Clay Gravel Research Articles

A novel creep-damage constitutive model of clay–gravel composite considering the effect of water content and saturation-undersaturation cycles and its engineering application

A novel creep-damage constitutive model of clay–gravel composite considering the effect of water content and saturation-undersaturation cycles and its engineering application

Research and analysis of the influence of recipe and technological factors on the strength of expanded clay concrete on quartz sand

The aim of the work is to study the strength and deformation properties of expanded clay concrete on cement-ash binder and to prove the technical possibility and economic feasibility of its study in structural elements of civil buildings. The five-factor plan B5 was implemented. In the matrix, each of the technological factors changed at three levels (-1; 0; +1), which made it possible to obtain quadratic mathematical models of output parameters - the bulk mass of concrete, cubic and prismatic strength of the expanded clay concrete at the age of 1 (a.s), 28, 115, 180 and 360 days, when the expanded clay concrete mixture is mobile (the constant draught of the cone is DC= 2...6 сm). Processing of experimental results to identify regularities of influence of studied factors - consumption: cement (x1); lime (х2); fly ash (х3); expanded clay gravel (х4); quartz sand (x5) on water consumption of ceramic and concrete mixtures – B, volume of inter-grain voids Vn, the density of the ceramic concrete mixture – ρo and the density of the expanded clay concrete ρ allowed to obtain with 95% reliability quadratic regression equations, taking into account only significant regression coefficients. Based on the results of experimental studies with 95% reliability quadratic regression equations of cubic and prismatic strength in the age of 1 (a.s), 28, 180* and 360* days are obtained, expanded clay concrete on CLF-binder and quartz sand with only significant regression factors. The paper examines and analyzes the influence of recipe and technological factors on the strength of expanded clay concrete on quartz sand. The invention makes it possible to use the dependence of a cubic and prism strength expanded clay concrete on quartz sand using a large component binder with a further prospect of saving cement and fillers.

Production of effective materials on the basis of sulfuric acid industry wastes

Introduction. Solving the urgent problem of the production of special concretes using certain varieties of substandard natural raw materials and a number of industrial wastes will support introducing the principles of resource saving and improving the technological features of production.Aim. To make a comprehensive assessment of the impact of sulfuric acid production wastes and substandard natural clay raw materials on the production of high-quality and durable concretes for special purposes.Materials and methods. Easily fusible clay rocks serve as a raw material for the production of expanded clay gravel. Organic (solar oil) and ferruginous (pyrite cinders) additives were used. X-ray analysis was carried out to determine the crystalline phases in the clay of the Nikolskoe oil-field, in the resulting expanded clay gravel, as well as to analyze the factory bulk samples of pyrite cinders. A tubular electric furnace was used for firing in a two-stage mode of 700 and 1100 °C to obtain high-strength expanded clay gravel under laboratory conditions. The research involved studying parameters of phosphate binder formation and properties of iron phosphate concrete based on H3PO4 and sulfuric acid industry wastes – pyrite cinders.Results. It was found that Nikolskoye field clay forms a good raw material for the production of high-strength heavy expanded clay gravel with a strength of up to 550 kg/cm2, water absorption of 1.5 % and resistance to aggressive environments, thereby making it suitable for manufacturing special concretes. The results obtained specify the test methods and technical requirements, control methods and product acceptance rules, thus improving the quality and durability of the concretes considered.Conclusions. The investigated non-bloating clay can be used with organic and ferruginous additives to obtain high-strength expanded clay gravel for the manufacture of structural concretes. A mixed iron phosphate binder serves for producing heat-resistant concretes for linings of melting and casting units in non-ferrous metallurgy with high resistance and durability.

Jet grouting to new depths in the Lambeth Group and Thanet Formation beneath London

A jet grouting trial was undertaken within the Thames Tideway Tunnel shaft at Kirtling Street in Battersea, SW London, to assess the viability of the technique within the Lambeth Group and Thanet Formation sediments up to 60 m below ground level. There was no precedent industry experience of jet grouting in the UK at this depth and in these soil types. Four, separate, upper and lower grout columns were constructed respectively within upper and lower granular zones inside the shaft footprint, and then exhumed for inspection and measurement during ensuing excavation within the diaphragm wall lining. Target diameters for the upper columns were achieved within granular channel sand and Laminated Bed material, with minimal vertical deviation. These were not so successfully achieved, however, within stiff cohesive Laminated Bed and Lower Shelly Clay materials. Formation of the lower columns was severely restricted in dense gravel belonging to the ‘Pebble Bed’ and stiff gravelly clay, at the top of the Upnor Formation, but target diameters were being achieved in the lower portion of the formation, comprising Upnor sand. At their base, the column diameters were, again, restricted in the very dense sand at the top of the Thanet Formation.

