Production Of Artificial Aggregates Research Articles

Obtaining an Artificial Aggregate from Cement-Asbestos Waste by the Melting Technique in an Arc-Resistance Furnace

Nowadays, asbestos waste still remains a serious problem. Due to the carcinogenic properties of asbestos, which are related to its fibrous structure, the exposure to asbestos mineral and asbestos-containing materials (ACM) causes dangerous health effects. This problem can be solved by recycling techniques, which allow the re-use of neutralized asbestos waste, instead of disposing it in special landfills. The article presents the results of research aimed at investigating the possibility of obtaining aggregates from asbestos waste by the fusion process in the electric arc-resistance process. A mixture of ACM with selected fluxes was were melted and then cast to form a grain of aggregates. The chemical composition of the material was determined before and after the melting process. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were applied to evaluate the effects of the fusion process. The main properties of the obtained aggregate were also measured. The results confirmed that the fibrous structure of asbestos was destroyed in the obtained material, which can be successfully used for the production of artificial aggregates.

Evaluation of the influence of aggregate type on selected properties of epoxy mortars

Aggregates, or granular materials, are currently one of the most sought-after construction materials. Natural aggregate deposits are quite common in the world, but their widespread consumption and progressive environmental degradation forces many countries to take measures to reduce the depletion of natural resources. One of the solutions is the use of alternative aggregates. The use of this type of aggregates enables further minimization of the volume of wastes and their adverse impact on the environment and the neutralisation of the remaining waste by, among others, production of artificial aggregates. Forecasts for the future assume a reduction in the production of artificial aggregates, brought about by the production of alternative aggregates from recycling. Many research centres around the world conduct research on the assessment of the effect of various aggregates on the properties of concrete and mortar. This article compares selected properties, i.e. the flexural and compressive strength and bulk density of epoxy mortars, in which the natural aggregate has been partially replaced by perlite, expanded clay and rubber waste pellets. The type of filler used differentiates the mortar characteristics recorded. The tested properties of composites indicate the possibility of their use in construction industry.

Properties of cold-bonded lightweight artificial aggregate containing bottom ash with different curing regime

Cold-bonded pelletizing technique is frequently used in aggregate manufacturing process as it can minimise the energy consumption. It has contributed to both economical and environmental advantages because it helps to reduce the gas emissions problems. Bottom ash collected from municipal solid waste incineration (MSWI) plant was selected as raw material in this study and was utilised as a partial replacement for cement for artificial aggregate production. Several percentage of ash replacement was selected ranged from 10 to 50%. Aggregate pellets were subjected to different types of curing condition which is room-water (RW), room-room (RR), oven-room (OR) and oven-water (OW) condition. Properties of aggregate pellets were examined to obtain its density, water absorption, aggregate impact value (AIV) and specific gravity (SG). The results indicated that the most efficient curing regime is by exposing the aggregate in RW condition. The optimum aggregate was selected at 20% where it has satisfied the required density of 739.5kg/m3, and classified as strong aggregate with AIV 14. However, the water absorption of aggregate increased proportionately with the increment of ash content.

Lightweight Aggregate Produced with Cold-Bonding of Fly Ash and Binder

Main object of this paper are results of ash usage in order to create artificial aggregates. Ashes are mineral residue of coal burning in thermal power stations. Fly ashes (high temperature ashes) are highly used in practice as supplement of cement and silicate components of silica materials. FBC ashes are not used such great scale. They can be used for restoration, mounds or for example also for production of ash autoclaved aerated concrete. [1] Production of artificial aggregate from sintered ash is possible mainly because of the fly ashes. [2] Focus of this paper is to compare various types of ashes for lightweight aggregate produced with cold-bonding. Apart from the fly ashes and FBC ashes are also tested bottom ashes from FBC technology. From the results could be assumed, that bottom ashes compared to their granularity could be used only very hardly. Fly ashes splendidly react with cement and reach higher strengths. But they need more than 10 % of binder in order to reach quality results. FBC ashes better cooperate with quicklime, but in order to reach suitable parameters they need smaller portion of binder.

