Water Stability Improvement of Acid Fine Aggregate-Based Asphalt Concrete

In general,acid aggregates are not used in combination with asphalt concrete because of their poor compatibility with the asphalt binder,which typically results in a scarce water stability of the concrete.In the present study,the feasibility of a new approach based on the combination of acid granite fine aggregate with alkaline limestone coarse aggregate and Portland cement filler has been assessed.The mineral and chemical compositions of these three materials have first been analyzed and compared.Then,the effect of different amounts of Portland cement(0%,25%,50%,75%and 100%of the total filler by weight)on the mechanical performance and water stability of the asphalt concrete has been considered.Asphalt concrete has been designed by using the Marshall method,and the mechanical performance indexes of this material,including the Marshall stability and indirect tensile strength(ITS),have been measured together with the related water stability indexes(namely the Marshall stability(RMS)and tensile strength ratio(TSR)).The results indicate that the alkaline limestone coarse aggregate and Portland cement filler can balance the drawback caused by the acid granite fine aggregate.The asphalt concrete has good mechanical performances and water stability when the amount of common limestone powder filler replaced by cement is not less than 75%.

Novel protection systems for the improvement in soil and water stability of expansive soil slopes

To improve the soil and water stability of expansive soil slopes and reduce the probability of slope failure,novel protection systems based on polymer waterproof coatings(PWC)were used in this study.Herein,three groups of expansive soil slope model tests were designed to investigate the effects of polyester nonwovens and PWC(P-PWC)composite protection system,three-dimensional vegetation network and PWC(T-PWC)composite protection system,and nonprotection on the soil and water behavior in the slopes under precipitation–evaporation cycles.The results showed that the moisture change of P-PWC and T-PWC composite protected slopes was significantly smaller than that of bare slope,which reduced the sensitivity of slope moisture to environmental changes and improved its stability.The soil temperature of the slope protected by the P-PWC and T-PWC systems at a depth of 70 cm increased by 5.6℃ and 2.7℃,respectively.Using PWC composite protection systems exhibited better thermal storage performance,which could increase the utilization of shallow geothermal resources.Moreover,the maximum average crack widths of the bare slopes were 7.89 and 3.17 times those of the P-PWC and TPWC protected slopes,respectively,and the maximum average crack depths were 6.87 and 3 times those of the P-PWC and T-PWC protected slopes,separately.The PPWC protection system weakened the influence of hydro–thermal coupling on the slopes,inhibited the development of cracks on the slopes,and reduced the soil erosion.The maximum soil erosion of slopes protected by P-PWC and T-PWC systems was 332 and 164 times lower than that of bare slope,respectively.The P-PWC and T-PWC protection systems achieved excellent"anti-seepage and moisture retention"and anti-erosion effects,thus improving the soil and water stability of slopes.These findings can provide important guiding reference for controlling rainwater infiltration and soil erosion in expansive soil slope projects.

Influence of Seasonal Ground Water Level Fluctuations on the Stability of the Rohingya Refugee Camp Hills of Ukhiya, Teknaf, Cox’s Bazar, Bangladesh—A Threat for Sustainable Development

Bangladesh is a south Asian Monsoonal Country and the recent precipitation pattern in the Cox’s Bazar area of Bangladesh is changing and increasing the number of monsoonal slope failures and landslide hazards in the Kutubpalong & Balukhali Rohingya camp area. An attempt has been made to see the influence of seasonal variation of ground water level (G.W.L.) fluctuations on the stability of the eco hills and forests of Ukhiya Teknaf region. Ukhiya hills are in great danger because of cutting trees from the hill slopes and it is well established that due to recent change of climate, short term rainfall for few consecutive days during monsoon might show an influence on the factor of safety (Fs) values of the camp hill slopes. A clear G.W.L. variation between dry and wet seasons has an influence on the stability (Fs) values indicating that climate has a strong influence on the stability and threatening sustainable development. A stable or marginally stable slope might be unstable during raining and show a variation of ground water level (G.W.L.). The generation of pore water pressure (P.W.P.) is also influenced by seasonal variation of ground water level. During wet season negative P.W.P. called suction plays an important role to occur slope failures in the Ukhiya hills. Based on all calculated factor of safety values (Fs) at different locations, four (4) susceptible landslide risk zones are identified. They are very high risk (Fs = 0.18 to 0.46), high risk (Fs = 0.56 to 0.75), medium risk (Fs = 0.76 to 1.0) and marginally stable areas (Fs ≈ 1). Proper geo-engineering measures must be taken by the concerned authorizes to reduce P.W.P. during monsoon by installing rain water harvesting system, allowing sufficient drainage & other geotechnical measures to reduce the risk of slope failures in the Ukhiya hills. Based on the stability factor (Fs) at different slope locations of the camp hills, a risk map of the investigated area has been produced for the local community for their safety and to build up awareness & to motivate them to evacuate the site during monsoonal slope failures. The established “Risk Maps” can be used for future geological engineering works as well as for sustainable planning, design and construction purposes relating to adaptation and mitigation of landslide risks in the investigated area.

