Production Of Cement Composites Research Articles

Assessment of the possibility of using waste aggregate dust for the production of vibro-pressed concrete paving blocks

Significant amounts of rock dust with a grain size similar to cement are generated during aggregate dedusting in the production of mineral-asphalt masses. These wastes are collected in tanks or silos and must be managed in such a way as not to generate costs related to disposal. On the other hand, the use of natural resources must be reduced in the production of cement composites. The objective of this research is to investigate the possibility of utilising aggregate dedusting waste (ADW) in vibro-pressed concrete paving blocks (VPCPB). Stage one of this research includes testing the compressive strength of concrete samples where cement was partially replaced by ADW or/and fly ash (FA). Stage two discusses the effect of cement replacement by ADW or FA on the splitting tensile strength of VPCPB. Using ADW in VPCPB is a promising option. Splitting tensile strength increased after both 7 and 28 days when ADW was used.

Statistical approach to the production of cement composites doped with ZnO and ZnO-based materials

In this study, physical and functional properties of the cement composites containing ZnO, ZnO/lignin and lignin admixtures were investigated using Response Surface Methodology (RSM). The I-optimal design based on RSM was used to assess the influence of ZnO-based doping agent, of either commercial or synthetic origin, on cement composite production in the function of average compressive strength and cost. Polynomial mathematical models were developed by RSM confronting results from the experimental design. The accuracy and precision of the utilized models established by I¬-optimal design were tested using Analysis of Variance (ANOVA). The first stage of formulation optimization revealed that the use of commercially available ZnO-based admixture no. 4 (ZnO-SA, supplied by Sigma Aldrich) allowed to achieve the desired results, passing all the requirements, i.e., the best microbial purity combined with reasonable cost, followed by satisfactory physical properties. In the second stage of formulation optimization, the influence of implementing the hybrid materials, i.e., ZnO-SA mixed in different proportions with lignin was evaluated. RSM revealed that doping admixture no. 3, i.e., ZnO-SA/lignin (5:1), is the best candidate, which comprised augmented functional and physical properties of the fabricated cement composite. This component exhibited the best microbial purity as well as the lowest total pore volume, followed by satisfactory physical properties. Verification of the model findings indicated considerable agreement between the predicted and experimental values. From the findings, it was confirmed that a reasonable cost-performance balance for cement composites can be achieved using ZnO-SA and ZnO-SA/lignin (5:1).

A multi-site study of a new cement composite brick with partial cement substitutes and waste materials

The building industry is a major contributor to climate change since it emits massive amounts of greenhouse gases. As a result of this research, a cement composite brick with partial cement substitutes and waste material was developed. The fresh formula mixture and hardened concrete were tested for physical, mechanical, and thermal properties to ensure that the assumptions were true. In this study the role of zaolite, metakaolinite and micrometakaolinite at different proportions, i.e. 5%, 10%, and 15% as well as recycled fibers (glass, polypropylene and steel) at 0.5%, 1.0% and 1.5% dosage in the production of cement composites was researched. 20 recipes in total have been tested until achieving the final recipe of the mentioned brick. The main purpose of this research was to develop the concrete mixture that will be used to produce cement bricks with increased physical, mechanical and thermal parameters. The compressive strength of the brick developed with the modified formula increased by 22% compared to the reference sample. Also, higher mechanical values were obtained for the splitting strength and flexural strength, which increased by 14% and 32%, respectively, compared to plain concrete. Based on the thermal test results it was developed that zeolite, metakaolinite and micrometakaolinte have no effect on thermal properties of concrete. Only after incorporating fibers into mixture, those properties changed. Also, the SEM images showed an even distribution of the fibers in the composite matrix and a crack-free structure. Moreover, the image analysis results confirmed the failure character consistent with traditional concretes in the case of compression and the lack of split into two independent samples in the case of bending. Therefore, the new composite brick has great potential to be used as a primary replacement for traditional concrete masonry in civil engineering projects.

