Capillary Rise Of Water Research Articles

Leaching Efficiency During Autumn Irrigation in China’s Arid Hetao Plain as Influenced by the Depth of Shallow Saline Groundwater and Irrigation Depth, Using Data from Static Water-Table Lysimeters and the Hydrus-1D and SIMDualKc Models

The need for controlling salinity in arid zones is essential for sustainable agricultural production and irrigation water use. A case study performed for two years in Hetao, Inner Mongolia, China, is used herein to rethink the contradictory issues of arid lands represented by water saving and controlling soil and water salinity. Two sets of static lysimeters, where water table depths (WTDs) were fixed at 1.25, 150, 2.00, and 2.25 m, were continuously monitored, and soil water and solute data were used to calibrate and validate two models: the soil water balance model SIMDualKc and the deterministic soil water and salt dynamics model HYDRUS-1D. Once accurately calibrated, the models were used to simulate maize water use, percolation, and capillary rise, along with the observed variables for the actual WTD and the autumn irrigation applied. Simulation scenarios also considered agricultural system degradation and dynamic water table behavior. Results have shown that large leaching efficiencies (Lefs) were obtained for large irrigation depths in cases of shallow water tables, but higher Lefs corresponded to high application depths when the water table was deeper. Agricultural system degradation, particularly increased groundwater salinity, lowered Lef, regardless of WTD. Conversely, water savings were minimal and only achievable when considering the dynamic nature of groundwater. These results indicate that there is a need to define different WTDs based on soil characteristics that influence fluxes and root zone storage, as well as the impacts of newly installed drainage systems aimed at salt extraction.

Selected issues concerning the use of Shredded Rubber Waste (SRW) in binder-bound mixtures

This paper presents the results of a composite consisting mainly of industrial waste bound by a hydraulic binder. The composite consists of unburnt coal-mining slate, shredded rubber waste (SRW), fly ash and CEM I cement. The purpose of using the above components was to protect the unburnt coal-mining slate from the negative effects of water, which causes degradation of the aggregate grain size and significantly affects the load-bearing capacity of the aggregate. This was achieved through the use of a binder consisting of shredded waste rubber, fly ash and cement, which imparts hydrophobic properties to the composite. The composite is to be used in road pavement construction and earthworks as a substitute for standard materials. This paper focuses on testing the effects of 5, 10 and 15% additions of shredded rubber waste (SRW) on the physical and mechanical parameters of the composite, mainly compressive strength, water absorption by mass, capillary rise and deformability under cyclic loading. The composite was tested under cyclic loading conditions using a measurement system based on digital image correlation (DIC), with which the deformations occurring on the surface of the test specimens were determined. The results obtained showed the influence of shredded rubber waste additives on the decrease in compression strength (after 7 and 28 days of specimen care), mass water absorption and capillary rise, as well as an increase in the deformability of the composite under destructive loading and cyclic loading.

Influence of Long-Term Mulched Drip Irrigation on Upward Capillary Water Movement Characteristics in the Saline–Sodic Region of Northwest China

Capillary water, serving as a crucial intermediary between groundwater and crop root layer moisture, is important for both soil retention and crop utilization. To investigate the effect of mulched drip irrigation (MDI) on upward capillary water in cotton fields with different application years (0, 10, 14, 18, 20, and 24 years) in the saline–sodic region of Northwest China, an indoor soil column test (one-dimensional capillary water rise experiment) was conducted. The results showed that the wetting front transport law, capillary water recharge, and wetting front transport rate over time exhibited an increasing trend in the early stages of MDI application (10 and 14 years), peaking at 18 years of application, followed by a decreasing trend. The relationship between the capillary water recharge and rising height was fitted based on the Green–Ampt model, and their slopes reveal that 14 and 18 years of MDI application required the largest amount of water per unit distance, indicating an excellent water-holding capacity beneficial for plant growth. Conversely, 0 years required the smallest amount of water per unit distance. Based on the movement characteristics of upper capillary water, we confirmed that the MDI application years (0–18 years) improves soil infiltration capacity, while the long-term application years (18–24 years) reduces groundwater replenishment to the soil. Furthermore, the HYDRUS-1D model was employed to simulate the capillary water rise process and soil moisture distribution under different MDl application years. The results showed an excellent consistency with the soil column experiments, confirming the accuracy of HYDRUS-1D in simulating the capillary water dynamics in saline–sodic areas. The results would provide suggestions to achieve the sustainable development of long-term drip-irrigated cotton fields.

