This study investigates the enhancement of copper-functionalized graphene oxide (Cu-GO) on cement composites. Graphene oxide (GO) was synthesized and functionalized with copper ions to improve its electrical conductivity. The experiment consisted of uniaxial compressive strength tests to evaluate strength enhancement and electrical resistance measurements to assess conductivity improvement. The results showed that Cu-GO was well-dispersed within the cement matrix, maintaining the dispersibility of GO while increasing the compressive strength by 11%. The electrical resistivity of the composites decreased by 52%, indicating a significant enhancement in electrical properties. Furthermore, the study included experiments to monitor changes in resistivity due to cracking. During the compression fracture process, substantial changes in resistivity were observed just before failure, demonstrating the high sensitivity of Cu-GO composites to crack development. These findings indicate that Cu-GO improves both the mechanical strength and electrical properties of cement composites, presenting a promising potential of using Cu-GO composites on structural health monitoring with further studying. With these results, this study expects Cu-GO to be an ideal option for next-generation smart city construction material.

This study examines natural zeolite as a fine aggregate in cement mortar to improve thermal performance and energy efficiency in cold-climate buildings. Mortars with 25%-100% zeolite replacing sand were tested for physical, mechanical, and thermal properties. After 28 days, compressive strengths ranged from 29 to 50 MPa, while thermal conductivity decreased by up to 65% with full zeolite replacement. EnergyPlus simulations of a 16 m2 single-room house showed improved indoor temperature stability and lower sensitivity to outdoor changes. Higher zeolite content and greater mortar thickness yielded the most energy savings, with heating energy reductions of 43-487 kWh for partial and 667-1523 kWh (up to 24.7%) for full replacement. Corresponding CO2 emission reductions ranged from 43 to 1142 kg annually. Overall, zeolite-based mortars offer enhanced indoor comfort, lower energy use, and significant carbon savings, highlighting their potential as sustainable, energy-efficient materials for cold-region construction.

The thermal properties of a building’s wall are crucial for building energy efficiency, directly influencing heat loss of buildings and contributing to global warming. This paper aims to enhance the thermal properties of cement mortar, as concrete and mortar often exhibit poor thermal properties. The study investigated the mechanical and thermophysical properties of cement mortar with different percentages of natural zeolite aggregates (NZA). Sand aggregate was replaced by 25%, 50%, 75% and 100% of NZA. The results showed that cement mortar using 100% NZA exhibited reduced density, with compressive strength of 28.6MPa at 28dys. The thermal conductivity of these cement mortars using NZA decreased by 13-67% compared to control mortar. This suggested that mortar with 100% NZA decreases the heat loss, increases thermal resistance, and enhances heat storage. The findings indicate that use of NZA as fine aggregate influences mechanical and thermophysical properties of cement mortar due to their higher porosity compared to sand aggregate. Therefore, cement mortar with zeolite aggregate can be considered an environmentally friendly cement mortar that is both mechanically stable and thermally efficient.

This study investigates the potential benefits of using the 150nm level Hydrogen Nanobubble Water (HNBW) in cement concrete. Given the significant greenhouse gas emissions associated with the cement and concrete industry, enhancing building materials performance and environmental friendliness becomes crucial. In this work, experiments were conducted to evaluate the various properties of this particular concrete formulation such as hydration heat, compressive strength, slump, air content, water absorption, electrical resistivity, rapid chloride permeability, and SEM. The results of the analysis showed that the HNBW improved the workability of the concrete by 50%. The HNBW improved the mechanical properties and durability of the concrete, resulting in an increase in compressive strength of 18.03% at 3 days and over 6% at 7 and 28 days. It reduces water absorption while improving electrical resistivity and chloride permeability resistance. Additionally, SEM imaging confirms that HNBW contributes to a more compact structure with pore and micro-crack size, thereby improving the overall performance of the concrete. Therefore, hydrogen nanobubbles, as a nanomaterial, exhibit favorable effects in meeting the demands of concrete.

This study has utilized self-assembled monolayers technology to improve electrical property of graphene-oxide, which has been seperated graphine powder through a chemical exfoliation. Aluminum sulfate (Al2(SO4)3) was applied on graphene-oxide as a reactant, and the fundamental research was carried out to apply on the self-sensing of cement-based construction structures. Electric resistance measurement result has shown that cement-composites with GO and Al-GO can be used as a conductor, electric resistance of GO and Al-GO contained composites improved by 10.2% and 15.9% respectively when compared to the standard cement-composite. Microstructure analyzation shown the formation of Al(OH)3 gel when Al-GO was added, which is speculated to result the smooth flow of current by improving the density of cement-composite. This implies that graphene-oxide has a possibility to be utilized as smart building materials and construction structure itself rather than just a structure.

