Availability Of Sand Research Articles

Pemanfaatan Sumber Daya Alam Pasir Laut sebagai Komoditas Tambang Masyarakat di Perairan Kabupaten Karimun, Kepulauan Riau

Potential mining commodities in Karimun Regency, Riau Islands Province, include: tin, granite, land sand and sea sand. Areas in Karimun Regency that have the potential for sea sand are Babi Island Waters, Meral District, Karimun Regency and Tulang Village Waters, Selat Gelam District, Karimun Regency. This study was carried out to measure the optimal level of utilization of natural sea sand resources that can guarantee its sustainability. This is done by measuring the level of availability of sea sand; and measuring available sea sand reserves, the level of utilization that does not erode reserves, as well as estimated supply projections for future needs. The method used is the observation method, by collecting field data. Data were analyzed descriptively, with bathymetry measurements, spatial analysis using Geographic Information Systems (GIS), and literature study. The resources of the Community Mining Area with sea sand as a commodity in area A of Babi Island waters are 1,174,626.58 m3 and the resources of the Community Mining Area in area B of Gelam Strait waters are 502,088.58 m3

Investigation of the Tensile Strength of Sea Sand Concrete Against the Compressive Strength of the Plan

The availability of sea sand on the beach of Ujung Tape Pinrang is in very large quantities that can be used as materials in making concrete. The purpose of the study is to analyze the characteristics of beach sand, compressive strength and tensile strength produced. An experimental research method in the Civil Engineering Laboratory, University of Muhammadiyah Parepare with a treatment system for ordinary water immersion and analysis of the characteristics of concrete mechanical properties using a compression machine test. The results of the study at the maintenance age of 28 days with a planned compressive strength of 20 MPa produced a compressive strength of 28.29 MPa and a tensile strength of 7.78 MPa, a planned compressive strength of 24 MPa resulted in a compressive strength of 29.98 MPa and a tensile strength of 8.22 MPa, and a planned compressive strength of 28 MPa produces a compressive strength of 31.40 MPa and a tensile strength of 8.44 MPa. The results of the study on compressive strength and tensile strength showed an increase in each increase in planned compressive strength.

Reservoir Mud Releasing May Suboptimize Fluvial Sand Supply to Coastal Sediment Budget: Modeling the Impact of Shihmen Reservoir Case on Tamsui River Estuary

AbstractRegular release of sediment from reservoir has been increasingly adopted as a strategy for sustainable management. Here, we use a process‐based morphodynamic model to simulate the estuarine sediment dynamics impacted by turbidity current venting implemented by the Shihmen Reservoir during three typhoon events in 2008. Upon validation with the post‐event bathymetries, the model hindcasts reveal that mud releasing can be effective in mitigating reservoir siltation, yet may be a suboptimal strategy for alleviating coastal sediment deficit. A vast majority of the released muds were delivered through the estuary and exported to offshore by flood advection, wave dispersion, and tidal flushing. The flood‐driven sands, sourced mainly from downstream tributaries, were instead the major contributor to coastal sediment budget. However, mud mantling (covering and immobilizing sand deposits by the reservoir‐released muds) reduced sand availability and thus sand delivery to the coast. For the present case, 25% of the released muds were deposited along the way, presence of these mud covers reduced sand delivery by 15%, compared to a hypothetical scenario of clear‐water flood releases. The relative sand transport deficit is found to increase linearly with the degree of bed mud saturation, 1–D/R, with D/R the ratio of single‐event mud deposit to release. Given broad relevance to global reservoirs encountering the problems of siltation and coastal sediment deficit, our findings highlight that sustainable management needs to look beyond just a bulk amount of sediment, but it is critical to consider how different sediment fractions are interacting and impacted by human activities.