Influence of plant covering with nonwoven agrotextile on the vegetative growth characteristics and yield of sweet potato (Ipomoea batatas L.): A Slovenian case study

The objective of this study was to evaluate the impact of cultivar and covering with nonwoven agrotextile on vegetative growth parameters and the productivity value of sweet potato (Ipomoea batatas L.). A field experiment was conducted during the 2018 growing season, at the experimental field of the Biotechnical Faculty in Ljubljana (46° 04′ N latitude; 14° 31′ E longitude, 305 m above sea level). The soil was gravel clay with a pH of 6.7, and a soil depth of 40–60 cm. The research involved the following Slovenian cultivars of sweet potatoes: Lučka, Janja, and Martina. Distance between rows was 1.2 m, while in-row distance was 1.4 m. The experiment was conducted in a randomized complete block design with plots arranged factorially and replicated four times. The seedlings were planted on 20 May. A half of the plots were covered with polypropylene nonwoven textile (17 g/m2). The uncovered half of the plots served as control plots. The recommended cultural practices were performed as needed during the experiment. The temperature under the covers was on average 5.5 °C higher than in the unprotected area. The crops were harvested 132 days after planting. Covering significantly and positively affected vegetative growth – that is the height of the vines, leaf number, leaf area index, and haulm dry weight. In contrast, the nonwoven polypropylene cover had no significant effect on the number of branches per crop. The use of agrotextile significantly increased tuber length and diameter, tuber number, tuber weight, and total yield in comparison with traditional cultivation with no plant cover. Statistical analysis showed that cv. Janja had the significantly higher yield (7.49 t/ha) compared to cv. Lučka (6.68 t/ha) and cv. Martina (6.16 t/ha).

Equivalent Compression Curve for Clay–Sand Mixtures Using Equivalent Void-Ratio Concept

Clay–sand mixtures are deposited worldwide, such as naturally sedimentary soils and dredged clays in human activities. These mixtures usually have a fine fraction above the transitional fine content, and the compressibility is dominated by clay matrix and affected by sand fraction. In this paper, an explicit equivalent compression curve is proposed for clay–sand mixtures. This is done by directly incorporating the equivalent void ratio into the intrinsic compression model of the clay matrix. The roles of initial and evolving soil structure developed during the compression process are described by a structural variable, which can be directly computed from the experimental data. Experimental data compiled from various literature are used for evaluating the accuracy of the suggested model. They indicate that the proposed relationship of stress versus equivalent void ratio is simple yet effective to evaluate the compressibility of clay–sand mixtures with a wide spectrum of sand fraction. The model is also practically useful for estimating the compressibility of other gap-graded soils, such as clay–gravel mixtures. The proposed stress versus equivalent void-ratio equation is an elementary function and can be readily implemented into general elastoplastic models.

Influence of cohesion on California bearing ratio of clay–gravel mixtures

An understanding of the behavior of cohesive sediment is required to solve various engineering problems such as scour around bridge elements, mitigation of soil erosion, pavement design, river bed degradation, stable channel design. Pavement foundation designers principally use the California bearing ratio (CBR) to describe the subgrade and subbase materials and their strength. Several laboratory experiments were done to study the variation in the CBR of cohesive mixtures comprised of clay–gravel mixtures. Nine different clay–gravel mixtures were used in which the clay content varies from 10% to 50% by weight. The variation of the CBR with clay percentage, moisture content, and undrained shear strength parameters was studied. The CBR value reduces with the increase in the moisture content and clay fraction in the mixtures and increases with an increase in the dry density of the mixture under unsoaked conditions. The CBR also increases with the increase of the angle of internal friction of clay–gravel mixtures. A functional relation has been identified to estimate the CBR of clay–gravel mixtures. Using multiple linear regression analysis (MLRA), a relation is proposed to estimate the CBR of clay–gravel mixtures under unsoaked conditions. A statistical analysis was done to judge the behavior of the pertinent variables on the CBR. The proposed relation predicts the CBR of clay–gravel mixtures very well. Artificial neural network (ANN) analysis using R programming was also done to determine the effects of the pertinent variables on the CBR. ANN methodology was applied to predict the contribution of each variable. Three different methods: Garson algorithm, Olden algorithm, and Lek's profile model are used to assess the influence of variable parameters. The Olden algorithm and Lek's profile both show positive association of cohesion with CBR in an unsoaked condition. The role of moisture content was found to be marginally negative in the Olden algorithm and Lek's profile results. It is found that both the ANN and MLRA models are accurate in predicting the CBR of clay–gravel mixtures. It was further found that the MLRA and ANN models are reliable and rapid tools for correct assessment of the CBR of cohesive soil mixtures using the basic soil properties.

