scholarly journals Experimental Study on Early Age Characteristics of Lime-GGBS-Treated Gypseous Clays under Wet–Dry Cycles

Geotechnics ◽  
2021 ◽  
Vol 1 (2) ◽  
pp. 402-415
Author(s):  
Samuel J. Abbey ◽  
Eyo U. Eyo ◽  
Jeremiah J. Jeremiah
Keyword(s):  
Water Absorption ◽  
Environmental Changes ◽  
Microstructural Analysis ◽  
Calcium Content ◽  
Underground Water ◽  
Early Age ◽  
Microstructural Characteristics ◽  
Gypsum Content ◽  
Soil Pores ◽  
Underground Water Table

Gypseous soils are capable of presenting ground construction challenges to civil and geotechnical engineers due to their unpredictable deformation characteristics. These undesirable responses are sometimes caused by environmental changes in moisture content due to temperature variations, fluctuation of underground water table, surface water, and gypsum content. Hence, the adoption of effective and economical means of stabilising gypseous soils is imperative. This study’s focus is on the early age strength and microstructural characteristics of gypseous soils treated with lime and GGBS. Treated and untreated gypseous soils with 5%, 15%, and 25% gypsum content were subjected to wet–dry cycles while investigating unconfined compressive strength (UCS), water absorption, pH, microstructural changes, and swell. The analysis of the results shows that at zero cycle, the UCS of the untreated gypseous soils increases from 0.62 to 0.79 MPa and swell decreases from 69 to 23%, respectively, as gypsum content increases. However, upon subjection to wet–dry cycles, the UCS reduced from 0.16 to 0.08 MPa at the end of the sixth cycle due to dissolution of gypsum within the soil pores which reduced the strength. The result also shows that gypsum content increases water absorption and reduces the pH of the untreated gypseous soils because of the neutral pH of gypsum. Furthermore, lime-GGBS-treated gypseous soils maintained a higher pH after six wet–dry cycles compared to untreated gypseous soils due to the high pH of lime and the increase in calcium content which improved bonding. In addition, microstructural analysis using SEM indicated early age precipitation of cementitious compounds (CSH) for increasing strength of lime-GGBS-treated gypseous soils compared to untreated gypseous soils.

scholarly journals Calculation of the Height of Capillary Rise of Water in Soils

2020 ◽  
Vol 8 (6) ◽  
pp. 4832-4835
Keyword(s):  
Water Saturation ◽  
Underground Structure ◽  
Capillary Rise ◽  
Soil Layer ◽  
Underground Water ◽  
Wall Material ◽  
Capillary Water ◽  
Temporary Streams ◽  
Filter Water ◽  
Soil Pores

Rain and melt water will form temporary accumulations of surface water on the surface. When they seep into the ground, temporary streams of leaky filter water are formed. If a limited section of water-resistant soil layer or the roof of an underground structure is encountered in the path of these waters, a temporary aquifer-the upper layer of ground water-may form above them. In temporary and permanent aquifers, the soil pores are completely filled with gravitational water, the degree of water saturation is equal to one, and there is pressure under the surface of underground water. Above this surface is a zone of capillary moisture, while the level of capillary rise is determined by the granulometric composition of the soil and ranges from tens of centimeters in sand to several meters in dusty and clay soils. Capillary water rises in the ground on free canals formed by mutually communicating pores, or is kept in them in limbo.The lifting of the liquid in the capillary continues until the gravity acting on the column of the liquid in the capillary becomes equal to the resulting force. Capillary water penetrates from the ground into the walls and rises to a height of up to 2 meters. The normal moisture content of the brick walls is 0.02...0,03, and in the case of unprotected contact with moist soil is increased to 0.15...0.25. On the inside of the walls there is a damp, mildew. Evaporating water increases humidity in the room, and the salts released when it evaporates from salt solutions lead to peeling paint, destruction of plaster and wall material.

scholarly journals Evolution of Secondary Deformations Captured by Satellite Radar Interferometry: Case Study of an Abandoned Coal Basin in SW Poland

