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The issue of interfacial shear damage has been a significant challenge in the field of geotechnical engineering, particularly in the context of diaphragm walls and surrounding soils. Polymer grouting is a more commonly used repair and reinforcement method but its application to interface repair and reinforcement in the field of geotechnical engineering is still relatively rare. Consequently, this paper presents a new polymer grouting material for use in grouting reinforcement at the interface between concrete and soils. The bonding characteristics and shear damage mode of the interface after grouting were investigated by the direct shear test, and the whole process of interface shear damage was investigated by digital image correlation (DIC) technology. Finally, the reinforcement mechanism was analyzed by microscopic analysis. The results demonstrate that the permeable polymer is capable of effectively filling the pores of soil particles and penetrating into the concrete-soil interface. Through a chemical reaction with water in the soil, the polymer cements the soil particles together, forming chemical adhesion at the interface and thereby achieving the desired reinforcement and repair effect. In the shear process, as the normal stress increased, the horizontal displacement and horizontal compressive strain at the distal end of the loading end decreased, while the maximum vertical displacement and maximum vertical strain of the cured soil also decreased. The results of scanning electron microscopy (SEM) demonstrated that the four groups of test polymers exhibited a reduction in soil porosity of 53.47%, 58.79%, 52.71%, and 54.12%, respectively. Additionally, the form of concrete-soil interfacial bonding was observed in the concrete-cohesive layer-cured soil mode. The findings of this study provide a foundation for further research on diaphragm wall repair and reinforcement. [ABSTRACT FROM AUTHOR]

Silty-fine sand in the Yellow River floodplain is prone to geological hazards such as collapse, subsidence, gushing water, and sand routing triggered by groundwater seepage. As a new type of grouting material, permeable polymer is effective for solving silty-fine sand geologic hazards. With the rise and fall of the water table, capillary water, and transpiration, the reinforced silty-fine sand will be subjected to dry-wet cycles. Investigating the strength loss mechanism of specimens reinforced with permeable polymer during dry-wet cycles is essential for mitigating silty-fine sand geological hazards. The strength characteristics of permeable polymer grout-reinforced silty-fine sand specimens under dry-wet cycles and its extreme case (long-time immersion) were analyzed from macro and micro perspectives employing unconfined compressive strength (UCS) test and scanning electron microscope (SEM). The functional calculation model between the specimens and the initial grouting conditions under dry-wet cycles was constructed, and the main influencing factors of the UCS loss of the specimens were obtained. After permeable polymer grouting, the porosity of silty-fine sand is reduced effectively and the porous structure is changed. The grouted specimens maintain structural integrity and demonstrate excellent water stability even after dry-wet cycles.

This study aims to investigate the compressive and microstructural properties of loess before and after treatment with a new permeable polymer. To enhance the compressive properties of loess, specimens were infused with the new polymer, and one-dimensional consolidation tests were performed to assess the compressibility of solidified loess (SL) and unsolidified loess (UL) at different water contents. Additionally, the microstructure and pore morphology of UL and SL were examined using a scanning electron microscope (SEM) and the Particles (Pores) and Cracks Analysis System (PCAS). Statistical methods were employed to analyze the relationships between microstructural parameters and compression modulus. The experimental results demonstrate a significant improvement in the compressibility of loess when treated with the polymer. The complexity of pore structure and variability in pore size are reduced, leading to a more uniform pore distribution. Moreover, all microstructural parameters exhibit a strong correlation with the compression modulus. The results pertaining to the compressive and microstructural properties of loess reinforced with permeable polymer grouting can provide insights into the variations in the curing effect, serving as a theoretical foundation for the application of permeable polymer in loess treatment. [ABSTRACT FROM AUTHOR]

