Concrete Recipes Research Articles

The oxidative stress-dependent pulmonary inflammation of inhalable multi-walled carbon nanotube-containing nano-concrete dust and its comparison with conventional concrete dust and DQ12

Nano-concrete, which is an admixture of nanomaterials in concrete recipes, has been investigated to overcome the limitations of existing concrete, such as its stability and strength. However, there is no information on the human health effects of broken-down dust released during the construction and demolition efforts. In this study, we prepared an inhalable fraction of multi-walled carbon nanotube-containing nano-concrete dust and performed comparative toxicity studies with conventional concrete dust and DQ12 using a rat intratracheal instillation model. Although the recipes for concrete and nano-concrete are entirely different, the pulverized dust samples showed similar physicochemical properties, such as 0.46–0.48 µm diameter and chemical composition. Both concrete and nano-concrete dust exhibited similar patterns and magnitudes, representing acute neutrophilic inflammation and chronic active inflammation with lymphocyte infiltration. The toxicity endpoints of the tested particles at both time points showed an excellent correlation with the reactive oxygen species levels released from the alveolar macrophages, highlighting that alveolar macrophages are the primary target cells and that the oxidative stress paradigm is the main toxicity mechanism of the tested particles. In addition, the toxicity potentials of both concrete and nano-concrete dust were more than 10 times lower than that of DQ12.

Output Performance of Collaborative Governance: Examining Collaborative Conditions for Achieving Output Performance of the Dutch Flood Protection Program

Despite abundant research on collaborative governance, relatively little attention has been paid to explaining its performance. When are collaborations performing and what conditions are required to achieve high performance? This study fills this gap by building on the performance matrix for assessing collaborative governance regimes by Emerson and Nabatchi. Drawing on survey data, we use a fuzzy set qualitative comparative analysis (fsQCA) to explore the performance of 26 collaborative flood risk governance projects in the Netherlands. We analyze how conditions of engagement, shared motivation, external expertise, connective leadership and resource availability shape the output performance of these collaboratives. The results reveal four “success” configurations. Success stems, in particular, from “connective leadership” and resources for collaboration working in tandem, or with one of these conditions combined with respectively “external expertise” and “shared motivation.” Failure, in contrast, stems from the absence of multiple conditions. Consequently, we draw lessons about the spectrum of different concrete recipes of collaboration fostering output performance.

Anisotropic properties of additively manufactured concrete elements

AbstractRobotic concrete extrusion is a novel additive manufacturing process (three‐dimensional concrete printing) and is part of a continuously digitally controlled value chain. According to the state of the art, concrete is considered to be an isotropic material due to the manufacturing process. However, for the additive manufacturing process, the isotropic approach has to be reconsidered due to the layered structure. It can be assumed that due to the layered structure, the material properties vary depending on the deposition direction and the geometry of the layers. The aim of the work was to record the material‐technical characteristics of extruded elements manufactured according to standards in comparison with concrete recipes. Process‐related influences on the mechanical parameters of additively manufactured concrete elements were examined and evaluated in more detail. Based on the findings obtained, the dimensioning, design and measurement of components can be carried out and thus guidelines for components can be derived. With these derived guidelines, the material utilization and economic efficiency can be improved.

Recycled Fine and Coarse Aggregates' Contributions to the Fracture Energy and Mechanical Properties of Concrete.

This paper investigates the fracture mechanical properties of concrete, using crushed concrete aggregates (CCA) and granulated blast furnace slag (GGBS) for partial cement replacement. CCAs made from prefabricated concrete replace 100% of the fine and coarse fractions in concrete recipes with w/c ratios of 0.42 and 0.48. Two pre-treatment methods, mechanical pre-processing (MPCCA) and accelerated carbonation (CO2CCA), are investigated for quality improvements in CCA. The resulting aggregates show an increased density, contributing to an increase in the concrete's compressive strength. The novelty of this paper is the superposition of the effects of the composite parts of concrete, the aggregate and the cement mortar, and their contributions to concrete fracture. Investigations are directed toward the influence of fine aggregates on mortar samples and the influence of the combination of coarse and fine aggregates on concrete samples. The physical and mechanical properties of the aggregates are correlated with mortar and concrete fracture properties. The results show that CCA concrete achieves 70% of the fracture energy values of concrete containing natural aggregates, and this value increases to 80% for GGBS mixes. At lower w/c ratios, MPCCA and CO2CCA concretes show similar fracture energies. CO2CCA fine aggregates are the most effective at strengthening the mortar phase, showing ductile concrete behavior at a w/c ratio of 0.48. MPCCA aggregates contribute to higher compressive strengths for w/c ratios of 0.42 and 0.48. Thus, mechanical pre-processing can be improved to produce CCA, which contributes to more ductile concrete behavior.

