Dry Weight Of Sand Research Articles

Mechanical Properties of Sandy Soil Improved with Cement and Nanosilica

Abstract In the literature, studies show that nanosilica particles and artificial pozzolans possessing can improve structural properties of cement-based materials. This paper studies the effect of cement and nanosilica on the engineering properties (compaction, unconfined compressive strength) of sand. Three different cement ratios (5, 9, and 14% by weight of dry sand) were mixed with four different nano silica ratios (0, 5, 10, and 15% by weight of cement), and then compacted into a cylindrical specimen. The results of the study presented that the addition of the cement and nanosilica improves the engineering properties of sands. The increase of maximum dry unitweight of sand was noted with the increase in the cement content. The presence of nanosilica in optimal percentages can significantly improve the mechanical properties of cement sand.

Prediction of combined effects of fibers and cement on the mechanical properties of sand using particle swarm optimization algorithm

In this research, a series of laboratory tests have been performed to investigate the effects of cement and polyvinyl alcohol (PVA) fiber on the performance of sand. Unconfined compression strength and compaction are also assessed in the present study. The cement contents were 0.5, 1, 2, 4, and 6% by weight of the dry sand. Fiber length and diameter were 12 and 0.1 mm, respectively, and were added at 0.0, 0.3, 0.6, and 1% by weight of dry sand. Finally, the obtained results from the experimental data with particle swarm optimization algorithm are used to generate a polynomial model for prediction unconfined compression strength, modulus of elasticity, and axial strain at peak strength. The results of the study indicate that the inclusion of PVA fiber increases the unconfined compressive strength and the peak axial strain. The elastic modulus of specimen decreased with increase in fibers. Maximum dry density of the sand–cement–fiber mixture increases with the increase in cement content and decreases with the increase in fiber content.

The Potential of Lime and Grand Granulated Blast Furnace Slag (GGBFS) Mixture for Stabilisation of Desert Silty Sands

This study describes experimental results achieved on the use of Grand Granulated Blast Furnace Slag (GGBFS) and Lime in stabilising desert silty sand for possible use in geotechnical engineering applications, especially for roadways and railways constructions. The GGBFS and lime were added in percentages of 5, 10 and 15% and 1, 3, and 5% respectively, by dry weight of sand. Different laboratory tests such as mechanical aggregation test, hydrometer analysis, liquid-plastic limit, pH value test, compaction, unconfined compressive strength (UCS), California bearing ratio test CBR , were performed on samples to understand the engineering characteristic of soil and influences of mixtures on the silty sand soil. The study results demonstrate significant improvements in unconfined compressive strength and California bearing ratio strength. Moreover the swelling behaviour of mixtures was decreased effectively. Thus mixture of GGBFS and lime can be suggested to improve engineering characteristic of desert silty sands.

Effects of Reinforcement on Liquefaction Resistance of Solani Sand

AbstractA study on liquefaction resistance of Solani sand reinforced with geogrid sheet, geosynthetic fiber, and natural coir fiber is reported. Tests were carried out on shake table (vibration table) with sand samples prepared at a relative density of 25%, with and without reinforcements. Synthetic geogrid sheets were used in three different combinations of three, four, and five layers. In case of fibers, the percentage of fibers by weight of dry sand were taken as 0.25, 0.50, and 0.75% and mixed randomly with the sand sample. The liquefaction parameters, such as the maximum pore water pressure (Umax⁡), maximum pore water pressure built-up time, stay time for Umax⁡, and pore water pressure dissipation time were measured corresponding to various levels of accelerations varying from 0.1–0.4 g. The frequency of the dynamic load was kept constant at 5 Hz. The liquefaction resistance of sand was evaluated in terms of maximum pore water pressure ratio (rumax⁡). Test results indicated that on inclusion of fiber...

Hsp70 level in progeny of aging grasshoppers from variously polluted habitats and additionally exposed to zinc during diapause

The hsp70 level in the bodies of 1st instars of grasshoppers Chorthippus brunneus from unpolluted (Pilica) and polluted (Olkusz, Szopienice) sites and additionally exposed to various doses of zinc during diapause and embryonic development prior to hatching were measured by Western blotting. The main aim of our work was to assess the relationship between the age of female grasshoppers originating from variously polluted habitat and the hsp70 level in their progeny. Possible reasons for population variation in hsp70 levels were discussed. The hsp70 level in the offspring's body depended on the place of origin. The strongest expression of hsp70 was found in the bodies of larvae hatching from the eggs laid by young females from Pilica (reference site). In contrast, a low initial level of hsp70 in larvae from polluted sites, especially in young females’ progeny, was observed. The application of zinc during diapause influenced the hsp70 level in grasshopper larvae; however, the direction of the changes depended on the insects’ place of origin. In larvae from the reference site, and also (but to a lesser degree) from Olkusz, the increase in the hsp70 level after zinc treatment was most pronounced. Whereas in grasshoppers from Szopienice, zinc (in 100 μg g −1 dry weight of sand) did not change the hsp70 level, or (in 500 μg g −1 dry weight of sand) caused a reduction in hsp70. The differences may result from maternal effects; however, possible adaptation also cannot be excluded. To confirm this statement further studies are needed.

Stabilization of desert sands using municipal solid waste incinerator ash

This paper presents experimental results on the use of incinerator ash in stabilizing desert sands for possible use in geotechnical engineering applications. The incinerator ash was added in percentages of 2, 4, 8, 10 and 12%, by dry weight of sand. Laboratory tests such as compaction, unconfined compression, shear box and hydraulic conductivity were performed to measure the engineering characteristics of the stabilized material. The results showed substantial improvements in unconfined compressive strength and shear strength parameters (c and φ). Thus, incinerator ash can be used to improve the shear strength characteristics of desert sands. The permeability of the sand–incinerator ash mixture was relatively low.

Mortality of Grasshoppers Exposed to Beauveria bassiana during Oviposition and Nymphal Emergence

In a controlled environment, Beauveria bassiana conidia in a sand oviposition substrate caused extensive mortality in ovipositing grasshopper ( Melanoplus sanguinipes) females, associated males, and subsequently, in emergent nymphs. Population densities of viable conidia at the time of oviposition ranged from 7.2 × 10 6 to 4.2 × 10 7 colony-forming units/g dry weight of sand. Abdomens of ovipositing females were heavily infested and many of the conidia were aggregated near or in abdominal intersegmental folds. Mating activity was noticeably reduced 5 days after exposure, and by 9 days, 81 to 100% of the females were dead. Mortality of males due to B. bassiana was delayed relative to females but reached 50 to 100% after 14 days. Females exposed to sand amended with viable or nonviable conidia laid similar numbers of eggs during the first oviposition period (1 to 7 days). However, very few eggs were laid by treated females in the sand containing viable conidia during the second oviposition period (8 to 14 days) due to high mortality. Over the 14-day experimental period, the females exposed to viable conidia produced 57.0% fewer eggs. After emergence, exuvia from vermiform larvae were heavily infested with conidia. Newly emerged nymphs were also infested and the incidence of mycosis was 63.9% after 10 days, compared to 0.13% in the control treatment. Unhatched eggs and egg chorions in sand containing viable conidia were frequently colonized by B. bassiana but the hatchability of the eggs was not affected. This study shows that adult grasshoppers of both sexes and emerging nymphs, but not eggs, are susceptible to infection by B. bassiana in sand and that soil inoculation might provide an alternative method for the application of this entomopathogen for control of grasshoppers.