Durability and Microstructural Behavior of Nano Silica-Marble Dust Concrete

czxvsdg

An Experiment and Study of M30 Grade of Concrete by Partially Replacing Fine Aggregate with Marble Dust Powder and Phosphogypsum in Rigid Pavement

The Project is to study about M30 grade of concrete by adding waste materials. Marble dust powder and phosphogypsum which is easily available marble which are standard among the most imperative materials, utilized as a part of the development business. Marble dust is a waste material from the construction site is mixed with concrete as a replacement material. Marble dust powder is acquired from sawing and moulding of marble rock. Phosphogypsum is produced as an outgrowth of the production of fertilizer from phosphate rock. There is a high gypsum content and gypsum is a widely used material in constructions. It is weakly radioactive in nature because it is a by-product of phosphate fertilizers. In the M30 grade of concrete fine aggregate is partially replaced by marble dust powder and phosphosgypsum in some proportions. The fine aggregate is replaced by 10%, 20% and 30% in which marble dust powder and phosphogypsum and are added in an equal proportion. Keywords: Marble dust powder, phosphogypsum, grade of concrete, rigid pavement, green concrete.

Management of Solid Waste Marble Powder: Improving Quality of Sodium Chloride Obtained From Sulphate Rich Lake/Subsoil Brines With Simultaneous Recovery of High Purity Gypsum and Light Basic Magnesium Carbonate

Marble industry worldwide produces large amount of non-degradable marble dust powder (MDP) waste during mining and processing stages. MDP mainly comprises of CaCO3 with small amounts of Mg, Fe or Si in various forms. In India, mainly in Rajasthan state, marble is quarried in huge amounts and MDP thus produced is collected improperly and dumped at any abandoned land or identified disposal sites leading to several environment hazards. On the other hand, the composition of sub soil/lake brines of Rajasthan is typical in nature as it does not have much Ca2+ and Mg2+ impurities but contains higher levels of SO42-. Therefore, the common salt (NaCl) produced from such brines is contaminated with Na2SO4 (8-30 wt%) depending upon SO42- concentration in the brine. Such a salt produced is neither suitable for edible purpose nor for industrial usage. Herein, we have reacted MDP with HCl, and the resulting solution (CaCl2 and MgCl2 slurry) is used in stoichiometric ratio of Ca2+ to SO42- in brines to produce high purity NaCl and gypsum (CaSO4·2H2O) via fractional crystallization. Remaining magnesium containing solution was reacted with Na2CO3 to prepare high purity light basic magnesium carbonate hydrate. Purity of crystallized NaCl, CaSO4·2H2O and MgCO3·6H2O has been ascertained through analytical and spectral methods (TGA, FTIR, P-XRD). Field emission scanning electron microscopy (FE-SEM) was used to elucidate morphology of crystals. The method reported for improving purity of NaCl along with CaSO4·2H2O and MgCO3·6H2O production from sulphate rich brines is simple and economic, and allow management of MDP generated in huge amounts, which poses problems of disposal and creates environment hazards.

Holocene dust dynamics archives in archaeological ruins in arid and semi-arid environments in the Southern Levant

Ruins of archaeological structures, mainly dating to the Bronze Age till Byzantine period, were investigated in a case study in the Petra region in southern Jordan and in the northern Negev desert in Israel. They are covered by post-abandonment debris sediments which provided the parent material of initial soils now developed on the ruins. Such debris sediments have so far rarely been studied although they likely contain a significant aeolian dust fraction because structures and wall remains may act as effective dust traps. We analyzed different types of archaeological structures: cult sites on hilltops, runoff-irrigated terraces on slopes, and cisterns including associated cleanout mounds. As well, we collected current aeolian sediments in nearby dry marble dust traps. It was expected that the various ruins and location types would matter for sediment properties, but substrate composition in all investigated structures was similar. This suggests that most of the fine fractions of the debris material were primarily supplied by wind whereas fluvial processes only re-distributed aeolian sediments. A major aeolian contribution from local weathered rocks could be observed in the Petra region, but not in the Negev, which seems connected with the geology. In situ pedogenesis in both investigation regions is negligible. The ruins seem to act as current dust collectors, but their sediments cannot directly be compared with the material collected in nearby dry marble dust traps. Analogies to different types of collectors for aeolian sediments can be made: depending on design, dust traps gather aeolian material differently. Standard dry marble dust collectors are characterized by similar size of settling dust samples as compared to average aeolian deposition in the ruins, but are of dissimilar substrate composition with regard to particle size distribution and contents of major and trace elements. Sediments in the archaeological structures in southern Jordan show finer textures and higher contents of most major and trace elements which may indicate preferential fixation of silt and clay against sand in the ruins, whereas sediments in dry marble dust collectors in Jordan are relatively depleted in silt and clay. This could be due to crusts and clast covers because the studied archaeological hilltop structures were found covered by surface crusts and pavements of stones and pottery sherds. These may mirror the effect of desert pavements. In addition, current dust samples suggest that precipitation during aeolian sedimentation, in particular in case of snow, is connected with enhanced deposition of (possibly clay-coated) silt. Sediments in the archaeological structures include material from remote and local sources as well as from “recycled” paleosols. Average hilltop dust accretion rates were calculated as ~ 0.14 mm/year, which is in good agreement with results from dry marble dust collectors. They exceed rates calculated for Pleistocene hilltop loess in the Negev. This seems due to enhanced dust fixation in the archaeological ruins as compared to natural Negev loess soils, underlining a so far rarely considered but important role of sediment fixation mechanisms.