Determination of Clay and Sand Volume Using Vertical Electrical Sounding

This study presents the results of an electrical resistivity survey conducted in Agudama Epie, Yenagoa local government area, Bayelsa State, Nigeria. The primary objective of the survey was to estimate the volume of clay and sand within a rectangular land parcel measuring 100 m by 200m in the study area. The survey employed the Schlumberger electrode configuration and utilized nine vertical electrode sounding (VES) points.Data was collected using a Terrameter SAS 1000 and was processed using IPI2win software. The geophysical analysis revealed the presence of four distinct geoelectric layers across the study area, identified as layers 1 to 4 in the VES profiles. Layer 2, characterized by clay, exhibited an average thickness of 21.2 meters, while layer 3, consisting of sand, had an average thickness of 8.15 meters. The apparent resistivity values ranged from 8.45 to 79.43 ohm-meter to a depth of 10.14 meters for the clay layer and 8499.86 to 15013.11 ohm-meter to a depth of 33.5 meters for the sand layer. The study estimated a substantial presence of approximately 746,240 tonnes of clay and approximately 261,126 tonnes of sand in Agudama Epie. This discovery offers significant economic potential, including job creation, the establishment of small and medium-sized enterprises, and opportunities within the construction industry. The local extraction and processing of clay can drive economic growth and facilitate the production of concrete and building materials. Additionally, the availability of sand in the region can reduce transportation costs and stimulate local construction projects, thereby fostering economic activity and infrastructure development.

Morphological and sedimentary characteristics of raked linear dunes in the southeastern Taklimakan Desert, China

Raked linear dunes were rarely reported, except in the Kumtagh Desert, leaving little known about the dynamic process. However, numerous raked linear dunes have formed in the Kat Kum dunefield of the southeastern Taklimakan Desert, which provides a new case to study the morphodynamics of these dunes. We conducted a comprehensive analysis on the dune morphometry, wind regime, sedimentary characteristics, and sand availability of these dunes. We found that grain size variation is an essential factor affecting the formation of raked linear dunes in addition to wind regime and limited sand availability. These dunes in the Kat Kum present small scale and easily reshaped with fast migration rate compared with these in the Kumtagh Desert, and distributed in areas with low sand cover. The primary ridge extended obliquely to the resultant drift direction, whereas the subsidiary ridge extend is nearly parallel to this direction. The grain size of the primary ridge is noticeably coarser than that of the subsidiary ridge. These dunes seem to have evolved from barchans. Under a north-northeast wind, barchans reshaped to asymmetrical barchans by extending their southeast limbs and eroding their northwest limbs, causing the ridge to be oblique to the resultant drift direction. The strong east-northeast wind erodes and reshapes the primary ridge, transporting fine sand to the northwest and resulting in the formation of proto-subsidiary ridges. With the elongation and lateral movement of primary ridge, a continuous subsidiary ridge with regular dune spacing forms on the northwest flank.

The Precambrian continental record: A window into early Earth environments

The Precambrian was characterized by unique palaeoenvironmental conditions in the Earth’s atmosphere, biosphere and geosphere. This study presents a global quantitative analysis of Precambrian sedimentary successions of aeolian, alluvial, fluvial, lacustrine and glacigenic origins, examined in the broader context of Earth evolution. In the Precambrian, an apparent scarcity of aeolian successions is observed. This may be linked to: (1) differences in atmospheric density, which controlled wind erosion and sedimentation; (2) different astronomical configurations, which may have influenced tides and atmospheric circulation, thereby affecting sand availability and the width of subtropical zones; (3) potentially hotter and more humid climates, restricting dry-sand availability; (4) a lack of vascular vegetation that could prevent reworking of aeolian deposits; (5) poor preservation potential; (6) misinterpretation of the Precambrian record. Mixed aeolian-alluvial strata are more abundant, perhaps because their preservation in the geological record was favoured by water tables sustained by incursions of alluvial systems into otherwise aeolian dominated environments. Aeolian deposits were preferentially accumulated during phases of supercontinental breakup, where rapidly subsiding rift basins provided accommodation suitable for preservation. Other than in the Neoproterozoic record, where glacigenic deposits dominate, alluvial strata are the most common and thickest type of continental deposit in the Precambrian. Precambrian braided alluvial systems were more widespread than in the Phanerozoic. Major alluvial systems formed preferentially during phases of supercontinent assembly, whereby alluvial systems drained major orogens, and long drainage pathways developed from supercontinent interiors to coastlines. In the Paleoproterozoic, ephemeral, saline to partly arid lakes developed extensively in the desertic interior of Columbia. Glacial deposits preferentially formed in the breakup phase of supercontinental cycles; this supports theories invoking enhanced chemical weathering of uplifted rift shoulders as a driver of carbon dioxide sequestration, global cooling, and glaciation. Overall, the number of identified continental successions increases towards the Precambrian-Phanerozoic boundary. This may be an artefact of an increasingly more complete stratigraphic record as time progresses. However, the abundance of continental successions varies on a quasi-periodic cycle of 500 – 700 Myr, with peaks coinciding with the tenure and breakup of Precambrian supercontinents.