Rising Damp Treatment in Historical Buildings by Electro-Osmosis: A Case Study

Throughout the past century, numerous technologies have been suggested to deal with the capillary rise of water through the soil in historic masonry buildings. The aim of this study was to examine the effectiveness of capillary moisture repulsion apparatus that uses the electro-osmosis approach over a prolonged period of time. The Gül mosque was selected as a sample historical building affected by structural problems caused by the absorption of water through small channels on its walls due to capillary action. The moisture repulsion mechanism efficiently decreased the moisture level in the walls from a ‘wet’ state to a ‘dry’ state in roughly 9 months. After the installation of the equipment, the water mass ratio of the building decreased from 14.48% to 2.90%. It was determined that the majority of the water in the building was relocated during the initial measurement period. Furthermore, it inhibited the absorption of water by capillary action by protecting the construction elements that were in contact with the wet ground. Lastly, capillary water repulsion coefficients (C) for various measurement durations and time factors were proposed. The average value of C was calculated to be 0.152 kg/m2 s0.5 by measuring the point at which the water repulsion remained nearly constant.

Super absorbent polymer (SAP) on water‐salt transport in saline alkali soil: Effects of dosage, height and thickness

AbstractSoil salinisation is a pervasive form of land degradation posing a significant threat to the global environment. Saline soil, covering roughly 10% of the total land area, represents a crucial reserve of land resources. The use of super absorbent polymer (SAP) impacts capillary water movement through the soil because of its exceptional water absorption and retention capabilities. SAP is expected to influence the intricate water‐salt migration processes and their redistribution within soil. This study employed soil column experiments to investigate the impacts of varying SAP dosages (A), heights (B) and thicknesses (C) on soil water and salt transport in the Tianjin Binhai New Area, China. The main findings showed that: (1) average capillary water rise rate decreased with SAP dosage increase. The groundwater recharge trend in time was like that of capillary water rise height; (2) SAP usage increased water and salt content on the application layer and reduced surface soil salt accumulation; (3) the best SAP combination for application was 1.1% SAP at 17–18 cm from the groundwater level. This study provides basic effective SAP application strategies for preventing soil salinisation.

Enhancing Water Resistance and Mechanical Properties of Cemented Soil with Graphene Oxide.

Although cemented soil as a subgrade fill material can meet certain performance requirements, it is susceptible to capillary erosion caused by groundwater. In order to eliminate the hazards caused by capillary water rise and to summarize the relevant laws of water transport properties, graphene oxide (GO) was used to improve cemented soil. This paper conducted capillary water absorption tests, unconfined compressive strength (UCS) tests, softening coefficient tests, and scanning electron microscope (SEM) tests on cemented soil using various contents of GO. The results showed that the capillary water absorption capacity and capillary water absorption rate exhibited a decreasing and then increasing trend with increasing GO content, while the UCS demonstrated an increasing and then decreasing trend. The improvement effect is most obvious when the content is 0.09%. At this content, the capillary absorption and capillary water absorption rate were reduced by 25.8% and 33.9%, respectively, and the UCS at 7d, 14d, and 28d was increased by 70.32%, 57.94%, and 61.97%, respectively. SEM testing results demonstrated that GO reduces the apparent void ratio of cemented soil by stimulating cement hydration and promoting ion exchange, thereby optimizing the microstructure and improving water resistance and mechanical properties. This research serves as a foundation for further investigating water migration and the appropriate treatment of GO-modified cemented soil subgrade.

A robust superhydrophobic coating of siloxane resin and hydrophobic calcium carbonate nanoparticles for limestone protection

Hydrophobic calcium carbonate (CaCO3) nanoparticles (NPs), modified with dodecanoic acid (DA), are produced and dispersed in solutions of KSE 100, which is a silicic acid ester base product used for the conservation and maintenance of heritage and modern buildings. The dispersions are sprayed on limestone and marble specimens. By adjusting the relative concentrations of DA and NPs, the treated stones obtain superhydrophobic properties. Focusing on limestone it is reported that the treatment has negligible effects on the colour and vapour permeability of the original stone and offers protection against water capillary rise. Several studies are performed to test the durability of the composite (KSE + CaCO3-DA NPs) coating against rain impact, freezing and thawing, salt attack and UV radiation. Moreover, the mechanical, chemical and thermal durability of the coating is studied according to the tape peeling test, contact angles of drops which correspond to a vast range of pH, and heat treatment. The results of the aforementioned tests reveal the very good stability of the composite coating. In sum, it is reported that the wetting properties of the KSE 100 stone strengthener, which is used in building conservation, can be highly improved by adding a small amount of modified CaCO3 NPs. The latter are chemically compatible with calcareous stones.

