Conductivity Of Concrete Research Articles

The Effect of Fly Ash Additive on the Thermal Conductivity of Polystyrene Concrete

The use of fly ash in compositions as a substitute for a part of cement is economically favorable and ecologically feasible in connection with large accumulations of waste at the enterprises of the energy sector. In addition, the technology of cement production provides high-temperature treatment of mineral substances in kilns with significant emissions of carbon dioxide. One of the most effective directions of the utilization of fly ash is their use in concrete composites. The use of this material will provide the required temperature and humidity conditions in residential premises, solve the problem of “cold bridges” in structures, minimize heat losses of the structure, and increase the energy efficiency of buildings in general. At the same time, polystyrene concrete, due to its structural structure and the presence of thermally conductive concrete, has limited opportunities for thermal and physical–mechanical properties. To improve the operational properties of polystyrene concrete, it is proposed to use composite binders, including fly ash from the thermal power station of Astana. The main aim of this study is to develop compositions of polystyrene concrete with reduced thermal conductivity and improved physical and mechanical properties. The objectives of this study include the determination of characteristics of fly ash from Astana, formulation of polystyrene concrete mixtures with different proportions of fly ash, and evaluation of their thermal conductivity properties. These tasks are in line with the objectives of the ISO 50001 standard to improve energy efficiency and reduce environmental impact. The results showed that the addition of fly ash from Astana to polystyrene concrete leads to a marked reduction in thermal conductivity, contributing to improved energy efficiency of the building envelope. Optimal results were achieved by using 15% of Astana fly ash as an additive in polystyrene concrete, which led to a significant reduction in thermal conductivity of 51.47%. This reduction is in line with improving the energy efficiency of building materials, especially in cold climates.

Development of Test Methods in the Process of Electrically Conductive Concrete Production

Abstract Prevention of climate change, implementation of sustainable development principles in building industry, creation of Green buildings, Three-zero buildings (zero energy, zero emissions, zero waste), energy independent buildings maybe on the base of Smart Concrete. Electrically Conductive Concrete as type of Smart Concrete have the possibilities to create multifunctional hybrid structures for various purposes. The production of electrically conductive concrete is usually based on the introduction of carbon materials and carbon nanomaterials (CNMs) as electrically conductive fillers into its concrete composition. The theory of conductive percolation is used for design of electrically conductive concrete. To select electrically conductive carbon filler, it is necessary to summarize their electrically conductive characteristics. Today, there is no standard for determining the electrical conductivity of carbon fillers, nor is there a method for designing the composition of electrically conductive concrete; the development of both is imperative. Features of the preparation of electrically conductive concrete with hydrophobic carbon nanoparticles prone to aggregation are indicated. To obtain high quality electrically conductive products an operating system for quality control at the stages of the technological process of manufacturing must be proposed. Homogenization of the electrically conductive filler is very important. It is necessary to propose a method for assessing the stability of an aqueous suspension of a hydrophobic carbon material used for homogeneous distribution of a filler. Due to the lack of a standard, a method for determining the electrical conductivity of concrete is also needed.

Study on physical properties and snow-melting performance of multilayer composite conductive-pervious concrete for improving the snow-melting efficiency and energy consumption of ECON

One of the most significant challenges facing transport networks in cold regions is snow accumulation on road surfaces. This can lead to traffic congestion and safety issues. While electrically conductive concrete (ECON) heated pavement systems (HPS) offer several advantages, including stability, and low environmental impact, they also present certain limitations, such as low snow-melting efficiency and high snow-melting energy consumption. In this study, a SiO2 aerogel mortar thermal-insulation layer and a self-compacting concrete structural layer were set underneath the reduced graphene oxide (RGO) composite conductive concrete, and the straight pervious channels were prefabricated, to reduce the snow-melting efficiency and energy consumption through the preparation of multilayer composite conductive-pervious concrete integrated specimen. The initial objective was to investigate the influence of SiO2 aerogel substitution rate on the mechanical properties and thermal conductivity of thermal-insulation mortar. Secondly, the impact of the thickness of the conductive layer and thermal-insulation layer on the mechanical properties of the integrated specimen was analyzed. Finally, the impact of SiO2 aerogel thermal-insulation mortar and straight pervious channels on the integrated specimen's snow-melting performance was evaluated through a snow-melting test, which assessed the efficiency and energy consumption of the snow-melting process. The results indicate that when the SiO2 aerogel substitution rate was 40 %, the thermal-insulation mortar exhibited favorable mechanical and thermal-insulation properties. The 5 cm conductive layer and the 1 cm thermal-insulation layer achieved good mechanical properties of the integrated specimen. In comparison to single-layer composite conductive concrete, the snow-melting time and energy consumption of multilayer composite conductive-pervious concrete integrated specimen were reduced by 23.05 % and 21.30 %, respectively. The straight pervious channels permit the immediate discharge of water produced by snow melting, thereby reducing the heat transfer from the snow-melting board to the water film. The setting of SiO2 aerogel thermal-insulation mortar enables the retention of heat for the heating of the snow-melting board and snow melting, which improves the snow-melting performance.

