In this paper, the traditional, silicate-based Portland cement (PC) was employed as the control to explore the impact of adding varying amounts of metakaolin (MK) on the mechanical properties of cement mortar. In fact, as a mineral admixture, metakaolin (MK) has the ability to significantly improve the early strength and sulfate resistance of cement mortar in traditional, silicate-based Portland cement (PC). In addition to this, the performance of Portland cement mortar is greatly affected by the curing mode. The previous research mainly stays in the intermittent curing and alkaline excitation mode, and there are few studies on the influence of relatively humidity on it. Moreover, the paper investigated the impact of four different curing methods about humidity on the mechanical properties and sulfate resistance. The results show that the best content of metakaolin in Portland cement is 10% (M10), and the best curing method is 95% humidity in the first three days followed by 60% humidity in the later period (3#). Based on previous literature that suggests that adding MK thickens water film layer on the surface of mortar, the mechanism of MK increasing the early strength of cement was analyzed. The compressive strength of the Portland cement containing 10% MK (M10) after 1 day curing is 3.18 times that of pristine PC mortar, and is comparable if PC is cured for three days under the same curing conditions. The traditional PC mortar is highly dependent on the wet curing time, and normally requires a curing time of at least seven days. However, the incorporation of MK can greatly reduce the sensitivity of Portland cement to water; MK cement mortar with only three days wet curing (3#M10) can reach 49.12 MPa after 28 days, which can greatly shorten the otherwise lengthy wet curing time. Lastly, the cement specimens with MK also demonstrated excellent resistance against sulfate corrosion. The work will provide a strong theoretical basis for the early demolding of cement products in construction projects. At the same time, this study can also provide a theoretical reference for the construction of climate drought and saline land areas, which has great reference value.

In the present study, cogasification of straw and polyethylene was investigated in a fixed-bed gasification system. The fusion characteristics of ash during cogasification of two different kind of straw and polyethylene were investigated by AFT (Ash Fusion Test), XRD (X-ray diffraction), XRF (X-ray fluorescence), and SEM-EDX (scanning electron microscopy and energy dispersive X-ray). The results showed that the addition of polyethylene had little influence on the mineral species in the gasified ash and only affected the deformation temperature (DT) of gasified ash. The degree of disintegration of gasified ash was positively correlated to the amount of polyethylene, which was beneficial for the gasification process. The changes in relative contents of acidic oxides (SiO 2 +P 2 O 5 +Al 2 O 3 +SO 3 ) and basic oxides (Na 2 O+K 2 O+CaO+MgO+Fe 2 O 3 ) showed a consistent trend in influencing DT of the gasified ashes of two kinds of mixtures while showed different trends in influencing the softening temperatures (ST). PE addition reduces the amount of KCl formed in gasification of RS.