Ready Mixed Concrete Production Research Articles

Sustainable concrete production with recycled concrete wash water beneficiated with CO2

A significant amount of wastewater is generated through the cleaning of equipment utilized within the ready mixed concrete production cycle. The reuse of concrete wash water as mix water is limited by the negative material performance impacts associated with the suspended solids; the effects are exacerbated with increasing solids contents and water aging. A novel carbon dioxide treatment to allow the use of high solids wash water (specific gravity 1.10) as mix water was examined. Seven batches of concrete were produced and compared: a reference mix, two batches with untreated wash water and four batches with CO2 treated wash water. The carbon dioxide treatment mineralized CO2 at 28% by mass of the treated solids. Acceptable concrete was produced through adjusting admixtures for workability. The compressive strength at 1, 7, 28 and 56 days was improved relative to both the reference and the concrete produced with untreated wash water. The suspended solids containing mineralized CO2 served as a viable cement replacement. The avoided cement and bound carbon dioxide served to lower the carbon impact of the concrete by about 14%. The approach allows three waste streams (CO2, wash water and wash water solids) to be reused to produce more sustainable concrete.

An investigation of flexural and compressive strengths of fly ash coarse aggregate concrete beams

Fly ash is a great cement alternative that may be utilized in the cement manufacturing process or as a separate addition at the batching plant during ready-mix concrete production on-site or at a ready-mix concrete facility. As a by-product, India’s 85 thermal power plants produce a massive amount of Fly ash (140 million tonnes per year), almost equalling the annual cement output. Fly ash is dumped in open fields, causing ecological and environmental issues. In this case, three considerations—environmental safety, energy savings, and the intrinsic benefits of using Fly ash—necessitate a thorough examination of the implications of using Fly ash in concrete construction by the construction industry. Thus, there is a lot of interest in using fly ash in concrete, which is reflected in the concrete industry’s current growth. As a result, the focus of this work is on an experimental investigation of the characteristics of fly-ash concrete. The flexural behaviour of fly ash concrete beams with and without reinforcing is the subject of this study. The prepared fly ash concrete beams surface morphology and porous of materials was analyzed by SEM and by XRD analysis. Fewer than two point loads, all beams have the same dimensions. Fly ash aggregate concrete has higher Ultimate load, Energy absorption potential, and Deflection values than ordinary concrete, according to the results of the experiment. The crack value is calculated as same.

Utilization of concrete slurry waste for soil stabilization

The stabilization of clay soils is one of the crucial problems of engineering, because it determines the long-term stability and operability of structures, especially in case of infrastructure. Present work is focused on the experimental investigation of the utilization of concrete slurry waste (CSW), which is generated during ready-mix concrete production, as a stabilizing agent of clay soil. The alkaline character and content of cement residues in the studied waste material provide suitable potential for the proposed application. The contribution of CSW to soil stabilization was investigated in terms of compressive strength, the California bearing ratio (CBR) and Immediate bearing index (IBI). The nature of the stabilization process was documented by scanning electron microscopy (SEM) and monitored by thermal analysis and X-ray powder diffraction (XRD). The performed experimental program was organized as benchmark test to express the stabilizing properties of CSW in comparison to ordinary Portland cement (OPC). The studied CSW contributes to soil stabilization by the calcium ion exchange, what was documented by IBI, and by the formation of hydraulic products. The studied CSW attained a stabilizing effect by 38% than with the same dose of OPC in terms of compressive strength. The studied waste material has great potential to achieve economic and environmental savings, if applied to soil stabilization.

Development of High-Strength Concrete Mixed Design System Using Artificial Intelligence

The quality inspection of high-strength concrete construction sites consists of a compressive strength test that is considered the most important, but this can be confirmed through a compressive strength test after 28 days of high-strength concrete application. Therefore, it is of paramount importance to ship high-quality products to ready-mixed concrete factories by increasing the reliability of the mixed design that affects high-strength concrete production. In addition, there is a need to develop an efficient management system for mixed design that determines high-strength concrete quality by measuring the mixing ratio of materials in the ready-mixed concrete factory production stage. This study used matrix laboratory(MATLAB) using Deep learning, a language that performs mathematics and engineering calculations based on matrices, and presented a mixed design model by adjusting the strength through input and output variables, learning data collection, model structure determination, learning error, and repetition results. The predicted mean value of 40 MPa was measured at 40.75 MPa, showing a difference of 0.75 MPa and 40 MPa, and the error rate was confirmed to be 4.13%. And the predicted mean value of 55 MPa was measured as 55.55 MPa, showing a difference between 55 MPa and 0.55 MPa, and the error rate was confirmed to be 1.73%. Through this study, the reliability of high-strength concrete quality management is secured by applying a high-strength concrete mixed design system using artificial intelligence(AI) and adjusting it in connection with all fields of the production process.