Impact of different water-reducing agents on the properties of limonite self-compacting conductive concrete

The application environment for concrete is becoming increasingly complex, accompanied by an intensification of its functional requirements. This paper presents a method for developing self-compacting concrete with conductive properties using limonite and graphite as the concrete conductive phases. In the process of concrete preparation, the limonite is initially treated by a pre-wetting method to prevent the surface depression caused by the addition of limonite during the concrete curing process. The second stage of the process involved optimising different proportions of limonite and graphite and different dosages of water-reducing agent, defoamer and dispersant to prepare concrete. The influence of different dosages of limonite and graphite and different dosages of water-reducing agent on the mechanics and electrical conductivity of concrete was studied in order to obtain self-compacting conductive concrete with performance indicators meeting the requirements of self-compacting and electrical conductivity. The results demonstrate that the mechanical and electrical properties of self-compacting conductive concrete prepared with polycarboxylic acid superplasticizer and retarding superplasticizer combined with superplasticizer are satisfactory, and the composite superplasticizer can function in conjunction with dispersant. The self-compaction index, slump expansion, expansion time T50 and J-ring expansion of fluid concrete meet the requisite standards. Once the concrete has reached the designated curing age, its compressive strength and flexural strength align with the anticipated design expectations, while its resistivity meets the stipulated conductivity index requirements.

Electric Resistance and Curing Temperature Development of Carbon Fiber-Reinforced Conductive Concrete: A Comparative Study.

The development of electric resistance is a key factor affecting the performance of conductive concrete, especially the electrical-thermal performance. In this work, the effects of different influencing factors (including the water-to-binder ratio, coarse aggregate content and carbon fiber (CF) content) on the electric resistance of conductive concrete were systematically investigated. At the same time, ohmic heating (OH) curing was applied to fabricate CF-reinforced conductive concrete (CFRCC) under a negative temperature environment at -20 °C. The effects of different factors on the electrothermal properties (curing temperature and conductive stability) of the samples were studied. The mechanical strengths of the CFRCC cured by different curing conditions were also tested, and the feasibility of OH curing for preparing CFRCC in a negative-temperature environment was verified at various electric powers. This work aims to give new insights into the effects of multiple factors on the performance of CFRCC for improved concrete construction in winter.

Electrical resistivity of eco-friendly hybrid fiber-reinforced SCC: Effect of ground granulated blast furnace slag and copper slag content as well as hooked-end fiber length