The Technology of Processing of Bed Combustion Fly Ash for Cement Composite Production

Insufficient offer of high-temperature fly ash meeting the requirements of standard EN 4501 is becoming an increasingly significant problem for concrete technology. This trend is generally caused by relentless effort to green electricity generation and reduce the carbon footprint, leading to the decommissioning of coal-fired power plants and the greening of existing. The most often ways are combustion processes of fluidized-bed and selective non-catalytic nitrogen oxide reduction (SNCR) processes. Thanks to these processes, the demand for this raw material has significantly exceeded its supply in recent years. It is, therefore, more than current to look for ways to use the large amount of ash produced from coal combustion, which is not high-temperature fly ash, but can be classified as a bed combustion fly ash or cinder. The paper aims to show the possible processing and subsequent use of these waste materials for the production of cement composites. The possibilities of grinding these coarse-grained fly ashes and the subsequent impact of their use on the cement composite in comparison with conventional fly ash according to the standard EN 450 from the same sources were verified. The impact of their use on the properties of composites in the fresh and hardened state was analysed, and these impacts were related to, for example, their chemistry, grain morphology, loss on ignition, or fineness.

Influence of the use of sanitary ware waste in self-compacting concrete production

In the production of concrete and mortar, fine and coarse aggregates from non-renewable natural resources are normally consumed. In order to minimize the environmental impacts caused by the extraction of these resources, recycled aggregates of different natures and granulometries has been use in the production of cement composites. The purpose of this paper was to investigate the influence of replacing natural sand by sanitary ware waste (SWW) on the properties of self-compacting concrete (SCC). Concretes were produced with replacement of fine sand by SWW in 20%, 40%, 60% and 80%. The SCC had their properties evaluated in the fresh and hardened state. The results shows that the increase in replacement teres reduces the scattering, fluidity and passing ability of the SCC. There was an increase in compressive strength from 30.1 MPa to 35.3 MPa at 28 days, when considering the 20% and 40% replacement mixes. The replacement contents of 60% and 80% had very similar values. The tensile tests by diametrical compression showed statistically equal values for all analyzed traits. Water absorption increased with higher levels of residues in concrete. The set of tests performed allow to affirm that replacements between 20% and 60% of SW resulted in concretes according requirements for self-compacting concretes, with structural application recommendation for various situations. For classification and indication of use, the tests results should be observed in each of the mixtures. In this way, sanitary were waste have the potential to be used as a substitute for natural sand, reducing the consumption of natural resources.

Research on the production of cement composites with autonomous self-healing performance

In a time when the attention paid to identifying the possibilities of reducing problems due to urban pollution is increasing, the construction industry has a lot to gain if it aligns itself with the new trends of sustainable development in the field. In this context, the objective of obtaining a concrete with self-healing properties of cracks is more than appropriate, becoming a sustainable alternative for reducing the maintenance costs of transport infrastructure by increasing their operating time and by decreasing the need for the volume of repair and maintenance works, thus indirectly contributing to the reduction of environmental pollution. Preliminary results obtained using a cementitious composite with waterproofing admixture content by mass crystallization are encouraging by identifying the existence of an autonomous healing degree (closure of cracks with average opening 20-40 µm) in a proportion of at least 65% after only 96 hours of exposure in a wet-dry environment, respectively and of at least 96% after 480 hours of conditioning. The degree of novelty and value of this research is mainly due to the approach of this type of composite produced by adapting the general principles to local raw materials, including the use of specific industrial waste and by-products available in Romania (fly ash and limestone slurry).

Lightweight cement composites containing end-of-life treated wood – Leaching, hydration and mechanical tests

A huge amount of treated wood waste containing hazardous substances is produced every year all over Europe that simply ends up in landfills. In this study, the authors investigate the practical feasibility of using end-of-life treated wood for producing innovative lightweight cement composites. For this purpose, wood waste from four different sources was characterised to assess the presence of leaching substances and to ascertain physical properties relevant to the production of cement composites. Afterwards, cement pastes containing, firstly, wood extractives, and later, wood particles were prepared to assess the compatibility between the wood and Portland cement binder. To improve the wood-cement compatibility, additional tests were carried out using extracted and chemically treated wood particles. The results were discussed in terms of hydration heat and mechanical properties. Finally, a concrete mix containing selected wood particles was produced for a preliminary examination of the effect of wood waste on the mechanical properties of a reference concrete.The results show that the concentration of leaching substances can vary significantly depending on the source of wood waste. Small variations were found in the hydration heat profile of different cement composites containing up to 10 %(w/w) of wood particles, contrasting with the significant reduction found in compressive strength. The results of the concrete mixes further show that the incorporation of wood particles significantly reduces the mechanical performance of the hardened material, though such composites can still be used in applications with low-structural requirements.

