Cement Waste Research Articles

Effect of using agricultural wastes in cement blocks production

Effect of using agricultural wastes in cement blocks production

Utilization of Silica Fume and Steel Powder as an Additive in Concrete

Abstract: Cement concrete are designed to resist the disastrous surrounding effects such as hightemperature variations, high humid environments, coastal areas, industrial areas and other pollutant types. Engineers are continuously studying its properties and performance by blending several waste and modern materials in cement or other aggregates. The major advantage of these materials is the replacement of cement or other ingredients partially in concrete and presenting the comparable cementitious property. The use of waste material can consume these materials and also saves the principal ingredients of concrete. This can also improve the properties of concrete in fresh and hydrated states or may presents the properties comparable to the basic properties of concrete. In the current study a set of experiments had been performed to compare the use of 3 different types of mixes formed by replacing cement by silica fume, sand by steel powderand in third mix both the materials are used together. Cement and sand were replaced in different proportions such as 10%, 15%, 20%, 25%, and 30% by these materials. The ingredients are mixed in 1:1:2 proportions. The properties studied are 7 days, 21 days and 28 days compressive strengths and compaction factor. The main conclusions drawn are inclusion of silica fume increases the compressivestrength up-to a certain proportion and then reduces the strength, it also effects the setting time and consistency. Steel powder increases the strength but reduces the compaction factor. Comparatively higher early strength gain (7-days) is obtained with steel powder concrete.

An intelligent soil-cement mixing column driver

Conventional soil–cement columns fail to fully consider the layered structure of foundation soil, resulting in cement waste. Owing to the concealment of the installation site, soil–cement mixing column installation is labor-intensive, and its quality is considerably affected by the skills and experience of the laborers and operators. In this study, soil–cement mixing column installation technology and quality control were investigated by improving the automation and intelligent ability of installation equipment based on the Internet of Things (IoT) technology. An intelligent soil–cement mixing column driver was developed. Field test and engineering application results showed that frequency grouting, installation quality assessment, and on-site and remote monitoring can be implemented. The intelligent soil–cement mixing column driver improved the installation capacity and quality, reduced the cost, and simplified the construction management. The intelligent soil–cement mixing column driver has great potential for engineering applications and development. In the future, a wider range of applications and further intelligent upgrades will be investigated.

One-part alkali-activated binder produced from inertized asbestos cement waste

Owing to its carcinogenic potential and the environmental impacts associated with its disposal, the search for inertization technologies that enable the reuse of asbestos cement waste (ACW) is a priority in several countries. Among the proposed methods, optimized heat treatment is a promising methodology. However, there is a lack of studies aimed at the application of asbestos cement waste, even after proper treatment. Thus, this study investigates the potential use of heat-treated asbestos-cement waste (ACWT) as a precursor of one-part alkali-activated binders. Eleven formulations were established using the I-Optimal algorithm, strategically varying the mass fractions of ACWT, solid sodium metasilicate (SSM) with a molar ratio of SiO2/Na2O equal to 0.98, and water. These formulations served as the basis for the construction of models that relate the properties of pastes with the proportion of materials. The pastes were evaluated by isothermal calorimetry, X-ray diffraction, autogenous shrinkage, drying shrinkage, and compressive strength. The results show that the formulations with an SSM concentration of approximately 5% and molarities close to 1 M presented the best mechanical properties. The addition of SSM had a strong influence on the accumulated heat rate, with the formulations containing the activator showing superior mechanical behavior compared to the mixtures without the activator. Furthermore, the pastes without an activator exhibited lower drying shrinkage and chemical shrinkage. It was possible to verify that ACWT can be applied for the production of alkali-activated binders and that the statistical mixture design is an efficient method for predicting the evaluated properties.