Preliminary Study on the Effect of Different Ecological Cultivation Modes on the Water Stability of Soil Aggregates in Rubber Based Agroforestry Systems

Rubber trees (Hevea brasiliensis Müll. Arg.) have been commercially cultivated for a century and a half in Asia, particularly in China, and they constitute a common element of plantation ecosystems in tropical regions. Soil health is fundamental to the sustainable development of rubber plantations. The objective of the study is to explore the influence of different complex ecological cultivation modes on the stability of soil aggregates in rubber based agroforestry systems. In this study, the ecological cultivation mode of rubber—Alpinia oxyphylla plantation, the ecological cultivation mode of rubber—Phrynium hainanense plantations, the ecological cultivation mode of rubber—Homalium ceylanicum plantations and monoculture rubber plantations were selected, and the particle size distribution of soil aggregates and their water stability characteristics were analyzed. The soil depth of 0 - 20 cm and 20 - 40 cm was collected for four cultivation modes. Soil was divided into 6 particle levels > 20 cm. soil was divided into 6 particle levels > 5 mm, 2 - 5 mm, 1 - 2 mm, 0.5 - 1 mm, 0.25 - 0.5 mm, and 0.053 - 0.25 mm according to the wet sieve method. The particle size proportion and water stability of soil aggregates were determined by the wet sieve method. The particle size proportion and water stability of soil aggregates under different ecological cultivation modes were analyzed. The results showed that under different ecological cultivation modes in the shallow soil layer (0 - 20 cm), the rubber—Alpinia oxyphylla plantation and the rubber—Phrynium hainanense plantation promoted the development of dominant soil aggregates towards larger size classes, whereas the situation is the opposite for rubber—Homalium ceylanicum plantation. In soil layer (20 - 40 cm), the ecological cultivation mode of rubber—Phrynium hainanense plantation developed the dominant radial level of soil aggregates to the diameter level of large aggregates. Rubber—Alpinia oxyphylla plantation and rubber—Homalium ceylanicum plantation, three indicators, including the water-stable aggregate content R0.25 (>0.25 mm water-stable aggregates), mean weight diameter (MWD), and geometric mean diameter (GMD), were all lower than those in the rubber monoculture mode. However, in the rubber—Phrynium hainanense plantation, the water-stable aggregate content R0.25, mean weight diameter, and geometric mean diameter were higher than in the rubber monoculture mode, although these differences did not reach statistical significance.

Stability analysis of different cotton genotypes under normal and water-deficit conditions

Cotton plant observes significant reduction in seed cotton yield when subjected to water stress.To find out genotypes having better drought tolerance,seven genotypes of Gossypium hirsutum L.were tested under two moisture levels,i.e.,normal and water deficit stress conditions at five locations of Punjab,Pakistan(Faisalabad,Sahiwal,Vehari,Rahim Yar Khan,and Bahawalpur)in 2013 and 2014.Genotype×environment interaction(GEI)was studied using the genotype main effects and genotype by environment interaction(GGE)biplot and additive main effect and multiplicative interaction analysis.The genotypes G3(7001/11)and G6(FH-942)were stable under normal condition,while under drought condition,the stable genotype was G5(FH-326)when analysed using additive main effects and multiplicative interaction(AMMI)biplot scheme.While GGE biplot analysis on the basis of best performance revealed that under normal condition the genotypes,G1(L-13/10)and G2(FH-2056/10),carrying the common position in biplot.Whereas,under water deficit stress condition,G5 was the best adaptive genotype at all five locations.In the same way,ranking of genotypes showed that the G5 was the ideal genotype under both conditions.So,it is concluded that the genotype G5(FH-326)was found best for water deficit stress condition and can be cultivated under water scarce areas of Punjab.