Impacto do transporte nas emissões de CO2 do concreto: um estudo de caso em Rio Branco/Brasil

Abstract Due to the scarcity of crystalline massifs in the north of Brazil, concrete producers have been using crushed stone and cement from suppliers located hundreds of kilometers away. In this case, CO2 emissions related to material transportation for concrete production may become significant. Thus, this study aims to analyze the influence of the transportation of the materials in CO2 emissions of ready-mix concrete production in Rio Branco (Acre). Concrete compositions were obtained from a local concrete producer. Brazilian methods of dosage were not applicable due to the high fineness of the regional sand available; the mix designs were adjusted empirically. Two types of cement (CP V-ARI and CP IV) were considered to create the studied scenarios. Transportation distances of the raw materials (cement and aggregates) ranged from 20 km (local sand supplier) to 3,592 km (cement supplier from Sete Lagoas, MG). CO2 emissions to produce concrete (fck of 25 MPa, cement consumption of 426 kg/m3) ranged from 208 kgCO2/m3 to 573 kgCO2/m3. Transportation was responsible for up to 20% of total emissions. The emissions in this study are considerably higher than the national data of concrete production available in the Construction Environmental Performance Information System (Sidac) due to the higher cement consumption and higher transportation distances. Although cement consumption in Acre represents less than 1% of Brazilian consumption, the results reveal the impact of transportation distances in CO2 emissions of concrete in cities that deal with local scarcity.

Application of an Improved Empirical Model for Rheology Prediction of Cement Pastes Modified with Filler from Manufactured Sand

Abstract There is a need for simple but precise prediction models for proportioning concrete with manufactured sand, for use in ready-mix concrete production. For the last two decades, the particle-matrix model has been used in Norway for proportioning and prediction of concrete flow based on the properties and proportions of two concrete phases: coarse particles and filler modified cement paste (matrix). This paper presents experimental testing of 117 cement pastes of which 107 contain filler, i.e. particles < 125 microns, from manufactured sand. Based on compositions and properties of ingoing materials in these mixes, an empirical equation is developed that predicts the rheological properties plastic viscosity, yield stress, flow resistance ratio and mini slump flow. Optimization by regression analysis provides a practical microproportioning equation that readily can be used as input in concrete proportioning with the particle-matrix model. The equation provides a coefficient of determination R2 = 0.98 for plastic viscosity, R2 = 0.95 for mini slump flow, R2 = 0.91 for flow resistance ratio and R2 = 0.80 for yield stress.

Design of High-Strength Concrete for Ready-Mixed Concrete Production

The high-strength concrete is a cement composite reaching high compressive strength, namely, pursuant to the legislation, higher than 60 MPa in the terms of cube compressive strength. The development of high-strength concretes exceeding 100 MPa is still an up-to-date issue and the production of these concretes is still limited only to a prefabrication. Contemporary construction industry and projecting activity have begun to focus on a construction of statically demanding buildings, which can include e.g. high-rise buildings. Such projecting often requires using of the state-of-the-art materials like cement composites with high mechanical parameters for construction of more subtle buildings. Within this article, the procedure of ready-mixed concretes development with the compressive strength around 100 MPa designed according to a project documentation for actual construction of high-rise building with the height up to 160 meters and 46 floors is described, together with the influence of the aggregate on the resulting composite strength.

Strength and Durability Characteristics of Cement Composites with Recycled Water and Blast Furnace Slag Aggregate

Recently, interest in sustainable development has been increased. In this regard, efforts have been made to prevent environmental pollution, and research on the recycling of construction industry byproducts has been actively conducted in the construction industry. In South Korea, about 20 million tons of waste wash water from the ready-mixed concrete production process are generated, and some of them are recycled using recycling facilities in a ready-mixed concrete plant, but a significant portion of them is discharged or landfilled without permission, causing environmental problems. To increase the recycling rate of steel slag and reduce environmental pollution in the construction industry, we simultaneously applied blast furnace slag fine aggregate (BSFA) and recycled water (RW) to cement mortar. In this study, to examine the feasibility of RW and BSFA, we evaluated the fluidity, compressive strength, tensile strength, drying shrinkage, carbonation depth, and chloride penetration resistance of cement mortar using RW and BSFA. From the test results, the 28-day compressive strengths of all samples using RW and BSFA were higher than that of the control sample. In the case of samples using RW, as the BSFA replacement ratio was increased, the carbonation depth of the samples decreased. Therefore, when RW and BSFA are used properly, the mechanical properties of cement mortar, carbonation resistance, and chloride ion penetration resistance are expected to be effectively improved.