Life cycle sustainable assessment of natural vs artificial lightweight aggregates

Optimal selection of concrete aggregates can promote sustainable construction practice from the bottom line, which is a feasible strategy to cope with resources crisis and solid waste pollution. In this study, a two-level tree structure framework was thus proposed for the sustainability assessment of lightweight aggregates (LWA) based on the life cycle assessment concept. The evaluation system was divided into four criteria categories marked as society demands, economic costs, environmental impacts and technical performance, and each of them was assigned a number of sub-index. A qualitative questionnaire survey with seven sub-index and a quantitative calculation with eight sub-index were executed in the target system. Sintering fly ash aggregates (SFFAA), cold-bonding fly ash aggregates (CBFAA), waste clay brick aggregates (WCBA) and natural pumice aggregates (NPA) were chosen as typical artificial and natural lightweight aggregates objectives and evaluated in the framework. Impact and sensitivity analyses were conducted to comparably discuss the sustainability of various lightweight aggregates. The impact analyses represented that the waste clay brick aggregate has better sustainability. The sensitivity analysis shows that the supply-demand relationship of raw materials greatly impacts the sustainability of lightweight aggregate, and the transportation distance of raw materials is the critical factor in the production of LWA. At the same time, artificial lightweight aggregates are sensitive to cement binder consumption, and zero cement addition or waste cement powder is an optimistic option. From the sustainable life cycle assessment results, waste clay brick aggregates, sintering fly ash aggregates and cold-bonding fly ash aggregates are suggested as the alternative to the natural pumice aggregates for the lightweight aggregates concrete production. The emphasis on the weight of the social dimension will tend to prefer the selection of SFAA, and the economic or environmental dimension will lead to the preference of CBFAA for sustainable development. The framework proposed in this work could be used in choosing other sustainable construction materials or cleaner products.

Radioactive Waste Embedding in Cement Matrix and the Establishment of Cemented Waste Testing Laboratory at Paks Nuclear Power Plant

For the treatment of low and intermediate level radioactive wastes generated at the Nuclear Power Plant of Paks, a new compact waste package will be created with a new cementation technology currently under construction. During the operation, the solid waste will be placed in steel drums, which then will be put into a thin-walled steel container. The cavity volume of the containers will be filled with cemented slurry made using liquid radioactive waste. The compact waste packages must comply with the waste acceptance criteria described in the National Radioactive Waste Repository Safety Report. The task of the cemented waste testing laboratory, which is under construction, will be the in-service inspection of the finished cemented material and the determination of properties such as compressive strength and leachability (diffusion coefficient) of the specimens made thereof. During the installation of the laboratory and testing of the devices used in the cement / concrete industry, it turned out that in many cases special moulds are required due to the low viscosity and corrosive properties of the radioactive paste. In addition, the collection of debris generated during the measurement of compressive strength of radioactive cement stone and the minimization of dusting are important requirements.

Leaching and transport of technetium from reducing cementitious waste forms in field lysimeters

Field lysimeters tests examined leaching of technetium-99 (99Tc) from two types of cementitious waste forms and found that the presence of blast furnace slag reduced the overall leaching of 99Tc from the waste form. The two cementitious waste forms were a slag-grout 45%/45%/10% mixture of fly ash, blast furnace slag, and cement, respectively, referred to as slag-grout or a 55%/45% mixture of cement and fly ash, respectively, referred to here simply as cement. Duplicate sources of each composition were buried in four lysimeters for approximately 10 months to evaluate leaching characteristics under natural meteorological conditions in South Carolina, USA. Effluent samples were collected four times during the experiment, and the distribution of 99Tc in the sediment was determined by destructively segmenting the lysimeters at the end of the experiment.The transport of Tc within the lysimeter was simulated by assuming advection, dispersion, and sorption in partially saturated porous media, and by using a shrinking-core type approximation for the release of Tc from the source. The shrinking-core model predicted that the oxidation front created by the oxygenated infiltrating groundwater moved into the cementitious source at a rate of 14 μm/day. As this front moved through the source, Tc(IV) was oxidized to the highly mobile Tc(VII) (as TcO4−) species, which then was transported through the sediment primarily via advection due to a small partitioning coefficient (Csolid/Caq; Kd = 0.14 mL/g). The simulations predicted a cycle of accumulation of Tc in sediment at the source between rainfall events, followed by downward advection due to infiltration during rainfall events. The anomalous upward movement of Tc peak was predicted to be due to upward flux caused by evaporation after the experiment was terminated by capping the lysimeter. These experiments demonstrate that Tc leaching from cementitious waste forms under simulated vadose zone oxidizing conditions can be reasonably approximated by the shrinking core model, and the migration of Tc through the sediment is profoundly influenced by the presence of slag in the grout formulation and hydraulic conditions due to the low sorption affinity of TcO4−.

