scholarly journals Effect of Soil Replacement on Collapsibility of Footing Resting on Calcareous Sand- A Prototype Study

2014 ◽  
Vol 7 (4) ◽  
pp. 82-98
Author(s):  
Waad Abdulsattar Zakaria
Keyword(s):  
Calcium Carbonate ◽  
Calcareous Soils ◽  
Strength Properties ◽  
Prototype Model ◽  
Weak Soil ◽  
Calcareous Sand ◽  
Calcium Carbonates ◽  
Collapsible Soils ◽  
Replacement Technique ◽  
Laboratory Prototype

Soil replacement technique is not a new method to improve a soil stratum possessing poor strength properties. Before, such a problem of facing a location with weak soil properties is simply solved by changing that spot of estate by another one. Nowadays, such a proposal is no longer valid as a solution since the finance of real estates is rising considerably so that altering a location to the favor of other is not a choice. Calcareous soils are soils rich of calcium carbonate which occur manly in the semiarid subtropics for both hemispheres. This soil is one of the famous collapsible soils similar to the well-known gypseous soils. It has very good strength properties when dry, but once wetted it undergoes large and almost instantaneous settlement, potential collapse of productivity, even if there is no additional load applied on it. This research is concerned in studying the effect of soil replacement technique in reducing collapse settlement. A laboratory prototype model is used in study using SW soil mixed with different percentages of calcium carbonates, and gradual replacement of calcareous soil with sand is carried out in terms of width of footing B. Each model is leached for continuous seven days, and time-settlement data are recorded. This is done again for different percentages of calcium carbonate ratios mixed with sand. Laboratory tests revealed that the degree of improvement in terms of settlement for replacing B/2 depth by sand is 0.36 (B is footing width), that for replacing B is 0.65, for replacing 2B is 0.88, and for replacing 3B is 0.92. The amount of CaCO3 in soil does not affect the degree of improvement observed. An empirical formula is derived using finite differences for relating degree of improvement with depth of soil to be replaced.

RATES OF CALCIUM CARBONATE REMOVAL FROM SOILS

1988 ◽  
Vol 68 (2) ◽  
pp. 449-454 ◽  
Author(s):  
N. VAN BREEMEN ◽  
R. PROTZ
Keyword(s):  
Calcium Carbonate ◽  
Calcareous Soils ◽  
Water Drainage ◽  
Carbonate Weathering ◽  
Soil Chronosequence ◽  
Drainage Rate ◽  
Wide Range ◽  
Subarctic Climate ◽  
Equilibrium Concentrations ◽  
Study Sites

Mean annual rates of calcium carbonate removal from soils in a subarctic climate estimated from data on two chronosequences of calcareous storm ridges, appeared to be relatively constant through time. Concentrations of dissolved calcium carbonate in the soil solution in the study sites calculated from the rates of weathering of CaCO3 and of water drainage are in the range expected for equilibrium with calcite. The same conclusion could be drawn from published studies elsewhere. Over a wide range of conditions, the dissolution rate of calcite appears to be high enough to maintain equilibrium concentrations in water percolating calcareous soils and rocks. Consequently, the rate of calcium carbonate weathering can be predicted from (1) the solubility of CaCO3 and (2) the water drainage rate. Key words: Calcium carbonate weathering, soil chronosequence, subarctic soils

SOLUBILITY OF CALCIUM CARBONATE IN CALCAREOUS SOILS

Soil Science ◽  
1959 ◽  
Vol 88 (3) ◽  
pp. 123-129 ◽  
Author(s):  
STERLING R. OLSEN ◽  
FRANK S. WATANABE
Keyword(s):  
Calcium Carbonate ◽  
Calcareous Soils

scholarly journals Characterization of calcium carbonates used in wet flue gas desulphurization processes

2012 ◽  
Vol 10 (5) ◽  
pp. 1556-1564 ◽  
Author(s):  
Simion Dragan ◽  
Alexandru Ozunu
Keyword(s):  
Calcium Carbonate ◽  
Flue Gas ◽  
Absorption Capacity ◽  
Bet Surface Area ◽  
Experimental Characterization ◽  
Calcium Carbonates ◽  
Calcium Carbonate Precipitate ◽  
Influential Parameters ◽  
Flue Gas Desulphurization

AbstractThis paper presents an experimental characterization of two sources of calcium carbonate, limestone and calcium carbonate precipitate (CCP) used in wet flue gas desulphurization processes. Characterization of the two carbonate sources was carried out by chemical analysis, IR spectra, thermal behavior, particle size distribution for CCP, BET surface area and absorption capacity of SO2 in calcium carbonate suspensions. The absorption temperature, suspension concentration and carbonate grain size were found to be the most influential parameters in the absorption capacity measurements.

