Documents published in Scipedia

• Effect of Alkali-free Accelerator Containing Nano-silica on the Durability of Shotcrete

  W. Liya, W. Kaiyu, C. Guisheng, Y. Maoqian, Y. Guangnuan

  DBMC 2023.

  
  

  Abstract

  The effect of nano-silica-containing alkali-free accelerator and ordinary alkali-free accelerator on the durability of C30 shotcrete was investigated by means of seepage resistance tests and frost resistance tests. The results show that under the same conditions, the C30 shotcrete with nanosilica-containing alkali-free accelerator has a lower electrical flux and a greater impermeability rating than P10. The C30 shotcrete with nano-silica-containing alkali-free accelerator maintains a mass loss rate of about 0.4% after 200 freeze-thaw cycles, a 10.5% decrease in relative dynamic modulus of elasticity, a compressive strength loss rate of less than 20%, the bubble spacing coefficient and the average bubble diameter increased by 20.9% and 60.5% respectively, showing good frost resistance performance. This indicates that alkali-free accelerator containing nano-silica can improve the durability of shotcrete. In addition, a comparison was also made between ordinary accelerator shotcrete with nano-silica, and when 5% nano-silica was added, the properties of shotcrete were comparable to those of 2% nano-silica alkali-free accelerator shotcrete.

  Abstract
  The effect of nano-silica-containing alkali-free accelerator and ordinary alkali-free accelerator on the durability of C30 shotcrete was investigated by means of seepage resistance [...]

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• Combining Wood Protection Options to Enhance Resistance against Decay and Improve Fire Safety of Engineered Wood Products like CLT

  J. Van Acker, W. Li, X. Jiang, M. Durimel, L. De Ligne, B. Parakhonskiy, A. Skirtach, J. Van den Bulcke

  DBMC 2023.

  
  

  Abstract

  Bio-based building products are considered key in our future socio-economic environment, since they are a very relevant nature-based solution (NbS) to climate change. The statement of President von der Leyen (European commission) to turn the construction sector into a carbon sink is critical in this respect: bio-based materials should be used on a larger and more targeted scale in the future. The long-term use of materials is therefore very important since we need to improve the lifespan of renewable materials to increase its carbon sink potential. Hence wood is increasingly considered as a main building material. Service life aspects are critical in relation to the EU Construction Products Regulation (CPR). Traditional treatments to protect against fungal decay and the impact of fire are not always performing adequately and often environmental impact has been an important consideration. The option to enhance wood properties using innovative technologies can be combined with better definition of the expectations and requirements. Besides focusing on combined innovative treatments of the wood matrix, also envelope treatments similar to the use of coatings can be envisaged. This all should lead to an increased use of timber and engineered wood products for green building. This paper mainly focusses on the increased use and high potential of CLT (Cross Laminated Timber) and options to use hardwoods and modified wood (like TMT) in relation to moisture dynamics to come to fit-for-purpose material properties even under more hazardous circumstances.

  Abstract
  Bio-based building products are considered key in our future socio-economic environment, since they are a very relevant nature-based solution (NbS) to climate change. The [...]

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• Capacity of Wood as Flooring Material: Improvement of Thermal Performance of Wood/Phase Change Material Composites

  W. Duk Suh, J. Nam, Y. Uk Kim, Y. Choi, S. Kim, S. Kim

  DBMC 2023.

  
  

  Abstract

  Wood is a biomaterial with good carbon fixation capacity. Phase change materials (PCMs) can impart thermal storage performances to materials. The goal of this study is to improve thermal performance by impregnating PCM into porous wood. The chemical stability of the composites was analyzed to evaluate whether it was appropriate for PCM to be impregnated into wood. Thermal performance of the composites was evaluated through latent heat analysis and thermal conductivity analysis. As a result of the analysis, the composites showed improved thermal performance compared to pure wood. In addition, in order to evaluate the applicability of the composites for floor heating, the dynamic heat transfer test was conducted using specimens as flooring material. As a result, it was confirmed that room temperature maintained the indoor comfort temperature range for longer time in rooms where composite specimens were applied as floor material. Result suggests that the composites can reduce the time for operating heating energy for floor heating. Thus, composites produced in this study proved to have the potential to be used as floor finishing material for floor radiant heating systems.

  Abstract
  Wood is a biomaterial with good carbon fixation capacity. Phase change materials (PCMs) can impart thermal storage performances to materials. The goal of this study is to [...]

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• Transforming low-quality sand into construction materials under 110℃ and Recycling of the Waste Solution

  P. Qiu, Y. Sakai

  DBMC 2023.