Fine sandy concrete reinforced with polypropylene fibre for rural and desert housing

This research aimed to design a low-cost fibre concrete as an alternative to earth-concrete reinforced with biomaterial fibres, where the latter is characterized by mechanical defects such as low strength, water degradation and air erosion, as well as the continuous deformation related to the self-compression and unlimited subsidence of the bearing surface soil.The designed concrete is composed of fine sand, cement at small quantities and polypropylene fibre available on the daily market. This material is easy to form due to the availability of fine sand in nature and the possibility of its production without much skill. At the same time, it is made at a low cost and short implementation time, unlike earth concrete where it needs time to dry and acquire the appropriate strength. Laboratory work has shown good results as the light density, the large ductility, and an acceptable strength capacity of this material.

To study the mechanical and durability characteristics of concrete utilizing waste foundry sand

Currently, the availability of high-quality natural river sand is scarce, requiring transportation over long distances, and its rapid depletion is a significant concern. In this project, the focus lies on assessing the behavior of concrete by partially replacing natural sand with waste foundry sand. The experimental investigation primarily examines the mechanical and durability, split tensile strength, Ultrasonic Pulse Velocity Test, flexural strength, and permeability of concrete. This evaluation involves replacing natural river sand with varying percentages (0%, 10%, 20%, 30%, 40%) of waste foundry sand by weight. Tests are conducted on cubes and beams to analyze the mechanical properties and durability characteristics of concrete with waste foundry sand compared to concrete with natural sand as fine aggregate. The study includes assessments of splitting tensile strength and flexural strength at different ages (7, 28, 56, and 90 days). Results indicate a decrease in workability as the percentage of waste foundry sand in the mix increases.

Formation and evolution of barrier coast under condition of sand scarcity; an example from the Polish coast of the southern Baltic sea

The formation and evolutionary history of intracontinental, tideless sea barrier coasts is still poorly known in comparison to open-ocean and tidal sea barrier systems. This paper describes the morpho-geological structure of the barriers and its substrate along a 90-km section of the middle part of the Polish southern Baltic coast. The main goal of the study is a better insight into the evolution of the barriers in case of sand scarcity and relations to sea level changes. The study area was examined by analysis of the published and historical data from 120 borehole profiles supplemented by new 18 core drillings. In addition to lithological and biostratigraphical data, a large set of radiocarbon ages was acquired and analysed. The barriers during its whole middle and late Holocene history were retrogradational despite of varied geological and morphological features of its substrate. The average rate of barrier's retreat has shown considerable variation in a close relation to the rates of sea-level rise. During the period 8500-7500 yr b2k when the sea level rose by 6–5 mm/yr, the coast retreated ca. 4.6–3.5 m/yr. Between 7500 and 6000 yr b2k, the sea-level rise slowed down to ca. 1.7 mm/yr and the rate of coastline retreat fell to ca. 1.0 m/yr. During the last 6000 years, coastal retreat slowed down to ca. 0.3 m/yr as the average sea level rise was ca. 0.5 mm/yr. The permanent retrogradational history of the barrier coast, even in the case of sand availability in the barrier's substrate, is explained by the existence of a divergence zone of longshore currents and a related source zone for the alongshore sandy streams. The divergence zone is present within the study area not only today, but it has existed most probably also at least since the beginning of the late Holocene. As a result, the erosional trend (sand scarcity) dominates here, which contributes to the presence of retrogradational barriers.

