Rubber bark dust-zeolite composite improved mechanic strength of soft paddy soil through improved microstructure

<p>Soft paddy soils are not a stable soil structure that leads to the decline of rice production in Kedah, Malaysia. The soil had high compressibility and water content, and low soil strength thus the agricultural machines could not be operated above this soil. Therefore, this study was conducted to improve the mechanical strength of soft soils in paddy fields using an organic amendment. The organic amendment used in this study was made from amended materials comprising clinoptilolite, kieserite, humic acid, and rubber bark dust. The study was carried out in the paddy field area of Alor Pudak district, Kedah, Malaysia, and it was divided into five treatments of amendment dose, i.e: 0 kg (control or P0), 125 kg (P1), 250 kg (P2), 375 kg (P3) and 500 kg (P4) with each plot size about 0.20 ha. The soil samples were then analyzed using X-ray diffraction (XRD), scanning electron microscope (SEM), and the unconsolidated undrained triaxial compression test (UU-test) to characterize their amended properties. The XRD results clearly exhibited changes in the mineralogical composition of all treated plots with an increasing smectite content (1200 to 1300 intensity). Furthermore, the SEM results showed that clay particles in the treated plots have been flocculated to form close-knit, more stable soil structures. After the organic amendment application, the mechanical strength of the treated plots increased to an optimum level (50 kPa in P2) for resisting mechanical pressure from agricultural machinery. Overall, this study of the efficacy of organic amendment offers new insight into a soft paddy soil remediation method that is more effective and economical than the conventional method.</p>

Improving the Mechanical Properties of Red Clay Using Xanthan Gum Biopolymer

The traditional treatment of red clay using inorganic materials leads to many serious environmental problems. The study investigates the mechanical properties of red clay using an environmental-friendly material—xanthan gum—through confined compression, direct shear, and scanning electron microscope tests. At the macroscale, xanthan gum content and curing age had obvious effects on the compressibility, presenting the treated red clay was in the category of low compressibility which gradually increased when xanthan gum content exceeded 1.5%. The xanthan gum content and curing age also had significant influences on the cohesion but not on the internal friction angle. The shear strength of red clay can be improved by increasing the cohesion without obviously changing the friction characteristics. After curing for 28 days, the cohesion and internal friction angle of 2.0% xanthan gum-treated soil were effectively improved to 170.44 kPa and 20.56°, which were increased by 69.79% and 9.36°, respectively, compared with untreated red clay. Microscopic analysis indicated that the strengthening mechanism by xanthan gum was derived from changing the arrangement characteristics of soil particles and forming hard biopolymer-red clay matrices. The proper xanthan gum can effectively wrap clay particles and fill pore spaces. However, the extensive stacking of gels would also reduce the effective connection of clay particles and produce local weak points in the soil, resulting in attenuation of mechanical properties. This study enriches the treatment measure of red clay and provides beneficial experiences for biopolymer application on special clay.

Oxidation of pyrite (FeS2) and troilite (FeS) impurities in kaolinitic clays after calcination

Valorisation of locally available clays for producing blended cements is crucial for a widespread adoption of sustainable binders incorporating these materials. In some places, clays can be intermixed with small amounts of iron sulfides, which could eventually expand in the alkaline media of concrete and lead to cracking if clay particles are sufficiently fine. This study explored the stability of iron sulfides, namely troilite and pyrite, during calcination of clays and their influence in reactivity. It was found that both troilite and pyrite decompose and oxidize into hematite under typical calcination conditions for clays. Furthermore, there is no negative influence of the presence of iron sulfide phases on the reactivity of calcined clays. This shows that these clays are suitable for use in blended cements, provided that adequate quality control is conducted to ensure a complete decomposition of the iron sulfide phases.

Evaluation of Compression Behaviors of Marine Clay Reinforced with Waste Shredded Tires

This study evaluates the compression behaviors of a soft marine clay reinforced with waste shredded tire (WST) at different sizes (<0.5 mm, 0.5–2.0 mm, and 2.0–4.0 mm) and contents (15%, 35%, and 50%). Results from compression tests indicate that the compression index (Cc) of WST-reinforced soft clay decreases with increasing WST shred size and content. The swelling index (Cs) increases as the WST shred size and content increase. The difference in compression curves becomes more significant for composite reinforced at large shred size. The void indexes of WST-reinforced Lianyungang clay can be well normalized regardless of WST shred size and content by a regression line. The WST dominates the compression behavior of the WST-clay composite, as the WST would be compressed prior to the clay particles. The results in this study provide an optimum WST content at 50% with shred size of 2.0–4.0 mm for reinforcing the Lianyungang marine clay for achieving higher compressibility, contributing to the input database of machine learning for WST-reinforced soil.

New Developments in the Formation of Nanocomposites between Starch and Clay

Biodegradable polymers, like Polycaprolactone (PCL), have recently received a lot of attention in the science establishment because of the growing global interest in non - petroleum-based polymeric materials. 3-amino - 4 - ((3-hydroxyphenyl) diazenyl) - N(pyrimidine-2-yl) benzenesulfonamide (AZO) one of the organic materials used to reconfigure natural clay (sodium montmorillonite). The clay particles were modified by stirring them in an aqueous medium of AZO-MMT, which increased the wavelength from 1.27 to 2.04 nm. The reconfigured clay would have been used to make PCL/corn-starch mixture nanocomposites. They were created by combining 0.5–5% AZO-MMT. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) were utilized to characterize the interaction of the modifier in the clay layer. The nanocomposites were prepared by solution casting method the reconfigured clay and a PCL/corn-starch mixture at a weight ratio of 80/20, which leads to an increase in the scope of tensile strength which that considers the biggest blend. The results of survey electron microscopy, transmission electron microscopy, and XRD was proved the creation of nanocomposites materials. Additionally, that PBS/corn-starch reconfigured clay nanocomposites exhibit that superior thermal stability significantly and a great increase over the PCL/corn-starch mixture.

