Lime Sludge Research Articles

Characterisation studies on the particle size effect of calcium carbonate in high-strength concrete

The main objective of this study was to determine the hydration activity and shrinkage of high-strength concrete (HSC) after the incorporation of different particle sizes of calcium carbonate (CaCO3). Three different sources of calcium carbonate – lime sludge (a residue collected from the paper and pulp industry, size ∼43 μm), commercial micro-calcium carbonate (size ∼13 μm) and commercial nano-calcium carbonate (size <100 nm) – were used as partial replacements of cement in HSC. Particle size analysis, heat of hydration, compressive strength and shrinkage aspects for various mixes were studied. The results showed an enhancement of the hydration reaction due to the nucleation effects of calcium carbonate and a considerable improvement in the reduction of shrinkage volume, hence the minimisation of shrinkage cracks. It was also found that shrinkage was significantly reduced with the incorporation of nano-sized particles rather than micro-sized particles. Compared with the control mix, all the mixes with different sizes of calcium carbonate showed a significant increase in compressive strength. To substantiate the obtained results, qualitative and quantitative analyses (X-ray diffraction, thermogravimetric analysis and differential thermogravimetric analysis, Fourier transform infrared spectroscopy and scanning electron microscopy) were carried out to determine the hydration behaviour of cementitious pastes incorporating calcium carbonate without aggregates.

Thermal Performance Assessment of Walls Made of Three Types of Sustainable Concrete Blocks by Means of FEM and Validated through an Extensive Measurement Campaign

The thermal behavior of three different walls, made with and without by-products, is assessed by means of the Finite Element Method, aiming to evaluate its performance in terms of the sustainable construction of the blocks. Results were compared to those obtained from an experimental campaign, aiming at validation of the model. The by-products used for the blocks were “lime sludge” and “sawdust”, whose performance was compared against the traditional blocks made of concrete as a reference, aiming to demonstrate its sustainability, showing decreases of the thermal transmittance up to 10.5%. Additionally, following the same methodology, the thermal behavior of these above-mentioned blocks but now with added internal insulation made of “recycled cellulose” was assessed, showing higher decreases up to 25.5%, increasing sustainability by addressing an additional reduction in waste, so the right combination of using by-products and the insulating filler in their cavities has been revealed as a promising way of optimizing the walls, offering a relevant improvement in energy savings. Finally, when comparing the U-values of the blocks made of concrete without insulation versus those made of by-products, with insulation, improvements up to 33.3% were reached. The adaptation of the procedure through a moisture correction factor was also incorporated.

Sustainable Utilization of Paper-Industry Lime Sludge through Development of Metakaolinite-Based Cementitious Binder

The emphasis of the current study was on the calcination of lime sludge, performed at different temperatures from 650°C to 750°C, which consumes less energy as compared to the industrial process of calcination. Different proportions of calcined lime sludge and raw lime sludge were used with cement to form cementitious binders. M25 grade concrete was prepared with the application of the prepared binders and tested for strength properties at 7 and 28 days of curing. The binder consisted of 10% substitution of cement with as-received lime sludge and 30% substitution with calcined lime sludge and produced a compressive strength of concrete approximately similar to the control concrete. Reactive lime and metakaolinite performed an active role after the calcination of lime sludge at 650°C, which worked as pozzolana. This effect is also confirmed with isothermal calorimetry of the prepared binder. The prepared binder was sustainable with approximately 20% less production cost and 55% less emission of greenhouse gases as compared to ordinary portland cement.

Investigation of potential use of waste lime sludge in bituminous binder

The amount of waste generation has increased massively owing to the large production in manufacturing industries which has led to the problem of disposal for this waste. The wisest way to reduce the burden on landfills for disposal of waste is to utilize it in construction industry. Therefore, a study has been undertaken to use waste lime sludge containing CaCO 3 from toothpaste industry to amend the properties of asphalt. In this paper, the conventional test of the modified binder prepared by adding waste sludge was compared to unmodified binder. Moisture susceptibility of modified binder was evaluated to check the moisture resistance and to evaluate the grade of bitumen the kinematic viscosity test was conducted. It was found that by adding waste lime sludge, soft grade bitumen was converted to hard grade and it showed better resistance to moisture damage.