  
  

  Abstract

  A strong and eco-friendly material was transformed from low-quality sand via sol-gel method with ethanol as the solvent. 110oC was chosen as a target temperature because it is the average day temperature of the moon, which may be the first place for extraterrestrial development. The appropriate KOH content and ethanol concentration can improve the reaction degree and limit the side reaction. The main results indicated that the highest compressive strength (38 MPa) of the produced material could be obtained by using 20 mass% KOH and 90 V/V% ethanol. According to XRD and FTIR analysis, the formation of sanidine, zeolite, and tetraethoxysilane is the main reason for strength enhancement. Sanidine and zeolite could fill the gap between sand particles and tetraethoxysilane is a good consolidate. Excess ethanol in the waste solution can be reused with recycle rate above 65%. The total carbon emission is 197 kg CO2 eq/m2 after recycling waste solution, which is 35.82% of that produced by normal concrete. Therefore, a tough construction material can be synthesized from lowquality sand, which can partially substitute concrete. This material can address the shortage of raw materials for concrete and can be utilised for extra-terrestrial construction.

  Abstract
  A strong and eco-friendly material was transformed from low-quality sand via sol-gel method with ethanol as the solvent. 110oC was chosen as a target temperature because it [...]

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• Recycling of Silty Waste Soil by CO2 Treatment for Construction Block Manufacture

  Y. Du, Q. Zeng

  DBMC 2023.

  
  

  Abstract

  The poor engineering performance of silty waste soil (SWS) seriously restricts its utilization in new constructions that, in turn, need a large amount of building materials. Meanwhile, traditional sintering technology of clay brick production is prohibited due to its high CO2 emissions. In the present work, a rapid CO2 mineralization method is proposed to treat SWS with active lime after the pressing forming process of building block manufacturing. The optimum mix proportion and pressing forming parameters of SWS blocks are presented. Microstructure of selected SWS block samples is characterized by mercury intrusion porosimetry (MIP) and X-ray computed tomography (XCT), and mineral changes are analyzed by X-rays diffraction (XRD). CO2 emissions from the SWS block production are evaluated considering the entire manufacturing process. Overall, the present study provides a proof-of-concept path that enables recycling of SWS for construction block production with low CO2 emissions.

  Abstract
  The poor engineering performance of silty waste soil (SWS) seriously restricts its utilization in new constructions that, in turn, need a large amount of building materials. [...]

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• Partial Replacement of Fly Ash & Modified Bottom Ash as a Cement & Fine Aggregates in Concrete

  P. R. Khare, D. P. Wanjari

  DBMC 2023.

  
  

  Abstract

  This study envisaged the application of Bottom ash as a replacement of fine aggregate. In this study, bottom ash is thoroughly mixed with a PC-based High range superplasticizer ( HRSP) having solid content more than 60%, this sand is called as modified bottom ash (MBA are mixed at doses of 0%, 0.25%, 0.5%, 0.75%, and 1% by weight of bottom ash. This prepared bottom ash is referred to as modified bottom ash (MBA). MBA is substituted for fine aggregates in ordinary concrete in varying amounts from 0 to 50% by river sand and the concrete has been tested for Compressive strength, flexural strength, split tensile strength, and other durability characteristics it has been found that 10% MBA produce superior outcomes, the purpose of use was not achieved. Therefore, MBA has been increased up to 60% replacement with fine aggregates, the strength and durability properties achieved for concrete produced by 50% MBA with fine aggregate (sand) are compared to 100% fine aggregate (sand) concrete and has observed similar results due to addition of HRSP. In the end, it can be concluded that High Range Superplasticizer HRSP is quite efficient for replacing Bottom ash with fine particles.

  Abstract
  This study envisaged the application of Bottom ash as a replacement of fine aggregate. In this study, bottom ash is thoroughly mixed with a PC-based High range superplasticizer [...]

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• Durable Textile-reinforced Concrete Made of Fast-setting, Mineralimpregnated Carbon-fibers (MCF) Reinforcements and Alkaline-activated Matrix

  J. Zhao, A. Ameer Hamza, M. Liebscher, A. Bartsch, E. Ivaniuk, M. Butler, V. Mechtcherine

  DBMC 2023.

  
  

  Abstract

  Textile Reinforced Concrete (TRC) is a class of material with massive potential to strengthen existing or build entirely new thin-walled structures. However, state-of-the-art polymer-based textile reinforcements commonly suffer under weak compatibility with concrete and insufficient reinforcing efficiency at elevated temperatures. Mineral-impregnated carbon-fiber (MCF) composites represent instead a promising alternative reinforcement with a wide-ranging innovation potential regarding digital and automated processability, freedom design, chemical compatibility and ecological and environmental footprints. Among the existing variants of mineral impregnation, geopolymer (GP) impregnation for carbon fiber (CF) enables stable early-age rheological properties and fast-setting by moderate-temperature activation. The paper at hand presents a methodology to automatically manufacture textile reinforcements made of MCF composites via a continuous pultrusion and robotic–assisted structuring process to meet future market demands. After an advanced geopolymerisation process by thermal curing, the resulting gridlike reinforcements were implemented in a fine-grained, alkali-activated material (AAM) based concrete matrix and characterized with respect to their uniaxial tensile performance. By further applying AAM as cement-free binder, sustainable and fireproof reinforced concrete can be designed with an evident reduction in CO2 emission as compared to conventional cementitious systems. The improved chemical affinity facilitated by GP impregnation governs the cracking phase, resulting in a finer and more diffuse pattern, whereas the higher unidirectional strength of epoxy (EP)-impregnated yarns is responsible for the higher ultimate strength of the composite.