Investigation of erosive wear effect on concrete water structures: the case of Porsuk Dam, Turkey

Water structures usually consist of concrete surfaces. The concrete surfaces are subjected to erosive wear under the flow of water containing suspended sediment in high concentrations. Such flow-induced erosion is a significant problem for ageing structures because it can shorten their service lives. In this study, Böhme, ASTM C 1138 and newly developed sand–water jet abrasion test methods were used to determine the abrasion behaviour of different concrete types. Various mineral additives, such as fly ash (FA) and ground blast furnace slag (GBFS) were used to improve the wear resistance of the concrete specimens. In the study, the spillway of the Porsuk dam, Turkey, was chosen as a case study. By taking the spillway concrete recipe of this dam as a reference, its abrasion resistance was analysed for different mineral-added concrete recipes. According to the results of the study, it was observed that mixtures using 10% FA and GBFS considerably improved the resistance to abrasion.

CO2 reduction in tunnel construction from a material technology point of view

AbstractTunnelling and underground construction is a material‐intensive undertaking that involves the use of large quantities of concrete. Analyses of the life‐cycle assessment of a new tunnel show that the carbon footprint is largely determined by cement and concrete consumption. Optimising the quantity used, composition and properties of this construction material is thus crucial to reducing ‘'grey'' emissions – CO2 emissions arising from the construction phase. While strength and durability requirements along with exposure classes are clearly set out in directives and tender specifications, CO2 emissions per cubic metre of concrete are not currently considered a relevant criterion when it comes to project design, award and implementation. And this, despite the fact that the current state of knowledge and research shows that substantially lower‐carbon concretes could be used than is generally the case today. A paradigm shift is required to achieve the goal of carbon neutrality in the construction industry.This paper shows how CO2 emissions per cubic metre of concrete can be declared and reduced in tunnel construction, and how concrete recipes can be formulated using climate‐friendly materials, while maintaining the required strengths and durability properties. Using the design approaches outlined here, it is possible to increase clinker efficiency and reduce CO2 intensity without adversely affecting the structure and its functionality.

The Effect of Cement Mortar Recipe on Early Age Strength Development

The paper summarises the results of experimental analysis focused on the maturity method. The method is used to determine the early-age compressive strength of concrete on a construction site to optimise the construction process. All presented calibration curves of different recipes were determined experimentally. Comparison of calibration curves shows effects of specific changes in the recipe on early-age compressive strength development of cement mortar. Investigated changes in the recipe are the following: use of different cement types from different sources, amount of cement, water-cement ratio, used fine aggregates, admixtures and additions. Besides mentioned comparison, the topic of accuracy and deviations is included. Deviations were investigated by repeated determination of calibration curves at a specific time after the creation of the first batch of the calibration curves. The experience acquired during cement mortar experimental analysis will be later used in upcoming experiments at a concrete supplier with different concrete recipes.

THE USE OF RECYCLED MATERIALS FROM ELECTRONIC AND GLASS WASTE IN CEMENT CONCRETE RECIPES

The paper presents two cement concrete recipes containing industrial waste. The first recipe uses a waste resulting from the mechanical processing of electronic boards, used to make industrial prefabricated and a recipe that uses aggregates of crushed glass sort 0-4 mm, used to make prefabricated products. The use of waste is important in the protection of the environment and from the economic point of view the prices of the products decrease.

Principal Component Analysis as a Statistical Tool for Concrete Mix Design.

With the recent and rapid development of concrete technologies and the ever-increasing use of concrete, adapting concrete to the specific needs and applications of civil engineering is necessary. Due to economic considerations and care for the natural environment, improving the methods currently used in concrete design is also necessary. In this study, the author used principal component analysis as a statistical tool in the concrete mix design process. Using a combination of PCA variables and 2D and 3D factors has made it possible to refine concrete recipes. Thirty-eight concrete mixes of different aggregate grades were analyzed using this method. The applied statistical analysis showed many interesting relationships between the properties of concrete and the content of its components such as the clustering of certain properties, showing dependence between the properties and the quantities of certain ingredients in concrete, and reducing noise in the data, which most importantly simplifies interpretation. This method of analysis can be used as an aid for concrete mix design.

Model-Based Adaptive Machine Learning Approach in Concrete Mix Design.