Preparation of calcium oxide nanoparticles from industry rejects: Recovery and value addition of mineral values

Abstract Lime sludge is one of the major unutilized industrial reject and has promising potential as an alternative source for calcium. The present work illustrates a viable process developed for rapid and cost-effective extraction of calcium mineral values from the alkaline lime sludge. A comparative assessment of formic and acetic acid used for extraction of calcium from the reject has been discussed. The chemical method at ambient conditions extracted remarkable amount of calcium from lime sludge. Detailed analytical characterization revealed that recovery efficiency of calcium is much more superior for acetic acid. The organic salt of calcium obtained was re-crystallized for better purity and further treated to obtain inorganic salt viz chloride / nitrate as precursor to convert into nano calcium oxide by sol-gel method. The final product was characterized by XRD, ICP and SEM. The average crystallite size of obtained nanoparticles was 42.44 nm based on XRD analysis results.

Influence of fly ash, lime Sludge and Polypropylene fibre on Compaction and Strength Properties of Subgrade

The development of population, quick urbanization and more development of structures and buildings has brought about the decrease of good quality land. To improve the accessibility of good quality land, strength and compaction properties of land should be improved. The fundamental goal of this examination is to explore the utilization of fly ash, lime sludge and polypropylene fiber in Geotech highway application and to assess their impact on quality and compaction of soil, utilized for subgrade. The soil samples were gathered from the zones of Chandigarh where clayey soil is present in abundance. The laboratory testing led to decide the strength and compactive effort of the clay soil. This investigation includes three principle tests. The primary test is standard proctor test. The subsequent test is California bearing ratio and the third test is the direct shear test. Proctor test gives the compactive effort of the soil and CBR gives the subgrade strength. The outcomes acquired are thought about for the examples and inferences are drawn towards the unstability and effectiveness of admixture support at different percentages, as replacement for high quality subgrade and cost-effective approach.

Application of thermo-chemically activated lime sludge in production of sustainable low clinker cementitious binders

Lime sludge, an industrial by-product, is thermo-chemically processed at 850 °C in presence of sodium hydroxide and characterised for its hydraulic properties. Lime absorption is assessed as per Indian Standard: 1727. Various binder mixes using Portland cement clinker, processed lime sludge, ground granulated blast furnace slag (GGBFS) and calcined clay were prepared. The Blaine’s surface area and particle size distributions of binder mixes were determined. The setting time and compressive strength of binder mixes were evaluated. Micro-structural examination was carried out to assess the strength developing phases with help of X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscope/energy-dispersive X-ray (SEM/EDX) and Fourier transform infrared spectroscopy (FTIR) It was found that developed binder with 20% processed lime sludge was found suitable as alternative binder. Life cycle analysis was carried out for developed binder using SIMA PRO software. Global warming reduction in terms of CO2 emission was 51% compared to ordinary Portland cement. Abiotic depletion potential in terms of resources depletion was reduced by 50% showing its sustainability as construction material.

Modeling of UCS value of stabilized pond ashes using adaptive neuro-fuzzy inference system and artificial neural network

This paper investigates the capability of adaptive neuro-fuzzy inference system (ANFIS) and artificial neural network (ANN) modeling approach to predict the unconfined compressive strength (UCS) of stabilized pond ashes with lime alone and in combination with lime sludge. Out of 170 data set, a total of 119 data were randomly selected for training, whereas remaining 51 were used for testing the model. Four membership’s functions (MFs) such as Gaussian, generalized bell-shaped, triangular, and trapezoidal were used with ANFIS model. Statistical parameters were used to compare the performance of four MF-based ANFIS and ANN models. A comparison of results suggests that Triangular MF-based ANFIS model exhibit better predictive performance with higher CC = 0.980 and lower MSE = 3028.515 and RMSE = 55.032 than other MF-based ANFIS and ANN model. The results of single-factor analysis of variance indicate that there is an insignificant difference between measured and predicted values of UCS using different models. Further, results of sensitivity analysis depict that the curing period, lime sludge, and lime are the most important parameters which affect the performance of Triangular MF-based ANFIS in predicting the UCS of stabilized pond ashes. Thus, the Triangular MF-based ANFIS model could be a useful tool in predicting the UCS value of stabilized pond ashes because of its adequacy in handling uncertainties in the test results with accuracy.