  Abstract
  Textile Reinforced Concrete (TRC) is a class of material with massive potential to strengthen existing or build entirely new thin-walled structures. However, state-of-the-art [...]

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• Durable Structural Concrete Using Fine and Coarse Recycled Aggregates (Type A and Type B)

  C. Vintimilla, M. Etxeberria

  DBMC 2023.

  
  

  Abstract

  The use of Recycled concrete aggregate (RCA, type A) and mixed recycled aggregate (MRA, type B) is an alternative for structural concrete production to reduce natural resource exploitation and landfilling of construction waste. However, the lower quality of recycled aggregate compared to that of natural aggregate, and consequently the lower durability of recycled concrete, make it necessary to limit the percentage of replacement of raw aggregates by recycled aggregates. The objective of this study is to analyse the adequacy of using different percentages (following European standards) of coarse and fine type A and type B recycled aggregates for structural concrete production. All the concrete mixtures were produced using 300kg/m3 of cement and an effective water: cement ratio of 0.48 to be exposed to the XC1-XC4 environment. In addition, the conventional concrete (0% recycled aggregates) was also produced using an effective water: cement ratio of 0.52. The physical and mechanical properties, drying shrinkage values, and durability property of sorptivity and water penetration values were determined in all the produced concretes. It was concluded that the concrete produced with up to 60 % coarse RCA and 30 % fine RCA (type A) aggregates achieved adequate properties for structural concrete. In addition, the use of MRA mixed recycled aggregate (type B) was also possible for structural concrete production when it was employed in the replacement of natural aggregates up to 40% for coarse MRA and 15% for fine MRA simultaneously.

  Abstract
  The use of Recycled concrete aggregate (RCA, type A) and mixed recycled aggregate (MRA, type B) is an alternative for structural concrete production to reduce natural resource [...]

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• Carbon Neutral Concrete – Challenges and Solutions for Sustainable Future

  M. Plançon, Z. Shu Qiang, J. Wong

  DBMC 2023.

  
  

  Abstract

  As the climatic impact is becoming a more important topic for most of the nations which signed the COP 26 accords; many concrete and cement companies have announced their carbon reduction ambitions. Although the CO2 reduction pace varies from one country / company to the other, many of them have clearly stated their commitment towards concrete carbon neutrality in 2050. As a result, we can observe the accelerated emergence of a multitude of new technologies targeting the reduction of carbon content in concrete. The presentation proposed will go over the consequences for the concrete industry of this construction industry’s endeavor climatic impact reduction. It will explain some of the main challenges paving the cement and concrete industry’s journey towards carbon neutrality. It will deep dive in the principles and impacts of the most recent and advanced regulations in terms of low carbon construction such as, for example, RE2020 in France. It will also illustrate some of the realistic solutions currently implemented to reduce the carbon footprint of concrete and cement and adapt to this new market environment, including the use of the latest loT technology which allows the concrete producer to improve their material management, operational efficiency as well as the commercial leverage. In a world where raw materials scarcity becomes increasingly stringent, it will also explore the solutions for the concrete industry to promote circular economy. Finally, it will describe the most probable paths towards carbon neutral concrete and how they will inevitably include environmental footprint reduction beyond climatic impact.

  Abstract
  As the climatic impact is becoming a more important topic for most of the nations which signed the COP 26 accords; many concrete and cement companies have announced their [...]

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• A posteriori error estimation for second-order optimally convergent G/XFEM

  M. Bento, S. Proença, C. Duarte

  admos2023.

  
  

  Abstract

   This work presents a ZZ-BD a posteriori error estimator tailored for 3-D linear elastic fracture mechanics problems that are approximated by second-order pFEM-GFEM formulations. The proposed error estimator is shown to estimate well discretization errors in the energy norm, with the estimated discretization error converging at the same rate as the exact discretization error. Also, the computed effectivity indexes are close to the optimal value of 1 for a LEFM problem that exhibits 3-D effects.

  Abstract
   This work presents a ZZ-BD a posteriori error estimator tailored for 3-D linear elastic fracture mechanics problems that are approximated by second-order pFEM-GFEM formulations. [...]

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