2019 ◽  
Vol 11 (3) ◽  
pp. 884 ◽  
Author(s):  
Jan Blachowski ◽  
Anna Kopec ◽  
Wojciech Milczarek ◽  
Karolina Owczarz
Keyword(s):  
Water Table ◽  
Radar Data ◽  
Underground Water ◽  
Coal Basin ◽  
Mining Areas ◽  
Surface Deformations ◽  
New Development ◽  
Satellite Radar ◽  
Underground Water Table ◽  
Coal Fields

The issue of monitoring surface motions in post-mining areas in Europe is important due to the fact that a significant number of post-mining areas lie in highly-urbanized and densely-populated regions. Examples can be found in: Belgium, the Czech Republic, France, Germany, the Netherlands, Spain, the United Kingdom, as well as the subject of this study, the Polish Walbrzych Hard Coal Basin. Studies of abandoned coal fields show that surface deformations in post-mining areas occur even several dozen years after the end of underground coal extraction, posing a threat to new development of these areas. In the case of the Walbrzych area, fragmentary, geodetic measurements indicate activity of the surface in the post-mining period (from 1995 onward). In this work, we aimed at determining the evolution of surface deformations in time during the first 15 years after the end of mining, i.e., the 1995–2010 period using ERS 1/2 and Envisat satellite radar data. Satellite radar data from European Space Agency missions are the only source of information on historical surface movements and provide spatial coverage of the entirety of the coal fields. In addition, we attempted to analyze the relationship of the ground deformations with hydrogeological changes and geological and mining data. Three distinct stages of ground movements were identified in the study. The ground motions (LOS (Line Of Sight)) determined with the PSInSAR (Persistent Scatterer Interferometry) method indicate uplift of the surface of up to +8 mm/a in the first period (until 2002). The extent and rate of this motion was congruent with the process of underground water table restoration in separate water basins associated with three neighboring coal fields. In the second period, after the stabilization of the underground water table, the surface remained active, as indicated by local subsidence (up to −5 mm/a) and uplift (up to +5 mm/a) zones. We hypothesize that this surface activity is the result of ground reaction disturbed by long-term shallow and deep mining. The third stage is characterized by gradual stabilization and decreasing deformations of the surface. The results accentuate the complexity of ground motion processes in post-mining areas, the advantages of the satellite radar technique for historical studies, and provide information for authorities responsible for new development of such areas, e.g., regarding potential flood zones caused by restoration of groundwater table in subsided areas.

scholarly journals An Extension of Taylor’s φ-Circle Method and Some Stability Charts for Submerged Slopes

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Ping Li ◽  
Luanhua Dong ◽  
Xiaowen Gao ◽  
Tonglu Li ◽  
Xiaokun Hou
Keyword(s):  
Analytical Solutions ◽  
Factor Of Safety ◽  
Classical Method ◽  
Circle Method ◽  
Failure Surface ◽  
Underground Water ◽  
Submerged Condition ◽  
Stability Calculation ◽  
Critical Failure Surface ◽  
Underground Water Table

Taylor’s φ-circle method is a classical method for slope stability calculation, which has analytical solutions. Taylor derived equations in two cases separately, namely, (i) the outlet of the critical failure surface is at the slope toe and (ii) the outlet of the failure surfaces is not at the slope toe. The method is only appropriate for two conditions (without underground water table in slopes or totally submerged slopes). In this study, a general equation that unifies the equations of the two cases is proposed and partially submerged condition is introduced. The critical failure surfaces corresponding to the minimum factor of safety are determined using the computer program proposed by the authors. The general expression of the safety factor of slopes under the following four conditions is derived, namely, (i) partly submerged, (ii) completely submerged, (iii) water sudden drawdown, and (iv) water slow drawdown. The corresponding charts for practical use are available.

scholarly journals Development and characterization of sustainable lightweight geopolymer composites

Cerâmica ◽  
2019 ◽  
Vol 65 (373) ◽  
pp. 153-161 ◽  
Author(s):  
H. M. Khater
Keyword(s):  
Compressive Strength ◽  
Water Absorption ◽  
Aluminum Powder ◽  
Building Materials ◽  
Microstructural Characteristics ◽  
Imaging Results ◽  
Lightweight Composites ◽  
Sem Imaging ◽  
Geopolymer Composites