Umetni agregat iz sintranega pepela premoga

Fly ash is one of the most commonly used secondary raw materials in the Czech Republic. It is used predominantly for re-cultivation, roads and additions to cement or plasters. The use of fly ash in the technology of sintering-based artificial aggregate was tested in the 1980s. However, the production was stopped for various technological and economic reasons. Nowadays, possibilities for the production of artificial aggregate are tested with fly ash produced in the Czech Republic and could be promising for future technologies, mainly with respect to the stability of production. The paper presents part of the study describing the possibilities of using microsilica and Fe2O3 for the optimization of a raw-material mix and fly-ash body. Three samples of high-temperature lignite combustion fly ash were selected from prospective sources in the Czech Republic. The fly ash was mixed with 5 % or 10 % additions. Then, samples were fired at temperatures of 1150 °C and 1200 °C. After firing, the physico-mechanical properties of the fly-ash bodies and microstructure were evaluated. The results imply that the addition of microsilica unambiguously improves the quality of the fly-ash body. The addition of Fe2O3 did not take part in the formation of the melt and weakened the fly-ash body’s structure.

Effect of Firing Temperature on the Structure of the Aggregate from Sintered Ashes

Production of artificial aggregate from ashes is worldwide known technology that uses up to 100% of ash in the mixture. There are known two types of aggregate. First is based on binders and known as cold-bonded. Second type of aggregate is produced by self-firing process that uses a content of combustible substances in the mixture. After ignition this fuel generates enough energy for the sintering process. The paper gives an account of the influence of parameters of ash and conditions of firing on the quality of ceramic body made from ash. Temperatures of 1050°C, 1150°C and 1200°C were examined. The research focused on the structure of the ceramic body as well as its physic-mechanical parameters. The results show also that firing temperature is essential for forming the structure. An important indicator is the share of melt that form a solid ash body.

The Effect of Granulation Time of the Pan Granulation on the Characteristics of the Aggregates Containing Dunkirk Sediments

The wet granulation process presents complex interactions between equipment variables as well as material properties making the outcome of a granulation process hard to predict. A frequently encountered difficulty is the process control for optimal condition of the granulation. This requirement depends largely on the operator and the desired properties of the final product.In this study, before the fabrication of aggregates by the pan granulation by associating the sediments with a specific hydraulic binder, the ingredients were characterised. Then, the evolution of the aggregate size with the granulation time has been explored. Finally, the physical and mechanical properties of artificial aggregates formulated by the pan granulation were discussed. The results of this study show firstly, that the use of marine sediments dredged from Dunkirk harbour in France in the production of artificial aggregates is a flexible and positive approach. Secondly, that the granulation time is an important parameter that controls the granulation by wet granulation plate.

EAF Slag Treatment for Inert Materials’ Production

Danieli & C. in collaboration with Politecnico di Milano, designed an innovative, patent pending, treatment plant to solve some issues associated to metals leaching (i.e., Ba, V, and Cr), and high free lime concentration for carbon steel EAF slag, for the production of artificial aggregates featured by mechanical properties suitable for the building purposes. The plant is featured by an innovative pneumatic transport system to convey the stabilizing agent to intercept the molten slag flux during the deslagging operation. The new system promotes stable microstructural phases’ formation, able to retain metallic ions leaching, maintaining the same mechanical properties of the as-cast slag. The main advantages of the new implemented stabilization plant are a simple installation and an easy process operation.

Influence of Firing Temperature on the Quality of Fly Ash Body

Nowadays, over 95 % of fly ash is used as construction products in the Czech Republic. However, around 80 % of fly ash is used for renovation of open-pit quarries and areas affected by human activity. Production of artificial aggregate is the way to use over 90 % of energy by-products in the building material industry. It is necessary to find appropriate combination of parameters of input materials and conditions of production to get optimal properties of aggregate. The paper gives an account of the influence of parameters of fly ash and conditions of firing on the quality of ceramic body made from fly ash. Temperatures of 1050 °C, 1150 °C and 1200 °C were examined. The research focused on the structure of the ceramic body as well as its physico-mechanical parameters.