The effect of SH-lime composite material on capillary water rise resistance in the Great Wall

Capillary rise of water leads to salt migration and accumulation, which is the main cause of erosion at the bottom of the Great Wall in Northwest China. In this study, we evaluated the effectiveness of SH (modified polyvinyl alcohol) and lime composite material against capillary water rise. We conducted comparative capillary rise cycle tests on two sample types: untreated Great Wall soil and soil treated with the SH-lime composite, using solutions of NaCl and Na2SO4 of specified concentrations. The surface hardness, strength, water-salt distribution, and pore size distribution of the samples were also evaluated. The results showed that: in the salt solution capillary rise cycle, the untreated soil samples quickly changed color and precipitated white crystals. As the test proceeded, the untreated soil samples developed cracks, followed by fragmentation at the corners, and finally collapsed. In contrast, the SH-lime solidified soil had less white crystal precipitation and no visible cracks after 7 cycles. This indicates that the overall integrity of the SH-lime solidified soil was higher. The capillary rise cycles also changed the pore size distribution of the samples. NaCl crystals tended to occupy and expand micropores and small pores, while Na2SO4 crystals tended to grow in large pores. In addition, Na2SO4 was more destructive to soil than NaCl. The SH-lime composite material reduced porosity and strengthened soil structure, which slowed down the expansion of large pores. The study concludes that SH-lime effectively inhibits capillary rise-induced water-salt migration and associated damage, making it a suitable choice for repairing capillary rise-prone Great Wall sites.

Experimental study on multi-scale migration characteristics of capillary water in tailings

The increase of water content in tailings is the key cause of various diseases. In order to study the microscopical mechanism of tailings capillary water transport, an online monitoring capillary water rise test system was developed by itself, which mainly includes distortionless high definition digital microscope, 3-D mobile microscopic observation frame, CAMERA/VIEW PLAY CAP wireless acquisition system and computer. The system is used to carry out the dynamic real-time observation experiment of the capillary water rising process of tailings, analyze the movement trajectory and migration characteristics of the capillary water, and clarify the evolution law of the unsaturated tailings micro-structure under the hydraulic path. The results show that: There is a power exponential relationship between the rising height of capillary water and time, and the rising process can be divided into pure inertia stage, viscosity-inertia stage and pure viscosity stage. Capillary absorption is a process of non-uniform water absorption, the water content of the capillary zone decreases with the increase of the height, and its relationship curve shows an inverse ?S? shape, the water content varies from 4.15% to 21.3%. Capillary water migration is a dynamic process in both vertical and lateral directions and the most obvious change in the microscopic structure of tailings is the occurrence of water in pores, with the change of the saturation from low to high, the occurrence shows the shape of pendulum, ring cord, capillary and serous liquid bridge. The capillarity of tailings follows the order of macropores, mesopores and micropores to absorb water, most of which occurs in mesopores, the mechanism of ?in the macropores and mesopores, capillary water increased preferentially? in tailings granular materials is proposed. The research results revealed the internal correlation mechanism of macro and micro capillary mechanics of tailings, clarified the evolution model of the micro-structure of tailings during the rise of capillary water, and further clarified the reasons for the macroscopic damage phenomenon of granular materials caused by the development process of tailings particle drying to humidification.

Development of Pairwise Force Smoothed Particle Hydrodynamics for Capillary Rise Modelling

This research conducted a series of numerical experiments employing the Pair-Wise Force Smoothed Particle Hydrodynamics (PF-SPH) model to simulate the capillary action of water in the soil column. Initially, analytical relationships were formulated to connect various PF-SPH model parameters to surface tensions, static contact angles, and pore radius. Subsequently, the model was utilized to investigate PF-SPH equations and develop a modified function between numerical and physical parameters that incorporate the pore radius variable. The findings of this research reveal that capillary rise profiles in a steady state condition and Soil Water Characteristic Curve (SWCC) profiles closely align with empirical data obtained from published laboratory experiments. In conclusion, we observed that the PF-SPH model could simulate the capillary rise of water through the soil column by adjusting parameters such as surface tension, contact angle, and soil particle properties.