Strength Development in Bio Mineralised Steelslag Bricks using Micp Process

Steel slag annual production in India is about 12 million tonnes per annum. Steel slag is one of the industrial residue came out from steel industries. The amount of steel slag produced from different steel industries is 150-200kg per tonnes of steel produced These steel slag is dumped in land and pollute the environment. Paper mills produce the large amount of lime sludge is about 5 lakh tonnes per annum. These steel slag used as binder material and coarse aggregate also in different sieve sizes. These both steel slag and lime material contains large amount of calcium mineral compared than other waste materials. The conventional burnt clay brick manufacturing firing process develops the 750 million tonnes of co2 emissions per year. The Bio mineralised steel slag bricks developed by using these waste materials and bacillus bacteria. These microbes generates the calcium carbonate precipitation in the steel slag bricks. The strength development of these BMSS bricks were achieved by addition of NBU medium supply and carbonation process. The scanning electron microscope (SEM), mineralogical composition analysis, X-ray diffraction analysis, compressive strength and water absorption test are conducted to support the strength development in bio mineralised steel slag bricks.

Assessment of the Polypropylene Fiber Reinforced Concrete with Wastewater Lime Sludge

The study investigated by the reuse of wastewater lime sludge is replaced for cement and addition of polypropylene fiber in the production of concrete for external use. The textile wastewater covers the cotton dyeing and printing operations. Nowadays the demand of cement has concern increased. This will contribute to increased cement production because of the cement industry is one of the major subscribers of carbon dioxide emission [15-18]. This work is directed towards developing low cost concrete from wastewater treatment plant. The study utilized in the sludge-cement replacement percentages of 10%, 20%, 30%, 40% and 50% by weight of cement. The test conducted on concrete examines were slump test, compaction factor test and then the mechanical properties on cube, cylinder, Beam and also NDT tests. Finally, the study concluded that the dry sludge can be used in as an improver to concrete mixture till up to 30%. Many more researches are needed to evaluate the durability of sludge concrete and the performance of reinforced sludge concrete.

A Taguchi approach for study on impact response of ultra-high-performance polypropylene fibrous cementitious composite

The present work emphasized on identifying and optimizing mix proportions for ultra-high-performance polypropylene cementitious composites (UHPPFCC) made with lime sludge, micro silica and polypropylene fibre. In this connection, UHPPFCC was prepared by replacing the cement with lime sludge by 0%, 15%, 30% and 45%; micro silica as replacement of cement by 0%, 2%, 4% and 6%. In addition the polypropylene fibres were incorporated to the mix at a dosage of 0%, 0.2%, 0.4% and 0.6%. The UHPPFCC was optimized by Taguchi design approach with L16 orthogonal array. The number of trials were configured with three varying factors at four levels each. Besides that, the contribution of lime sludge, micro silica and polypropylene fibre were analysed using mean response data and ANOVA technique. The optimized mix proportions attained from the Taguchi design approach is verified with the experimental and modeling results of impact energy. It was found that the optimized compressive strength and impact energy using Taguchi method was higher than those of proposed in initial 16 series. Findings revealed that the highest compression strength and impact energy of UHPPFCC were found in the mix comprising 30% of lime sludge, 6% of micro silica and 0.6% of polypropylene fibre.

Compaction and strength characteristics of an expansive clay stabilised with lime sludge and cement

The chemical stabilization of expansive soils has been found to be quite successful in controlling detrimental volume changes due to swell-shrink behaviour. Lime, cement, CaCl2, fly ash, pond ash and other chemical reagents have been effective in stabilizing expansive soils and improving their characteristics. The influence of lime sludge, a by-product of the paper industry, on the index properties of expansive clays was investigated. Their LL, PI and FSI, and the engineering characteristics of these clays were measured after being treated, including their compaction characteristics, stress-strain behaviours at different curing periods and CBRs. The index and engineering properties of the clay-lime sludge blends were studied for different lime sludge contents. As the compacted density did not show a satisfactory improvement upon addition of lime sludge, 10% cement was added to all the lime sludge-clay blends to study its influence on the above properties of lime sludge–treated expansive clay. The addition of 10% cement resulted in lower LL, PI and FSI and higher densities, strengths and CBRs.