Modified Cost-Benefit Analysis of the Production of Ready-Mixed Self-Consolidating Concrete Prepared with a Recycled Concrete Aggregate

AbstractRecycled concrete aggregate (RCA) is sustainable, recycled concrete waste that is used as a component of green concretes and that, in the long term, can be a substitute for natural aggregat...

Beneficiation of concrete wash water with carbon dioxide

Wash water is generated as a by-product of ready mixed concrete production. Reuse of the water as mixture water is limited, in practice, by the negative material performance impacts associated with the water chemistry and suspended solids (i.e. hydrating binder phases and very fine aggregate); the effects are intensified with increasing content of suspended solids and water age. A novel carbon dioxide treatment to allow the use of high solids wash water as mixture water was examined through mortar and concrete testing. An industrially sourced wash water with a specific gravity of over 1.20 was treated with CO2. Seven batches of concrete were produced and compared: a reference mixture at three different w/b, and four batches with a 6% reduction in cement where wash water was used as mixture water (diluted to a specific gravity of 1.08, comparing untreated versus CO2 treated conditions, aged either 1 day or 5 days). The treatment mineralized CO2 at 27% by weight of the cement in the solids and reduced or eliminated negative aspects associated with the untreated water (set acceleration, workability loss, strength reduction with water age). The CO2-treated solids displayed latent hydraulicity. The approach allows three waste streams (CO2, wash water and wash water solids) to be reused to produce more sustainable concrete.

Resource recycling sustainability assessment in ready-mixed concrete manufactured on energy consumption and environmental safety in China.

With the rapid development of construction industry, consumption of ready-mixed concrete has increased rapidly in China. As a kind of green building material and waste comprehensive utilization product, industrial solid waste-based ready-mixed concrete have better performance in terms of resource conservation and durability. However, some typical issues are associated with industrial solid waste resource recycling in ready-mixed concrete production process such as energy and material consumption, as well as leaching pollutant emissions. So, a "life cycle assessment" of the particular elements has been carried out, determining the resources consumption of all the processes of the ready-mixed concrete production. Through preparation of several different strength grades of concrete, the embodied energy and resources consumption indicator are quantitative evaluation. In addition, the environmental safety assessment was also proposed. The results show a certain linear relationship of concrete with various strength grade and its resources consumption, the higher strength grade, the more resources consumption potentials in the production of concrete. In this case, the linear correlation coefficient R2=0.98313 between them, and the equivalent coefficient's order of the main resources, is as follows: the first is oil, then natural gas, iron ore, limestone, gypsum, and fly ash, and the last is coal. The more preceding shows more scarcity. Meanwhile, the general leaching of heavy metals Cu, Zn, Ni, Cr, Pb, Cd, and Ba of solid waste-based C20 concrete were also checked out. So, to further ensure the environmental safety, the potential ecological risk method was adopted to assess the heavy metal security and solid waste resource utilization.

Waste Wash-Water Recycling in Ready Mix Concrete Plants

The management of waste wash-water (WWW) is one of the most significant environmental problems associated with ready-mix concrete production worldwide. The problems are exacerbated should it be disposed of in an inappropriate manner. This study evaluated the potential of WWW recycling in ready mix concrete plants in Jordan. A representative waste wash-water sample (400 L) was collected from a basin in a ready-mix concrete company. A pilot plant on the lab scale was fabricated and installed. The treatment system consisted of a concrete washout reclaimer, wedgebed slurry settling pond, slow sand filtration unit, and a neutralization unit. Water samples were collected from all stages of the pilot plant and analyzed. The collected waste wash-water samples were utilized for replacement of well water (mixing water) at various ratios. Fourteen concrete mixtures were produced and cast, as well as tested at various curing ages (7, 28, and 90 days). The results show that the raw WWW was not acceptable as mixing water even after dilution as it led to significant reductions in concrete compressive strength and low workability. However, the WWW from the settling pond, the filtered WWW and the filtered-neutralized WWW at dilution ratios up to 75% were shown to be potential alternatives to fresh water for ready-mixed concrete. Therefore, the current guidelines for mixing water quality should be revised to encourage the reuse of the WWW.