Development of Composites from Iron-Rich Galvanized Sludge with Slag Based Cementitious Material and Waste Foundry Sand

Galvanized sludge (GS) generated from the cable wires manufacturing industry, waste foundry sand (WFS) from steel manufacturing and granulated blast furnace slag (GBFS), are the wastes that pollute the environment. This study investigated the use of these three materials to develop a value-added composite that can be utilized in the building and construction industry. The GS was stabilized with alkaline activated WFS and alkaline activated GBFS. The chemical composition of the materials was studied by analyzing the elemental composition, mineralogy, and micrography. To determine the optimum mix design, the unconfined compressive strength and water absorption tests were carried out on the developed composites. The GS was predominated with ferric oxide, while the WFS was laden with mainly, silicon dioxide and aluminum oxides. The results obtained showed that alkaline activated WFS yielded the highest UCS of 3.3 MPa, as compared to 1 MPa from the GBFS binder. The microstructure of stabilized GS changed from heterogeneous particles to finer homogeneous particles. The WFS stabilized GS can be used for different applications, for semi-load bearing applications.

Waste Alkaline Residues Impact in Desertification Treatment in Iraq

Waste Cement waste (the by-product of the cement industry) is produced from a dry and wet method for manufacturing cement. These wastes are produced in large quantities from various cement factories that are estimated in tons thrown in the land located in different places of the country, for example, Kufa cement factory in addition to a huge amount of cement dust produced by (450Tons per day) and their influence on the environment. Therefore, a safe method must be found so that can eliminate these wastes because the by-product contains heavy metals and their oxides which are harmful to the human and to the environment especially air pollution and desertification. In this research it has been utilized these wastes as major and minor nutrients for sand soils (major nutrients Ca, K, S, Fe and small nutrients (Mn, Zn, Cu)), cement dust is added in certain proportions to the sandy desert lands. The result showed significant yields by increasing the content of sandy soil from the major and minor nutrients. This enables us to gain a safe environment and solve desertification problem which has a major cause to the environmental pollution

Study on Properties of Cement Stabilized Macadam with Recycled Aggregate of Different Replacement Rates under Vibrating Mixing

It has the goal of green construction to use recycled aggregate of waste cement concrete in cement stabilized macadam base to replace recycled aggregate of base. In this paper, the properties of cement stabilized macadam with natural aggregate and recycled aggregate under different replacement ratios are compared. The test results show that the physical properties (apparent density, mud content, crushing value, water absorption, etc.) of recycled aggregate are lower than those of natural aggregate, but meet the requirements of the specification. With the increase of the proportion of recycled aggregate in cement stabilized macadam, the optimal moisture content required for the maximum dry density of fully recycled aggregate mixture increased by 20.6% compared with that of natural aggregate mixture; the unconfined compressive strength of cement stabilized macadam with recycled aggregate at 7d and 28d showed a downward trend, and the strength of cement stabilized macadam with fully replaced recycled aggregate at 7d and 28d decreased by 10% and 1% respectively 0%. In addition, the strength of full substitution 28 increased by 11.1%. The research shows that the recycled aggregate base can meet the construction requirements, and the vibration mixing has better advantages, which provides a reference for engineering application.

Experimental Study of Mix Design of Concrete by Mixing Sand with Plastic Waste

Abstract: Cement concrete are designed to resist the disastrous surrounding effects such as high temperature variations, high humid environments, coastal areas, industrial areas and other pollutant types. Engineers are continuously studying its properties and performance by blending several waste and modern materials in cement or other aggregates. The major advantage of these materials is the replacement of cement or other ingredients partially in concrete and presenting the comparable cementations property. The use of waste material can consume these materials and also saves the principal ingredients of concrete. This can also improve the properties of concrete in fresh and hydrated states or may presents the properties comparable to the basic properties of concrete. In the current study a set of experiments had been performed to Compare the use of one type of mixes formed by replacing sand with Plastic waste. Sand was replaced in different proportions such as 5 %, 10 %, 15% And 20 % by these materials. The properties of concrete are studied for 7days, 14days, 21days and 28days.

