Accidents and life loss caused serious concern on the liquefaction problem of some solid bulk cargoes such as iron ore fines during transportation at sea. To understand the liquefaction property of a type of iron ore fines, a series of tests, e.g. SEM observation, monotonic loading triaxial test, cyclic loading triaxial test etc. were conducted. Test results show that this unusual material possesses some special properties, for instance, much higher specific gravity Gs (average Gs=4.444) as compared to common materials in geotechnical engineering. SEM observation unveils that the tested iron ore fines has a multi-layer, micro-porous structure which may affect its water retention ability under unsaturated states. The result from the undrained monotonic loading test indicates an angle of internal friction of 45.6o according to the Mohr-Coulomb failure criterion. Interestingly, the peak strength and the residual strength were achieved at values of axial strain of approximately 2.5% and 13%, respectively, regardless of confining pressure among three undrained monotonic loading tests. The undrained response of tested iron ore fines to cyclic loading shows similar characteristics as those of common sands and the liquefaction resistance of this material defined based on the relationship between CSR and number of cycle is not significantly affected by change of confining pressure.

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Coral gravel soils, which are composite soils consisting of finger-coral fragments and silt matrix, are often found in coastal regions of sub-tropical islands. In this study, for reconstituted soils with various coral gravel fractions up to 44% that was the densest package, a series of triaxial CU-bar and CD tests was conducted to study determination method for soil design parameters in consideration of interaction between soil skeleton consisted of coral fragments and silt matrix. The soil parameters were significantly influenced by volumetric percentage of coral fragments in association with particle interaction and particle crush, when the percentage was larger than 20% for the coral gravel soils examined in this study.

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Physical properties of contaminated soils are different from uncontaminated ones, it is necessary to detect whether site was contaminated before construction. How to quickly, precisely judge whether the soil was contaminated is a problem need to research, soil electrical resistivity can be used as an index to determine whether the soil was contaminated. Diesel oil contaminated soil as a common contaminated soil gained more and more attention. This paper choose the classical Yangtze River back swamp soil as study material, 0# diesel oil (in Chinese national standard) as contamination, mixed soil samples with water content at 7%, 10%, 13%, 16%, 20% and 25%, every water content inject diesel oil content of 4%, 8%, 12% (water and oil content all calculated in weight). The prepared contaminated soils were placed in standard curing room for 14 days, 28 days, 56 days. At every curing time, each soil particle size distribution, pH were measured according to different standards. Atterberg limits, electrical resistivity of the contaminated soils was measured at 14 days curing time. Resistivity was measured by the devices designed according to Miller Soil Box, using alternating current (AC) as input power. Soil resistivity was measured at different water content, density and degree of saturation. Results show that diesel contamination can decrease soil particle size and soil pH, also can decrease soil liquid limit and liquid limit, increase soil resistivity. Resistivity of contaminated soil decrease in power function with the increase of water content, density and degree of saturation. These results would be a help in the future work when choose soil index to judge whether the soil was contaminated.

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More and more attention has been paid to the effects of heavy metal pollution of soil in China, but the studies of physical and electrical properties of the heavy metal contaminated soil is still at the preliminary stage. The related physical properties will change when the soil was contaminated by heavy metal. The electrical property is one of the inherent physical properties of soil; hence the electrical property will change after soil pollution. The muddy silt clay of floodplain in Changjiang River, which is unique in China, was used to study the physical and electrical properties of heavy metal-Zn contaminated soil. In this article, the heavy metal contaminated soil was prepared by adding the solution of zinc nitrate hexahydrate. X-ray diffraction experiment (XRD) and Scanning Electron Microscope test (SEM) were adopted to analyze the mineral and chemical composition of natural silt clay. Besides, particle size analysis, liquid-plastic limit test, pH test and resistivity test were taken to analyze the variation rules of relevant physical and electrical properties in heavy metal-Zn contaminated soil, in which, the age of fines content test, liquid plastic limit test, mobility test and pH test was considered to make sure the long-term effects of heavy metal zinc pollution. For electrical properties, the resistivity was used to analyze the soil after contamination. The resistivity that was changed with different pollution concentration, water content was compared. The corresponding relationship of resistivity was established and the evaluation of pollution degree and the polluted area using resistivity was qualitative analyzed in the heavy metal-Zn contaminated silt clay.