Effect of Crystal Contolling Agents on Shapes of Nanometer Calcium Carbonate

2010 ◽  
Vol 92 ◽  
pp. 79-85
Author(s):  
Li Mei Bai ◽  
Yue Xin Han ◽  
Li Xia Li ◽  
Ri Xiao ◽  
Shu Juan Dai
Keyword(s):  
Grain Size ◽  
Calcium Carbonate ◽  
Aspect Ratio ◽  
Average Length ◽  
Calcium Carbonates ◽  
Average Grain Size ◽  
Average Size ◽  
The Given ◽  
Grain Diameter

In laboratory, there polymorphs’ nano-calcium carbonates were synthesized through adding on different crystal controlling agents by the bath-type carburizing reagent in the given conditions. When selecting addition J as the crystal controlling agent, lamellar nano-calcium carbonate products with average size about 150×110×15 nm were synthesized. When selecting annexing agent I as the crystal controlling agent, rod nano-calcium carbonates were synthesized, which average grain diameter was 90 nm, average length was 944 nm, and aspect ratio was 10.5. When selecting annexing agent G as the crystal controlling agent, chain nano-calcium carbonate with average grain size 20~30nm, aspect ratio 10~15nm were synthesized.

scholarly journals A rainfall simulation study of erosion of some calcareous soils

2013 ◽  
Vol 3 (3) ◽  
pp. 179-183 ◽  
Keyword(s):  
Calcium Carbonate ◽  
Cation Exchange Capacity ◽  
Soil Loss ◽  
Clay Fraction ◽  
Calcareous Soils ◽  
Exchange Capacity ◽  
Rainfall Simulation ◽  
Runoff And Soil Loss ◽  
Raindrop Impact ◽  
Rain Simulator

In order to study the erodibility characteristics of some calcareous soils from Central Greece, the instability of aggregates of 2.0-4.7 mm in water was studied. Soil loss experiments were also conducted in the laboratory using a rain simulator where soil loss was measured and the soils’ attitude was studied under the conditions of simulated rainfall. It was found that the instability of aggregates is negatively correlated with cation exchange capacity and the total specific surface of soils. Also the calcium carbonate content affects positively the aggregates instability. The process which seems to control dominantly the time that runoff occurs and the runoff and soil loss quantity, is the creation of surface seals with raindrop impact due to large calcium carbonate quantities that are met in the clay fraction.

scholarly journals Evaluation of the Potential of Modified Calcium Carbonate as a Carrier for Unsaturated Fatty Acids in Oxygen Scavenging Applications

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5000
Author(s):  
Bettina Röcker ◽  
Gabriel Mäder ◽  
Fabien Wilhelm Monnard ◽  
Magdalena Jancikova ◽  
Matthias Welker ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Calcium Carbonate ◽  
Surface Area ◽  
Food Packaging ◽  
Unsaturated Fatty Acids ◽  
Oxygen Absorption ◽  
Scavenging Activity ◽  
Oxygen Scavenger ◽  
Calcium Carbonates ◽  
Oxygen Scavenging

Modified calcium carbonates (MCC) are inorganic mineral-based particles with a large surface area, which is enlarged by their porous internal structure consisting of hydroxyapatite and calcium carbonate crystal structures. Such materials have high potential for use as carriers for active substances such as oxygen scavenging agents. Oxygen scavengers are applied to packaging to preserve the quality of oxygen-sensitive products. This study investigated the potential of MCC as a novel carrier system for unsaturated fatty acids (UFAs), with the intention of developing an oxygen scavenger. Linoleic acid (LA) and oleic acid (OA) were loaded on MCC powder, and the loaded MCC particles were characterized and studied for their oxygen scavenging activity. For both LA and OA, amounts of 20 wt% loading on MCC were found to provide optimal surface area/volume ratios. Spreading UFAs over large surface areas of 31.6 and 49 m2 g−1 MCC enabled oxygen exposure and action on a multitude of molecular sites, resulting in oxygen scavenging rates of 12.2 ± 0.6 and 1.7 ± 0.2 mL O2 d−1 g−1, and maximum oxygen absorption capacities of >195.6 ± 13.5 and >165.0 ± 2.0 mL g−1, respectively. Oxygen scavenging activity decreased with increasing humidity (37–100% RH) and increased with rising temperatures (5–30 °C). Overall, highly porous MCC was concluded to be a suitable UFA carrier for oxygen scavenging applications in food packaging.