As cement manufacturing is associated with CO2 emissions that contribute to environmental problems, cement usage must be reduced and alternative aggregates must be developed. Thus, we developed and evaluated a mortar that uses feldspar as a fine aggregate, which does not require additional mineral admixtures. Feldspar and conventional plastering sand-based specimens were prepared with a fine aggregate proportion of 75%, 80%, or 85%. The compressive strength test results confirmed that the strength of the feldspar-based mortar was 1.1–4.5 times higher than conventional plastering sand-based mortar. Microstructure analysis after 3 and 7 d of curing revealed the existence of capillary micropores and gel pores, which improved water tightness. C-S-H and C-S-H gel hydration was also observed at the early stage, and the amount of C-S-H also increased. Further, an additional reaction may have occurred between feldspar compounds, SiO2 and Al2O3, and Ca(OH)2 that accelerated C-S-H production and contributed to the higher compressive strength. The relatively high-strength feldspar-based mortar is expected to reduce cement dependency, which can be achieved using a fine-aggregate feldspar mixing ratio according to project requirements. Thus, the proposed fine aggregate alternative can help alleviate the environmental problems associated with cement usage. It also has potential as an eco-friendly building material.

This study describes life cycle assessment (LCA) results of the excavation depth and ground condition of a medium-sized excavation ground in order to examine the effect of construction methods on environmental and economic feasibility for an earth-retaining wall. LCA is conducted in consideration of eight environmental impact categories according to the construction stage of the earth-retaining wall. In addition, the environmental cost of construction method for the earth-retaining wall was calculated, and its selection criteria were analyzed based on the calculation results. The evaluation results of the environmental load of construction methods for the earth-retaining wall show that the H-Pile+Earth plate construction method has low economic efficiency because the construction method significantly increased the environmental load due to the increased ecological toxicity. The environmental load characteristics have a greater effect on the selection of construction methods in sandy soil than in composite soil when the excavation depth is the same. The evaluation result of the environmental cost of the construction methods for the earth-retaining wall shows that the environmental cost increased as the excavation depth increased, and the sandy soil conditions have higher environmental costs than complex soil conditions.

ABSTRACTThe modern society is a world made of concrete. Many buildings, ports, dams, and other infrastructure are made of concrete. Concrete is mainly composed of aggregate and cement. It is mixed with blended water and used after curing. This study used porous feldspar known to react well with cement to replace fine aggregate and reduce cement content. Although feldspar mortar reduced cement content by 5% (25%–>20%), the compressive strength increased 1.4 to 2.9 times compared to its counterpart, Ready-Mixed Mortar (RMM). Using Hydrogen Nano-Bubble Water (HNBW) as blended water, compressive strength was increased from 7% to a maximum of 23%. This proved that hydrogen nano-bubble water could promote cement hydrate creation and reaction. When hydrogen nano-bubble water was used as blended water, thermal conductivity decreased by a maximum of 30% compared to the use of plain water as blended water. Results of this study indicate that construction materials with improved thermal efficiency could be developed.

Most food waste is incinerated and reclaimed in Korea. Due to the development of industry, soil and groundwater pollution are serious. The purpose of this study was to study recycled materials and eco-friendly remediation methods to prevent secondary pollution after remediation. In this study, recycled food waste ash was filled in a permeable reactive barrier (PRB) and used as a heavy metal adsorption material. In situ remediation electrokinetic techniques (EK) and acetic acid were used. Electrokinetic remediation is a technology that can remove various polluted soils and pollutants, and is an economical and highly useful remediation technique. Thereafter, the current density increased constantly over time, and it was confirmed that it increased after electrode exchange and then decreased. Based on this result, the acetic acid was constantly injected and it was reconfirmed through the water content after the end of the experiment. In the case of both heavy metals, the removal efficiency was good after 10 days of operation and 8 days after electrode exchange, but, in the case of lead, it was confirmed that experiments are needed by increasing the operation date before electrode exchange. It was confirmed that the copper removal rate was about 74% to 87%, and the lead removal rate was about 11% to 43%. After the end of the experiment, a low pH was confirmed at x/L = 0.9, and it was also confirmed that there was no precipitation of heavy metals and there was a smooth movement by the enhancer and electrolysis after electrode exchange.

