Clay Stabilization Research Articles

INVESTIGATION OF CLAY STABILIZER POTENTIAL FOR HIGH CLAY CONTENT FORMATION

Clay swelling has been studied for decades due to its damaging problem in the reservoir. It has caused permeability impairment due to blockage at the pore throat and reduction of the available pore spaces in the reservoir. The past few decades have seen rapid development of clay stabilizers to treat clay minerals near-wellbore region areas. However, there a limited study investigating the potential of clay stabilizers to prevent clay swelling throughout the reservoir. The present study aimed to investigate the potential of potassium chloride (KCl) and Poly-diallyldimethylammonium chloride (PolyDADMAC) as cationic clay stabilizers to mitigate the clay swelling phenomenon throughout the reservoir. This study conducted a series of free swelling tests on bentonite with varying brine salinity and clay stabilizer concentration. In addition, the rheological properties of KCl and PolyDADMAC were measured at 24°C and 98°C and at a 7.34 s–1 shear rate to determine its flow potential throughout the reservoir. The results showed that 0.3 wt.% to 1.5 wt.% of KCl and PolyDADMAC were able to control the expansion of bentonite immersed in an aqueous solution, with PolyDADMAC has shown excellent performance, whereas the bentonite expansion in PolyDADMAC solution is significantly lower than KCl. This result is driven by the fact that PolyDADMAC has greater amounts of cationic charges to neutralize abundant negative charges on clay mineral surfaces. Furthermore, the viscosity of 0.3 wt.% to 1.5 wt.% of KCl and PolyDADMAC at 24°C and 98°C recorded is low, which is 0.25 cP to 1.45 cP and 0.83 cP to 2.32 cP respectively. This low value proves its potential to be penetrated throughout the reservoir, not limited to near the wellbore region only.
 Keywords: Cationic clay stabilizer, salinity, bentonite swelling, viscosity

Green utilization of modified biomass by-product rice husk ash: A novel eco-friendly binder for stabilizing waste clay as road material

The use of traditional binders such as cement or lime has induced critical resource consumption, carbon emission, and environmental issues. Recycling biomass/industrial solid wastes as a novel eco-friendly binder is a promising alternative. This paper explores the critical problems of effectively stimulating the activity of waste RHA and the environmental compatibility of the developed waste-based binder. A series of unconfined compression, chemical, and leaching toxicity tests were conducted to evaluate the feasibility of the waste-based binder for waste clay stabilization in road engineering. The results show that the pozzolanic activity of waste RHA was strongly activated by CS with strong alkalinity. The most significant performance improvement for stabilizing waste clay was achieved at 6% RHA with adding 6% CS as an alkalinity activator and 3% MK as a supplement of aluminum phase composition. The 7d soaked compressive strength qiu of stabilizing waste clay reached 1.4 MPa, which met the requirements of the road base for freeway/first-class highway. There was a positive promotion for the reuse and elimination of massive waste RHA and CS. Moreover, many hazardous elements existing in raw materials RHA, CS, and clay were rarely detected in leaching solutions and satisfied groundwater safety. The utilization of RHA, CS, clay wastes in road engineering did not cause marked environmental risks. Finally, abundant newly generated hydration products can be observed due to the carbonization reaction and pozzolanic reaction, thus exhibiting excellent mechanical properties and environmental compatibility. This study presents a promising recycling and reuse way of biomass/industrial solid wastes as an alternative to cement/lime for soil stabilization in road engineering, contributing to carbon neutralization/carbon peak and sustaining economics.

Influence of Biomass Silica Stabilizer on Unconfined Compression Strength of Sodium Silicate Stabilized Soft Clay Soils