Over the last 20 years, the development of electrically conductive composites for removing snow and ice from transportation infrastructure has received exceptional traction. However, these composites need to exhibit stable electrical conductivity and high mechanical properties to be sustainable and cost-effective. Towards this goal, the article investigates the roles of ground granulated blast furnace slag (BFS) and copper slag (CS) content, in addition to hooked-end steel fiber length, on the electrical properties of eco-friendly ultra-high performance hybrid fiber-reinforced self-compacting concrete (HFR-SCC) for the first time in the literature. For this purpose, sixteen eco-friendly electrically conductive ultra-high-performance HFR-SCC were designed based on the variable parameters of four different BFS/total binder ratios (20, 40, 60, and 80 %), a CS/total fine aggregate ratio of 50 %, and two different hooked-end fiber lengths (30 and 60 mm), while all mixes used 1.75 % by volume fraction of steel fibers. After determining the workability properties (slump-flow and T500 values) of all mixes, compressive strength and electrical resistivity/conductivity tests of 90-day specimens were conducted. Additionally, environmental and economic evaluations of all mixes in terms of sustainability were performed in order to clarify the effects of the variable parameters. Taking into account the experimental results obtained, it was observed that all electrically conductive ultra-high performance HFR-SCC mixes demonstrated satisfactory workability properties, while the compressive strength values reached to impressive values of 127 MPa. The optimum BFS/total binder ratio was identified to be 40 % for higher compressive strength and conductivity of ultra-high performance HFR-SCC specimens. On the other hand, the addition of CS to the mixes resulted in an increase of almost 9 % in compressive strength compared to one without CS, while at the same time, a significant increase of approximately 363 % was observed in the electrical conductivity values of the specimens. As for the influence of different lengths of hooked steel fibers, the use of 30 mm length hooked-end steel fibers in HFR-SCC mixes performed better in terms of compressive strength, whereas 60 mm fibers performed better regarding electrical conductivity. In conclusion, this experimental work has evidenced that it is possible to develop an eco-friendly and sustainable electrically conductive ultra-high performance cementitious composite (the optimal mix compressive strength and electrical resistivity values were 127 MPa and 2242 Ω.cm, respectively) by using waste from different industries such as iron and copper. Thus, it will provide important insights for the design and application of future electrically conductive concretes, which can be an important alternative in efficient active deicing and snow-melting applications.

Innovative GQDs and supra-GQDs assemblies for developing high strength and conductive cement composites

Recently, there has been significant interest in using several types of graphene derivatives to enhance the performance of cement composites. There are novel graphene quantum materials called graphene quantum dots (GQDs) in ultrafine scales, and none has been explored in cement materials. This work presents the effects of these two synthesized graphene derivatives (Qds and BC) on the flow, bulk density, permeable void, water absorption, compressive strength, flexural strength, sulphate attack, electrical conductivity, thermal conductivity, and microstructures of cement composites, compared with commercial graphene oxide (GO) and plain mix. The findings show that the composites containing GQDs have excellent fresh, physical, mechanical, and sulphate attack properties. The 1.2% BC composites has the highest compressive and flexural strengths, with 40% and 108% higher than the control, respectively. Moreover, their electrical and thermal conductivity properties increased as a function of GQDs content. The microstructural bridging mechanism regarding the seeding and crystal growth of C-S-H phase were seen. This study offers novel insights into the role of using GQDs in cement composites such that the materials can be used as a high performance, high conductive concrete, which can be a future of the GQDs in the construction industry.

Carbon materials for electrically conductive concrete

In recent decades, the direction of building materials science related to the creation of Smart Concretes has been rapidly developing. Smart Concretes, in addition to the functions of a structural material, also perform other functions that are related to their new properties. Among the large number of Smart Concretes, it is necessary to highlight Electrically Conductive Smart Concrete. This type of concrete is obtained by adding conductive fillers to the concrete mixture. Among them, carbon materials are the most promising in terms of their properties. Despite the large number of conducted studies of conductive fillers and conductive concrete, there is still no generalization and systematization of them. In addition, there are no standards for testing the conductive properties of both fillers and concretes. Therefore, the authors aimed to systematize data on Electrically Conductive Smart Concrete, as well as electrically conductive carbon fillers. A method for testing the electrical conductivity of Carbon Nanomaterials (CNMs) as fillers for Electrically Conductive Concrete is proposed. Approbation of the proposed method was carried out by determining the electrotechnical indicators of carbon fillers, such as coke breeze and carbon black.

Electrical sensing properties of smart concrete enhanced with nano materials

The structures have to be assessed for its failures caused by design and construction errors, material deterioration, adverse environment effect hence monitoring the structural health has shown to be a reliable method of assuring the structural integrity. The advanced development of sensor technology and sensing material are the most attractive parts of evaluating structural health. The change in stress, strain, crack formation, temperature variation is measured using fiber optic sensors, piezometers and other sensor types are often utilized in health monitoring systems. Sensors can degrade over time due to exposure to moisture, temperature fluctuations, wearing and tearing or physical impacts. Additionally, installing and maintaining sensors can be costly. These restrictions might be addressed by incorporating sensing technology, such as smart sensing concrete, into concrete structures. This paper explores the piezo resistive properties in concrete by introducing functional fillers like carbon fiber, carbon nano tubes, graphene materials to make electrically conductive concrete that are used to assess its own deformation. This technology could lead to more efficient maintenance and repair processes, ultimately increasing the lifespan of buildings and bridges reduces the wastage of resources leads to sustainability