Spatial diversity and habitat characteristics of seagrass meadows with management recommendations in the Andaman and Nicobar Islands, India

The Andaman and Nicobar Islands, India, a geographically remote region, harbor a diverse island ecosystem. Limited exploration has hindered our understanding of marine floral biodiversity in this area. To address this gap, we investigated seagrass meadows in the Andaman and Nicobar Islands to understand their spatial distribution, species composition, and habitat characteristics. We assessed 66 seagrass meadows, including 32 newly discovered ones, filling data gaps in the region’s seagrass coldspots. Seagrasses were found across a wide range of depths, with the majority occurring in shallow subtidal waters (< 8 m). Large-sized species such as Thalassia hemprichii, Enhalus acoroides, Cymodocea rotundata, Cymodocea serrulata, and Syringodium isoetifolium dominated the littoral and shallow subtidal zones, while smaller species such as Halophila spp. and Halodule spp. exhibited broader depth distributions. H. beccarii and H. decipiens were strictly intertidal and subtidal species, respectively. Water depth significantly influenced seagrass occurrence (p < 0.0001), cover (β = -0.2759; SE = 0.02471; p < 0.0001), shoot densities (β = -0.3556; SE = 0.1231; p = 0.005), and biomass (β = -0.3526; SE = 0.1159; p = 0.003). Sand availability emerged as the second significant predictor of seagrass distribution, cover, and biomass (p values < 2e-16, < 2e-16, and 0.01, respectively). Habitat heterogeneity decreased with increasing water depth, and seagrass species exhibited strong preferences for specific substrata, resulting in spatial niche partitioning. Our study provides novel insights into the seagrass spatial diversity, habitat characteristics, and seagrass-environment relationship in the Andaman and Nicobar Islands. Further, it highlights the importance of water depth, habitat characteristics, and substratum heterogeneity in seagrass distribution and growth. Lastly, our findings imply that any change to the benthic profile of the meadows will influence the seagrass species distribution and growth. Understanding these factors is crucial for seagrass conservation and management in the region, aiding the development of targeted strategies to protect these valuable marine habitats and associated biodiversity.

Spatial contrasts in mid-Holocene dune activities in deserts of northern China: Results from PMIP4 simulations in comparison with geological data

Numerous studies have explored paleoenvironmental conditions in China's dune fields around the mid-Holocene (MH), ∼6000 calendar years ago, often based on individual paleosol-aeolian sand depositional sequences and local-scale landscape dynamics. So far, continent-scale modeling studies have only indirectly assessed dune activation and stabilization processes via changes in simulated precipitation, net precipitation (precipitation minus evaporation), and effective moisture (precipitation divided by evaporation). Here we conducted a comprehensive study using gridded data on potential evapotranspiration, precipitation, and surface wind velocity from 13 climate models participating in the Paleoclimate Modeling Intercomparison Project phases 4 (PMIP4) and compared the model results with geological records. Our evaluation of spatial patterns of dune activity in northern China around the MH reveals that the intensity of annual MH dune activity exhibited significant differences between the eastern and western parts of Chinese deserts compared to those of the preindustrial period (PI). Dune activity was significantly weaker in the eastern region, while in the western part, it was considerably stronger. The key drivers of this disparity were the distinct spatial variations in near-surface wind speed and effective moisture between the two regions. Compared with the optically stimulated luminescence ages of the paleosol-aeolian sand sedimentary sequences derived from a compilation of geological records from 88 sites across northern China, the model results suggest that the weakening of dune activity and the process of dune stabilization in eastern China around the MH were mainly attributed to a significant increase in effective moisture and a concurrent decrease in near-surface wind speed due to the intensified East Asian summer monsoon. Additionally, the weakening of westerlies in western China resulted in reduced effective moisture, contributing to increased sand availability for dune development and subsequent desert expansion.

An Experimental Study on Partial Replacement of River Sand by Manufactured Sand in Self-Compacting Concrete

Abstract: SCC was first developed in Japan to achieve durable concrete structures in 1980’s. Self-compacting concrete (SCC) is an innovative concrete which can be placed and compacted under its own weight with little or no vibration effect and at the same time cohesive enough to be handled without segregation or bleeding. Adoption of SCC offers substantial benefits in enhancing construction productivity, reducing overall cost, and improving work environment. Cost reduction in the building is the primary objective in developing countries like India. This paper puts forward the applications of manufactured sand as an attempt towards sustainable development in India. It will help to find valuable solution to the declining availability of natural sand to make eco-balance. Manufactured sand is one among such materials to replace river sand, which can be used as an alternative fine aggregate in mortars and concretes. The use of manufactured sand in concrete is gaining momentum these days. The present experimental investigations have been made on concrete using manufactured sand as fine aggregate and observed the effects of crushed manufactured sand on strength properties of concrete. The application of concrete meeting the specification is of paramount importance, to ensure construction of durable R.C.C. structure. A well processed manufactured sand as full replacement to river sand is the need of the hour as a long-term solution in Indian concrete industry until other suitable alternative fine aggregate are developed.