Soft clay often causes difficulty in construction operations with regards to strength and low hardness properties. Therefore, the need for soil stabilization is crucial in construction to ensure the stability of the soil strength and stiffness for each building to be built. This research was carried out to study the stabilization of clay in Batu Pahat using additional materials namely sodium silicate liquid and biomass silica powder. Soft clay samples were collected from the Research Centre for Soft Soils of Universiti Tun Hussein Onn Malaysia. The result shows that the liquid limit of the soil decreases while plastic limit increases with the addition of sodium silicate and biomass silica. As a result, the plasticity index reduces with the increment of both stabilizer's content. The strength increases at as early as 3 days after stabilization and constantly increases from 7 to 28 days curing period. The results of the unconfined compression strength test showed that the optimum amount of this stabilization process for the soil sample was three and nine percents of sodium silicate and biomass silica stabilizers, respectively. Additionally, the voids were filled with a stabilizing substance during the SEM testing. Cementation product was detected via the SEM test as a result of the stabilizer given to treated samples. The EDAX test established that the appearance of the Calcium element in the treated sample is a result of the stabilizer's chemical composition. This study demonstrates how biomass Silica significantly affected the increase in soil strength by creating cementation in the soft clay structure. Furthermore, sodium silicate plays a role in increasing soil strength, largely by acting as a binder between soil particles.

Experimental Study Using Recycled Waste Tyre as Sustainable Clay Soil Stabilisation

Clay presents construction challengesto geotechnical engineers as it shows high compressibility, low shear strength and high level of volumetric changes behaviour. Therefore, the properties of clay need to be improved before it can be used in any type of construction. Clay soil stabilisation using either mechanical or chemical methods are normally adopted to improve its properties. However, some of these methods are reported to be ineffective, expensive and harmful to the environment. In Malaysia, around 8.2 million tyres are dumped in landfill annually. The dumping of tyres will lead to long-term environmental impact. Hence, it is proposed to reuse waste tyres for clay soil stabilisation. This research investigates the effects of recycled waste tyres on the compaction and strength properties of clay soil. Clay soils were firstly mixed with 0, 5, 10, 15 and 20% of waste tyres and each mixed sample was tested for compaction and unconfined compressive strength tests. The results show that the optimum moisture content (OMC) increases, and maximum dry density (MDD) decreases with increasing waste tyre content. Meanwhile, unconfined compressive strength (UCS) reaches a maximum value at 10% waste tyre content and then decreases with further increments of waste tyre. It can be concluded that waste tyres have the potential to be used as an additive for sustainable clay soil stabilisation.

Clay swelling inhibition mechanism based on inhibitor-water interaction: A COSMO-RS molecular simulation approach

• Four inhibition mechanisms employed by amino-acids for stabilizing clay-rich formations are proposed. • New data on the inhibition techniques employed by amino acids is introduced. • Natural amino acids mainly inhibit clay swelling via their interactions with the eater-based fluid and not the clay formation. The inclusion of clay stabilizers in water-based fluids (WBFs) during drilling, imparts WBFs with clay swelling-inhibitive properties. This protects the formation from damage due to the enhanced reduction of the swelling components (clay portions) of the formation by these chemicals during drilling. With the increasing demand for ‘green’ clay stabilizers for WBFs, knowledge of their inhibitive mechanisms is necessary for their effective selection and usage. Earlier, we proposed Amino acids (AAs) as effective “green and cheap’ clay stabilizers, However, the mechanisms through which AAs and other clay stabilizers perform shale stabilization have not been adequately described in open literature. This study is a follow-up work employed to evaluate and succinctly describe all the inhibition mechanisms utilized by AAs to prevent the swelling of the reservoir formations. Furthermore, we discovered a novel mechanism for describing the inhibitive potentials between clay stabilizers in WBFs. Herein, we employed five experimental techniques alongside a modelling tool - COSMO-RS, to evaluate and describe the inhibitive mechanisms of six AA clay stabilizers. This study confirmed that the interaction of AA and the water component of the WBF is a significant factor for AAs effective stabilizing potentials. This is an addition to literature which only highlights the interactions of clay stabilizers and clay minerals for the stability of the formation. This work evaluated all the possible interactions during a clay stabilization process and utilized statistical analyses to compare the percentage contributions of all the interactions among the clay stabilizers (AAs), clay minerals and WBFs. It was revealed that 38% of the swelling inhibition potentials of AAs depend on their interactions with the water component of the WBFs. Concurrently, 28% of the AAs inhibition potentials are based on their ability to modify the surface of reactive clays, while 15% is based on AAs ability to replace the exchangeable cations of swelling clays resulting in the strengthening of the clay's cleavage spacing. Lastly, 18% of AAs stabilizing potentials are based on their ability to neutralize the reactive moieties of swelling clays. The percentage distribution reveals that the effective interactions of AAs with the WBFs significantly contribute to their effectiveness in stabilizing shale formations. This study is essential as it provides researchers with a holistic methodology to characterize and evaluate clay stabilizers.