Experimental Study on Engineering Properties of Recycled Olivine Aggregate Filled CF Reinforced Electrically Conductive Mortars

Electrically conductive concretes produced for different purposes were introduced years ago and since then, intensive scientific research has been going on. Studies in the literature have generally been carried out on conventional concretes with electrical conductivity for floor applications. The current study investigates carbon fiber reinforced mortars filled with fine olivine aggregate. Fine aggregate filled mortars are generally produced for building facade applications. Within the scope of the study, the mechanical, electrical, dynamic and microstructural properties of cementitious mortars containing 0.5%, 0.75% and 1.0% carbon fiber and 100% recycled olivine aggregate were investigated. The purpose of performing dynamic resonance tests was to investigate the effect of carbon fiber on damping ratio. 28-Day compressive, flexural, dynamic resonance, ultrasonic pulse velocity (UPV), Leeb hardness and dry density tests of conductive mortar samples obtained from four different mixtures were performed. In addition, 2, 14, 28, 90 and 180 days electrical conductivity tests were carried out to determine their resistivity in different time intervals. The purpose of performing dynamic resonance tests was to investigate the effect of carbon fiber on damping ratio. While a significant positive effect of CF on electrical conductivity and damping ratio was observed, a negligible decrease in mechanical results was observed. Calcium silicate hydrate (C-S-H) structure formed by hydration using olivine filler in the cement mixture confirmed the binding formations.

Snow-melting performance of the thermally conductive concrete pavement – experimental evaluation in field application

This paper evaluated the snow-melting performance of thermally conductive concrete incorporating silicon carbide (SiC) and copper powder (CP) in the field experiment. Before conducting the in-situ test, a mock-up test was previously performed. In the investigated properties of the mock-up test, the thermal conductivity test, normal concrete was 1.71 W/mK, the concrete with SiC 50% and CP 10% was 6.82 W/mK, and the concrete with SiC 100% and CP 10% was 9.22 W/mK. In addition, the ice layer melting test followed the thermal conductivity results as expected. The possibility of the snow-melting performance improvement was found in the mock-up test, therefore, the in-situ test was conducted. In the in-situ experiment, the thermal conductivity result of normal concrete (OPC-F) was 1.62 W/mK and the thermally conductive concrete (TC-F) was 3.23 W/mK. In addition, the compressive strength of OPC-F was 41 MPa and TC-F was 45 MPa. This phenomenon is related to the filler effect of SiC and CP according to the existing studies, it could be found in the field test as well. The key point was the snow-melting performance of TC-F, TC-F showed faster melting speed than OPC-F the 2 h after the starting time of the snow-melting test. Consequently, substituting a portion of aggregate with SiC and adding CP significantly enhances thermal transfer performance and snow-melting efficiency in cement composites. This study highlighted the importance of high thermal conductivity materials for cold-region road pavements and demonstrated practical application potential.

Self-Consolidated Concrete-to-Conductive Concrete Interface: Assessment of Bond Strength and Mechanical Properties

In this paper, the mechanical properties and bond strength of composite samples that consist of a conductive concrete (CC) layer and a self-consolidated concrete (SCC) layer are investigated. The bond strength study includes two parameters: (1) surface preparation and (2) casting and testing directions. The surface preparation study shows that, compared to the other methods in this study, the shear key method is the most suitable surface preparation method to fully utilize the CC in a composite. Moreover, the casting direction study reveals that the strength is heavily dependent on the type of test used along with CC’s layer positioning. The flexural strength study confirms that positioning the CC mix in the tensile region is beneficial since it can increase the flexural strength of a structure because of the hybrid steel fibers included in the mixture. Finally, different codes/specifications and published theoretical results are used to predict the CC’s mechanical properties, and the predictions are not as accurate as the SCC predictions, which can be attributed to the presence of conductive fillers in the CC mix.