Utilization of Silica Fume and Steel Powder as an Additive in Concrete

Abstract: Cement concrete are designed to resist the disastrous surrounding effects such as high temperature variations, high humid environments, coastal areas, industrial areas and other pollutant types. Engineers are continuously studying its properties and performance by blending several waste and modern materials in cement or other aggregates. The major advantage of these materials is the replacement of cement or other ingredients partially in concrete and presenting the comparable cementitious property. The use of waste material can consume these materials and also saves the principle ingredients of concrete. This can also improves the properties of concrete in fresh and hydrated states or may presents the properties comparable to the basic properties of concrete. In the current study a set of experiments had been performed to compare the use of 3 different types of mixes formed by replacing cement by silica fume, sand by steel powder and in third mix both the materials are used together. Cement and sand were replaced in different proportions such as 10%, 15%, 20%, 25%, and 30% by these materials. The ingredients are mixed in 1:1:2 proportions. The properties studied are 3 days, 21 days and 28 days compressive strengths and compaction factor. The main conclusions drawn are inclusion of silica fume increases the compressive strength up-to a certain proportions and then reduces the strength, it also effects the setting time and consistency. Steel powder increases the strength but reduces the compaction factor. Comparatively higher early strength gain (3-days) is obtained with steel powder concrete.

The role of calcium silicates and quicklime on the reactivity of rehydrated cements

Construction and demolition waste recycling is mandatory in the context of circular economy. Specifically, applications for the cementitious waste fines are less discussed in scientific literature and barely implemented. Apart from the use of cementitious waste fines as raw materials for clinker production, thermal treatment by the decomposition of fines at temperatures lower than 600 °C has been explored to produce an alternative binder implying under this limit in low CO2 emissions during production. However, there are doubts if its reactivity results from the hydration from residual calcium silicates, and quicklime (CaO) eventually formed after the thermal treatment. This paper investigated quantitively the contributions of calcium silicates and quicklime by thermogravimetry (TG) and quantitative X-ray diffraction (QXRD) on the reactivity of the rehydrated cements. After hydration of the high initial strength Portland cement, only 5% (g/g) of calcium silicates remained, mostly larnite. After dehydration at 500 °C, only 6% (g/g) of quicklime was formed due to the decomposition of portlandite. Intermediate silicates increased in function of temperature of dehydration until 500 °C, but the contents were lower than 18%-g/g. Those phases can explain partially the heat released during rehydration. The heat seemed to be also related to the chemically bound water in the reformation of amorphous C-S-H. In fact, for a fixed water/cement ratio, the increase of chemically bound water explained both, the increase of heat released and the compressive strength of the rehydrated cements. This supports our finding that the calcium silicates or quicklime are not the only responsible for the reactivity of this binder.

Preparation and characterization of biochar from cement waste for removal of rhodamine B dye

Preparation and characterization of biochar from cement waste for removal of rhodamine B dye

Experimental Investigation on Concrete Using Agricultural Waste Ash-A Review

The present study is aim to develop a high strength concrete bye using mineral admixtures of bamboo leaf ash and pawpaw leaf ash. In order to check the compatibility, physical and chemical properties of materials are studied. This aims to provide a comprehensive review of recent trends incorporating biomass ashes from agricultural waste in ordinary Portland cement(OPC).The material properties of different leaf ashes and their effect on fresh and hardened concrete properties are review. Partial replacement of OPC with by products, such as bamboo leaf ash, pawpaw leaf ash. Partial replacement of OPC with by products, such as bamboo leaf ash, pawpaw leaf ash. It will also contribute to the effort of achieving zero waste technology and sustainable development.

Durability analysis and optimization of a binary system of waste cement concrete and glass-based geopolymer mortar

Durability analysis and optimization of a binary system of waste cement concrete and glass-based geopolymer mortar

Impact of carbonation on leaching of constituents from a cementitious waste form for treatment of low activity waste at the DOE Hanford site

Carbonation can be a major aging process during disposal of alkaline cementitious waste forms and can impact constituent leaching by changes in material alkalinity, pore structure, and controlling mineral phases. The effect of carbonation on the leaching of major and trace constituents from Cast Stone, a cementitious waste form developed to treat high salt content low activity waste, was studied through a combination of leaching experiments and reactive transport simulations. Diffusive transport of constituents in the waste form was evaluated using reactive transport modeling of diffusion-controlled leaching test results and a geochemical speciation model derived from pH-dependent leaching. Comparisons between Cast Stone materials aged under nitrogen, air, and 2% carbon dioxide in nitrogen showed that carbonation impacts solubility, physical retention and observed diffusivity of major and trace constituents. Carbonation under 2% CO2 decreased the diffusion-controlled leaching of chromium by two orders of magnitude. Modeling results suggest that carbonation may also decrease solubility of technetium while changes to microstructure by carbonation increases effective diffusivity of constituents in Cast Stone.