Comparative analysis of strength and deformation characteristics of clayey soil, when treated with fly ash and ground granulated blast furnace slag

Clayey soils swell on absorbing water and shrinks on drying, any constructions built on them are subjected to the differential settlements due to the loss of support from soil. Stabilization of clays with various additives have considerable successes. Lime, cement, CaCl2, fly ash (FA), ground granulated blast furnace slag (GGBS), pond ash and other chemical reagents have been effective in stabilizing expansive soils and improving their characteristics like strength. This paper presents the comparison for strength and compressibility characteristics of clays when treated with FA and GGBS. In this investigation, FA content of 10%, 15%, 20%, 25% and GGBS of 10%, 15%, 20%, 25% were been used with the soil. The strength was observed to be high at 20% of FA & 20% of GGBS when compared with normal clayey soil. The time required for 90% consolidation and compression index were considerably reduced for both FA and GGBS at addition of 20% to soil.

Experimental and mechanistic study of mudstone volumetric swelling at the bottom of salt cavern gas storage

Salt cavern gas storage is one of the vital strategic natural gas reserves and emergency peak shaving facilities all over the world. However, rock salt in China is primarily bedded salt, usually composed of many thin salt layers and interlayers (e.g., anhydrite, mudstone, and glauberite). During the water solution mining process of the cavern, the insoluble mudstones fall to the bottom and account for 1/3 up to 2/3 of the storage capacity. The bulk volume of the insoluble mudstones is almost twice its in-suit volume. It is of great urgency to investigate the swelling mechanisms of the bottom insoluble mudstones. Given this, we first analyzed the mineral composition of salt rock and insoluble mudstones by using XRD and SEM methods. Then, experimental studies were carried out considering both clay swelling and physical packing. At last, the zeta potential tests were conducted to reveal the swelling mechanisms of the bottom mudstones. Results show that the volumetric expansion of mudstones is made up of three parts: clay swelling, particle surface bound water volume, and pore space free water volume increase. Because the content of expansive clay in the bottom mudstones is less than 2%, and the high salinity brine in the cavern has excellent clay stability performance, clay swelling is not the main contributor to the volumetric expansion of the bottom mudstones. Measurement results show that the surface of the mudstones is negatively charged after hydration. Electrostatic repulsion can increase the spacing between small rock particles and creates approximately 47.6% of the pore space, which is the main factor in the volumetric expansion of mudstones. This study provides a theoretical basis for the mining solution and capacity enlargement during the construction of bedded salt cavern gas storage in China.

Research progress on magnesium silicate hydrate phases and future opportunities

This short letter summaries the latest research on the structure and thermodynamic modelling of the magnesium silicate hydrates (M-S-H) phases. M-S-H structure is comparable to hydrated clays, with a smaller and rounder microstructures compared to clay platelets. Similar to clay minerals, M-S-H can incorporate ions such as aluminium and hydrated exchangeable cations to compensate the negative surface charge. This fundamental understanding of M-S-H structure allowed to develop structure-based thermodynamic models, which can further help to optimise the conditions for M-S-H formation and its use as cementitious materials. Optimized binders containing M-S-H have the advantages of presenting: i) good mechanical properties, ii) dense microstructure and potentially good resistances to leaching and iii) low pH values. These types of binders could therefore be used for cement products with non-steel reinforcement, for the encapsulation of specific wastes, for products containing natural fibres or for the clay stabilisation, etc.

Performance of Treated Soft Clay with Nano-Modified Cementitious Binders at Reference and Cold Temperatures