RESEARCH ON THE WATER-RESISTANCE OF MAGNESIUM OXYCHLORIDE CEMENT——I:THE STABILITY OF THE REACTION PRODUCTS OF MAGNESIUM OXYCHLORIDE CEMENT IN WATER

In this paper .the change of the crystalline phases in hardened magnesium oxychloride cement (MOC) paste in mater was analyzed by XRD. It was developed that the reaction products 5 phase or 3 phase of MOC are instable in water and can be changed into Mg(OH)2 by the action of water, which causes the content of 5 phase or 3 phase to be less and less,the content of Mg(OH)2 to be more and more and the strength to be the lower the lower,after hardended MOC paste was immersed in water. The change of 5 pliase and 3 phase into Mg(OH)2 is not a dissolve process, but a hydrolysis process. The hydrolysis products of 5 phase and 3 phase are Mg(OH)2 precipitation and soluble Cl-,AIg+ ions and H2O. The hydrolysis is sponta-neous thermodynamically and its chemical kinatic equation is C = C,,e-k Thus .it is suggested that only by enhancing the stability of 5 phase or 3 phase in water and preventing 5 phase or 3 phase from the hydrolyzing can the water resistance of MOC be improved well.

Iron stability in drinking water distribution systems in a city of China

A field study on the estimation and analysis of iron stability in drinking water distribution system was carried out in a city of China. The stability of iron ion was estimated by pC-pH figure. It was found that iron ion was unstable, with a high Fe （OH）3 precipitation tendency and obvious increase in turbidity. The outer layer of the corrosion scale was compact, while the inner core was porous. The main composition of the scale was iron, and the possible compound constitutes of the outer scale were α-FeOH, γ-FeOOH, α-Fe2O3, γ-F2O3, FeCl3, while the inner were Fe3O4, FeCl2, FeCO3. According to the characteristics of the corrosion scale, it was thought that the main reason for iron instability was iron release from corrosion scale. Many factors such as pipe materials, dissolved oxygen and chlorine residual affect iron release. Generally, higher iron release occurred with lower dissolved oxygen or chlorine residual concentration, while lower iron release occurred with higher dissolved oxygen or chlorine residual concentration. The reason was considered that the passivated out layer of scale of ferric oxide was broken down by reductive reaction in a condition of low oxidants concentration, which would result more rapid corrosion of the nine and red water phenomenon.

Dynamic Study on Water Stability of Soil Structure and Soil Characteristics of Several Types of Soils in Southwest China

Three suborder soils in southwest China were adopted, namely Ustic Vertisol, Stagnic Anthrosol and Ustic Ferrosol, so as to carry out the basic physical and chemical analysis respectively, to design a dynamic measuring method for water stability of soil structure and conduct the comparative study on the quality of the soil structure. The results indicated that （1） The water stability dynamic characteristic of the soil structure could well reflect the maintaining capability of the soil structure as time goes on. （2） The quality of several soil structures in southwest China was sequenced as follows： Stagnic Anthrosols 〉 Ustic Vertisols 〉 Ustic Ferrosols. （3） The water stability of soil structure is very positively correlated with the capillary porosity and the clay particle （D 〈 0.002 mm） content （Co）, but is very negatively correlated with the silt （D is 0.05-0.002 ram） content （Csc）, and （4） The dynamic functional equation of the water stability of soil structure in southwest China was established, so that the water stability characteristics of various soil structures could be quantitatively expressed and the quality of different soil structures can be quantitatively compared from each other.