Determination of parameters of anti-heave structures of the subgrade taking into account the freezing system

Background: in the Northern Hemisphere, during the construction and operation of railways, one of the pressing problems is frost heaving. One of the key factors influencing the amount of frost heaving is the occurrence of groundwater relative to the freezing front of the subgrade soils, which is not fully taken into account by existing approaches to determining the parameters of anti-heaving structures. This factor is usually characterized by freezing regimes, there are two of them - open and closed freezing systems. An open system is characterized by the proximity of groundwater to the freezing front, at which there is a constant influx of water (migration) to the zone of phase transitions, which makes the process of frost heaving unpredictable, and the determination of the frost heave ratio incorrect. A closed freezing system assumes the absence or deep location of groundwater (the difference in the level of the freezing front and groundwater exceeds the height of the capillary rise of water).
 Aim: development of a method for calculating the parameters of anti-heaving. structures depending on the freezing regime of railway subgrades.
 Materials and Methods: comparative analysis of methods for calculating the parameters of anti-heaving structures, experimental studies of the process of frost heaving in an open system of freezing of clay soils.
 Results: based on experimental studies of freezing regimes, a differentiated approach to assessing the characteristics of frost heaving is proposed, taking into account the peculiarities of the frost heaving process.
 Conclusion: the proposed method with a differentiated approach compares favorably with existing ones, allowing to reduce the consumption of building materials when designing anti-heaving measures.

Design and fabrication of fibrous media to facilitate autogenous smart self-healing properties in cracked-cementitious structures using polyethylene glycol (PEG) and silicon dioxide nanoparticles

A novel approach is introduced for smart of cracked cementitious structures using a fibrous media occupied by polyethylene glycol (PEG) and silicon dioxide (SiO2) nanoparticles. A series of fibrous media were designed and fabricated using different fiber types (polyethylene terephthalate (PET), hollow polyethylene terephthalate (HPET) and polypropylene (PP)), areal densities, thicknesses and porosities. The fibrous media was filled by PEG/SiO2 nanoparticles to perform further hydration and then healing the crack by capillary rise of water into the cracked paths. An analytical model was proposed to predict the minimum critical crack radius in cementitious structure to initiate smart release of nano-particles through fibrous media. The developed model calculates minimum crack radius based on properties of polymeric components and associate media’s porosity with capillary rise of nano-particles in accordance with Washburn’s equation. An artificial neural network (ANN) based on multilayer perceptron (MLP) was used to determine the most important parameter influencing self-healing efficiency. The self-healing efficiency of samples were also evaluated via ultrasonic test, field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS) and X-Ray diffraction (XRD) analyses. CaCO3 formation and C-S-H growth deducted from FESEM image analysis and EDS/XRD results. The PET media showed more healing efficiency because of less crack radius. The areal density parameter was found to be the most effective parameter in reducing the capillary radius. The new proposed method is simple and applicable to promote hydration and crack filling of cement products such as canvas concrete.

Variations in pore size and contact angle distributions control rhizosphere rewetting

Rhizosphere wettability decreases upon severe drying leading to periods of prolonged low water content around roots after precipitation or irrigation. These observations were explained by the temporal hydrophobic character of mucilage, while structural alterations of the pore space caused by mucilage, such as pore clogging, remained mostly unexplored. In this study, time-series neutron radiography and a pore network model were used to assess the impact of pore geometry and wettability on water flow following the addition of mucilage in a sand substrate. To do so, we monitored the capillary rise of ethanol and water separately for mucilage contents, ranging from 0.0 to 2.0 mg g−1. A pore network model was developed to analyze the impact of alterations in pore geometry and wettability. Results are compared with analytical solutions of the Lucas-Washburn equation. Rewetting dynamics were explained by a combination of a decrease in effective pore throat size and a global decrease in wettability. The local distribution of wettability, however, appeared of minor importance as dynamics of water imbibition could be matched by a uniform effective contact angle. For 0.1 mg g−1 mucilage content increased wettability was predicted for both approaches: the analytical solution and the pore network model fit. At larger contents, a decrease in wettability occurred which was accompanied by a decrease in derived effective pore and pore throat size. On a minute scale, rewetting appeared to steadily progress at all mucilage contents with accelerated rewetting observed at 0.6 mg g−1 likely related to an increased wetting front length. This study highlights the importance of mucilage on pore geometry in combination with wettability modifications in the rhizosphere. Aside from rhizosphere rewetting, the presented approach provides an opportunity to investigate further wettability-related processes in other soil environments on various spatial scales.