Influence of the Amount of Conductive Component on the Electrical Resistivity of Fine-Grained Electrically Conductive Concrete

Approaches to the production of electrically conductive concrete and the possibility of its application through the use of electrical properties in various industries are considered. The results of testing the compositions of fine-grained self-compacting concrete based on Portland cement CEM I 52.5 N, sand with a size modulus Mk=2.43 and polycarboxylate plasticizer for changes in electrical resistivity during hardening are presented. The increase in specific electrical conductivity was provided by the introduction of conductive components in various quantities, such as construction soot, carbon black K-354, graphite EUT-2. The positive effect of increasing the amount of the conductive component on the electrical resistivity for 28 days of normal hardening of the samples and on the ability to resistive heating by changing the surface temperature of the samples when passing a direct current with a voltage of 30 V. is shown.

Design and performance evaluation of an electrically heated concrete panel for sustainable winter maintenance

This study focuses on developing an electrically heated concrete panel system incorporating carbon fiber (CF) and carbon nanotube (CNT) as electrical media. Properties of 8 different electrically conductive concrete mixtures, such as workability, air content, compressive strength, and electrical resistivity, were experimentally evaluated to find optimum mixture proportions. Subsequently, three laboratory specimens with different geometric designs were fabricated using a two-lift concrete placement scheme: a normal concrete (NC) layer at the bottom and a conductive concrete (CC) layer at the top. Conventional ribbed rebars were embedded as electrodes to supply electrical power. The electrical heating performance of the specimens was evaluated based on the temperature rise and thermal strain changes during the imposed heating cycles. The findings demonstrated the potential use of the developed electrical HPS for sustainable winter maintenance, which will contribute to advancing heated pavement technologies and minimize the environmental impact caused by traditional snow removal practices.

Preparation of carbon fiber conductive concrete and study on its mechanical and heating properties

Carbon fiber conductive concrete demonstrates great potential for effectively removing ice and snow from road surfaces. This study investigates the electrical conductivity and electromagnetic heating effects of carbon fiber conductive concrete, considering different carbon fiber dosages and temperatures. Experimental and numerical simulation methods were employed to assess the material's performance. The results show that as the carbon fiber content increases to 0.38 % and 1.5 %, the compressive strength decreases by 19 % and 55 %, respectively, which is related to the introduction of more bubbles and the agglomeration of carbon fiber when the carbon fiber is added, making it easier to produce stress concentration when the concrete is compressed. However, when the content of carbon fiber is small, the tensile properties of carbon fiber itself can improve the overall splitting tensile strength of concrete. With the increase of carbon fiber content, carbon fiber gradually forms a conductive network in the concrete, and the overall resistivity of the concrete decreases, but there is a certain threshold. Overall, 0.75 % fiber is the best solution. In addition, the heating process is accurately simulated by numerical simulation method. The simulation results are in good agreement with the experimental results, showing that the heating rate decreases with the increase of energizing time until reaching the heat equilibrium state. And the precise temperature distribution and change process that can be obtained through simulation provides valuable insights for engineering design.

The permeability, mechanical and snow melting performance of graphene composite conductive-pervious concrete

Snow on the roads poses a serious threat to the safety of vehicles, and the traffic system will be paralyzed under harsh conditions. In this study, composite conductive concrete with straight pervious channels were prepared by using carbon fiber, steel fiber and reduced graphene oxide (RGO) as conductive materials to remove snow from roads as soon as possible. The effects of RGO on the workability, mechanical properties and electrical conductivity of composite conductive concrete were studied, and the influence of pervious channels on snow melting efficiency and energy consumption of composite conductive concrete snow melting slabs were analyzed. Results showed that the permeability coefficient of composite conductive concrete with pervious channels reached 6.28 mm/s, meeting the requirements of pavement pervious concrete. For the RGO content of 0.09 % cement mass, the mechanical properties and conductivity of the composite conductive concrete were improved because of the filling effect of nano-RGO on the matrix, while it exerted adverse effects when RGO contents were over 0.09 %. The pervious channels weakened the mechanical and conductive properties of composite conductive concrete. However, compared with the composite conductive concrete without straight pervious channels, the snow melting time and energy consumption were reduced by more than 10 % and 15 %, respectively.

