Effects of water content change path on laboratory and field compaction of lime stabilized expansive soil

Generally, the soil requires to be compacted in highway construction. The expansive soil is a special type of soil that is highly susceptible to variations in water content, which affects the degree of compaction at the same compaction energy. In the present study, a series of wet compaction tests and dry compaction tests were carried out in the laboratory. Laboratory test results show that dry compaction will produce a higher optimum water content and a higher maximum dry unit weight compared to wet compaction, because its matric suction is smaller. Field compaction tests were also conducted, the results showed that there might be a risk of under-compacting soils during construction caused by different water content change path in actual field conditions

Effects of Different Irrigation and Drainage Modes on Lodging Resistance of Super Rice Japonica 9108

In order to determine the optimal irrigation and drainage mode for the anti-lodging cultivation of Super Rice Japonica 9108, barrel loading tests of different irrigation and drainage modes were carried out in the Water-Saving Park of Hohai University in Nanjing from June to October in 2019 and 2020. Three treatments were set up: Frequent and Shallow Irrigation (FSI), Rain-catching and Controlled Irrigation (RC-CI) and Drought Planting with Straw mulching (DPS). In each mode, the growth index, stem morphology index, material production index and stem mechanical index of rice at yellow maturity period were measured, and their relationship with the lodging index was analyzed. The results showed that compared with FSI, the lodging index of RC-CI was reduced by an average of 24.0%. RC-CI can promote the lateral development of the base internodes, increase the accumulation of stem sheath dry matter and the internode fullness and enhance mechanical strength and anti-lodging ability of the stem. Meanwhile, RC-CI can appropriately reduce the plant height, so as to reduce the bending moment of the base internodes. As a consequence, the lodging risk was effectively reduced. The lodging index of DPS was reduced by an average of 16.0% compared with FSI. Because DPS was subject to severe water deficit, its internodes thickness and stem wall thickness were inferior to that of FSI, leading to the weakening of the mechanical strength of stem, and the morphological characteristics and mechanical characteristics of the stem were not improved. Despite this, DPS still had a strong resistance to lodging. The output rate and conversion rate of the stem sheath were reduced, and while the plant height and center of gravity height were significantly reduced, the bending moment remained low. Thus, DPS can still reduce the lodging risk of rice. Compared with FSI, the average yield of RC-CI increased by 5.8% in two years, and the average yield of DPS was reduced by 4.4% in two years. DPS under severe water deficit reduced the accumulation of dry matter in the panicle and the yield index of rice, which was not conducive to a high yield. Considering the yield and lodging resistance of the super rice “Japonica 9108”, RC-CI is the best irrigation and drainage mode, followed by DPS. This study can provide data support and theoretical support for regulating the lodging resistance of super rice through irrigation measures

The annealing microstructural evolution of Al-10Zn alloy prepared by continuous extrusion of mixed heterogeneous elemental powders

Al and Zn powders in the ratio of 9:1 (wt%) were alloyed into rods with a dense structure by using the continuous extrusion technique. To promote metallurgical bonding of heterogeneous elements, the microstructures of these rods with different holding times (1, 3, and 5 min) at the same annealing temperature were investigated. With the increase of annealing time, the microstructure consisted mainly of ( α -Al) and ( α  +  η ) phases and an ( α  + η )-rich phase. The solid solubility of Zn into Al also gradually increased. The calculated x-ray diffraction (XRD) data showed that the lattice parameter of Al decreased to 4.04793 Å after 5 min of annealing, which was decreased by 0.062% compared to the lattice parameter of Al in the powder state. The microscopic stress and dislocation density of Al were increased by 0.27% and 12.52 × 10 ^14 m ^−2 respectively after extrusion, and the microscopic deformation and dislocation density were decreased to 0.2% and 8.71 × 10 ^14 m ^−2 respectively after being annealed for 5 min. The dislocation density and lattice distortion after annealing gradually decreased with increasing annealing time, and the scanning electron microscopy (SEM) results indicated that the mass percentage of Zn increased with increasing annealing time