ABSTRACT Porous feldspar is a silicate mineral that is made up of more than 80% of SiO 2 and Al 2 O 3 as components. It has a large specific surface area than sand. It has an excellent reactivity with cement as a pozzolanic component. A normal mortar as a construction material is composed of 75% of sand and 25% of cement. Carbon dioxide (CO 2 ) is a cause of environmental pollution. It is often made when making cement contained in mortar. Therefore, it is necessary to study alternative materials that can reduce the amount of cement used. This study was conducted using feldspar as a fine aggregate instead of sand. First, feldspar was standardized through physical testing. Compressive strength tests were then carried out to compare feldspar mortar and sand-based mortar. Hydration products of mortars were confirmed using a scanning electron microscope (SEM). Result of these tests revealed that when feldspar was used, the compressive strength tended to be high. In this study, Case 3 consisting of feldspar 80% and cement 20% with reduced use of cement was found to be the most suitable one. Secondly, to confirm the appropriateness of using feldspar mortars as a floor material, thermal conductivity and thermal efficiency experiments were conducted using mortars with ingredients that differed from a normal mortar. Results of these experiments revealed that feldspar mortar was more effective as an insulating material than a normal mortar because it had lower thermal conductivity and longer heat retention time than a normal mortar. Therefore, the use of feldspar mortar could have an energy reduction effect compared to a normal mortar as a flooring material in an ondol (under-heating) type floor-heating system in Korea.

The present study purpose was to identify the flow characteristics of the drainage filter considering the characteristics of the landfill site, and to study the basic technology for efficient remediation of heavy metals. To this end, copper heavy metal was selected in consideration of landfill characteristics, and a study on flow characteristics was conducted using hydrophobic coated capillary tubes and microparticles. It was confirmed that the flow rate decreased as the pH increased at the hydrophobic surface, and pH 4, 6, and 8 flowed similarly in the center of the capillary tube, but decreased at pH 10. In the bottom part, it moved at the slowest speed of 1~4 μm/s and middle of center moved 17~25 μm/s. There was little change in flow in the CFD (Computational Fluid Dynamics) numerical analysis considering the surface contact angle, which is a hydrophobic characteristic, and the velocity coefficient was presented by regression analysis through the experimental results. In this way, the current study will be a basic examination of the selective remediation process of pH on hydrophobic coated surfaces.

In this study, highly concentrated hydrogen nanobubble water was utilized as the blending water for cement mortar to improve its compressive and flexural strengths. Highly concentrated nanobubbles can be obtained through osmosis. This concentration was maintained by sustaining the osmotic time. The mortar specimens were cured for 28 days, in which the nanobubble concentration was increased. This improved their flexural strength by 2.25–13.48% and compressive strength by 6.41–11.22%, as compared to those afforded by plain water. The nanobubbles were densified at high concentrations, which caused a decrease in their diameter. This increased the probability of collisions with the cement particles and accelerated the hydration and pozzolanic reactions, which facilitated an increase in the strength of cement. Thermogravimetric analysis and scanning electron microscopy were used to confirm the development of calcium silicate hydrate (C-S-H) and hydration products with an increase in the nanobubble concentration. Quantitative analysis of the hydration products and the degree of hydration were calculated by mineralogical analysis.

In response to the carbon emission reduction trends and the depletion of natural sand caused by the use of cement in construction works, graphene oxide and porous feldspar were applied as countermeasures in this study. By using (3-aminopropyl)trimethoxysilane-functionalized graphene oxide with enhanced bond characteristics, a concrete specimen was prepared with 5% less cement content than that in a standard mortar mix, and the compressive strengths of the specimens were examined. The compressive strengths of the specimen with (3-aminopropyl)trimethoxysilane-functionalized graphene oxide and porous feldspar and the specimen with standard mixing were 26MPa and 28MPa, respectively, showing only a small difference. In addition, both specimens met the compressive strength of cement mortar required for geotechnical structures. It is believed that a reasonable level of compressive strength was maintained in spite of the lower cement content because the high content of pozzolans, namely SiO2 and Al2O3, in the porous feldspar enhanced the reactions with Ca(OH)(2) during hydration, the nano-sized graphene surface acted as a reactive surface for the hydration products to react actively, and the strong covalent bonding of the carboxyl functional group increased the bonding strength of the hydration products.

This paper presents an experimental study on the pullout resistance of a newly improved reinforcement. The applied reinforcement was a smooth steel strip reinforcement with transverse members used to improve the pullout-resistance problems of the smooth steel strip reinforcement. The pullout and bearing resistance of the improved reinforcement were evaluated using results of large-scale pullout tests. The evaluation result confirmed that the bearing resistance of the improved reinforcement was about 33–66% of the total pullout resistance, and it had an evenly distributed friction and bearing resistance. The bearing bond coefficient, considering the interference effect, gradually converged when normal stress was higher than a certain value. This result confirmed that the increment of interference effect is caused by the increment of the transverse member and normal stress. In the pullout-resistance evaluation of the improved reinforcement, a number of transverse members can be predicted using the relationship between bearing-resistance stress and the bearing bond coefficient due to normal stress, which can be applied as a reasonable prediction method.