The use of construction and rubber recycled material for the production of cement composites with thermal insulation function

This article presents the results of the possible use of construction waste and rubber granulate as a filler substitute for the production of cement composites with thermal insulation properties. It describes the individual components of the materials necessary for the designing of recipes and their properties. The article presents the thermal insulation properties and strength characteristics of the designed recipes of non-traditional cement composite after 7, 14, 28 and 90 days.

Treatment and utilization of artificial aggregate in the production of cement composites

The aim of the work is to find a suitable way of treatment of steel ladle slag for subsequent use as a partial replacement of the binder component in cement composites. The goal is based on the raw materials policy of the Czech Republic. Within this work is solved the issue of possible use of steel slag as the largest by-product of steel production. The work is focused on a specific ladle slag from ladle furnaces, by which are equipped the modern steel plants. Ladle slag is similar in chemical composition to Portland cement. However, its mineralogical composition should be taken into account in relation to its expansion reactions and lower hydraulic activity. One of the goals is the research of effect of particle size in cement-slag mixtures. The slag was ground for research on two different specific surfaces - coarsely in a vibrating mill and finely in a ball mill. The research within the experimental part of the work verified the positive influence of ladle slag on the properties of fresh and hardened mortar mixtures. Tensile bending strengths and compressive strengths are for some mixtures with ladle slag even higher than the strengths of the reference mixtures.

Reuse of Heat Resistant Glass Cullet in Cement Composites Subjected to Thermal Load.

The article describes the possibility of using waste glass cullet as an alternative aggregate for the production of cement composites. Three concrete mixes based on Portland cement CEM I 42.5 R with different contents of recyclate were designed. Borosilicate glass cullet was introduced into the batch by reducing the content of natural aggregate by 0%, 2.5% and 7.5%. Apparent density, water absorption and compressive strength at elevated temperature were measured. The temperature distribution, in cubic samples, was followed by thermocouples. The elements were heated in a special furnace at the temperatures of 200 °C, 400 °C, 600 °C and 800 °C. The composite topography and phase composition were observed using X-ray energy scattering electron microscopy. The results show that the appropriate modification of the cement composite with 2.5% heat-resistant glass cullet improves both the thermal and mechanical properties. Compressive strength reaches an average value of 48.6 MPa after 28 days. The increase in temperature weakens the structure of the composite. It was found that the obtained cement composite has good physico–chemical properties. The research results are presented in the article.

Evaluation of the Use of Cellulose, Latex and Metakaolin in the Production of Cement Composites with Low Water Absorption and High Modulus of Elasticity

ABSTRACT In this work, the aim was to study the influence of cellulose Kraft pulps, natural rubber latex, and metakaolin in the optimization of the values of flexural strength and water absorption of cementitious composites through the design of experiments (central composite design) at 28 days of age. According to the design of experiments, the composite with 1.252% cellulose, 1.126% latex and 37.06% metakaolin presented the optimized value of the modulus of elasticity (21.89 GPa). In addition, an increase in the values of modulus of elasticity for composites with lower cellulose contents was observed. Latex and metakaolin provided small variations in the modulus of elasticity. For water absorption, only cellulose exhibited significant interference. Thus, lower values of water absorption were found for lower concentrations of cellulose. The optimized composite that showed less water absorption was with 1.5% cellulose, 0.02% latex, and 4% metakaolin, with 10.28% absorption. In view of the results obtained, it was concluded that the use of central composite design, the molding method adopted, and the limits of constituents used allowed the optimization the values studied responses (modulus of elasticity, and absorption).