Lime is considered the preferred choice for the treatment of the high plasticity clayey soils; however, for environmental concerns (quality of water and vegetation), it is prohibited in many regions, including Manitoba, Canada. Hence, it is imperative to find a suitable treatment alternative that provides an optimal solution for such a problematic soil type during different periods of the construction season. Hence, improvement of problematic/weak soils such as soft clay by nano-modified cementitious additives was tested under normal and cold conditions. This approach may significantly impact the construction of roads/pavements in cold regions. This current study focused on investigating the effects of single, binary, and ternary cementitious systems, comprising General Use cement (0–15%) with/without slag (0–15%), and nano-silica (0–3%), on the properties of soft clay (Type A7/CH) under reference (22 ± 2 °C) and cold temperatures (+ 5 °C). The mechanical performance of the control and treated mixtures were tested in terms of California Bearing Ratio (CBR) as well as unconfined compressive strength at 7, 28, 56, and 91 days of curing, while the durability properties were assessed based on the resistance to freezing–thawing cycles [durability factor (DFF/T)]. Moreover, thermogravimetry and scanning electron microscope analyses were conducted to corroborate the trends of the aforementioned tests. In comparison to the untreated clay, increasing the binders’ content significantly enhanced the mechanical/durability properties of the soil treated herein. The ternary mixtures comprising cement, slag and nano-silica showed the highest mechanical and durability properties at both reference and cold temperatures. Its CBR, 7-day compressive strength, 28-day compressive strength, and DFF/T were 46.3 and 31.6%, 700 and 562 kPa, 1349 and 891 kPa, and 94 and 71%, respectively. Such mixtures may present a viable option for soft clay stabilization at low temperatures, thus contributing to extending construction activities during fall and spring periods in cold regions.

Use of Cement and Bottom Ash in Deep Mixing Application for Stabilization of Soft Bangkok Clay

Use of Cement and Bottom Ash in Deep Mixing Application for Stabilization of Soft Bangkok Clay

Stabilization of Amol fat clay using seashell ash

Stabilization of Amol fat clay using seashell ash

A High Effective Acid System to Stimulate Sandstone Reservoirs

Mud acid is regularly applied to recover or increase permeability of sandstone reservoir. However, due to its rapid reacting rate and heterogeneous displacement, the stimulation effect of conventional mud acid is relatively limited in sandstone formations. For mud acid, it is important to choose proper chemical additives to retard reaction rate and make it distributed homogenereously in formation. To overcome these shortcomings of mud acid, a new proprietary mud acid system has been developed for sandstone formations stimulation. The new system is composed of 2.0% multichemical solutions (MCS) +6.5%HCl+1.5% HF, and the combined solution contains nonionic surfactant, clay stabilizer, and dispersant which were specifically formulated. Core flooding experiments were conducted with the high effective mud acid; meanwhile, XRD and SEM analysis were performed before/after the core flooding tests. Retarded tests were also conducted for the new mud acid reacting with sandstone samples. Treatments with ten pores volume of the new high effective mud acid system were found to increase permeability of sandstone core approximately three times of its initial permeability. From the results of SEM and XRD analysis, most of clays were dissolved, and permeability was increased after core flooding by this new mud acid solution. On the basis of acidizing theory, the reaction retarded mechanism was explained about the new composite mud acid. Other properties of the new composite mud acid were also discussed. In comparison of conventional mud acid, the new composite mud acid can retard acidizing reaction rate and distribute evenly in formation; therefore, it can extend acidizing penetration and stimulate sandstone formation thoroughly. The new composite mud acid is more compatible and desirable than conventional mud acid, and it will be applied extensively for sandstone matrix stimulation.

Study on the Relationship between the Relative Molecular Mass of a Polymer Clay Stabilizer and the Permeability of a Tight Reservoir.

Water-sensitivity damage is inevitable during hydraulic fracturing for tight reservoir stimulation. A polymer clay stabilizer is the most effective and commonly used agent for reducing this kind of permeability damage. However, due to the small pore throat radii of tight reservoirs, polymers may be captured and detained, resulting in secondary permeability damage caused by polymer plugging. Therefore, it is necessary to clarify the matching relationship between the relative molecular mass of the clay stabilizer and the permeability of tight cores, which has not been reported yet. In response to this problem, the residual resistance factor and the permeability damage rate of PDMDAAC (poly dimethyl diallyl ammonium chloride, a kind of commonly used polymer clay stabilizer) to tight cores from Xinjiang Oilfield were investigated in cores with permeabilities of 0.10 × 10–3 μm2 (0.08–0.17 × 10–3 μm2), 0.05 × 10–3 μm2 (0.035–0.065 × 10–3 μm2), and 0.01 × 10–3 μm2 (0.007–0.020 × 10–3 μm2) through flow experiments. It was found that the relative molecular masses of PDMDAAC, which did not cause obvious core permeability damage, should be less than 10 000, 5000, and 2000, respectively. In addition, the bridging flocculation principle between the hydrodynamics radius of the clay stabilizer and the radius of the tight core pore throat can be used to explain the matching relationship between the relative molecular mass of the polymer clay stabilizer and the permeability of the tight reservoir. This study points out the direction for the optimization of the polymer clay stabilizer used in tight reservoir hydraulic fracturing and provides some references for the construction of hydraulic fracturing fluid systems for the efficient development of unconventional oil and gas resources.