Weight-based and Digital Payment Process Flow Design to Decrease Quarry Sand Sales Fraudulence Risk

Databases have risen to the level of being one of the most important corporate assets. The availability of data in a company is required to make the right profit decision. In running a business aiming to achieve high profitability, companies must recognize profitable items by making decisions that require knowledge of the supply chain, knowledge of past, present, and future buying patterns, and costs derived from data obtained from many different systems. In this study, a company running a quarry sand mining business is experiencing disproportions of the resource availability of quarry sands, operating expense, and profit. It leads to suspicion of fraudulence risk during the operations and transaction of the product. This study aims to minimize the fraudulence risk of quarry sand sales by using data re-verification and analytical techniques. The study implemented a process analysis and root-cause method using process flowcharting and fishbone diagram tools. The root causes of this issue happen during the initial data input process caused by three main factors namely machinery or equipment, people, and systems. The newly designed system utilizes a digital weighing scaling system for trucks in recording the initial data and deposit payment system based on the accurate truck final weight.

Late Quaternary eolian dune-field mobilization and stabilization near the Laurentide Ice Sheet limit, New Jersey Pine Barrens, eastern USA

Well-preserved stabilized dune fields are widespread in the New Jersey Pine Barrens, northern Atlantic Coastal Plain, USA. In this area, which was unglaciated throughout the Quaternary, quartz-rich Miocene–Pleistocene age fluvial and marginal marine sands provided source sediments for eolian mobilization. Parabolic and transverse dunes within fluvial source-bordering dune fields in small-river watersheds migrated to the east-southeast (110–125°) over unconsolidated sands and gravels. The short eolian transport distance of most dune-field sand in the presence of moderately to sub-rounded quartz grains with low sphericity indicates eolian abrasion and dune-sand fashioning occurred within a short duration of transport. Although the absolute duration of eolian transport remains unknown, dune stabilization occurred about 23–17.5 ka, with a weighted mean of 19.5 ± 0.5 ka from six dated dunes. Dune stabilization coincided with northward retreat of the Laurentide Ice Sheet from its maximum position at ∼41.500° N (∼100 km north of the study area), to ∼41.375°N (∼200 km north). The well-preserved dune morphology and narrowly constrained ages suggest rapid dune stabilization. Dune-forming katabatic winds from the WNW declined abruptly with northward migration of the ice sheet, accompanied by climatic amelioration and stabilization by vegetation. A short-lived period of eolian mobilization may have been associated with a temporary increase in sand availability from adjacent fluvially derived sediments. Post-depositional processes included soil eluviation, with dissolution features and breakage blocks on quartz grains signifying long-term in-situ soil weathering.

Evaluation of Morphological and Quality Parameters in Adult Male Red King Crabs (Paralithodes camtschaticus) Raised to Commercial Weight from Juveniles

Red king crab (RKC) has become a valuable resource, and most of this fishery operates in a quota-regulated area (QRA) east of 26°E. West of the QRA, a free fishery area (FFA) is established to limit further migration. Today, juvenile RKCs from the FFA are not utilized. This study investigated morphological and quality parameters in adult RKCs (≥800 g) after live holding (LH) of 23 months starting from juveniles (on average 500 g). During the LH, the RKCs were kept in two separate tanks, one at ambient seawater temperature (AST) and one at elevated seawater temperature (AST-E). The RKCs were fed ad libitum. Both tanks were divided into two sections, one with a sand tray. After 23 months, the RKCs were processed and analyzed. The hepatosomatic index, abdomen index, meat content, cluster yield, moisture, whiteness index, and instrumental chewiness differed significantly ( P < 0.05 ) between the wild RKCs and the RKCs from one or both LH groups. The availability of sand indicated improved habitat conditions as several parameters were positively affected. Also, lower variation in morphology and quality parameters of the processed muscle was observed in RKCs from the subgroups with access to sand than those without sand.