Strength, Hydraulic, and Microstructural Characteristics of Expansive Soils Incorporating Marble Dust and Rice Husk Ash

Expansive/swell-shrink soils exhibit high plasticity and low strength, which lead to settlement and instability of lightly loaded structures. These problematic soils contain various swelling clay minerals that are unsuitable for engineering requirements. In an attempt to counter the treacherous damage of such soils in modern geotechnical engineering, efforts are underway to utilize environmentally friendly and sustainable waste materials as stabilizers. This study evaluates the strength and consolidation characteristics of expansive soils treated with marble dust (MD) and rice husk ash (RHA) through a multitude of laboratory tests, including consistency limits, compaction, uniaxial compression strength (UCS), and consolidation tests. By using X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses, the effect of curing on UCS after 3, 7, 14, 28, 56, and 112 days was studied from the standpoint of microstructural changes. Also, the long-term strength development of treated soils was analyzed in terms of the interactive response of impacting factors with the assistance of a series of ANN-based sensitivity analyses. It is found from the results that the addition of MD and RHA lowered down the water holding capacity, thereby causing a reduction in soil plasticity (by 21% for MD and 14.5% for RHA) and optimum water content (by 2% for MD and increased by 6% for RHA) along with an increase in the UCS (for 8% MD from 97 kPa to 471 kPa and for 10% RHA from 211 kPa to 665 kPa, after 3 days and 112 days of curing, respectively). Moreover, from the oedometer test results, m v initially increased up to 6% dosage and then dropped with further increase in the preconsolidation pressure. Furthermore, the compression index dropped with an increase in the preconsolidation pressure and addition of MD/RHA, while the coefficient of permeability (k) of RHA stabilized soil was higher than that of MD-treated samples for almost all dosage levels. The formation of the fibrous cementitious compounds (C-S-H; C-A-H) increased at optimum additive dosage after 7 days and at higher curing periods. Hence, the use of 10% RHA and 12% MD as replacement of the expansive soil is recommended for higher efficacy. This research would be helpful in reducing the impacts created by the disposal of both expansive soil and industrial and agricultural waste materials.

Effect on CBR Values with Addition of Coir Geotextile and Marble Dust in Silty Sands

The subgrade is the foundation of pavement. The conventional method of replacing weak soil with good soil can cause an increase in the cost of a project. Due to this reason ground improvement techniques are much popular nowadays. The major goal of this research work is to compare California Bearing Ratio (CBR) values of the virgin soil and soil reinforced with coir geotextile in one layer and a combination of two layers at different heights from the top surface of the soil. To see the change in CBR values one layer of coir geotextile was reinforced at three different heights (i.e., H/3; H/2 and 2H/3). After that, the effect on CBR values by reinforcement of combination of two layers of coir geotextile at different heights (i.e., H/3 and H/2; H/2 and 2H/3; and H/3 and 2H/3) from the top surface of the soil was studied. Thereafter, the soil is replaced by various percentages of marble dust ranging from 10% to 25% with an increment of 5% and again CBR values of soil samples reinforced with one layer of coir geotextile and a combination of two layers of geotextile at three different heights were compared with virgin soil. The test results reviewed that the maximum dry density (MDD) decreased and optimum moisture content (OMC) increased with the replacement of marble dust in the soil. The CBR test results specify an enhancement of the value of CBR with the addition of coir geotextile and marble dust. The maximum value of CBR is obtained when one layer of coir geotextile was introduced at the height of H/3 and in the case of a combination of two layers of coir geotextile maximum CBR values is obtained when the coir geotextile was introduced at a height of H/3 and 2H/3 from the top surface of the soil.