This study described the relationship of settlement-lateral displacement and settlement-heaving according to the DCM type using the model test results, in order to evaluate the behavioral characteristics of the soft ground improved with DCM. As a result, it was found that the total settlement of the model ground was relatively small in the soft ground, to which the DCM was applied, and the settlement was less in the order of the grid type, wall type, and pile type under the same load conditions. This trend was also the same for the lateral displacement and heaving. In addition, the relationship between settlement and lateral displacement of soft ground was analyzed to be similar to that of previous study (Leroueil et al., 1990). Therefore, the DCM of grid type was evaluated to be superior to other types for lateral flow and heaving in the improvement effect of soft ground.

This study analyzed the effects of applying highly concentrated hydrogen nanobubble water (HNBW) on the workability, durability, watertightness, and microstructure of cement mixtures. The number of hydrogen nanobubbles was concentrated twofold to a more stable state using osmosis. The compressive strength of the cement mortar for each curing day was improved by about 3.7–15.79%, compared to the specimen that used general water, when two concentrations of HNBW were used as the mixing water. The results of mercury intrusion porosimetry and a scanning electron microscope analysis of the cement paste showed that the pore volume of the specimen decreased by about 4.38–10.26%, thereby improving the watertightness when high-concentration HNBW was used. The improvement in strength and watertightness is a result of the reduction of the microbubbles’ particle size, and the increase in the zeta potential and surface tension, which activated the hydration reaction of the cement and accelerated the pozzolanic reaction.

In this study, the overconsolidation ratio (OCR) of soft clay soil was calculated by conducting an indoor physical experiment and a dynamics test using undisturbed soil samples from a soft clay soil field in South Korea. The OCR by depth was predicted by comparing the experimental results with the existing empirical equations. Methods using the liquidity index and the existing empirical equation by the Naval Facilities Engineering Systems Command (NAVFAC) were examined, and the results were compared with the actual measured values. The method using the liquidity index was found to be suitable for estimating the rough OCR of the ground. However, the effect of drying was not considered for the ground above the groundwater level. Therefore, an equation for the correlation equation between the depth and OCR of each region, including the ground above the groundwater level, was proposed. The proposed equation was applied to the OCR prediction of the adjacent area. The predicted values in the area composed of clay (CL, CH) were found to be in good agreement with the actual values. In the region composed of silt (ML), however, the predicted values were not consistent with the actual values. This suggests that the sedimentation and compositional characteristics, rather than the engineering characteristics of the soil, are important factors that affect the OCR prediction.

In this study, to reduce the use of cement and sand, porous feldspar with excellent economic efficiency was used as a substitute in the heat storage concrete layer. When porous feldspar and four other silicate minerals were used as substitute materials for sand in cement mortar, the specimen with the porous feldspar exhibited approximately 16-63% higher compressive strength, thereby exhibiting a higher reactivity with cement compared to the other minerals. To compensate for the reduction in strength owing to the decreased cement content, mechanical and chemical activation methods were employed. When the specific surface area of porous feldspar was increased, the unit weight was reduced by approximately 30% and the compressive strength was increased by up to 90%. In addition, the results of the thermal diffusion test confirmed that thermal diffusion increased owing to a reduction in the unit weight; the heat storage characteristics improved owing to the better porosity of feldspar. When chemical activation was performed after reducing the cement content by 5% and replacing the sand with porous feldspar, the compressive strength was found to be approximately twice that of an ordinary cement mortar. In a large-scale model experiment, the heat storage layer containing the porous feldspar exhibited better heat conduction and heat storage characteristics than the heat storage layer composed of ordinary cement mortar. Additionally, energy savings of 57% were observed.

In this study, the effect of ground improvement was to be verified by granular compaction pile from the ground reclaimed with Fly Ash landfill site. The depth and strength parameters of the Fly ash layer was determined using the ground investigation and cone penetration test. And the STONE C program was used to predict the strength parameter, bearing capacity and settlement of the improved ground. As a result of the plate bearing test, the bearing capacity of improvement ground was higher than the design load and the settlement was smaller than the reference value. After the construction, the improvement effect by the cone penetration test was confirmed. The cone penetration resistance value(q(c)) increased by 250% to 500% and the effect was excellent.