Analisis Nilai Nilai Kadar Air Optimum Dan Kepadatan Kering Pada Tanah Lempung Dengan Penambahan Abu Cangkang Kemiri

The purpose of this study was to determine the effect of adding Candlenut Shell Ash to the maximum dry density and optimum moisture content in clay soil. Pecan shell ash as a clay soil density stabilization agent which was carried out by standard proctor testing. The research method used is Atterberg Limits testing, Moisture Content testing, Specific Gravity testing, Gradation testing (sieve analysis and hydrometer), and Compaction testing. From the characteristic tests it showed that the soil was classified as clay soil and the compaction test at point 1 and point 2 with mixed variations of 0%, 5%, 7%, 9% experienced an increase in the optimum water content. and maximum dry density. In the compaction test, 5 samples were carried out with the optimum moisture content value at point 1 of 0% variation, namely 22.855%, which continued to increase at the highest variation of 9%, namely 25.388 and at point 2, variation of 0%, namely 21.880%, continued to increase at variation of 9%, namely 24.217%, while the value of The maximum dry density at point 1 of 0% variation, which is 0.992, continues to increase at the highest variation of 9%, which is 1.058 and at point 2, variation of 0%, which is 0.957, also continues to increase at the highest variation of 9%, which is 1.047. From the results of the research conducted, it was found that Pecan Shell Ash increased the value of the optimum water content and the maximum dry density value so that it could be used to stabilize the soil.

PERBANDINGAN ABU VULKANIK DAN KAPUR SEBAGAI MATERIAL STABILISASI TANAH LEMPUNG

Clay soil as a subgrade is problematic if it has a low California Bearing Ratio (CBR) value. There are many choices of stabilizing materials that can improve the CBR value, but it is necessary to consider the availability of materials around the project. This study examines partial soil improvement in CBR specimens by differentiating thickness and soil stabilizing materials. The clay stabilization materials used were volcanic ash and lime as much as 6% and 12% of the dry weight of the soil. Laboratory CBR tests were carried out on original soil specimens, 1/3 and 2/3 parts of stabilized soil, and entirely of stabilized soil. The results showed that the CBR value of the stabilized soil with lime was higher than the volcanic ash. The thickness of the stabilized soil has an effect on the CBR value, the overall CBR value is obtained stable in the stabilized soil 2/3 part of the thickness of the soil and the rest is the original compacted soil.

The Effect of Limestone and Fly Ash on Clay Stabilization on CBR and Soil Compressive Strength

The subgrade in the road access construction project must have a strong soil bearing capacity so that it can withstand the load on it. Clay soil has high water content and expands easily. Various ways have been done to overcome it, one of them is by improving the original soil properties using the stabilization method. The research conducted is the stabilization of expansive clay soil using fly ash and limestone with a percentage of fly ash 5%, 10%, 15%, 20% fly ash and 25% limestone. Existing soil used from a wellpad construction project, in Ujung Pangkah, Gresik, East Java. The tests carried out are specific gravity, Atterberg, compaction, CBR and UCT tests. The CBR test was conducted to determine the appropriate CBR value to support DDT. The compressive strength of the soil was tested using the UCT test. The results of the study of the effect of fly ash and limestone are an increase in the dry weight of the soil and a decrease in soil water content. The increase in CBR and maximum soil compressive strength with a mixture variation of 20% fly ash + 25% limestone, Qu is 2.98 kg/cm 2 and CBR is 10.56%. This is due to a decrease in the water content thereby increasing the dry weight of the soil.