The effect of CO2 on the strength characteristics of cement composites based on recycled rubber from waste tires

This paper presents the results of a research into the use of a combination of recycled rubber from waste tires as a 100% aggregate replacement in the production of cement composites. The aggregate was replaced with rubber recycled material in two ratios. At a ratio of 50/50 and a ratio of 40/60 fraction 0/1 mm and fraction 1/3 mm. The test specimens were further subjected to CO2 effect in a Lamart laboratory chamber, where CO2 effect was simulated as equivalent to an aging period of 50 years. The presented results show that the effect of CO2 reduces the strength characteristics of the composite compared to the comparative samples.

Oxidized thermally expanded graphite as a raw material for the production of cement composites

One of the current tasks is to improve the performance of cement composites. Effective ways to solve a problem is to use a new generation of carbon - containing modifiers. The regulation of the physical and mechanical and operational properties of cement composites must be carried out at the micro level, by regulating the structure formation of the cement matrix One of the promising directions is the use of graphene as a carbon-containing modifier. The article represents research data on oxidized thermally expanding graphite. The results of microscopic and laser diffraction granulometric analyzes are represented. The performed studies allowed to characterize the properties of the research material. The analysis of particle size distribution was carried out on a Fritsch NanoTec laser particle size measuring device with a dispersion unit in a liquid space with a total measurement range from 0.01 to 2100 μm and showed a decrease in size from 574 μm to 22.2 μm. Microscopic research was carried out by using a scanning (raster) electron microscope TESCAN Mira 3 with a magnification range of x1 – x1 000,000. The experimental results presented in the present research prove the effectiveness of using oxidized thermally expanding graphite as a modifier of cement composites.

The Utilization of a Combination of Recycled Rubber from Waste Tires and Waste Waters from a Concrete Plant in the Production of Cement Composites

This article presents the results of a study dealing with the use of a combination of recycled rubber from waste tires as a 100% replacement of aggregate and waste sludge water from a concrete plant as a partial replacement of mixing water in the production of cement composites. The aggregate was replaced with recycled rubber material in two ratios. The first ratio was 50/50 and the other one was a 40/60 ratio of fraction 0/1 mm and fraction 1/3 mm. The mixing water was replaced with waste sludge water from a concrete plant in the amounts of 25% and 50%. The designed cement composite formulas were subjected to the test of their physical and mechanical characteristics in order to determine the properties when using a combination of recycled rubber and waste sludge water from a concrete plant. The tested properties include: consistency of the grain curve, mixing water properties, consistency of cement mortar, strength characteristics (tensile flexural strength and compressive strength). The study presents the results that are fundamentally different from the comparative samples and their use in the building industry but, at the same time, they also open up new possibilities of their use as building material.

THE PROPERTIES OF RECYCLED RUBBER FROM WASTE TIRES IN THE PRODUCTION OF CEMENT COMPOSITES

This article presents the results of a study dealing with the use of a combination of recycled rubber from waste tires as a 100% substitute in the production of cement composites. Aggregate was replaced with recycled rubber in two ratios, namely the ratio of 50/50 and the ratio of 40/60 of the share of fraction 0/1 mm and fraction 1/3 mm. The designed formulas of cement composites were subjected to the tests of their physical and mechanical properties in order to determine the properties of the used recycled rubber combination. The tests included the consistency of the grain curve, mixing water properties, consistency of cement mortar, and strength characteristics (tensile flexural strength and compressive strength). The study presents results that are fundamentally different from the comparative samples and their use in the building industry; however, at the same time, they open up new possibilities of their utilization as a building material. Keywords: Composite; Concrete; Mixing water; Recycled rubber granulate; Waste tire DOI 10.35180/gse-2020-0028

Towards the sustainable use of granite powder waste for manufacturing of cementitious composites

The article is devoted to the description of the current state of knowledge about the possibilities of sustainable use of granite powder waste for manufacturing of cementitious composites. Granite powder waste is waste material resulting from the treatment of granite stone. In dry form, it is harmful to the environment and causes its degradation. One way to reduce its harmful effects is to use it for the sustainable production of cement composites and to use it as supplementary cementitious material (SCM). The results of researches carried out so far related to the impact of granite powder waste on the properties of fresh and hardened cementitious mixes are described. These results were compared and research gaps related to these studies were indicated. In summary, conclusions have been pointed out that indicate that granite powder waste can potentially be used as supplementary cementitious material, but comprehensive, comprehensive research related to this additive should also be carried out.