Analysis on Biological Stability and Influencing Factors of Northern Living District Water Distribution System

A northern living strict water network was employed to investigate interaction among biological stability and classical water quality indexes. Key water quality indexes on water quality were determined by the static test,then the correlations between biological stability and traditional water quality parameters were analyzed. Traditional water quality parameters and limited factors on bacteria were measured in summer and winter respectively. The results show that BDOC concentration change differently in summer and winter.Among classical parameters turbidity has a positive relation with BDOC but pH has a negative relation with BDOC. Total bacteria number shows a positive correlation with BDOC in the water distribution system.Residual chlorine shows a negative relation with total bacteria number. Fe content increasing will induce turbidity rising in water. To guarantee water safety,BDOC and chlorine content control must be incorporated together to restrict bacteria regrowth.

Effects of pH on rheological characteristics and stability of petroleum coke water slurry

In this study, the effects of pH on slurrying properties of petroleum coke water slurry（PCWS） were investigated. The slurrying concentration, rheological characteristics and stability of PCWS were studied with four different types of additives at pH varying from 5 to 11.The results showed that the slurrying concentration, rheological characteristics and stability of PCWS all increased at first and then decreased with increasing pH from 5 to 11,and a pH of around 9 was found to be the most favorable acid–alkali environment to all these three slurrying properties. It was also indicated that only in a moderate alkaline environment can the additives be active enough to react with particle surfaces sufficiently to obtain good slurrying concentration and form a stable three-dimensional network structure, which can support strong pseudoplastic characteristics and good stability. An acid environment was a very unfavorable factor to the slurrying properties of PCWS.

Handily etching nickel foams into catalyst-substrate fusion self‐stabilized electrodes toward industrial‐level water electrolysis

The key challenge of industrial water electrolysis is to design catalytic electrodes that can stabilize high current density with low power consumption(i.e.,overpotential),while industrial harsh conditions make the balance between electrode activity and stability more difficult.Here,we develop an efficient and durable electrode for water oxidation reaction(WOR),which yields a high current density of 1000 mA cm−2 at an overpotential of only 284 mV in 1M KOH at 25°C and shows robust stability even in 6M KOH strong alkali with an elevated temperature up to 80°C.This electrode is fabricated from a cheap nickel foam(NF)substrate through a simple one-step solution etching method,resulting in the growth of ultrafine phosphorus doped nickel-iron(oxy)hydroxide[P-(Ni,Fe)O_(x)H_(y)]nanoparticles embedded into abundant micropores on the surface,featured as a self-stabilized catalyst–substrate fusion electrode.Such self-stabilizing effect fastens highly active P-(Ni,Fe)O_(x)H_(y)species on conductive NF substrates with significant contribution to catalyst fixation and charge transfer,realizing a win–win tactics for WOR activity and durability at high current densities in harsh environments.This work affords a cost-effective WOR electrode that can well work at large current densities,suggestive of the rational design of catalyst electrodes toward industrial-scale water electrolysis.

Inherent relations between yield stress and stability of bubble petroleum coke water slurry

The stability of petroleum coke water slurry（PCWS） is currently a hot topic. The inherent relationship between yield stress and stability of bubble-PCWS was studied through orthogonal experiments and range analysis in this work. The results showed that the stability of bubble-PCWS was positively related to the yield stress and that the yield stress could be greatly impacted by the operation conditions during preparation of bubble-PCWS. The main factors affecting the yield stress of bubble-PCWS were solid concentration, aeration time and dosage of frother. However, the effects of aperture size of air distribution plates and type of frother on the yield stress were slight within the experimental range. The optimal conditions for the greatest yield stress were as follows： aeration time of 30 min, solid concentration of 65 wt%, frother dosage of0.030 wt% of the air-dried pulverized petroleum coke, aperture size of air distribution plate of 2-5 lm and AOS frother.The yield stress and the pour rate of bubble-PCWS under this optimum operation condition could reach maxima of more than 0.4 Pa and 96%, respectively.