Earthing Resistance and Poldzolic Soil Resistivity at PT. Perta Samtan Gas Field Extraction Plant Prabumulih

It is important to undertake research at the location of PT. Perta Samtan Gas Field Extraction Plant Prabumulih with Podzolik soil type (yellow gravel clay) and analysis in order to prevent work accidents and the risk of fire caused by leakage current at the gas processing extraction installation. Direct measurement of soil resistance value is used as the basis for the methodology, which is followed by literature study as background information and technical comprehension of experimental research. The outcomes of the research study are then compared using Comsol simulation with the computational method of computational finite element analysis of the resulting resistance. According to the data, the resistivity of the podzolic soil was 214.4 Ωm, while the Comsol simulation yielded a resistance value per meter of 209.1 Ω and 196.7Ω, respectively. The Comsol simulation demonstrates that, in order to obtain a ground resistance value of 1 ohm on a Single rod system with Fe material, it is necessary to optimize the depth of the grounding electrode, which can range from 3 meters to 1053 meters d. In the simulation, the results of soil resistance measurements and the Comsol Multiphysics application are obtained, and the difference is calculated with a percentage error of 1.62%.

Analysis of the functional efficiency of enclosing structures made of expanded clay concrete

The introduction discusses the main advantages and disadvantages of the use of structural and structural insulated lightweight concrete in the manufacture of load-bearing structures of buildings based on an analytical review of the work of various researchers. It is demonstrated that in the Republic of Belarus there is a sufficient production base for the mass production of expanded clay and expanded clay concrete products. For the special case of designing load-bearing walls made of expanded clay concrete blocks considered in the article, the features of their design are given (for example, reinforced concrete belt, reinforcement of masonry with grids). In the main part, on the example of the design of load-bearing external walls of a warehouse building, the achieved economic effect is demonstrated by the calculation method based on variant design. The results of the practical calculation performed within the framework of the variant design of the enclosing load-bearing walls of the building are presented. Two options are considered: the traditional solution is a masonry of silicate bricks with a thickness of 380 mm, an alternative option is a masonry of expanded clay concrete blocks with a thickness of 300 mm. It is established that the economic effect of the use of expanded clay concrete blocks is 9.3 % per 1 cubic meter. walls compared to the masonry of silicate bricks without taking into account the positive effect in the selection of foundation blocks and slabs, which is achieved as a result of reducing the own weight of the walls. The ways to improve the physical and mechanical characteristics of expanded clay concrete are proposed: the use of expanded clay gravel as a coarse aggregate, increase the strength of expanded clay gravel at the stage of its production, the use of expanded clay fraction up to 10 mm, and fiber reinforcement by polypropylene fiber. In conclusion, it is stated that the use of expanded clay concrete products made of structural and heat-insulating concrete can improve the indicators of the functional efficiency of building structures.

Mobile Complex for the Production of Expanded Clay for the Northern Roads

Objective. International practices demonstrate advantages of expanded clay in road construction in difficult climatic and geotechnical conditions. The clay is present in abundance in Siberia and in the Far North which is suitable for the production of expanded clay gravel. At the same time there is a strong deficit of the road construction materials in these regions. The aim of the study is to develop a new approach for providing claydite for the construction of northern roads.Method. The modernization of the equipment means that each unit included in the complex can be transported on existing trucks, and then mounted in a line for the production of expanded clay in the field.Result. A mobile complex for the production of expanded clay gravel, serial and modernized equipment for the production of expanded clay has been developed.Conclusion. Large units - drying drums and rotary kilns for drying and firing pellets should be divided into prefabricated sections, for example, with a diameter of 2 m and a length of 5-7 m. For the electric drive of the units, a diesel generator of sufficient power must be included in the equipment set. The productivity of one complex is from 15 thousand cubic meters of expanded clay per year and above.