Soil resistivity measurements to evaluate subsoil salinity in rice production systems in the Vietnam Mekong Delta

AbstractRice is a staple crop in the Vietnam Mekong Delta (VMD) in which more than half of Vietnam's rice is produced. However, rice production in the VMD is threatened by increasing saltwater intrusion due to land subsidence and climate change induced sea level rise. Saltwater intrusion into lowland areas through the canal system or capillary rise of saline water from near surface saline water tables may result in salt accumulation in the topsoil. Therefore, it is important to disentangle the two effects and their relative importance to implement appropriate strategies for water and salinity management for adapting rice production systems of the VMD to climate change. Here, we report on the possibility of using geoelectrical methods to evaluate the potential threat of subsoil salinity to rice production. To evaluate the level of subsoil salinity, we measured soil electrical resistivity using an ARES II to a depth of 40 m in a case study comprising five locations in the VMD. Electrical resistivity measurements were calibrated to soil types, which were identified through evaluating 1 m core sections obtained by drilling down to 40 m depth. The relationship between drilling data and soil resistivity was determined by applying clustering and principal component analysis. Resistivity values smaller than 3 Ω m were clearly identified as indicative for a saline water table. The results show a direct link between the depth of the saline water table and the proximity to the sea, but not to the rice production system (single, double, or triple cropping). This study proved for the first time the applicability of the electrical resistivity tomography method for identifying groundwater tables and evaluating subsoil salinity on an agricultural field scale in the VMD.

Агроэкологическая оценка степени деградации лугово-чернозёмной почвы в яблоневых садах на примере ФГУП «Мичуринское» Тамбовской области

In the monoculture of a weakly growing apple tree, the fatigue of meadow-chernozem soils manifests itself at the age of 16-18 years of trees. A methodology for assessing the degree of soil degradation in apple orchards has been developed. Its approbation on the example of meadow-chernozem soil showed that the rate of capillary rise of water in aggregates of 0.25-5 mm, the amount of exchange bases, mobile phosphorus, exchangeable potassium, the number of bacteria, the intensity of cellulose destruction and the total nitrogen content in barley leaves in the tillering phase when grown as a test culture degraded to the greatest extent. The weakest degree of degradation of meadow-chernozem soil was noted by total porosity, maximum hygroscopic, capillary moisture capacity, the content of exchangeable potassium, magnesium, pH of salt extract and the amount of yeast. The soil parameters that have changed the least are the components of the buffering of meadow-chernozem soil: total porosity, maximum hygroscopic and capillary moisture capacity, the content of exchangeable potassium, magnesium, pH of salt extract and the amount of yeast. The degree of degradation of meadow-chernozem soil in 26-year-old low-growing apple orchards of the Federal State Unitary Enterprise "Michurinskoye" of the Tambov region on rootstock 62-396 with row spacing under black steam is low or medium. Assessment of the degree of soil degradation can also be used as a characteristic of the level of agricultural technology in a given farm. Keywords: APPLE ORCHARDS, SOIL TRANSFORMATION, SOIL DEGRADATION, SOIL FERTILITY ASSESSMENT

Hydrological forecasting at impact scale: the integrated ParFlow hydrological model at 0.6 km for climate resilient water resource management over Germany

In the context of the repeated droughts that have affected central Europe over the last years (2018–2020, 2022), climate-resilient management of water resources, based on timely information about the current state of the terrestrial water cycle and forecasts of its evolution, has gained an increasing importance. To achieve this, we propose a new setup for simulations of the terrestrial water cycle using the integrated hydrological model ParFlow/CLM at high spatial and temporal resolution (i.e., 0.611 km, hourly time step) over Germany and the neighboring regions. We show that this setup can be used as a basis for a monitoring and forecasting system that aims to provide stakeholders from many sectors, but especially agriculture, with diagnostics and indicators highlighting different aspects of subsurface water states and fluxes, such as subsurface water storage, seepage water, capillary rise, or fraction of plant available water for different (root-)depths. The validation of the new simulation setup with observation-based data monthly over the period 2011–2020 yields good results for all major components of the terrestrial water cycle analyzed here, i.e., volumetric soil moisture, evapotranspiration, water table depth, and river discharge. As this setup relies on a standardized grid definition and recent globally available static fields and parameters (e.g., topography, soil hydraulic properties, land cover), the workflow could easily be transferred to many regions of the Earth, including sparsely gauged regions, since ParFlow/CLM does not require calibration.