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At the present stage of binding materials science development the possibility of low-clinker and non-clinker binding materials effective using with non-fired clay minerals is theoretically and practically proved. However existing views for clay raw materials role in such systems are mainly based on its role as a plasticizer of hardening systems which doesn’t participate in basic phase-formation processes. Based on modern positions of nanochemistry, accumulated knowledge and own research results we present data on physical-chemical research of "clay-SiO2-CaO-H2O" system. The possibility to eliminate a specific property of clay inversion due to the directed combination of raw mix hardening conditions for phase-formation irreversible reaction provision is shown taking into account clay mineral aluminosilicate core participation forming a strong stone. It is shown that when South Kazakhstan clay materials using the low-temperature calcium hydro- and alumosilicates formation is possible in "clay-SiO2-CaO-H2O" system. Hereat sample compression strength can reach 5 MPa in already 15 days of natural hardening. The model system was studied at mixing of clay, sand, slaked lime and an alkaline additive of sodium carbonate. Components mixing and grinding was carried out in a ball mill. Reached high dispersion of products and also the factor of mechanic-chemical activation ensured the beginning of phase-formation processes with participation of aluminosilicate core of a clay component. It is revealed that water function in such systems can be changed in time. One can assume that the rate of new phase appearance co-ordinates closely with water condition at disperse system transition into stone-like condition. It is realized only when sufficient degree of macroparticles closing is provided. In this case the interlayer water role can be double, i.e. positive or negative one, and this phenomenon predetermines possibilities of management with structural-rheological properties of similar systems in the area of high specific surfaces and concentrations. It was especially demonstrated at clay-composite formation under high pressure. Clay-composites of 60 MPa strength and with water resistance factor more than 0.9 are obtained at optimal water content and component dispersion ability. Samples with smaller surface activity (smaller fineness degree) with identical water content of a shaped mix displayed rheological properties at smaller pressing pressures. In this case loosely-coupled "film" water plays a role of a damping agent in the pressing moment in systems with contact- condensation hardening mechanism. It is like «capsulated» in intergrain space of formed structures and is in loosely-coupled condition. Such structures aren’t water-resistant ones and their strength is lowered. Using various production methods one can provide conditions for this loosely-coupled water consumption exclusively for processes of hydroxylation and new near-border aluminosilicate phase formation. In this case strong stone-like water-resistant structures are formed. Such simple techniques as the component ratio, mechanic-chemical activation of mineral particles allow to operate with thin chemical processes of clay-composite product production by the non-clinker and non-fired scheme.

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Stone columns are widely used globally due to their versatility and relative wide applicability to treat different soil and foundation situations but much of the research undertaken to date has focused on their use in soft soils. In countries like Iraq the use of stone columns is still limited from a practical point of view, chiefly as many other soil conditions are commonly encountered. These include collapsible soils: soils that are prone to relatively rapid volume compressions (through collapse of metastable fabrics) that occur due to the action of load and/or increases in water content. Recent work has opened up the possibility to use stone columns in these soils by the use of encasement, thereby overcoming the impact of loss of lateral support when collapse occurs. Area of potential will be discussed; why stone columns could be beneficial for use in Iraq and how employing them as an alternative to conventional ground improvement techniques in number of Iraqi projects would be cost saving and has other benefits. Also, a review of soil conditions in Iraq will be presented and focusing how to treat collapsible soil by encasing the individual stone column by geofabrics illustrating the scope for developing a reliable design approach which suits Iraqi soils. An evidence of their potential applicability in Iraqi soils will be presented. Moreover, the installation technique, facts regarding failure, factors control the behaviour of encased stone columns, calculation of bearing capacity and settlement and some previous related laboratory work will be reviewed as well as recommendations regarding the proposal work in this field are produced with this paper.

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Pavements and embankments fail for different reasons; poor design, poor materials and poor construction methods are the most common. The pavement foundation (subgrade) represents one of the key elements in pavement design and its behavior shall influence the overall pavement performance. It was found necessary improving gypseous subgrade stiffness characteristics in order to prolong pavement design life. We also believe that too much emphasis in finding out untraditional methods in treating weak gypseous soils and then using them in subgrade layers taking into consideration type and values of loading effects in the employed design models. This has lead to erroneous predictions. In general, the more resistant to deformation the subgrade is the more loads it can support before reaching a critical deformation value. Gypseous soils cover about (35%) of the total area of Iraq and therefore the study of the properties of these soils to be used as subgrade embankments becomes very important due to the problems caused by these soils during leaching which lead to what is called collapsibility. Many trials were conducted in order to study the possibility of improving the properties of gypseous soils using chemical and natural materials. Results showed that some natural and chemical materials could improve the behavior of gypseous soils, but these results are based on routine laboratory tests. In this study, two types of local gypseous soils are selected to be improved by three chemical stabilizing materials, namely, 5% hydrated lime, and 2.5% hydrated calcium chloride and 6% kaolin. The soils employed are classified as (SP-SM) and (SP) with gypsum content of (48.3%) and (35%) for Baiji and Al-Thurthar area soils, respectively. An engineering model is adopted to carry out tests on these soils and to analyze their behavior before and after improvement especially their collapsibility property. The results show that all employed chemical and natural additives can be used to reduce the collapsibility property of gypseous soils, but with different degrees. Using lime reduces the collapsibility of gypseous soils to a small degree compared with calcium chloride and kaolin.

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