ДИСПЕРСНО–АРМОВАНИЙ ЛИТИЙ КЕРАМЗИТОБЕТОН НА МЕХАНОАКТИВОВАНОМУ ШЛАКОПОРТЛАНДЦЕМЕНТІ

The paper examines the properties of dispersed-reinforced cast expanded clay concrete on mechanically activated slag Portland cement with the addition of Super-PC polycarboxylate superplasticizer. Experimental studies have established the possibility of obtaining lightweight concrete based on high-mobility lightweight concrete mixtures with a diameter of a cone of at least 50 cm. It has been experimentally confirmed that the hydrophobization of expanded clay gravel helps to increase the spreading of the cone of the concrete mixture, and also increases the viability of the concrete mixture. The expediency of mechanical activation of slag Portland cement in the presence of Super-PC to obtain light concrete with increased characteristics in terms of frost resistance, abrasion and impact strength is shown. The results of research are presented, which indicate that the introduction of basalt fiber into slag Portland cement together with the mechanical activation of the binder allows to reduce the abrasion of concrete from 0.44 to 0.13 g/cm2, as well as to increase the impact strength of concrete by almost 2 times (compared to with control). The proposed complex of recipe-technological influences allows to ensure frost resistance of concrete not less than 350 cycles of alternating freezing and thawing. It was established that the mechanical activation of the binder causes an increase in the strength of concrete at the age of 3 days from 11.3 to 16.2 MPa, that is, by more than 40% compared to the control. The introduction of basalt fiber in the amount of 1% of the mass of the binder ensures an increase in the strength of concrete by 10-15%. The joint effect on slag Portland cement of mechanical activation, additives of poly-carboxylate Super-PC and basalt fiber causes an increase in the strength of concrete at the age of 28 days (compared to the control) from 11.3 to 29.5 MPa, i.e. more than 2.5 times. In general, the combined use of the listed recipe-technological factors ensures an increase in the main physical and mechanical characteristics of lightweight concrete.

Factors Influencing Post-Construction Responses of Underlying Tunnel below Excavation Base in Gravelly Clay

This paper investigates the response mechanism behind an existing tunnel subjected to a long and deep collinear excavation in Shenzhen granite residual strata. The maximum excavation depth was 18.0 m and the minimum residual soil depth above the tunnel crown was only 6.3 m, causing appreciable tunnel heave and transverse deformation. Two-dimensional parametric numerical study is adopted to examine the impacts of influential factors (excavation dimensions, ground permeability coefficient, and exposure time of the excavation base) on the tunnel responses. The hardening soil model with small strain (HS-Small) is used to model the soil stress–strain behavior. It is found that the long-term deformation of the tunnel after excavation and unloading cannot be ignored. The soil will continue to consolidate and deform, and the tunnel will continue to heave with soil due to the dissipation of the negative excess pore water pressure. The long-term deformation of the tunnel after excavation and unloading is significantly affected by the excavation geometry. With the increase in excavation width B, the final tunnel heave after excavation and unloading increases first and then tends to be stable. Furthermore, the relative position of the tunnel and the excavation base is also one of the major contributors to the long-term deformation of the tunnel. The growth of tunnel deformation Δf and the exposure time T are exponentially negatively correlated with Ly. The change in the permeability coefficient k has no effect on the final stable tunnel heave and the growth of tunnel deformation Δf, which is exponentially negatively correlated with the exposure time T.

Method of matching different background spectra based on spectrally tunable light source

It is a great challenge for traditional passive camouflage materials to respond to spectral changes with environmental transitions. Hence, a spectrally tunable light source (STLS) sample composed of multitype light-emitting diodes for matching different background spectra was proposed. The common background spectra were measured. These spectra can provide the guidance and verification of the STLS sample in terms of spectral matching. The STLS sample was designed by a spectral fitting method with an equal interval of the peak wavelength, and an optimization method was proposed to match the different background spectra quickly and accurately. The theoretical results show that at least 30 light sources with different peak wavelengths are required to match all the collected spectra from the typical backgrounds. The correlation index between the measured STLS spectrum and the background spectrum of the gravel clay can increase from 0.5045 to 0.9518 after the optimization, indicating an accurate match. Except for the extremely low energy spectra, the correlation indexes can be maintained above 0.9275 for the collected spectra versus the different environments and time, exhibiting the verification of matching the different background spectra. Thus, we confirm the feasibility of the proposed STLS sample, which can provide a preliminary exploration for the application and development of dynamic spectral matching.