Capillary rise induced salt deterioration on ancient wall paintings at the Mogao Grottoes

Salt deterioration has been found to be a major threat to wall paintings at culture heritage sites in arid areas along the Silk Road. However, the routes of water migration that cause the efflorescence have not been identified, and consequently, effective preservation measures have not been developed. Our microanalysis, by interrogating 93,727 individual particles collected in a Mogao cave in Dunhuang, China, revealed that capillary rise of water in the earthen plasters drives the deterioration of wall paintings. The vertical distribution of chloride and sulfate particles in the salt efflorescence and their morphologies implied a migration of salts through capillary rise and subsequent crystal growth under environmental conditions exerts sufficient pressure to cause surface decay and loss. These results indicate that blocking the water capillary rise under the porous structures is likely the most effective route to prevent rapid deterioration of the ancient wall paintings. These salt transport and deterioration mechanisms in an arid environment, suggests that a wide range of management strategies and protective measures could be developed to effectively preserve heritage sites in arid regions, especially along the Silk Road.

Ferrihydrite coating reduces microplastic induced soil water repellency.

Addition of microplastics (MP) to soil has the potential to increase soil water repellency. However, coating of MP with soil abundant substances e.g., iron compounds, can reduce this effect. Here, we tested if pre-coating or in situ coating of MP with ferrihydrite (Fh) reduces soil water repellency. We applied hotspots of pristine and coated MP (20-75 μm, PS and PET) to sand and imaged capillary rise via neutron radiography. Capillary rise experiments in wetting-drying cycles were conducted using water and Fh suspension. Pristine MP hotspots were not wettable. Capillary rise of water into coated MP hotspots differed in wettability depending on polymer type. While coated PS was still non-wettable, water imbibed into the coated PET hotspot. Capillary rise of Fh suspensions in wetting and drying cycles also showed varying results depending on polymer type. MP hotspots were still non-wettable and local water content increased only marginally. Our results indicate that Fh coating of MP changes MP surface wettability depending on polymer type and therefore counteracts the hydrophobic properties of pristine MP. However, MP coating is likely to be slowed down by the initial hydrophobicity of pristine MP. Dynamics of MP coating and increasing wettability are key factors for biotic and abiotic degradation processes.

Preventing the secondary salt deterioration in the repaired area of basal erosion of earthen sites based on capillary barrier effect

Basal erosion is one of the most typical salt deteriorations of earthen sites in arid and semi-arid areas. Its formation is mainly related to the water and salt migration and enrichment at the bottom of earthen sites walls, and can cause collapse of site walls. Rammed roof-propping reinforcement is the main repair technology for the basal erosion of the earthen sites, but there is a risk of secondary salt deterioration in the repaired area due to the subsequent water and salt migration. Based on the capillary barrier theory, this study regulates the particle size composition of repair soil to explore repair materials that can effectively mitigate the secondary salt deterioration. Firstly, Arya-Paris model and Fredlund-Xing’s model were used to convert the particle size distribution curves (PSDC) of soil with different particle composition into soil–water characteristic curves (SWCC), to preliminarily judge the capillary barrier potential of different soil structures. Then carry out water-salt migration test and mercury intrusion porosimetry test to verify the predictions. The research shows that when repair soil is coarser than earthen site soil, it can form an effective capillary barrier to block the capillary rise of water and salt, thus reducing the secondary salt deterioration in the repaired area. When repair soil is finer than earthen site soil, it will promote the capillary rise of water and salt, thus aggravating the salt deterioration in the repaired area. It is proposed to use the repair material of adding 20% sand on the basis of the original earthen site soil particle composition for the rammed roof-propping reinforcement of the earthen sites.

Study on prevention and treatment of capillary water rise for construction waste expansive soil subgrade

This paper solves the technical difficulties of the capillary water rising height of the construction waste improved expansive soil subgrade (CWS), analyses the capillary water rising mechanism of the construction waste improved expansive soil subgrade cushion and evaluates the improvement effect of the improved cushion by comparing different working conditions with simulation software. The analysis results show that: (1) a reasonable ratio of the improved subgrade bed can effectively improve the porosity of the cushion layer, thus effectively inhibiting capillary water rising height. (2) the practical improvement of the thickness of the cushion layer can slow the matrix suction effect of expansive soil, (3) the construction waste had a more significant influence on the particle gradation for the capillary water rise, poor grading cushion layer has a significant influence on the capillary water rise, (4) the construction waste particles in the improved graded cushion of construction waste have strong water absorption, which improves the matrix suction effect of expansive soil. (5) Through experiments and simulation tests, this paper concludes that the optimal grade subgrade bedding of construction waste expansive soil is of specific theoretical value and practical significance for developing the construction waste material transformation subgrade. Keyword: Construction Waste, the capillary water rise mechanism, well-graded CWS.