Pengaruh Fly Ash pada Stabilisasi Lempung Ekspansive Terhadap Nilai Tegangan Geser dan CBR

Expansive clay soils are categorized as poor as subgrades because of their low capacity for bearing soil. Therefore, it needed to stabilize with added lime and fly ash materials. This study aimed to determine the effect of adding lime and fly ash on the bearing capacity of expansive clay in the form of shear stress and CBR values. The research method used is observation, namely testing of physical and mechanical properties in the laboratory. The tests were carried out on the original soil, and soil was stabilized using 5% lime, and the fly ash content was 10%, 20%, 30%, 40%, and 50%. The biggest change in the value of the CBR test occurred in the CBR value that was not submerged after seven days of curing on a variation of a mixture of 5% lime (fixed) and 50% fly ash, which was 11.74% of the original soil CBR value of 1.39%. The largest increase in soil bearing capacity (qu) and undrained soil cohesion (cu) was obtained in the composition of the original soil mixture, 5% lime and 50% fly ash, namely 0.368 kg/cm2 and 0.184 kg/cm2. The results showed that the stabilization of expansive clay using lime and fly ash increased the bearing capacity of the soil.

Modification of Quaternary Clays Using Recycled Fines from Construction and Demolition Waste

Foundation of buildings in soft soil such as quaternary clay is often associated with difficult compaction, settlement, non-uniform and/or excessive deformation, and unsatisfactory shear resistance. The present study aims to assess the possibility of using recycled fines from construction and demolition waste, such as mechanically treated gypsum and waste concrete powder (WCP), instead of ordinary binders or industrial waste, in the stabilization of quaternary clay. A detailed characterization of soil components is presented. Seven mixes with various proportions of gypsum and WCP are prepared. Main geotechnical parameters of the modified soil are studied by applying standardized methods with a few deviations. XRD analysis and pH measurements are performed. It was found that the effect of 5% to 20% recycled di-hydrate gypsum is limited to improvement in moist soil compatibility. A gypsum content of 10% positively impacts soil cohesion and the oedometer modulus. WCP is an active component, containing non-hydrated cement, portlandite, calcite and calcium silicates hydrate. As a result, by adding 5% of WCP only, significant improvement can be achieved: greater soil cohesion, reduced deformability and higher UCS. When 5% of recycled gypsum is also added, soil cohesion is further improved because of ettringite formation.

High Sulfate-Bearing Kaolin Clay Stabilization with Waste Glass Powder before and after Mellowing Process

Road construction on sulfate-bearing soils is a worldwide concern because it is associated with a volume swelling stability issue due to the ettringite formation. Several treatment techniques were developed to solve this problem and improve geotechnical soil properties, including using pozzolanic materials and applying the mellowing process. This research evaluated the combined effect of cement and waste glass powder (WGP) on stabilizing sulfate-bearing soil before and after the mellowing procedure. Total six mixtures were developed, which includes 4% cement, 4% cement + 2% WGP, and 4% cement + 6% WGP before and after soil mellowing. The experimental program included particle size distribution of soil and stabilizers, chemical analyses of stabilizers, soil properties, unconfined compressive strength, and three-dimensional (3-D) swelling for the high sulfate-bearing kaolin clay. The test results demonstrated that the use of WGP in soil with a high sulfate content WGP improved strength development, decreased volumetric swelling, and reduced moisture susceptibility.

Hygroscopic behavior of water absorbed by capillarity and stabilization of a bio-composite building material: Clay reinforced with Chamarrops humilis fibers

The paper aims to study the hygroscopic behavior of water absorbed by capillarity of clay reinforced with Chamarrops humilis fibers as an ecologic building material strongly used in building construction in Morocco. This leads to provide a better understanding and controlling hydrothermal behavior of a building material, which integrates sorption phenomenon and its intrinsic characteristics. The static gravimetric method was used to determine sorption isotherms. Six salts were chosen so as to have a range of air relative humidity of 5.72% to 89.8%. The results showed that the water content absorbed by capillarity increases with the increasing of the air relative humidity at a given temperature, and the equilibrium water content absorbed by capillarity decreases with the increasing temperature. The sorption isotherms are of type IV, showing that the water absorption is enhanced at low humidities and a strong dominance of macropores. The differential enthalpy and entropy of sorption show that there is a strong dependence on the air relative humidity. Stabilization of clay by adding fibers indicated a strong influence on the rate of equilibrium moisture content loss, this leads to prevent cracking of earthen structures during the drying period by distributing the tensions due to shrinkage.