The issue of interfacial shear damage has been a significant challenge in the field of geotechnical engineering, particularly in the context of diaphragm walls and surrounding soils. Polymer grouting is a more commonly used repair and reinforcement method but its application to interface repair and reinforcement in the field of geotechnical engineering is still relatively rare. Consequently, this paper presents a new polymer grouting material for use in grouting reinforcement at the interface between concrete and soils. The bonding characteristics and shear damage mode of the interface after grouting were investigated by the direct shear test, and the whole process of interface shear damage was investigated by digital image correlation (DIC) technology. Finally, the reinforcement mechanism was analyzed by microscopic analysis. The results demonstrate that the permeable polymer is capable of effectively filling the pores of soil particles and penetrating into the concrete-soil interface. Through a chemical reaction with water in the soil, the polymer cements the soil particles together, forming chemical adhesion at the interface and thereby achieving the desired reinforcement and repair effect. In the shear process, as the normal stress increased, the horizontal displacement and horizontal compressive strain at the distal end of the loading end decreased, while the maximum vertical displacement and maximum vertical strain of the cured soil also decreased. The results of scanning electron microscopy (SEM) demonstrated that the four groups of test polymers exhibited a reduction in soil porosity of 53.47%, 58.79%, 52.71%, and 54.12%, respectively. Additionally, the form of concrete-soil interfacial bonding was observed in the concrete-cohesive layer-cured soil mode. The findings of this study provide a foundation for further research on diaphragm wall repair and reinforcement.

The grinding reinforcement of fine sand layers is a difficult problem in dam engineering construction. As a new type of grouting material, permeable polymer with excellent impermeability and high strength is widely used in dam engineering. In this paper, a series of compressive tests were designed considering different grouting pressures, curing days, moisture content, and porosity of fine sand. The influence of grouting parameters and sand layer conditions on the strength of fine sand layers reinforced by permeable polymers was analyzed. SEM and XDR tests were conducted to analyze the microscopic characteristics of the grouting stone. The functional calculation model of the strength and the influencing factors was established to explore the main factors influencing grouting stones. The compressive strength of grouted stones increases rapidly from the 7th to the 14th day, reaching about 96% of the maximum strength. The degree of influence of different factors is grouting pressure > moisture content > porosity. The compressive strength of the grouted stones increases with the increase of grouting pressure and the number of curing days. The compressive strength decreases with the sand layer's increasing moisture content and porosity. [ABSTRACT FROM AUTHOR]

Seepage prevention and reinforcement of sandy soft soil layer are the important subjects in geotechnical engineering. A set of constant pressure permeable grouting device has been developed to study the diffusion rule of new permeable polymer in sandy soil layer. Based on the orthogonal experimental design, the effects of grouting pressure, grouting time, sand moisture content and sand porosity on the diffusion of new permeable polymer in sand are studied. Through the establishment of spatial coordinate system, the diffusion range of permeable polymer slurry is studied. The experimental results show that: the main and secondary order affecting the diffusion range of permeable polymer in the X-axis and Y-axis are sand porosity, grouting pressure, grouting time, and sand moisture content. The primary and secondary orders of influencing factors on the Z-axis diffusion range of permeable polymer are sand porosity, grouting time, grouting pressure, and sand moisture content. The effects of grouting pressure, grouting time, sand layer porosity on permeable polymer diffusion and the effect of permeable polymer on soil displacement during diffusion are studied by COMSOL numerical analysis software. The results of numerical analysis show that the grouting pressure, grouting time, and porosity of sand layer promote the diffusion of permeable polymer. The slight deformation of soil mass and small disturbance to soil layer can be caused by slurry during diffusion process. A function model between slurry diffusion range and grouting parameters are established, and verified by numerical simulation for comparison. The results show that the numerical simulation values of permeable polymer grouting results in the three comparison scenarios A1, A2 and A3 are greater than the theoretical calculation values, and the difference between them is not significant. The difference between the calculated value and the theoretical value of the three comparison schemes are 6.3%, 11.7% and 7.39%, respectively. [ABSTRACT FROM AUTHOR]

The grinding reinforcement of fine sand layers is a difficult problem in dam engineering construction. As a new type of grouting material, permeable polymer with excellent impermeability and high strength is widely used in dam engineering. In this paper, a series of compressive tests were designed considering different grouting pressures, curing days, moisture content, and porosity of fine sand. The influence of grouting parameters and sand layer conditions on the strength of fine sand layers reinforced by permeable polymers was analyzed. SEM and XDR tests were conducted to analyze the microscopic characteristics of the grouting stone. The functional calculation model of the strength and the influencing factors was established to explore the main factors influencing grouting stones. The compressive strength of grouted stones increases rapidly from the 7th to the 14th day, reaching about 96% of the maximum strength. The degree of influence of different factors is grouting pressure > moisture content > porosity. The compressive strength of the grouted stones increases with the increase of grouting pressure and the number of curing days. The compressive strength decreases with the sand layer’s increasing moisture content and porosity.