Study on the Process of Creating Fly Ash Body

Production of artificial aggregate by clinkering process is currently relatively well-known way to efficiently use the potential of fly ash for building materials. Principle of clinkering can reduce the cost of natural gas and other potential external sources of heat through the use of own combustible substances. Course of firing and aggregate properties significantly depend on the type and character of the fly ash or fly ash mixture. Due to the high heterogeneity of these materials is relatively difficult to assess the impact of specific parameters (grain size, the content of Fe2O3, SiO2, CaO, amorphous phase, etc.). Due to the experimental testing of a large number of different types of fly ash and their mixtures, it will possible to verify at least some principles based on experience with the production of ceramic body. This article discusses the results of the sub-tests, dealt with influence of physico-mechanical properties, chemical and mineralogical composition of fly ash on the quality of the resulting ash body.

Fresh and hardened properties of concrete containing cold bonded aggregates

The properties of fresh and hardened concrete made using three types of artificial cold bonded aggregates are determined. The properties, namely, slump, water absorption, compressive strength and splitting tensile strength of concrete containing artificial aggregate are reported. The variables considered are aggregate type and water-to-cement ratio. Three types of cold bonded aggregates are prepared using fly ash and quarry dust. The water-to-cement ratio of 0.35, 0.45, 0.55 and 0.65 is used. The test result indicates that artificial aggregates can be recommended for making the concrete up to a strength grade of 38 MPa. The use of quarry dust in the production of artificial aggregate mitigates environmental concerns on disposal problems of the dust. Hence, the alternate material proposed in this study is a green technology in concrete production.

Production Possibilities of Concrete Based on Artificial Fly Ash Aggregates

Production of artificial aggregates is one of the suitable ways how to use the maximum ratio of fly ash in construction materials. Subsequent use of aggregates is directed in addition to various embankments, filter layers and also for lightweight concrete. Concrete can be used wherever required low weight while maintaining the necessary strength. The contribution is geared to verify the applicability of newly produced artificial aggregates from different types of fly ash for standard concrete.

Study of Influence of Fly Ash Character on its Behaviour during Clinkering Process

Fly ash is currently secondary raw material, which is produced in huge quantities and its applicability is still not optimal. Even though it is used in cement, concrete, mortars, aerated concrete, ceramics, etc., it is still used, more than 80 % of it, for the reclamation of industrial areas and open cast mines. The production of artificial aggregate by clinkering fly ash utilizes at least 90 % of fly ash in the mixture and it is, together with aerated concrete, one of the ways to make the most of the potential of this raw material. This article deals with the description of the nature of individual fly ash types produced in the Czech Republic and the study of its influence on the behaviour during the thermal process. Chemical composition is the decisive parameter; it indicates the ratio of silicon, iron and aluminium oxides, and thus affects the melting point of the entire complex. This article points out the differences among the various fly ash types and it directly shows, using a picture-analysis, the changes in a sample cross-section during annealing.

Use of Cement Kiln Dust, Blast Furnace Slag and Marble Sludge in the Manufacture of Sustainable Artificial Aggregates by Means of Cold Bonding Pelletization.

In this work, three different samples of solid industrial wastes cement kiln dust (CKD), granulated blast furnace slag and marble sludge were employed in a cold bonding pelletization process for the sustainable production of artificial aggregates. The activating action of CKD components on the hydraulic behavior of the slag was explored by evaluating the neo-formed phases present in several hydrated pastes. Particularly, the influence of free CaO and sulfates amount in the two CKD samples on slag reactivity was evaluated. Cold bonded artificial aggregates were characterized by determining physical and mechanical properties of two selected size fractions of the granules for each studied mixture. Eighteen types of granules were employed in C28/35 concrete manufacture where coarser natural aggregate were substituted with the artificial ones. Finally, lightweight concretes were obtained, proving the suitability of the cold bonding pelletization process in artificial aggregate sustainable production.