Influence of Lime Sludge and Sodium Salts on the Strength and Structural Behavior of Clayey Soils–Granite Stone Slurry Dust Composite with Curing

This study aims to show the changes in the properties of clayey soils in the presence of granite stone slurry dust and lime sludge collected from granite block sawing mill and sugar industry, respectively. Clayey soils in this study refer to black cotton soil and red earth. The changes in unconfined compressive strength of clayey soils–optimum granite stone slurry dust composite with curing stabilized with lime sludge and in the presence of sodium salts have been emphasized in this study. The unconfined compressive strength of clayey soils–optimum granite stone slurry dust composite increases marginally in the presence of lime sludge and sodium salts for samples tested immediately. However, the increase in strength was significant with curing. The maximum improvement in the strength has been observed in the presence of NaOH. Scanning electron microscope studies reveal the improvement in the structural behavior of the clayey soil–optimum granite stone slurry dust composite in the presence of lime sludge and sodium salts.

A Review on Pyroprocessing Techniques for Selected Wastes Used for Blended Cement Production Applications

Pyroprocessing is an important stage in cement manufacturing. In this process, materials are subjected to high temperatures so as to cause a chemical or physical change. Its control improves efficiency in energy utilization and hence enhances production for good quality assurance. Kilns used in cement manufacturing are complex in nature. They have longer time constants, and raw materials used have variable properties. They are therefore difficult to control. Additionally, the inclusion of various alternative fuels in burning makes the process more complex as the fuel characteristics remain inconsistent throughout the kiln operation. Fuel intensity standards for kilns using fuel oil are very high, ranging from 2.9 GJ to 7.5 GJ/ton of clinker produced. Grinding of clinker consumes power in the range of 2.5 kWh/ton of clinker produced. These and other pyroprocessing parameters make cement production costly. The pyroprocessing process in kilns and the grinding technologies therefore have to be optimized for best processing. This paper discusses the cement manufacturing and grinding processes. The traditional kiln technologies and the current and emerging technologies together with general fuel and energy requirements of cement manufacturing have been discussed. From the discussion, it has been established that the cement manufacturing and grinding technologies are capital‐intensive investments. The kiln processes are advanced and use both electricity and natural fuels which are expensive and limited factors of production. The raw materials used in cement manufacturing are also limited and sometimes rare. The calcination of the raw materials requires external energy input which has contributed to the high cost of cement especially to low‐income population in the developing countries. Self‐calcining materials, in which the pozzolanic materials burn on their own, are potential pozzolanic materials with great potential to lower the cost of cement production. Such materials, as shown from the previous research study, are rice husks, broken bricks, spent bleaching earth, and lime sludge. There is a need, therefore, for research to look into ways of making cement using kiln processes that would use this property. This will be cost‐effective if successful. It can be done at micro‐ and small‐scale enterprise.

Fibre Reinforced - Fly Ash, Lime Sludge Stabilized Clay Soil as Subgrade Material in Flexible Pavement

Fibre Reinforced - Fly Ash, Lime Sludge Stabilized Clay Soil as Subgrade Material in Flexible Pavement