Concrete mix design is one of the most critical issues in concrete technology. This process aims to create a concrete mix which helps deliver concrete with desired features and quality. Contemporary requirements for concrete concern not only its structural properties, but also increasingly its production process and environmental friendliness, forcing concrete producers to use both chemically and technologically complex concrete mixtures. The concrete mix design methods currently used in engineering practice are joint analytical and laboratory procedures derived from the Three Equation Method and do not perform well enough for the needs of modern concrete technology. This often causes difficulties in predicting the final properties of the designed mix and leads to precautionary oversizing of concrete properties for fear of not providing the required parameters. A new approach that would make it possible to predict the newly designed concrete mix properties is highly desirable. The answer to this challenge can be methods based on machine learning, which have been intensively developed in recent years, especially in predicting concrete compressive strength. Machine learning-based methods have been more or less successful in predicting concrete compressive strength, but they do not reflect well the variability that characterises the currently used concrete mixes. A new adaptive solution that allows estimating concrete compressive strength on the basis of the concrete mix main ingredient composition by including two observations for a given batch of concrete is proposed herein. In presented study, a machine learning model was built with a deep neural network architecture, trained on an extensive database of concrete recipes, and translated into a mathematical formula. Testing on four concrete mix recipes was performed, which were calculated according to contemporary design methods (Bolomey and Fuller method), and a comparative analysis was conducted. It was found out that the new algorithm performs significantly better than that without adaptive features trained on the same dataset. The presented algorithm can be used as a concrete strength checking tool for the concrete mix design process.

Sustainable Development of Human Society in Terms of Natural Depleting Resources Preservation Using Natural Renewable Raw Materials in a Novel Ecological Material Production

In the last few years, the building industry experienced a significant development as a response to the demographic growth of human society and to the increasing demand for housing. Their construction involves the traditional use of concrete as a material that provides added strength to the finished building. This is manufactured respecting standard recipes depending on the way of its use. Anyway, all concrete recipes involve the use of mineral aggregates extracted from the riverbed, as is happening in Romania, or rock blocks crushing, as reported in other countries. Under these conditions, the rationalization of the use of natural mineral resources and the identification of new possibilities to reduce their consumption through their replacement with vegetal waste has become an important research issue. In this study, two types of vegetal waste—namely, shredded corn cobs and sunflower stalks—were used to manufacture novel ecological concretes. The vegetal wastes, both in untreated and treated forms (with 20% and 40% of sodium silicate solution), were used to replace 50% of the river (mineral) aggregate volume. The obtained concretes were tested, and the values of some important parameters in the concrete characterization (such as bulk density, water adsorption capacity, compressive strength and splitting tensile strength) were compared with the concrete contains cement CEM II/A-LL 42.5R. The obtained results show that these vegetal wastes have the potential to be used in the manufacturing of new ecological concrete. In addition, this alternative material meets the requirements for the sustainable and healthy development of the environment, offering low-polluting solutions in the context of an increasing demand for constructions.

SYNERGIC EFFECTS OF SUNFLOWER STALKS AND SODIUM SILICATE IN DEVELOPING AN ECOLOGICAL CONCRETE

Building industry is a very large domain in the global economy and it has a lot of consequences over the environment through many and different aspects. These consequences are various, from the more and more extended area of construction up to gas emissions released during materials manufacture and transportation, construction process, exploitation of buildings and, finally, their deconstruction. The concrete, the most used material in construction industry all over the world, must become greener and greener every passing day. Involving natural and renewable raw materials in concrete composition is a variant to develop an ecological concrete that sustain a healthier environment by using less of depleting mineral resources and by decreased gas emissions released into the atmosphere. This research has a high degree of novelty due to its aim to study the effects of sunflower stalks used as partial replacement of the mineral aggregates from the concrete composition, combined with the effects of sodium silicate used as additive. There were developed concrete recipes with sunflower stalks shredded and treated with 40% sodium silicate solution as 20%, 50% and 80% replacement of mineral aggregates with regular concrete additives and then was supplementary added sodium silicate in 5% of the cement volume from the concrete composition. Tests were carried out on the density and compressive strength of the concrete at 28 days and 3 months and on its flexural and splitting tensile strength at 28 days. The results showed that the sodium silicate addition has positive effects on the concrete compressive strength and had no or a small negative effect on its density and tensile strength.