The reinforcement and durability of loess are of great importance for road performance. In this study, a self-designed grouting system and newly permeable polymers were adopted to investigate the mechanical properties and durability of solidified loess (SL), considering different dry densities and water contents. The unconfined compression test and piezocone penetration (CPTU) test were used to examine the mechanical properties. The mechanism of the loess solidified by permeable polymer was analyzed from the micro-level by SEM, MIP, and XRD tests. The test results show that the effect of polymer grouting is obvious, the unconfined compressive strength (UCS) of the SL after grouting is as high as 3.05–5.42 MPa; it is 11.83–20.99 times that of unsolidified loess (UL). The UCS of the SL after grouting is inversely proportional to the dry densities and water contents. After 56 days of immersion, the SL still shows a high compressive strength. The additional erosion of the SL was not caused by the salt solution; the durability is significantly better than that of cement mixing soil. The sensitivity of various factors on the UCS of the SL are service environment > water content > dry density. The SEM tests clearly show that the gel formed by the reaction of the polymer with water on the surface of soil particles makes the bond of soil particles tighter. It can be observed from the MIP test that the cumulative mercury of SL was 0.115 mL/g, which was 33.72% of UL (0.341 mL/g), and the cumulative mercury of SL after immersion in water and salt solutions was 0.183 mL/g and 0.175 mL/g, which was 53.7% and 51.3% of UL (0.341 mL/g), respectively. The XRD results show that there are no other new mineral components produced after grouting and the spacing between crystalline planes decreases, which proves that permeable polymer grouting makes the soil denser and does not erode the soil particles. [ABSTRACT FROM AUTHOR]

The reinforcement and durability of loess are of great importance for road performance. In this study, a self-designed grouting system and newly permeable polymers were adopted to investigate the mechanical properties and durability of solidified loess (SL), considering different dry densities and water contents. The unconfined compression test and piezocone penetration (CPTU) test were used to examine the mechanical properties. The mechanism of the loess solidified by permeable polymer was analyzed from the micro-level by SEM, MIP, and XRD tests. The test results show that the effect of polymer grouting is obvious, the unconfined compressive strength (UCS) of the SL after grouting is as high as 3.05–5.42 MPa; it is 11.83–20.99 times that of unsolidified loess (UL). The UCS of the SL after grouting is inversely proportional to the dry densities and water contents. After 56 days of immersion, the SL still shows a high compressive strength. The additional erosion of the SL was not caused by the salt solution; the durability is significantly better than that of cement mixing soil. The sensitivity of various factors on the UCS of the SL are service environment > water content > dry density. The SEM tests clearly show that the gel formed by the reaction of the polymer with water on the surface of soil particles makes the bond of soil particles tighter. It can be observed from the MIP test that the cumulative mercury of SL was 0.115 mL/g, which was 33.72% of UL (0.341 mL/g), and the cumulative mercury of SL after immersion in water and salt solutions was 0.183 mL/g and 0.175 mL/g, which was 53.7% and 51.3% of UL (0.341 mL/g), respectively. The XRD results show that there are no other new mineral components produced after grouting and the spacing between crystalline planes decreases, which proves that permeable polymer grouting makes the soil denser and does not erode the soil particles.