Hydrothermal Synthesis,Crystal Structure and Thermal Stability of a Novel Water Cluster [Mn(phen)_2·H_2O·Cl]·p-FBA·3H_2O

A novel water cluster [Mn（phen）2·H2O·Cl]·p-FBA·3H2O （p-FBA = p-fluorobenzoic acid and phen = 1,10-phenanthroline） was synthesized by the hydrothermal reaction of MnCl2 with p-FBA and phen at 150 ℃ and characterized by elemental analysis,IR spectra and TG. Its crystal structure was determined by X-ray single-crystal diffraction study. The crystal belongs to the triclinic system,space group P1,with a = 10.5768（1）,b = 11.5960（1）,c = 12.9916（2） ,α = 101.816（2）,β = 95.397（2）,γ = 103.052（2）o,V = 1502.8（3） 3,Z = 2,Dc = 1.463 g/cm3,R = 0.0399 and wR = 0.0997. The crystal structure shows that the manganese（Ⅱ ） ion is six-coordinated by four nitrogen atoms,one chloride ion and one oxygen atom forming a distorted octahedral coordination geometry. The structure includes three acyclically connected water molecules and one coordinated water molecule thus forming a （H2O）4 water cluster. This water pattern forms a cross-linked discrete ring. The steady （H2O）4 is further extended into a cage-like structure by the hydrogen-bonding interaction formed by dissociative aqua molecule and Cl-ligand. The dimer structure is further extended into a one-dimensional （1D） structure through C-H···O interaction. π···π Stacking interaction among adjacent phen aromatic rings further stabilizes the crystal structure.

Formation and Water Stability of Aggregates in Red Soils as Affected by Organic Matter

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Facile synthesis of composite polyferric magnesium-silicate-sulfate coagulant with enhanced performance in water and wastewater

The coagulation process is a widely applied technology in water and wastewater treatment.Novel composite polyferric mag-nesium-silicate-sulfate(PFMS)coagulants were synthesized using Na_(2)SiO_(3)·9H_(2)O,Fe_(2)(SO_(4))_(3),and MgSO_(4) as raw materials in this paper.The effects of aging time,Fe:Si:Mg,and OH:M molar ratios(M represents the metal ions)on the coagulation performance of the as-pre-pared PFMS were systematically investigated to obtain optimum coagulants.The results showed that PFMS coagulant exhibited good co-agulation properties in the treatment of simulated humic acid-kaolin surface water and reactive dye wastewater.When the molar ratio was controlled at Fe:Si:Mg=2:2:1 and OH:M=0.32,the obtained PFMS presented excellent stability and a high coagulation efficiency.The removal efficiency of ultraviolet UV254 was 99.81%,and the residual turbidity of the surface water reached 0.56 NTU at a dosage of 30 mg·L^(-1).After standing the coagulant for 120 d in the laboratory,the removal efficiency of UV254 and residual turbidity of the surface wa-ter were 88.12%and 0.68 NTU,respectively,which accord with the surface water treatment requirements.In addition,the coagulation performance in the treatment of reactive dye wastewater was greatly improved by combining the advantages of magnesium and iron salts.Compared with polyferric silicate-sulfate(PFS)and polymagnesium silicate-sulfate(PMS),the PFMS coagulant played a better decolor-ization role within the pH range of 7-13.

A Calculation Method of Double Strength Reduction for Layered Slope Based on the Reduction of Water Content Intensity

The calculation of the factor of safety(FOS)is an important means of slope evaluation.This paper proposed an improved double strength reductionmethod(DRM)to analyze the safety of layered slopes.The physical properties of different soil layers of the slopes are different,so the single coefficient strength reduction method(SRM)is not enough to reflect the actual critical state of the slopes.Considering that the water content of the soil in the natural state is the main factor for the strength of the soil,the attenuation law of shear strength of clayey soil changing with water content is fitted.This paper also establishes the functional relationship between different reduction coefficients.Then,a USDFLD subroutine is programmed using the secondary development function of finite element software.Controlling the relationship between field variables and calculation time realizes double strength reduction applicable to the layered slope.Finally,by comparing the calculation results of different examples,it is proved that the stress and displacement distribution of the critical slope state obtained by the improved method is more realistic,and the calculated safety factor is more reliable.The newly proposedmethod considers the difference of intensity attenuation between different soil layers under natural conditions and avoids the disadvantage of the strength reduction method with uniform parameters,which provides a new idea and method for stability analysis of layered and complex slopes.

