Mechanism of developing early strength of Portland cement-desert sand system under radiation in desert conditions

Infrastructure development in desert areas like desert highways places demands on sand fixation. While prior research has examined the effects of temperature and ultraviolet light on mortar, the use of Portland cement in desert areas has received minimal attention. This study examines the process of strength development in the Portland cement-desert sand (PC-DS) system under alternating infrared and ultraviolet radiation during day and night cycles. Characterization of the mechanical properties through surface penetration strength (SPS) and compressive strength (CS) was performed, and the strength growth mechanism of the PC-DS was investigated through microstructural characterization via XRD, SEM, FTIR, and TG-DTG. The results indicate that the strength of the PC-DS system peaked at 3d and decreased to 2 MPa at 7d, a decrease of 1/9, associated with the gypsum generation. Infrared radiation decreased the PC-DS system strength to 1.4 MPa after 7d, while the strength was essentially unchanged at 7d of ultraviolet radiation. Further studies revealed that infrared radiation raised the temperature from 24 °C to 40 °C, accelerating the cement hydration while accelerating water volatilization. Ultraviolet radiation enhances the cement carbonation reaction, carbonization reaction increases by 1/4, reducing the Ca 2+ concentration and hindering the gypsum formation. Microscopic experimental results showed that no new substances and structures were produced under infrared and ultraviolet radiation. This finding has implications for the facilities construction and sand fixation in desert areas. • Specimen surface properties characterized by SPS. • Radiation changes the early strength growth of the PC-DS system. • Gypsum production follows cement carbonation. • No new products are generated under radiation.