Effect on Radon Exhalation Rate Due to Cracks in Concrete

Abstract The second largest cause of lung cancer in the World is related to radon (222Rn) and its progenies in our environment. Building materials, such as concrete, contribute to the production of radon gas through the natural decay of 238U from its constituents. The Swedish Cement and Concrete Research Institute (CBI), part of RISE (Research Institute of Sweden AB), has examined the effects of cracks in concrete on two different concrete recipes where an Ordinary Portland Cement, OPC-CEM-I concrete (REF) and an OPC concrete including a hydrophobic additive (ADD) were addressed. Two concrete prisms from each concrete recipe were examined. The radon exhalation rate was measured in the pristine state and after concrete cracks had been induced into the concrete prisms. Measurements were performed with an ATMOS 33 ionizing pulsation chamber. The results indicate a strong influence of cracks on the radon exhalation rate. An increase in radon exhalation rate was calculated for every test prism. The increase in radon exhalation rate varied between 80 and 260 %. The crack apertures may play a significant role on the exhalation rate. The concrete prisms with the largest apertures (ADD) also generated the highest radon exhalation rates. The results imply that there could be a substantial variation in the exhalation rate, due to numerous factors, but nonetheless, the results should, raise the awareness of the impact cracks in concrete structures, may have on the final exhalation rate of radon. The exhalation rate of the recipe with an additive (ADD) also showed a lower exhalation rate than for the reference recipe (REF), when compared in a pristine state. This was in part expected. However, the effect of induced cracks and its aperture, seemingly trumps the effect that an additive may play on the radon exhalation rate, when cracks are induced. The hypothesis is in part verified in view of the results of the prism for the ordinary Portland recipe (REF-prisms), were an increase of approximately 100 % would be expected due to the total surface increase. The results also indicate this. The major increase in the radon exhalation rate of the ordinary Portland recipe including an additive, implies however other factors, such as minor internal cracks, that may substantially contribute to the final exhalation rate.

Machine Learning Techniques in Concrete Mix Design.

Concrete mix design is a complex and multistage process in which we try to find the best composition of ingredients to create good performing concrete. In contemporary literature, as well as in state-of-the-art corporate practice, there are some methods of concrete mix design, from which the most popular are methods derived from The Three Equation Method. One of the most important features of concrete is compressive strength, which determines the concrete class. Predictable compressive strength of concrete is essential for concrete structure utilisation and is the main feature of its safety and durability. Recently, machine learning is gaining significant attention and future predictions for this technology are even more promising. Data mining on large sets of data attracts attention since machine learning algorithms have achieved a level in which they can recognise patterns which are difficult to recognise by human cognitive skills. In our paper, we would like to utilise state-of-the-art achievements in machine learning techniques for concrete mix design. In our research, we prepared an extensive database of concrete recipes with the according destructive laboratory tests, which we used to feed the selected optimal architecture of an artificial neural network. We have translated the architecture of the artificial neural network into a mathematical equation that can be used in practical applications.

Detailed characterization of particle size fractions of municipal solid waste incineration bottom ash

Municipal Solid Waste Incineration Bottom Ash (MSWI BA) is of increasing interest as a secondary construction material worldwide. In most cases, MSWI BA is used in isolated conditions. However, according to the Dutch Green Deal B-076 in 2012, by 2020 all MSWI BA should be used in a non-sealed environment in the Netherlands. However, freshly produced. MSWI BA normally does not match environmental legislation due to high leaching of chlorides, sulfates, and potentially toxic elements. Because different particle size fractions of MSWI BA are of interest for designing optimized concrete recipes, it is beneficial to analyze the whole range of MSWI BA fractions in detail. In this study, 14 size fractions of MSWI BA were analyzed to determine the total elemental composition and leaching capacity, mineralogical composition, and shape variety of fine particles. From the point of view of mineralogical composition, 6 particle size fractions (<180 μm, 180–500 μm, 0.5–1 mm, 1–4 mm, 4–22 mm, > 22 mm) can be distinguished. All together the analyses showed that almost all fractions of the investigated MSWI BA can be used as secondary building materials. However, because the leaching of fine fractions is 5–10 times higher than of coarse fractions, all these fractions must undergo various treatments to allow them to match the environmental legislation. Thus, to decontaminate MSWI BA from potentially toxic elements, a division into three size groups is suggested: fine (<125 μm), medium (125 μm - 1 mm), and coarse fractions (over 1 mm).