Effect Mechanism of Structure-Changed Water on Heat Stability of Lysozyme

Based on the mechanism of the effect of hydration on the heat stability of lysozyme and the theory of water molecule clusters, the effect of structure-changed water on heat stability of lysozyme has been studied. The results obtained by differential scanning calorimetry (DSC) showed that the thermal denaturation temperature of lysozyme had been elevated 8.47 K through hydration of lysozyme with processed water whose structure had been changed so it was called "structured water" compared to ordinary water. The reason is that structured water changed the dipole moment of water molecules and easily formed cyclic water hexamer or cage-like water hexamer, so that the interacting force of maintaining three-dimensional conformation of lysozyme could be reinforced.

Evaluating Water Stability Indices from Water Treatment Plants in Baghdad City

Corrosion control is an important aspect of safe drinking water supplies. The effects of corrosion which may not be evident without monitoring are an important issue concerning both public health and economical aspects. Chemical stability parameters of water quality in water treatment plants in Baghdad city can improve drinking water quality. The treated water quality from water treatment plants in Baghdad city was investigated along the water flow path in this study. The water quality parameters related to chemical stability included temperature, alkalinity as mg/L CaCO3, calcium mg/L as Ca, pH and total dissolved solids (TDS) mg/L for different samples from WTPs within Baghdad city were investigated. The two water quality indices, Langelier saturation index (LSI) and the Ryznar stability index (RSI), were calculated in order to evaluate the chemical stability of the drinking water samples. The results of LSI and RSI of the effluents from Baghdad’s WTPs during 2000-2013 classified that corrosive water is produced and this indicates that the water is not safe for domestic use and will need the further treatment. The present study demonstrated the application of water stability indices in estimating/understanding the treated water chemical stability and appeared to be promising in the field of treated water quality management.

Stability control of water-enriched roofs of coal drifts

Excavation-and-support induced disturbances are likely to make water-enriched roofs to become weathered and fractured.The development and connection of cracks provide new water channels which may result in water loss,seriously affecting the in-tegrity and stability of roofs,leading to incidents of roof fall.Control of water-enriched rocks surrounding coal drifts is quite diffi-cult in China.Based on the practical situation of a water-enriched roof of a coal drift in working face 112201 of the Meihuajing coal mine,we studied the deformation features of surrounding rocks and the development of fractured areas and analyzed the major reasons for the decrease in load-carrying capacity,indicating that the key to maintain roof stability of this kind of coal drift is water retention.In addition,we proposed a staged control technology consisting of:1) surface grouting;2) cable anchor strengthening and 3) roof grouting,which has proven to be successful in this practical application.Our study indicates that,after the problem of water loss from the water-enriched roof had been effectively solved,a combined support system with high performance bolts can maintain the stability of the bearing structure,resulting in the control of roof stability in this kind of coal drift.

Slope stability of an unsaturated embankment with and without natural pore water salinity subjected to rainfall infiltration

Natural soils contain a certain amount of salt in the form of dissolved ions or electrically charged atoms,originated from the long-term erosion by acidic rainwater.The dissolved salt poses an extra osmotic water potential being normally neglected in laboratory measurements and numerical analyses.However,ignorance of salinity may result in overestimation of stability,and the design may not be as conservative as thought.Therefore,this research aims to first experimentally examine the influence of pore water salinity on water retention curve and saturated permeability of natural dispersive loess under saline and desalinated conditions.Second,the measured parameters are used for stability analyses of a railway embankment in an area subjected to regional rainfall incident.Eventually,a numerical parametric study is carried out to explore the significance of different rainfall schemes,construction patterns,and anisotropic permeability on the factor of safety.Results reveal that desalinization suppresses the water retention capability,which in turn results in a tremendous declination of unsaturated hydraulic conductivity.Despite the natural saline embankment,rainfall can hardly infiltrate into the desalinated embankment due to the lower conductivity.Therefore,the factor of safety for natural saline conditions drops notably,while only marginal changes occur in the case of the desalinated embankment.