The effect of CO2 on cement composites produced with an admixture of waste sludge water from a concrete plant

Abstract This article presents the results of a research dealing with the effect of CO2 on cement composites prepared on the basis of waste sludge water from the concrete plant. The designed formulas R1 and R3 use waste sludge water from the concrete plant as a partial or complete replacement of mixing water in the production of cement composites. The mixing water was replaced by waste sludge water in the amounts of 25%, 50%, 75% and 100%. Laboratory tests that are defined in ČSN EN 1008 standard were performed in order to determine the effect of partial or complete replacement of mixing water. The test specimens were further subjected to the effect of CO2 in the Lamart laboratory chamber, where the effect of CO2 was simulated for the period 50 years. Subsequently, the cement composites were tested for their strength characteristics (tensile flexural strength, compressive strength) and subjected to a mineralogical analysis. The results show that the effect of CO2 will reduce the strength characteristics of the composite compared to the comparative samples.

Reuse of Waste Material “Waste Sludge Water” from a Concrete Plant in Cement Composites: A Case Study

This paper presents the results of research dealing with the use of recycled waste sludge water from a concrete plant (CP) as partial or complete replacement of mixing water in cement mixtures. The need to recycle waste sludge water generated as a by-product (waste sludge water) during the production of fresh concrete in the concrete plant results from the environmental and economic problems associated with the operation of the concrete plant. Mixing water was replaced with recycled waste sludge water in the amount of 25%, 50%, 75%, and 100%. In order to determine the effect of partial or complete replacement of mixing water with waste sludge water from the concrete plant in the production of cement composites, laboratory tests of waste sludge water were carried out to determine whether the waste sludge water complies with the requirements for mixing water defined in CSN EN 1008. The tests also determined the properties of fresh cement mortar and hardened cement composites. These were tests of the beginning and end of cement mortar setting, and the strength characteristics (flexural strength, compressive strength). The results of these tests show that it is possible to replace the mixing water by waste sludge water from the concrete plant in the amount of up to 25% without significantly affecting the tested properties, in comparison with the formula containing pure mixing water.

Self-heating of electrically conductive metal-cementitious composites

Given the increasing demand for higher performance and economic gains in cement composite products, the self-heating performance of cement composites is becoming ever more assorted and progressive. This study investigates the effects of metal materials on self-heating of cement composites. Cementitious composite cubes containing up to 20% of metal materials were tested to improve their conductivity and hence investigate their performance in terms of electrical resistance heating. The metals that were studied were copper, iron, and brass shavings. The test variables were types of metals and input voltage. The tests showed that the presence of metal components improved cementitious cubes’ conductivity, and hence, they transferred heat. In addition, the tests showed that the heating temperature changed with the type of metal and input voltage. Analysis of energy consumption, heating rate and maximum surface temperatures was performed to evaluate the possibility of using metal materials as low-cost heating elements in large-scale heating systems.

Frost resistance of cement composites prepared on the basis of waste water from a concrete plant

Abstract This article presents the results of a research dealing with the use of waste water from concrete industry as a possible substitution of mixing water during the production of cement composites. This experimental research involved the preparation of two recipes of cement composites, named R1 and R3. Mixing water in these recipes was replaced with waste water from a concrete plant in the amount of 25, 50, 75 and 100%. Samples of recycled waste water, which were tested for the content of sulphates, chlorides and alkali according to ČSN EN 1008, were taken in order to determine the properties of waste water from a concrete plant. The prepared test specimens were tested for frost resistance after 100 freezing cycles according to ČSN 73 1322. The results of the frost resistance test showed that the required value of the frost resistance coefficient of 0.75 according to ČSN 73 1322 was achieved only in case of recipe R1 based on Portland cement CEM I 52.5R and 75 and 100% substitution of the mixing water with recycled water from a concrete plant.