Groundwater Characterization and Salinity Intrusion Studies using Electrical Resistivity Survey (ERS)-Winder, Balochistan, Pakistan

The groundwater resources have always been explored for its utilization in domestic and agriculture purposes. In this study, Winder area in Balochistan which is along the coast of Offshore Indus Basin has been explored using electrical resistivity method for deeper understanding of hydrogeological and hydrogeophysical conditions. Schlumberger electrode arrays have been used to acquire vertical electrical sounding data for 23 different sites in this area. The field data were calibrated with theoretical curves during processing using software with graphical interface. The true resistivities, depths, thicknesses, aquifer attributes, soil type and groundwater quality has been extracted from the processed data. Pseudo-sections and geo-electrical lithology sections have been generated for lateral distribution of hydrogeological settings. Furthermore, Dar-zarrouk parameters calculations have been made and 3D surfaces generated at 30m and 60 m depth for transverse resistance (T), longitudinal conductance (S) and anisotropy (λ) plotted for resistivity distribution and coastal salinity intrusion analysis. The soundings results depict five layers mainly composed of silty sand, sandy clay, sand, and sandy gravel and the depth ranges from 0-110m. The interpretation illustrates that freshwater unconfined aquifer are present in the quaternary sand and sandy gravel deposits. The water table is at shallow depth along the river and deeper in northeast and away from Winder river. The resistivity ranges 29-1091 Ωm in layer-3 interpreted as saturated zone. The approximate range of water table is 19-30 m. The higher value of T greater than 10000 shows fresh water and low value 8200 for salinity intrusion in southwest toward sea.

LLC «Vinzili Expanded Clay Gravel Plant» (Tyumen Region). Building Materials Made of Expanded Clay and Expanded Clay Concrete for Civil and Industrial Construction “From The Foundation to the Roof”

LLC «Vinzili Expanded Clay Gravel Plant» (Tyumen Region). Building Materials Made of Expanded Clay and Expanded Clay Concrete for Civil and Industrial Construction “From The Foundation to the Roof”

Prospects of Expanded Clay Gravel Production in Samara Region

Prospects of Expanded Clay Gravel Production in Samara Region

ВЫБОР РАЦИОНАЛЬНОЙ РЕЦЕПТУРЫ ОБЛЕГЧЕННЫХ БЕТОНОВ НА СМЕСИ КЕРАМЗИТОВОГО ГРАВИЯ, ПРИРОДНОГО ЩЕБНЯ И ГРАНУЛИРОВАННОГО ШЛАКА

In conditions of dense urban development and a variety of engineering and geological conditions, the use of concretes with a combined aggregate of a rationally selected composition will solve the existing problem of reducing the mass of reinforced concrete structures of buildings and structures and maintaining the required strength and deformability. In this paper, studies have been carried out on the choice of a rational formulation of lightweight concrete based on expanded clay gravel, natural crushed stone and granulated blast furnace slag by varying the volume content of porous coarse aggregate and the volume content of fine aggregate in relation to the mixture. In total, 9 series of prototypes and 1 series of control samples are manufactured and tested. One series of samples includes three cubes with dimensions of 10x10x10 cm. All samples are tested in terms of density and compressive strength, the coefficient of constructive quality is determined. The results of the study shows that the introduction of expanded clay gravel into the composition of heavy concrete instead of part of the dense coarse aggregate and the replacement of the fine dense aggregate with granular blast furnace slag leads to an increase in the structural quality factor, that is, a decrease in the compressive strength of concrete is compensated for by an even more significant decrease in the density of the material, and means weight reduction. The increase in the coefficient of constructive quality of concrete based on expanded clay gravel, natural crushed stone and granulated blast-furnace slag in comparison with the control composition is 15.6 %.