Effect of relative density and biocementation on cyclic response of calcareous sand

2019 ◽  
Vol 56 (12) ◽  
pp. 1849-1862 ◽  
Author(s):  
Peng Xiao ◽  
Hanlong Liu ◽  
Armin W. Stuedlein ◽  
T. Matthew Evans ◽  
Yang Xiao
Keyword(s):  
Calcium Carbonate ◽  
Relative Density ◽  
Pore Pressure ◽  
Soil Particle ◽  
Engineering Properties ◽  
Excess Pore Pressure ◽  
Calcareous Sand ◽  
Sem Images ◽  
Cyclic Response ◽  
Excess Pore

Microbial-induced calcium carbonate precipitation (MICP) represents a promising approach to improve the geotechnical engineering properties of soils through the precipitation of calcium carbonate (CaCO3) at soil particle contacts and soil particle surfaces. An extensive experimental study was undertaken to investigate the influence of initial relative density on the efficiency of the biocementation process, the reduction of liquefaction susceptibility, and the cyclic response in biocemented calcareous soils. For this purpose, stress-controlled undrained cyclic triaxial shear (CTS) tests were carried out on untreated and MICP-treated calcareous sand specimens for different initial relative densities and magnitudes of biocementation. Improvement in the cyclic response was quantified and compared in terms of excess pore pressure generation, evolution of axial strains, and the number of cycles to liquefaction. The cyclic experiments show that MICP treatment can change the liquefaction failure mechanism from flow failure to cyclic mobility and can significantly change the excess pore pressure generation response of initially loose specimens. Scanning electron microscope (SEM) images indicate the CaCO3 crystals alter the characteristics of the sand particles and confirm the physical change in soil fabric that impacts the dynamic behavior and liquefaction resistance of MICP-treated specimens. Furthermore, the effect of biocementation was contrasted against the effect of relative density alone, and MICP treatment was shown to exhibit greater efficiency in improving the cyclic resistance than densification.

Tensile Strength of Filled SBR Vulcanizates

1959 ◽  
Vol 32 (3) ◽  
pp. 680-691
Author(s):  
F. Bueche
Keyword(s):  
Tensile Strength ◽  
Calcium Carbonate ◽  
Carbon Black ◽  
Strength Properties ◽  
Carbon Black Concentration ◽  
Molecular Behavior ◽  
Concentration Degree ◽  
Observed Behavior

Abstract The molecular behavior responsible for the observed tensile strength properties of unfilled rubbers has been studied in a recent paper from this laboratory. In the present paper we intend to extend that work to the case of rubbers which are filled with carbon black. Measurements of the tensile strength of hot and cold SBR as a function of carbon black concentration, degree of vulcanization, and temperature are reported. An attempt is made to interpret the observed behavior in terms of molecular concepts. Some additional measurements with resin and calcium carbonate fillers are shown to lend support to the conclusions reached.

scholarly journals The influence of the amount and the origin of calcium carbonates on the isotopically exchangeable phosphate in calcareous soils

1964 ◽  
Vol 62 (1) ◽  
pp. 93-97 ◽  
Author(s):  
O. Talibudeen ◽  
P. Arambarri
Keyword(s):  
Isotopic Exchange ◽  
Calcium Phosphates ◽  
Calcareous Soils ◽  
Parent Material ◽  
Carbonate Content ◽  
Calcium Carbonates ◽  
Phosphate Ions ◽  
Geological Origin ◽  
Kinetics Of ◽  
Exchangeable Phosphate

The kinetics of the isotopic exchange of phosphate ions in soils with and without phosphate added in the laboratory were examined in relation to the amount and origin of the CaCO3 they contained. The isotopic exchange index, ‘Pr/Pe’, and the recovery of added phosphate were inversely proportional to carbonate content in soils containing carbonates of similar geological origin; soils from the Lower Lias showed the biggest change in Pr/Pe with carbonate content.In soils from the Cretaceous Chalk, the first-order rate of isotopic exchange of the ‘slow’ phosphate fraction was constant. It increased to a larger but constant value in the soils incubated for 6 months after adding phosphate in the laboratory. This rate constant is therefore specific to the calcium phosphates in a group of soils derived from the same calcareous parent material and with similar phosphate manuring.

Sign in / Sign up

Export Citation Format

Share Document