Shrinkage and sorptivity of mortars with thermoactivated recycled cement

This study aims to characterise the shrinkage and sorptivity behaviour of mortars produced with thermally activated recycled cement (RC) sourced from reference waste cement paste (RCP) or from the cementitious fraction of old concrete (RCC), the latter following a new patented method. Ordinary Portland Cement (OPC) was replaced with 5–100% RC, in mortars of similar consistency or equal water/binder (w/b). The influence of RC particle size and source material composition were also assessed. Moreover, selected mortars were produced with partial incorporation of fly ash to explore the high alkalinity of RC. Compared to OPC mortars of equal w/b, the compressive strength was not significantly altered for up to 15% RCP and reduced less than 25% for up to 100% RCP. For similar flowability, the water absorption and shrinkage were higher in RC mortars, following the necessary increase of the w/b. However, for fixed w/b, RC mortars presented a more refined interparticle porosity, and the coefficient of absorption decreased with RC content. Shrinkage consistently increased with RC content due to the refined interparticle microstructure, higher water demand and lower particle hardness of RC. Nevertheless, the 90 days shrinkage increased less than 17% for up to 50% RCP. Overall, RC's high potential was shown as an active supplementary cementitious material, with a negligible influence on shrinkage for up to 50% replacement.

Use of Cement Granulate in Road Construction

The possibility of using cement granulate, a product of processing old cement concrete and waste generated during the demolition of buildings and structures, has been studied in the construction, reconstruction and repair of highways. The use of recycled materials in the road industry is one of the sources of saving natural raw materials. In addition, the use of waste solves environmental problems through the disposal of old waste materials and structures. Having completed the study of cement granulate, the possibility of using it for the construction of foundations for road pavements, as well as a substitute for crushed stone in the manufacture of concrete slabs of prefabricated coverings, has been determined. In the first case of using cement granulate, the wedge method is effective. It has been experimentally confirmed that the remains of cement mortar on the surface of used crushed stone contribute to its better wedging, thereby creating a more durable base layer. In order to assess the possibility of using cement granulate as a substitute for crushed stone for the manufacture of prefabricated concrete slab, standard studies of this material were carried out, the composition of the cement concrete mixture was selected, and standard samples were manufactured and tested. The test results have shown that the use of cement granulate for such purposes is quite acceptable. In particular, the average strength of the samples in the tested batch turned out to be 45.13 MPa and the guaranteed strength was 35.13 MPa, which corresponds to the B35 class of concrete. These indicators demonstrate that the use of cement granulate may well be in demand in the construction and reconstruction of local roads. At present, as it is known, a program is being implemented to improve the transport and operational level of local roads, and this is about 70 thousand kilometers. And here, of course, a huge amount of road construction materials will be required.

A combined system for asbestos-cement waste degradation by dark fermentation and resulting supernatant valorization in anaerobic digestion

The use of biological processes for the treatment of asbestos cement waste (ACW) has gained interest in recent years. Nevertheless, this methodology is not yet consolidated because of the incomplete ACW conversion during the biological treatment and the consequent need for further treatments that generally require a high amount of energy and chemicals. In this study, the efficiency of both mesophilic and thermophilic dark fermentation (DF) fed with glucose in fed-batch conditions was assessed for ACW biological treatment. Both thermophilic and mesophilic DF of glucose resulted in a partial conversion of glucose into organic acids that successfully degraded all the asbestos fibers contained in an ACW sample. A hydrogen-rich biogas was produced as well: at the end of the mesophilic DF treatment 0.14 LH2 gglucose−1 were obtained. In addition, the anaerobic digestion (AD) of the DF supernatants led to the production of 0.38 LCH4 gCOD−1.