Silty-fine sand is widely distributed in the Yellow River floodplain and is frequently utilized in infrastructure construction. It is susceptible to engineering hazards due to its limited bearing capacity, inadequate stability, and high permeability under groundwater seepage. Grouting has emerged as an effective method to solve this problem, with the choice of grouting material playing a pivotal role. To address the urgent requirement for a suitable material to reinforce silty-fine sand, three types of traditional grouting materials are selected for comparison with the self-developed permeable polymer. The performance comparison of different grouting materials encompasses pre-grouting parameters including viscosity and gel time, as well as post-grouting contrasts of strength, water stability, and permeability coefficient of the reinforced silty-fine sand. The results indicate that the permeable polymer possesses low initial viscosity and optimal gel time, facilitating substantial injectability and adjustability. As the grouting pressure and curing period increase, the strength of the silty-fine sand reinforced with different materials demonstrates varying degrees of improvement, and specimens reinforced with the permeable polymer and high permeability epoxy resin display the highest strength at equivalent grouting pressure and curing periods. Over time, the strength of specimens reinforced with different materials exhibits a decline during immersion. Regarding water stability, the specimens reinforced with the permeable polymer show a minimal reduction of 10.87% after 7 days of immersion, exhibiting excellent water stability. Additionally, the permeability coefficients of the specimens decrease with longer curing periods, with the high permeability epoxy resin and permeable polymer exhibiting the lowest coefficients. By comprehensive comparison, the permeable polymer demonstrates the best overall performance and is suitably applicable for reinforcing silty-fine sand in the Yellow River floodplain. • A new self-developed permeable polymer was proposed by comparing with three kinds of traditional grouting materials. • The reinforcement effect of silty-fine sand with the self-developed permeable polymer were carried out. • The strength of silty-fine sand specimens reinforced with different materials ware compared. [ABSTRACT FROM AUTHOR]

• A set of visualized permeable grouting model test devices for sand layer was created. • Anti-seepage reinforcement mechanism of permeable polymer in sand layer is studied. • BP neural network prediction model for grouting effect is constructed. Permeation grouting is one of the important methods of anti-seepage reinforcement when the drainage pipes crosses loose diseases caused by leakage. With the development of grouting materials, permeable polymer slurry is widely used in engineering practice. Due to its low viscosity, fast reaction and micro-expansion, the diffusion and reinforcement law of slurry in loose area of drainage pipeline is more complex. To better understand the effects of water head pressure, grouting pressure, sand particle size and clay content on the anti-seepage and reinforcement effect of permeable polymer grouting in loose area of drainage pipeline, several types of tests, including permeability and uniaxial compressive strength tests, were performed. Then, based on the model test results, a BP neural network prediction model for the anti-seepage reinforcement effect of permeable polymer grouting in loose area of drainage pipeline is constructed, and the research results are applied to the treatment project of loose area of drainage pipeline for verification. The results show that: 1) after grouting, the order of magnitude of permeability coefficient of the consolidated body is reduced to 10-7cm/s, the anti-seepage performance of the sand layer is greatly improved, and the grouting pressure is the main controlling factor affecting the anti-seepage performance of the consolidated body. 2) The compressive strength of the consolidated body is obvious different under different working conditions. The water head pressure is the main controlling factor affecting the strength of the consolidated body. 3) Due to the limitation of test conditions, the relative error between the predicted value of BP neural network model and the actual value is about 20%, which can meet the general prediction needs. [ABSTRACT FROM AUTHOR]

ZnO nanowires are normally exposed to an oxygen atmosphere to achieve high performance in UV photodetection. In this work we present results on a UV photodetector fabricated using a flexible ZnO nanowire sheet embedded in polydimethylsiloxane (PDMS), a gas-permeable polymer, showing reproducible UV photoresponse and enhanced photoconduction. PDMS coating results in a reduced response speed compared to that of a ZnO nanowire film in air. The rising speed is slightly reduced, while the decay time is prolonged by about a factor of four. We conclude that oxygen molecules diffusing in PDMS are responsible for the UV photoresponse.

ZnO nanowires are normally exposed to an oxygen atmosphere to achieve high performance in UV photodetection. In this work we present results on a UV photodetector fabricated using a flexible ZnO nanowire sheet embedded in polydimethylsiloxane (PDMS), a gas-permeable polymer, showing reproducible UV photoresponse and enhanced photoconduction. PDMS coating results in a reduced response speed compared to that of a ZnO nanowire film in air. The rising speed is slightly reduced, while the decay time is prolonged by about a factor of four. We conclude that oxygen molecules diffusing in PDMS are responsible for the UV photoresponse.