Abstract Production of lightweight building materials attract the attention of the scientists worldwide with the need for reducing the structure deadweight, provide better thermal insulation for buildings, and cost less to transport. The current work focused on the production of lightweight geopolymer composites by the incorporation of aluminum powder and aluminum slag in various ratios for water-cooled slag/kaolinite sand composite; the activators used were 6% of equal ratio from sodium hydroxide and sodium silicate. The properties of the produced lightweight geopolymer composites were studied by measurement of compressive strength, bulk density, water absorption, FTIR, XRD and SEM imaging. Results showed the enhancement for both physicomechanical and microstructural characteristics with using aluminum powder and aluminum slag forming lightweight composites with densities below 2.15 g/cm3 depending on the studied mix composition.

Physical, mechanical, and durability properties of gypsum–Portland cement–natural pozzolan blends

2001 ◽  
Vol 28 (3) ◽  
pp. 375-382 ◽  
Author(s):  
Adnan Çolak
Keyword(s):  
Portland Cement ◽  
Water Absorption ◽  
Setting Time ◽  
Strength Loss ◽  
Natural Pozzolan ◽  
Durability Properties ◽  
Gypsum Content ◽  
Mechanical Durability ◽  
Binder Ratio ◽  
Cement Binder

This paper deals with the effect of gypsum–Portland cement and gypsum–Portland cement–natural pozzolan ratios on the physical, mechanical, and durability properties of gypsum–Portland cement–natural pozzolan blends. The results indicate that the setting time of these paste decreases with the increase of gypsum content in the mixture, ranging from 8 to 11 min. The addition of superplasticizer increases the setting time from approximately 11 to 35 min. This increase is greatly dependent on the plasticizer admixture dosage. These blends show a kinetic of capillary water absorption very similar to that of the Portland cement binder. Sorptivity is strongly influenced by the type of binder, binder composition and water–binder ratio. Porosity of blended gypsum binders ranges from 12% to 37%. Their water absorption is high, reaching 27% in the blends with a greater proportion of gypsum. The gypsum–Portland cement blends themselves possess good water resistance, which is further enhanced by the addition of natural pozzolan and superplasticizer. The water-cured blends with the composition of 41:41:18 (gypsum : Portland cement : natural pozzolan) and 41:41:18S1 (gypsum : Portland cement : natural pozzolan : 1% superplasticizer) offer a compressive strength of approximately 20 MPa at room temperature. These blends give excellent properties retention after aging in water at 20°C for 95 days. Their good resistance to water decreases as the gypsum content in the mixture is raised. However, the strength loss for the gypsum–Portland cement–natural pozzolan blends is generally less than that observed for the gypsum binder.Key words: gypsum, Portland cement, natural pozzolan, physical, mechanical, durability.

Microstructural Analysis of Petroleum Waste Containing Ceramic Tile

2008 ◽  
Vol 591-593 ◽  
pp. 845-848 ◽  
Author(s):  
Bruno C.A. Pinheiro ◽  
J.N.F. Holanda
Keyword(s):  
Water Absorption ◽  
Microstructural Evolution ◽  
Ceramic Tile ◽  
Sintered Density ◽  
Raw Materials ◽  
Microstructural Analysis ◽  
Linear Shrinkage ◽  
Ceramic Tiles ◽  
Petroleum Waste ◽  
Materials Used

In this work is done a study on the sintered microstructure of ceramic tile paste incorporated with petroleum waste. The raw materials used were kaolin, sodic feldspar, quartz and petroleum waste. The ceramic tiles containing up to 5 wt% petroleum waste were prepared by uniaxial pressing and sintered at 1200°C. The microstructural evolution was examined by SEM. In addition, water absorption, linear shrinkage, and sintered density were determined. The results showed that the microstructure of the ceramic tiles is influenced by the added petroleum waste.

