker with varying dosages to prepare the paste samples. The results indicated that the compressive strength of the pastes at 3 days, 7 days, and 28 days all follow an order of increasing firstly, then decreasing gradually, with increasing SDS content. Then, analytical calculation was applied to determine the strength of the SDS-cement paste and the values were compared with the experimentally measured values to probe into the role SDS played. Via combination with microstructure examination, it showed that when SDS was introduced, except for the dilution effect and nucleation effect, the chemical effect including that alkaline oxide, like Al2O3 and CaO could dissolve from the SDS and further participate into the hydration also plays a significant role in the strength development of the composite. The micro-morphology that the SDS particles and matrix pastes were chemically bonded with no distinct Interfacial transition zone observed also verified this. These both indicated that SDS could be used as a kind of supplementary cementitious material, rather than merely as a kind of inert admixture. Finally, the space coordination theory was applied to further illustrate the reason why 10 % is the optimal dosage. This research provides an approach of utilizing the DS in CBM industry with a more effective way.