Lab Scale Granulation Tests of Artificial Aggregate Production from Marine Sediments and Industrial Wastes

Preliminary experimental results on the solification/stabilzation of dredged marine sediments (MS) and the non-metallic fraction of automotive shredder residues (NMASR) with coal fly ashes (CFA) are reported. Lab scale experiments of wet granulation at room temperature of these wastes are presented and discussed: cement was used as a binder, while water addition was dosed to optimize granules amount and size. The obtained granules were then subjected to standard leaching tests according to Italian regulation. The results of the leaching tests showed, for all the experimented wastes, a good level of stabilization: heavy metals and ions content was within the limits provided by Italian regulation for landfill disposal as not dangerous waste, while a COD content exceeding the above mentioned limit was detected. This was attributed to plastics and an organic contamination by vehicles fluids in the case of NMASR, and to sulphides and iron content in the case of marine sediments.

The Discussion of Plan about Water Conservation and Afforestation of Xiaanxi Artificial Aggregate Production System in Three Gorges Project

The Xiaanxi artificial aggregate production system in Three Gorges Project is the largest one in the world by now. In the process of quarrying, the problems of serious water & soil erosion and primary ecological system injury causing by excavation and dreg have not been solved. This paper analyses the site condition of the region, and basing on it, discusses the plan of water conservation and afforestation on quarry slope, stockyard platform and tailing-dump slope. Synthetically applying different methods and technologies, it would be able to achieve the efforts of conserving water and soil as well as good ecological landscape.

Artificial aggregate made from waste stone sludge and waste silt

In this research, waste stone sludge obtained from slab stone processing and waste silt from aggregate washing plants were recycled to manufacture artificial aggregate. Fine-powdered stone sludge was mixed with waste silt of larger particle size; vibratory compaction was applied for good water permeability, resulting in a smaller amount of solidifying agent being used. For the densified packing used in this study, the mix proportion of waste stone sludge to waste silt was 35:50, which produced artificial aggregate of more compact structure with water absorption rate below 0.1%. In addition, applying vibratory compaction of 33.3 Hz to the artificial aggregate and curing for 28 days doubled the compressive strength to above 29.4 MPa. Hence, recycling of waste stone sludge and waste silt for the production of artificial aggregate not only offers a feasible substitute for sand and stone, but also an ecological alternative to waste management of sludge and silt.

Utilization of fly ash by pelletization process; theory, application areas and research results

Abstract Although pelletization process is a world wide known technique in the production of artificial aggregates, it has not been widely used in construction sector. The 1985 figures show that overall pellet production for use as metallurgical product was 435 million tons and with respect to statistical figures that belong to 1989 the agglomerated product use in construction sector as lightweight aggregate was only 1.2 million tons. The reasons of low utilization of coal combustion by-products as lightweight aggregates in the construction sector are: — the availability of natural resource products and relatively higher costs of agglomeration process due to initial investments and — energy requiring curing procedures to obtain adequate strength for construction applications (e.g. steam curing and sintering). However, depending on the agglomerated materials’ properties and process efficiency, artificial aggregates with adequate engineering performance may be produced by moisture treatment under atmospheric conditions. In this study, the engineering performance of moist cured fly ash pellets including the effect of lime and cement additions both for geotechnical application and concrete production purposes were investigated and the results obtained are quite satisfactory for the related design requirements.

Benefication of shale aggregate and production of artificial aggregate

In the Union Territory of Mizoram of India, the geological formation consists of silty soil and shale aggregate. On account of its poor quality, the shale aggregate is unsuitable for road construction. When used even in base courses, the aggregate absorbs water, becomes brittle, gets degraded under traffic and softens. Due to difficult terrain, transport of good quality aggregates from out-side becomes uneconomical.