The Study on the Early Age Cracking due to the Addition of Silica Fume into Concrete and the Trouble-Shooting Strategy

2011 ◽  
Vol 295-297 ◽  
pp. 824-829
Author(s):  
Chao Lung Hwang ◽  
Chun Tsun Chen ◽  
Le Anh Tuan Bui ◽  
Fondly Reymont Kurniawan
Keyword(s):  
Water Absorption ◽  
Silica Fume ◽  
Heat Of Hydration ◽  
Early Age ◽  
Design Algorithm ◽  
Shooting Technique ◽  
Trouble Shooting ◽  
Durability Index ◽  
Binder Ratio ◽  
Water To Binder Ratio

This study is mainly to investigate the early age cracking due to the addition of silica fume (SF) into concrete and to propose Densified Mixture Design Algorithm (DMDA) method as a trouble-shooting strategy. Specimens with different water-to-binder ratio (W/B) and silica fume content were prepared with ACI concrete (W/B = 0.23, 0.35 and 0.47; SF content = 0%, 10%, 20% and 30%) and DMDA concrete (W/B = 0.23, 0.35 and 0.47; coating paste thickness t = 5, 15 and 25 μm). Adding silica fume to the concrete system to replace part of cement may increase the crack intensity, and the rate of water absorption; but reduce the heat of hydration. DMDA method as a problem-shooting technique shows to have a better performance in reducing the crack intensities up to 41% with W/B = 0.23 and the better durability index than that of ACI method.

Hardened Properties of Lime Based Mortars Produced from Kaolin Wastes

2014 ◽  
Vol 600 ◽  
pp. 282-296 ◽  
Author(s):  
Aline Figueirêdo Nóbrega de Azerêdo ◽  
Arnaldo Manoel Pereira Carneiro ◽  
Givanildo Alves de Azeredo ◽  
Mauro Sardela
Keyword(s):  
Thermal Analysis ◽  
Microstructural Analysis ◽  
Construction Materials ◽  
Inert Material ◽  
X Rays ◽  
Historical Buildings ◽  
Microstructural Characteristics ◽  
River Sand ◽  
Lime Mortars ◽  
Hardened Properties

Many studies have been developed about the use of wastes as construction materials. The higher volume of waste generated by many types of industries has caused many environmental problems. Most of these wastes have not been placed in adequate sites, or even been reused. In Brazil the industries that produces kaolin generates a lot of wastes. Studies have been carried out on the use of kaolin wastes as replacement material for Portland cement concretes and mortars; and only few ones have studied it in hydraulic mortars for restoration of historical buildings. In this work kaolin wastes were studied as pozzolanic and inert material in lime mortars. Two lime/metakaolin ratios and different proportions of kaolin wastes as replacement of river sand were studied. Hardened properties of these mortars like compressive and tensile strength and water absorbed by capillarity were evaluated up to 180 days of curing. Microstructural characteristics also were assessed using thermal analysis (TG/DTG) and x-rays diffraction (XRD). Some mortars presented the highest strengths at 90 days of curing, and at 180 days their resistances dropped. The major phases found by microstructural analysis were monocarboaluminate (C4ACH11) and calcium carbonate (CaCO3).

scholarly journals Development and operation of a muon detection system under extremely high humidity environment for monitoring underground water table

2013 ◽  
Vol 2 (1) ◽  
pp. 29-34 ◽  
Author(s):  
H. K. M. Tanaka ◽  
A. Sannomiya
Keyword(s):  
Water Table ◽  
Detection System ◽  
Scintillation Counter ◽  
Underground Water ◽  
Water Levels ◽  
Complex Nature ◽  
Borehole Data ◽  
High Humidity Environment ◽  
Underground Water Table ◽  
Muon Detection

Abstract. In order to investigate the complex nature of landslides triggered by rainfall, dynamic muon radiography of the motion of the underground water table is planned in a drainage tunnel drilled underneath an estimated fault plane. However, the humidity inside the tunnel is almost 100%. In order to suppress moisture effects, a scintillation counter with Cockcroft–Walton photomultipler tubes (CW-MPT) was developed and tested at the observation site located in Shizuoka Prefecture, Japan. The counter was stably operated for 38 days without gain degrading. Based on the result, we constructed a muon detection system with CW-PMTs at the same site and started operation runs. In this work, the data from borehole-based water gauge measurements of the underground water levels were analyzed and discussed. It was confirmed that the comparison between muon and borehole data would be useful.

Sign in / Sign up

Export Citation Format

Share Document