Electrical and microstructural characterization of carbon nanotube-carbon fiber added cementitious conductive surface coating

In contrast to the traditional methods of directly adding conductive fillers to the cement matrix in the development of heatable conductive concrete, radiation shielding and smart sensing cementitious materials, this study proposes a more efficient approach by covering the non-conductive glass fiber reinforced concrete (GRC) surface with a thin conductive layer. Single-walled carbon fiber (SWCNT) and carbon fiber (CF) were used as conductive additives in the mixture of electrically conductive surface coating. Dosages of 0.1%, 0.2%, and 0.3% (wt) for SWCNT and 0.2%, 0.4%, 0.6%, 0.8%, and 1% (Vol) for CF were preferred. According to these ratios, a total of 15 different conductive cement coatings were carried out. White Portland cement and fine silica sand were used as binder and filler material, respectively. The conductive cement-based coating with a thickness of approximately 3 mm shows good adhesion and integration properties, since it is placed in the mold gradually at the same time as the GRC, which acts as the substrate. Resistivity, impedance, heatability (electrothermal), TGA-DTA and microstructure characterization were performed to investigate the electrical, thermal and microstructural properties of the coatings.The impedance/resistance properties of the cement-based composite samples containing CF showed superior performance compared to the other samples. In TGA/DTA analyses, the amount of CF in the cement mixture did not affect the thermal weightlossmuch. The lowest resistivity values were measured as 20 and 80 Ω.cm for the CF1.0 and CF0.8 samples, respectively, and the electrothermal test results showed that the temperature reached 45.5 and 28 °C from 23 °C, respectively, by applying 24 V voltage within 1 h with a power consumption of 750 W/m2 and 232 W/m2.

Mechanical and Electrical Properties of Multilayer Graphene Composite Conductive Concrete

Mechanical and Electrical Properties of Multilayer Graphene Composite Conductive Concrete

Effect of Nanographite Conductive Concrete Mixed with Magnetite Sand Excited by Different Alkali Activators and Their Combinations on the Properties of Conductive Concrete

In order to obtain conductive concrete with good electrical conductivity and good mechanical properties, nanographite and magnetite sand excited by different activators and their combinations are added to ordinary concrete to obtain high quality and efficient conductive concrete. The optimal mixture ratio of alkali-excited conductive concrete and the effects of different activators and their combinations on the mechanics and electrical conductivity of concrete were studied. The microstructure of alkali-excited conductive concrete was analyzed by scanning electron microscope (SEM) to study its conductive mechanism. Results show that the conductive concrete obtained by compounding sodium hydroxide, sodium sulfate and calcium hydroxide has optimal mechanical and electrical properties when the graphite is 6% cement, and magnetite sand is 40% fine aggregate. The conductive concrete sample prepared by this method has a flexural strength of 6.84 MPa, a compressive strength of 47.79 MPa and a resistivity of 4805 Ω·cm (28 days). Compared with ordinary concrete (no nanographite and no magnetite sand), the compressive strength of conductive concrete is increased by 122.3%, the bending strength is increased by 116.5%, and the resistivity is reduced by 99.1%. SEM shows that the distribution of conductive materials in concrete is more uniform due to alkali excitation and calcium silicate hydrate (CSH) gel can be formed, which leads to better performance. The research in this paper is only a preliminary exploration of the characteristics of green conductive concrete, and the conductive heating characteristics and electromagnetic wave absorption properties of concrete, along with strength characteristics after adding conductive fillers, need to be further studied. It is suggested that further research should be carried out on the deicing characteristics of conductive concrete and the electromagnetic wave absorption properties used in stealth military engineering.

Identifying the best mixing procedure practice for ready-mix concrete plant production of carbon fibre reinforced electrically conductive concrete

ABSTRACT Electrically-conductive concrete (ECON) can generate heat for melting pavement ice if an electrical voltage is applied, and this ECON-heated pavement system (HPS) is a viable alternative to the traditional snow removal methods. This study aimed at determining mixture proportions and procedures suitable for ready-mix concrete-plant-produced carbon fibre (CF)-reinforced ECON. Trial batches ECON production involving five different mixture proportions and procedures were performed at a ready-mix concrete plant. Study results suggest that CF begins to degrade with increased mixing time. A twelve-minute mixing time from the start of loading CF onto the mixer until the end produced the best-performing ECON, with an electrical resistivity of 224 Ω-cm and a heat-generation rate of 2°C/min. Scanning electron microscopic (SEM) image analysis shows that CF remained as blobs of fibre instead of being uniformly dispersed. Further research is recommended to find an efficient way of separating individual CF from the blobs and ensuring uniform CF dispersion to reduce the dosage rate and construction cost of ECON.