Experimental and numerical studies on the structural response of normal strength concrete slabs subjected to blast loading

To assess the blast performance of concrete structures, a shock tube has been used to simulate blast loading against concrete slabs of two different mixes ordered as C45/55 and C20/25. The C45/55 slabs were tested without reinforcement, whereas the C20/25 slabs were tested both with and without reinforcement to investigate the effect of adding steel bars on the structural response. The performance of the shock tube itself was also evaluated. Compression tests on cubes and cylinders of both concrete recipes were performed to obtain material input data for numerical simulations. Numerous compression tests were also conducted using the C20/25 mix to obtain insights into the statistical variation in the material properties as concrete is inherently heterogeneous at the macroscopic level. In addition, tensile splitting tests were conducted on both materials. The shock tube tests show that the boundary conditions are important and that the reinforcement will direct the crack pattern. Fluid-structure interaction (FSI) effects are not dominant for this particular problem, because the concrete slabs suffer relatively small deformations before through-thickness cracks appear. Once cracks extend through the thickness, FSI effects may become influential, but it appears that when this occurs there is little or no residual capacity left in the slabs. Numerical simulations were used to investigate the influence of various parameters, revealing that the results are highly dependent on the boundary conditions and particularly on the tensile strength of the concrete. It was found necessary to model the entire clamping assembly to recreate the experimental observations.

Supplementary Cementitious Materials and Additives – Effective Measures to Hinder Radon in Concrete

The second largest cause of lung cancer is related to radon (222Rn) and its progenies in our environment. Building materials, such as concrete, contribute to the production of radon gas through the natural decay of 238U from its constituents. The Swedish Cement and Concrete Research Institute (CBI) has examined ten different concrete recipes containing an additive or Supplementary Cementious Material (SCM), such as fly ash, slag or silica and combinations thereof. The SCM´s were added in small to moderate portions and substituted the reference Portland cement (OPC). The inputs of an additive as well as a supplementary cementitious material were made as a mean to investigate their potential influence on the radon exhalation rates of the concrete as well as the radon gas diffusion length (L) that could be expected from the different recipes. Measurements were performed with an ATMOS 33 ionizing pulsation chamber. The results indicate a reduction of the exhalation rate by approximately 10-55 % depending on recipe at an RH of 75 %. The diffusion coefficients, corrected for background subtraction vary in the interval 1.1 x 10-10 – 7.6 x 10-12 m/s2. The diffusion lengths vary between 2 and 9 mm. In the case where the largest reduction of the exhalation rate is achieved, this roughly correspond to &gt;2 mSv per year decrease in effective dose to a human. Consequently, using an additive or a SCM, as part of the mix, would be an option to effectively lower the radon gas exhalation in their initial stage of production. Secondly, the use of additives and SCM´s will contribute to a lower environmental impact (CO2).

Reduction of Radon Gas in Concrete Using Admixtures and Additives

Abstract The second largest cause of lung cancer is related to radon (222Rn) and its progenies in our environment. Building materials, such as concrete, contribute to the production of radon gas through the natural decay of 238U from its constituents. The Swedish Cement and Concrete Research Institute (CBI) has examined three concrete recipes where only an additive as well as fly ash were added as single constituents to a reference recipe and compared to a reference concrete. The inputs of an additive as well as a supplementary cementitious material (fly ash) were made as a mean to investigate their potential influence on the radon exhalation rates of the concrete. Measurements were performed with an ATMOS 33 ionizing pulsation chamber for at least five different occasions for each recipe during a 22 month period. The results indicate a reduction of the exhalation rate by approximately 30-35 % for each altered recipe. This means roughly 1.5-2 mSv per year decrease in effective dose to a human using an additive or a supplementary cementitious material such as fly ash in relation to the investigated standard concrete.

Shear Capacity of Reinforced Lightweight Concrete Beams: Concrete Recipes and Experimental Results

Shear Capacity of Reinforced Lightweight Concrete Beams: Concrete Recipes and Experimental Results

Methodology of calculating required chloride diffusion coefficient for intended service life as function of concrete cover in reinforced marine structures

For marine reinforced concrete (RC) structures, chloride initiated corrosion of reinforcement is generally accepted as the service life limiting degradation mechanism. A methodology is described for how the maximum required chloride diffusion coefficient (D) of a concrete for achieving an intended service life (t) can simply be calculated as a function of concrete cover thickness (x) over the reinforcement by D = constant·x2/t.The principle is based on the usual mathematical solution to Fick's 2nd law of diffusion. The constant is broken down into 3 factors; chloride concentration factor, aging factor and temperature factor, in which input parameters have to be selected. These factors are calculated for a range of selected input parameters illustrating their sensitivity. The largest uncertainty lays in proper selection of the aging factor of the diffusion coefficient. Some concrete recipes satisfying estimated chloride diffusion coefficients are proposed as part of the methodology.