The Study of Optimization of Flocculation and Destabilization Technology of Waste PEM Drilling Fluid in Bohai Oilfield

In light of the difficulty of solid-liquid separation of waste PEM drilling fluid in the Bohai oilfield, constructing an inorganic-organic flocculation system is proposed and the processing method of destabilization technology is optimized. The biggest influence factor on the flocculation process of PEM drilling fluid was determined by designing an orthogonal test. The flocculation mechanism was researched through single factor optimization, combined with zeta potential and particle size distribution test. The results showed that the most significant factors affecting the flocculation of waste PEM drilling fluid were the dosage of inorganic flocculant CaCl2 and flocculation pH value. When the dosage of inorganic flocculant CaCl2 was 1.2% (w/v), the dosage of organic flocculant SDYJ-2 was 0.05%, the flocculation pH value was 3, and the flocculation time was 5 min, the flocculation technology reached the optimization and then the liquid yield can reach 70.96%. The mechanism of flocculation and destabilization was as follows: the inorganic flocculant of CaCl2 mainly reduced the zeta potential of clay particles through electric neutralization. 1% CaCl2 could reduce the potential mean value of drilling fluid system from -38.1 mV to -32.5 mV, and then decrease the repulsion among suspensions. Through bridging curling and electric neutralization, the organic flocculant of SDYJ-2 can absorb and wrap the clay particles after flocculation destabilization to form a network spatial structure, which made clay particles aggregate into large flocs and particles. D50 can increase by 21.5 times, when the concentration of SDYJ-2 was 0.15%.

Construction and Application of Flocculation and Destability System of Biodrill-A Drilling Fluid in Bohai Oilfield

To protect the marine ecological environment of Bohai Bay, the waste drilling fluid in Bohai oilfield have to be treated. In the light of the composition characteristics of Biodrill-A drilling fluid, the compounding method of the inorganic–organic flocculants was adopted to assist the flocculation and solid–fluid separation of Biodrill-A drilling fluid. Through the orthogonal test design, the main factors impacting the flocculation effect on Biodrill-A drilling fluid were found to the concentration of inorganic flocculant CaCl2 and the flocculation pH value. The optimal flocculation treatment was further obtained through single-factor optimization. Specifically, when the inorganic flocculant CaCl2 concentration was 0.9 w/v%, the organic flocculant concentration was 0.01 w/v%, the flocculation pH was 8, and the flocculation time was 7 min. Eventually, the final dewatering rate could reach 84.02%. In the optimized compound flocculants, the inorganic flocculant CaCl2 reduced the zeta potential of clay particles by electric neutralization to decrease the repulsion among particles, and the organic one could absorb and wrap the clay particles through bridging curling and electric neutralization after flocculation destabilization. Both inorganic and organic flocculants facilitated the large flocs and particles of clay particles. The field test showed that the inorganic–organic flocculants were suitable for the on-line flocculation treatment process based on centrifugal machine. The waste drilling fluid was reduced by 82%, and the water content of the separated solid phase was as low as 25.7%.

MECHANICAL PROPERTIES AND WEAR BEHAVIOUR OF KAOLINITE CLAY PARTICLES REINFORCED EPOXY MATRIX COMPOSITES

Epoxy matrix composites reinforced with clay particles were developed by hand lay-up open mould casting technique. The clay used in this study was pulverized and processed into ultrafine particles through the sedimentation process. The composites were developed by blending the epoxy matrix and hardener with various weight fractions of the ultrafine clay particles (2, 4, 6, 8 and 10 wt%) in open test moulds. In order to accomplish a homogeneous blend of the constituents; manual mixing of the blend was carried out for 3 min. The test specimens were left to cure for 24 hours in the moulds and for additional 27 days at room temperature of 27 ± 2 °C and were thereafter detached from the moulds. The developed composites test specimens were subjected to mechanical tests (flexural, tensile and impact) in accordance with ASTM standards and performed at room temperature. Structural characteristics of the clay particles were determined with the aid of an X-ray diffractometer (XRD). The morphologies of the composites were determined using a scanning electron microscope (SEM). There was a progressive enhancement in the mechanical properties of epoxy composites containing 2-6 wt.% ultrafine clay particles while a drastic decrease in the mechanical properties was noticed in the epoxy/clay composites reinforced with 8-10 wt.% ultrafine clay particles. The SEM images revealed homogeneous particles distributions within the epoxy matrix at lower ultrafine clay particles weight fractions (2 wt. % and 6 wt.%).

The Mechanical Properties and Microstructure of Reticulated Red Clay-Sand Mixture Using X-Ray Diffraction

To assess the behavior of Reticulated Red Clay (RRC)-sand mixtures, a series of laboratory tests were performed on RRC-sand mixtures in which the weight ratio of sand ranging from 0% to 80%. Compaction test and direct shear test were conducted to evaluate the compactness of mixtures. The threshold sand content for the change of the mechanical properties of the mixture is 50%, and the mixture at this time has the densest structure. Oedometer test to the mixture indicate that the coefficient and compression modulus of it are only related to the ratio of its components. As the sand content in the mixture increases, the phenomena that the clay particles enclosing the sand particles and filling into the gaps of particles make the mixture denser. During the same time, there is a phenomenon of internal friction between sand particles caused by the inadequate wrapping of clay particles. Combined with the results of scanning electron microscopy and optical microscopy, the appearance of these phenomena and the transition process of the structure of the mixture from the clay structure to the sand structure were confirmed.