Precambrian aeolian systems: A unique record?

The Precambrian is associated with a set of geologically unique palaeoenvironmental conditions arising from differences in the Earth’s atmosphere, biosphere and geosphere. The extent to which these conditions operated to generate an aeolian stratigraphic record that is geologically distinct from that of the Phanerozoic remains poorly understood. This study presents a quantitative comparison of the preserved sedimentary architectures of 87 globally distributed aeolian successions from the Precambrian (30 case studies) and the Phanerozoic (57 case studies). Compared to those of the Phanerozoic, Precambrian aeolian successions are characterised by: (1) thinner aeolian dune sets, mostly documenting the accumulation of small, rapidly migrating barchan dunes; and (2) a greater occurrence of sandsheet, zibar, and damp and wet interdune deposits, many occurring interdigitated with non-aeolian strata. The nature of the Precambrian aeolian stratigraphic record reflects in part the absence of sediment-stabilizing terrestrial vegetation: compared to Phanerozoic systems developed since the evolution of land plants, aeolian processes (erosion, transport and deposition) were more active, even under markedly more humid climates. Precambrian aeolian successions record greater evidence of fluvial and marine incursions into contiguous aeolian dune fields. Water tables were commonly elevated close to the level of the accumulation surface for protracted episodes; extensive damp and wet substrates restricted the availability of dry sand for aeolian dune construction, thereby limiting dune size. In some Precambrian aeolian systems, sediment supply was additionally restricted by the development of cryptobiotic films and crusts that preferentially developed on damp substrates in the absence of vegetation. Common fluvial and marine aqueous interactions promoted the reworking of aeolian dunes into sandsheet deposits; many such accumulations likely represent eroded remnants of larger aeolian dune fields. Given the absence of vegetation-induced sediment binding and baffling, and wind-buffering effects, coarser sand fractions were more readily transported by the wind in the Precambrian; this led to the preferential development of coarse-grained zibar deposits. This study demonstrates how the Precambrian aeolian sedimentary record is geologically distinct from that of the majority of the Phanerozoic, providing new insights into the controlling factors that governed aeolian sedimentation during the Precambrian through interactions between the geosphere, biosphere and atmosphere.

An Experimental Research on Partial Replacement of Fine Aggregate with Granite Powder

Abstract: The most commonly used fine aggregate across world is river sand. River sand is expensive due to excessive cost of transportation from natural sources. The use of sand in construction activities results in the excessive mining. Due to excessive mining natural resources are getting exhausted results in increase in scour depth and sometimes flood possibility. Thus becoming inevitable to use alternative material in concrete. Also large scale depletion of the source creates environmental problems as environmental transportation and other constraints make the availability and use of river sand less attractive. A substitute or replacement product for concrete industry needs to be found. Granite is an igneous rock which is widely used as construction material in different forms. Granite industries produce lot of dust and waste materials. The wastes from the granite polishing units are being disposed to environment which causes health hazards. Granite fines are used as a filler material in the concrete, replacing the fine aggregate which will help in filling up the pores in the concrete. Filling up of the pores by granite fines to increase the strength of the concrete and also a material which is abundantly to investigate the strength behaviour of concrete with use of granite fines as an additive .In this project an attempt is made experimentally to investigate the Strength and durability behaviour of ordinary and high strength concrete with the use of granite fines as an additive. Concrete is prepared with granite fines as a replacement of fine aggregate in 6 different proportions namely 0%,10%,20%,30%,40%and 50%.To improve the workability of concrete 1% superplasticizer added to ordinary strength concrete. The test results indicate that granite as replacement for fine aggregate with has beneficial effect on the mechanical durability properties such as compressive strength, split tensile strength.