De-risking resource recovery value chains for a circular economy – Accounting for supply and demand variations in recycled aggregate concrete

The use of recycled material as an alternative constituent material in products replacing natural aggregate, if done at an industrial scale, exposes the supply chain to several risks. Raw material supply, which traditionally could be met on demand by extracting natural resources, could be replaced by providing recovered resources as a re-purposed raw material. This paper analyses the supply chain associated with the use of coarse recycled concrete aggregate, replacing natural coarse aggregate, to produce a new concrete product referred to as recycled aggregate concrete. If the recycled concrete aggregate is used in the production of concrete, the supply of coarse aggregate for ready-mix concrete production will depend on the supply of crushed recycled concrete aggregate, creating increased variability in supply, as this could not be produced on demand. Using dynamic model-based simulations, this paper analyses the behaviour of a supply chain using recycled concrete aggregate as a constituent material in concrete. Simulations of variability and differences in supply and demand, while meeting the market demand for the product, are developed.

Developing a Model to Estimate the Productivity of Ready Mixed Concrete Batch Plant

Productivity estimating of ready mixed concrete batch plant is an essential tool for the successful completion of the construction process. It is defined as the output of the system per unit of time. Usually, the actual productivity values of construction equipment in the site are not consistent with the nominal ones. Therefore, it is necessary to make a comprehensive evaluation of the nominal productivity of equipment concerning the effected factors and then re-evaluate them according to the actual values.
 In this paper, the forecasting system was employed is an Artificial Intelligence technique (AI). It is represented by Artificial Neural Network (ANN) to establish the predicted model to estimate wet ready mixed concrete (WRMC) plant production and dry ready mixed concrete (DRMC) plant production, in addition to determining the factors affecting productivity.
 The results showed that the artificial intelligence neural network is an effective technique to estimate the productivity of the dry and wet ready mixed concrete batch plant. The ANN model showed satisfying results of validation for both training and external datasets with the range of training dataset and poor results with the data that exceeds the range of training. At the same time, the skills of the operators, frequent failure of concrete, and lack of construction materials were the most important factor that affected productivity.

A Knowledge-Based System for Fine Aggregate Material Problem Selection in Concrete Production

One of the main problems of our country is inability to select the right materials of high quality in production. Decision making based on multiple criteria has an important role to do the right selections in each sector. One of these sectors is construction. Construction sector develops rapidly and using the right material is an important issue. Using the right material in this period when construction sector develops rapidly has a great importance. In the construction sector, the building material which has been used the most widely from past to present is concrete. In this study, a knowledge-based system via TOPSIS approach was proposed to generalize the multi-criteria decision making problems of fine aggregate material selection in concrete production. In addition, six different mortar series were produced by using the fine aggregates which were obtained from various plants used in the production of ready-mixed concrete in Kütahya and CEN Standard sand. The methylene blue, physical and mechanical tests were carried out on the produced mortars in order to get an idea for the strength and durability of concrete. The purpose of the study was to determine which of the five different fine aggregates had characteristics that are the closest to those of CEN Standard sand based on defined these multi criteria. It was found that the best fine aggregate series was A based on the defined criteria by considering the results of the experiments, assigning weights based on importance and analyzing these with TOPSIS approach.

SISTEM INFORMASI PENGADAAN BAHAN PRODUKSI BETON SIAP PAKAI (READYMIX) PADA PT. SCG READYMIX INDONESIA PLANT CILEGON

In the system of readymix concrete production material procurement at PT. SCG Indonesia Readymix Plant Cilegon, the company was still conduced by manual system. It used filing system that stored in the production division. The entry system used the form that submitted directly, therefore in making report, it needed inefficient time and created difficulties for the clerk to input the data manually in receiving production material. If the company required the data about material production, they must seek the data from the stack of existing archive. Besides that, the report generated less efficient because in the recording the data was conducted by employee that still used system manually. Therefore, sometime the result of report contained some errors. To overcome the existing problems, it is necessary to use the computer based of production materials procurement information system. The aims were 1) to facilitate the procurement of material for the production process, 2) to make easier for the employees to find out and to enter the necessary data of production materials procurement, 3) to create the effective and efficient work, and 4) to use in making report of production material procurement quickly and easily.