Building materials based on manmade waste of the mining industry and solid fuel energy – An environmental trend of the modern time

The building materials industry is one of the key sectors of the national economy due to its largecapacity and enduring demand. One of the main scientific directions of the outstanding Russian scientist, Academician of the Russian Academy of Sciences Leonid Abramovich Vaisberg was the search for the ways and means of solving the problem connected with waste recycling. To obtain products for construction purposes, Academician L.A. Vaisberg considered it promising to manufacture a granular porous aggregate based on a dust-like fraction of igneous rocks – basalts, granites and syenites – as well as ash and slag waste (ASW) from solid fuel power plants. Coal generation occupies a significant share on the territory of the Russian Arctic zone, as a result of which the problem of integrated recycling of the resulting ash and slag waste is a very urgent environmental problem for the entire Arctic zone of the Russian Federation. Ash and slag waste is 98–99% composed of free and chemically bound compounds of silicon, aluminum, iron, calcium, magnesium, potassium, sodium, etc. In terms of phase and mineralogical composition, ash and slag waste belong to multicomponent systems, including crystalline (grains of quartz, hematite, magnetite, etc.) and amorphous (glassy phase) components. Materials of this composition are suitable as raw materials for the production of constructing materials, including binders, aggregates, calcined and non-calcined materials for road construction, etc. A promising way of using ash and slag waste is their use in road construction in the Arctic zone in conditions of waterlogging and long periods with negative temperatures and the process of “swelling” of the roadbed. To prevent deformations of frost swelling, it is necessary to use various loosening materials, for example, crushed rock, sand, expanded clay gravel, as well as ash and slag waste from thermal power plants. In the conditions of the Arctic zone of the Russian Federation, the complex utilization of ash and slag waste from own thermal power plants for the needs of road construction will improve the environmental situation and ensure a new quality of roads.

The Source of Fracture-Cave Mud Fillings of the Ordovician Yingshan Formation and Its Paleokarst Environment in the Northern Slope of the Tazhong Uplift, Tarim Basin, China: Based on Petrology and Geochemical Analysis

The karst fracture-cave oil and gas reservoirs of the Yingshan Formation in the northern slope of the Tazhong Uplift are well developed and have achieved good exploration results. However, the karst fracture-cave near the top of the Yingshan Formation is basically filled with mud fillings, which seriously affect the reservoir property, and the source and filling environment of the mud fillings have been unclear. Through the petrological and geochemical analysis of the fracture-cave fillings system in the typical wells of the Yingshan Formation, it has been found that (1) the fracture-cave fillings are mainly composed of a mixture of the bedrock dissolution dissociation particles, clay minerals, and calcite cements of the Yingshan Formation, and the content of each component in the different wells or in the cave interval is quite different. (2) Rare earth element analysis shows that the rare earth distribution pattern of the fracture-cave fillings is similar to the bottom marlstone of the Lianglitage Formation, indicating that the fracture-cave fillings should be mainly derived from the early seawater of the deposition during the Lianglitage Formation. (3) Cathodoluminescence, trace element analysis, and previous studies have shown that the formation and fillings of the fractures and caves mainly occurred in the hypergene period, which had the characteristics of an oxidized environment, and that there are two filling effects. First, the limestone of the Yingshan Formation experienced the formation of karst caves due to meteoric freshwater dissolution during the exposure period, and the limestone of the Yingshan Formation was dissolved, resulting in some insoluble clay and residual limestone gravel particles brought into the cave by the meteoric freshwater for filling. Second, the seawater transgression also played an important role during the deposition of the Lianglitage Formation. The clay content in the seawater was high during the early deposition of the Lianglitage Formation, which led to the clay being brought into the caves by the seawater during the deposition of the Lianglitage Formation for further filling; at the same time, calcite deposited into the caves with the clay. The above research promotes the study of the formation mechanism of the karst cave reservoir in the Yingshan Formation and has important theoretical significance for the guiding of the next oil and gas exploration in this area.

An Improved Large-Scale Stress-Controlled Apparatus for Long-Term Seepage Study of Coarse-Grained Cohesive Soils.

Clay–gravel mixture has been widely used in high embankment dams and understanding its seepage characteristics is critical to dam safety. From the instrumental perspective, the realization of continuous pressurized water supply becomes a key technical challenge, significantly restricting the working conditions replicated in previous seepage apparatuses. To this end, a novel water provision system, relying on parallel-disposed sensor-based pressure devices, was introduced, so that the application of an existing large-scale stress-controlled apparatus can be expanded to long-term seepage tests regarding coarse-grained cohesive soils. Constant-head permeability tests were conducted on original-graded clay–gravel mixtures to investigate their hydraulic properties, incorporating the influence of stress relaxation. Test results show that with 35% gravel content, the clay–gravel mixture is suitable for dam construction as the core material. The stress relaxation holds a marginal effect on the hydraulic conductivity of soil. The functionality of this improved apparatus is verified, especially under long-term seepage conditions.