Spatial and temporal variation in the evolution of ancient aeolian dune-field. The Pennsylvanian Piauí Formation (Parnaíba Basin), Brazil

The sedimentary record of aeolian systems is the result of a complex interplay between the size of the dune and interdune morphologic elements, the rate of bedform migration and the rate of aggradation. Since these parameters are not constant over the time and space, the resulting preserved deposits display a complex architecture characterized by sets of variable thickness and climb angle. Such complexity is observed in both wet and dry aeolian systems of the Pennsylvanian Piauí Formation and is studied here using a numerical reconstruction of the controlling parameters, including dune wavelength and angle of climb each of which varied both spatially and temporally. Through facies analysis and stratigraphic correlation, three genetic units were identified. Spatial variation in the first unit is characterized by a dry aeolian system in which the dimensions of dunes increased to the NW, suggesting deceleration of saturated winds from a dune-field margin to its center. The second and third units are characterized by wet aeolian systems marked by progressively thicker sandsheet deposits and a reduction of dune/interdune thickness ratio. In both units, the spatial variations are marked by a reduction in the dimensions of dunes to the NW, suggesting progressively lower sand availability most likely related to higher water table or its capillary fringe from a dune-field center to its margin. The temporal variation was inferred from the drying-upward cycles observed in all three units. Although the first unit is marked by aeolian cosets overlying thinner simple dune sets, the second and third units are composed by sandsheet deposits at the base overlain by the deposits of progressively larger dunes, in some case culminating with the preservation of aeolian cosets of strata. Such observation suggests that both dry and wet units are marked by an increase in sand saturation allowing the preservation of larger dunes over time. The results of this study suggest a highly dynamic nature of the aeolian dune system where variations in sand supply, availability and wind energy exerted a direct effect on the aeolian system, triggering expansion or contraction of the dune-field. These expansion and contraction phases observed in the Pennsylvanian Piauí Formation are related to glacio-eustatic changes documented during the Pennsylvanian period.

An Experimental Study on Partial Replacement of Fine Aggregates with M-sand

Shortage of good natural sand due to depletion of resources and limitation due to environmental considerations has made concrete manufacturers to look for suitable alternative fine aggregate. One such alternative is “manufactured sand”. Manufactured Sand is a term used for aggregate materials less than 4.75 mm and which are processed from crushed rock or gravel . Due to booming of construction activities in our country, natural sand resources are increasing depleted and its costs is becoming increasing high. Workability strength and Durability of concrete with manufactured sand as replacement to natural sand in proportions of 0%,5%,10%,15%,20% and 25% is studied. This project was, therefore, conducted to study the influence that manufactured sand having compressive strength, split tensile strength of concrete for 7 days ,14 days ,28 days, and to access the prospects of using manufactured sand as a replacement of natural sand. The experiments were conducted on M30 concrete grade. Slump cone test is conducted to determine workability on fresh concrete. It can therefore, be concluded from the finding of the study that when the availability of natural sand is scarce are in cities where the price of natural sand is as expensive as manufactured one, manufactured sand concrete mix is a viable and better alternative to the use of natural sand.

Enhancement of shear strength of cohesionless granular soil using M-Sand dust waste

In recent times, shortage in the availability of river sand for construction activity has led to the production of Manufactured Sand (M-Sand) in huge quantities. This in turn has led to the production of huge volumes of M-Sand Dust Waste (MSDW) as a waste by-product which is disposed of nearby, in available open spaces and landfills. This leads to wastage of valuable land areas and also pollutes the air in surrounding areas leading to health hazards to the humans. An effort has been made in this project, to check the suitability of utilizing MSDW as a filling material in reinforced earth walls and to replace the conventional granular backfill materials with MSDW. As per IRC: SP: 102-2014, based on the particle gradation of MSDW, liquid limit, plastic limit test and direct shear test, it was observed that MSDW is suitable to be utilized as filling material in reinforced earth walls. Also, index properties of 3 types of granular backfill materials namely Silty Sand, M-Sand and River Sand were studied in this project and MSDW was used as a replacement to these granular soil in percentages of 20%, 40%, 60% and 80% by dry weight of soil. Based on the experimental results, it was concluded that ideal percentage replacement of Silty Sand and M-Sand with MSDW was found to be 20% for which maximum angle of internal friction (ϕ) was observed to be 43° and 49° respectively. Optimum percentage replacement of River Sand with MSDW was found to be 80% for which maximum ϕ value was observed to be 45° in comparison to 40° observed for River Sand without replacement.