Variability of environmental impact of ready-mix concrete: a case study for Brazil

Life Cycle Assessment is a powerful tool towards sustainable construction, but it often relies on average impact results, failing to identify the dispersion of environmental impact among construction product manufacturers. This work presents cradle-to-gate impact results for ready-mix concrete production, based on primary data provided by several plants in Brazil, and the associated variability among plants and in the upstream processes of cement and sand production. Four compressive strength classes are considered. Concrete, cement and aggregates inventories are modeled with Brazilian information and other upstream processes are based on ecoinvent. EN 15804 impact categories are assessed. The ranges between minimum and maximum impact values can be as large as 7.2 times the average impact result of the analyzed sample, which shows that the variability among manufacturers is high and decisions based on average impacts may be highly misleading. For some impact categories, the differences among concrete plants (mix design, cement type and operational conditions) represent the highest contribution for variability, while for others the dominant variation comes from upstream processes, especially clinker production. These results indicate a high potential for process improvement and that manufacturer selection based on environmental performance can be an effective strategy for sustainable construction.

Waste generation from the production of ready-mixed concrete

In Brazil, ready-mixed concrete (RMC) suppliers are adopting management strategies to reduce waste generation. This is because of the increasing scarcity of adequate places for the deposition of waste, which raises the associated costs. Therefore, it is necessary to know the actual volume production of residues in order to optimize the implementation of the recycling. The waste produced in RMC plants are mainly in the form of leftover concrete and adhered to the internal part of the drum of the mixer truck.The present study analyzed the data and produced an inventory of the amount of waste generated by of one of the largest Brazilian concrete companies. In parallel, an experimental study was performed in the real conditions of an RMC plant in order to measure the influence of concrete characteristics on the volume of concrete adhered to the drum.The results showed that about 3% of all the produced volume returns to the plant, comprising approximately 1.6% adhered concrete and 1.4% leftover concrete. The study proved that the volume of concrete adhered concrete depends on the cement consumption and the slump. The volume of concrete loaded and the region where the RMC plant is located do not influence those results. The inventory showed that the main cause of concrete leftovers is associated to over order and corresponds to 58% of this volume.

Quality Management to continuous improvements in process of Ready Mix Concrete production

The key benefits from Ready Mix Concrete (RMC) are good quality, lower Life cycle cost, the speed of work and friendliness of environment more than the site mixed concrete, but when the quality of RMC is below threat of several causes resulting poor quality or useless concrete. We will lose all advantages of RMC that we mention before. Therefore, this study investigate the using of Quality management to improve the process of company to produc (RMC) in batching plant and study the impacts of Quality Control (QC), Quality Assurance (QA) on the company by introduce them to the process in order to make improvements on current Quality system to make it continuous improvements. The idea of the work depends on finding the relationship between the Project Management Body of Knowledge (PMBOK) Guide and the quality management by combining them together in process to achieve the best results as soon as possible, higher productivity, less rework, increased customers satisfaction, increased profitability and sustainability by finding company’s problems and achieving it through guidelines and instructions of PMBOK Guide also the principles, the tools and the techniques of Quality Management. In order to achieve that, we have investigated three main points: the first one is gathering information to identify the current quality system, the second is identifying and analyzing of these problems and the third is finding solutions based on the principles of management. With a view to manage the process of production, the author used many techniques and tools for management such as Flow Chart for a process, Ishikawa diagrams to define seven main group of problems, Check Sheet to the number of problems occurrence, the FMEA Analysis for thirty-five problems, 5 Whys Analysis to find sources of the problems, Solution effect Analysis to propose the possible solutions. The most important results from this study are the main reasons for the absence of management methodology in the company which is a defect in the Quality system (structure of company, procedure, and resources), lack of management experience and communication and lack interest of Total Quality Management in management methodology. The researcher found lacks in the thoughtful scientific methodology for the management in process of production, therefore the developing of the system of production in the RMC plant is to build a methodology based on a guide of Project Management Body of Knowledge 5th edition because of the maturity level of the project management knowledge areas.

Statistical analysis of Portuguese ready-mixed concrete production

Abstract This paper evaluates and compares the statistics of compressive strength data from three Portuguese ready-mixed concrete plants. A hierarchical model showed that different groups of concrete strength records are not statistically equivalent, even if they were produced in the same plant and using the same concrete composition. This finding is related to autocorrelation. For the same specified strength class, compositions produced less often result in higher average compressive strength and variability. The statistics of one of the plants were quite different from those of the others, even though the concrete of this plant also complied with the specifications. It was found that the average compressive strength of a mix may be quite dependent on the plant that produced it, even if the compressive strength complies with quality control specifications. Conformity with the target slump and strength class was checked following the conformity criteria of EN 206-1 for continuous production. Nonconformity with slump is more frequent than failure to comply with the strength class. A bias factor for reliability analyses was proposed.