Experimental Studies on Mechanical Properties and Microscopic Mechanism of Marble Waste Powder Cement Cementitious Materials

The resource utilization of waste stone powder is a meaningful way to realize sustainable development. This paper aims to study the influence of marble waste powder particle size and replacement cement dosage on the mechanical properties of cementitious materials and evaluate its microstructure and mineral characterization by SEM and XRD. The results show that the early strength of cementitious materials is obviously improved when the dosage of marble waste powder is in the range of 0–15%, and the lifting effect of marble waste powder with a particle size of 600 mesh instead of cement on the strength and microstructure of cementitious materials is the most obvious. The replacement of cement with different particle sizes of marble waste powder found that it had low chemical activity and participated in the hydration reaction of cement, but the reaction degree was low. The smaller the particle size of marble waste powder instead of cement, the denser the early microstructure, the more obvious the nucleation phenomenon, and the more serious the agglomeration between particles. In addition, the mechanism model of marble waste powder replacing cement cementitious materials was proposed. The strength prediction function model between the material dosage and compressive strength was constructed, and the accuracy of the model was verified

Study on properties and mechanism of alkali-activated geopolymer cementitious materials of marble waste powder

In order to explore the effect and mechanism of marble waste powder on the properties of alkali-activated slag composite cementitious materials. The effects of different parameters on the properties of alkali-activated slag composite cementitious materials were studied by taking the particle size, content of marble waste powder and alkali liquid modulus as the change parameters. The results show that marble powder (SW) can effectively improve the fluidity of the slurry, and the larger the particle size, the more obvious the fluidity of the slurry. The alkali liquid modulus has a significant effect on the compressive strength of cementitious materials, and low alkali liquid modulus is beneficial to improve the compressive strength of cementitious materials. Alkali-activated marble powder cementitious material found Ca6(Si2O7)(OH)6 and Ca(OH)2, and Si–O bond vibration characteristic peak vibration peak in geopolymer unit. Based on the experimental results, the mechanism and reaction process of marble powder were established

Kelvin-Helmholtz Waves and Magnetic Reconnection at the Earth's Magnetopause Under Southward Interplanetary Magnetic Field

We present Magnetospheric Multiscale (MMS) observations of a K-H wave event under southward IMF conditions, accompanied by ongoing magnetic reconnection. The nonlinear K-H waves are characterized by quasi-periodic fluctuations, the presence of low-density and high-speed ions, and variations in the boundary normal vectors at both the leading and trailing edges. Our observations reveal clear evidence of on-going magnetic reconnection through the identification of Alfvenic ion jets and the escape of energetic magnetospheric electrons. Among the 36 magnetopause current-sheet crossings in this event, 19 exhibit unambiguous signatures of reconnection at both the leading (7) and trailing (12) edges. Notably, the estimated current-sheet thicknesses at both edges are comparable to the ion-inertial scale, confirming the compression effect resulting from the large-scale evolution of the K-H waves. The reconnection jets potentially contribute to the suppression of K-H growth through boundary-layer broadening and the development of complex flow and magnetic field patterns