Characterization, weathering and modeling of natural fibre based composites

Natural fibre based composite materials find their use in the manufacture of a large number of products and this makes them commercially valuable. In this study, a hybrid 3 ply jute/coir-epoxy composite was used to study the effect of natural fibres on the mechanical properties of the composites. Mechanical testing revealed that the properties enhanced with increasing fibre content as the stronger fibres contribute to a stronger and stiffer composite. Additionally, analytical analysis using the Halpin-Tsai method was employed to calculate elastic constants of the composites. Comparative analysis revealed better properties for hybrid composites than single fibre (jute or coir) composites due to the additive properties added by the two fibres. Moreover, increasing the fibre content led to the enhancement of the elastic constants except Poisson’s ratio which decreased with increasing fibre loading. Finite element modelling using ANSYS was simulated for tensile and flexural loading conditions for a 3 ply jute/coir/jute–epoxy composite (oriented 0°/90°/0°). It was found that the modelling results correlated well with the experimental results for 15 wt% fibre content in the composites. Composite materials since they are widely used, they may come into contact with harsh environmental conditions that may cause weathering. Hence weathering studies were conducted to study the water absorption at room temperature and under boiling conditions. It was found that the composites with lime sludge filler material had a higher water absorption rate than the jute and wood dust reinforced polyester composites. This was due to presence of CaCO3 which is a good water absorbent in lime sludge filler material. Moreover, jute fibres being hollow in nature, absorbed more water than wood dust with increasing time leading to more water absorption in case of jute-polyester composites than wood-polyester composites.

Utilization of Water Utility Lime Sludge for Flue Gas Desulfurization in Coal-Fired Power Plants: Part III. Testing at a Higher Scale and Assessment of Selected Potential Operational Issues.

The feasibility of lime sludge utilization for flue gas desulfurization was evaluated by continuing the previous laboratory-scale studies at a higher scale and investigating two potential operational issues, namely viscosity and metal corrosion. Two lime sludge samples and a baseline limestone sample, which were previously characterized and tested for SO2 capture from a simulated flue gas at a laboratory scale, were first tested at a 10-fold scale with a simulated flue gas, and then tested with a slipstream of flue gas from a coal-fired power plant. The tested lime sludge and limestone slurries reduced the SO2 concentration of the simulated flue gas from 2000 to <1 ppm, and they demonstrated similar Hg reemission profiles. Field-testing results revealed that the limestone and lime sludge slurries reduced the SO2 concentration of the flue gas from ~1500 to <1 ppm. These experiments confirmed our previous smaller scale laboratory results that lime sludge can function as a suitable substitute for limestone for SO2 removal from the flue gas of coal-fired power plants without negatively affecting Hg reemission. Two operational issues, namely viscosity and metal corrosion, were investigated to evaluate practical issues in the transition from limestone to lime sludge at power plants. Results of Marsh funnel viscosity experiments conducted at different solids contents and temperatures indicated the limestone and lime sludge slurries and their gypsum counterparts had similar flow characteristics. Carbon-steel, stainless-steel, and Hastelloy coupons were tested for corrosion by lime sludge and limestone slurries. Both stainless steel and Hastelloy were resistive to corrosion in slurries made from lime sludge or limestone samples or their gypsum counterparts. A considerable but similar amount of corrosion was observed for carbon-steel coupons exposed to lime sludge and limestone slurries. Adding 5000 ppm of Cl- to slurries considerably increased the corrosion rate of carbon steel.

Synthesis of nanosilica from fly ash and its utilization with lime sludge in concrete: an environmentally friendly and sustainable solution

Solid waste generation and its disposal is becoming the cause of concern all over the world. Paper industry is not exceptional as lime sludge and fly ash need appropriate utilization to reduce the threat for the environment. Application of these materials in other industries could be the appropriate alternative. In this paper, fly ash is utilized for nanosilica synthesis, because of the presence of silica precursor in very high amount. Nanosilica was synthesized with the alkali treatment of ash and acid precipitation. The produced nanosilica was characterized for crystallinity, specific surface area, size and morphology. This synthesized nanosilica is used with lime sludge in cement-based concrete. Concrete blocks were evaluated for compressive strength after 7 and 28 days of curing. It is observed that the compressive strength of concrete blocks with only lime sludge decreased up to 50% with the replacement of cement by lime sludge from 10 to 40%. Concrete blocks produced with the addition of 0.3, 0.6 and 1.0% nanosilica and different proportions of lime sludge attained up to 30% more compressive strength in comparison with the blocks without nanosilica.

Pyroprocessing and the optimum mix ratio of rice husks, broken bricks and spent bleaching earth to make pozzolanic cement

This paper presents the findings of an experimental investigation on optimizing pozzolanic activity of a blend of Rice Husks (RH), Spent Bleaching Earth (SBE) and Broken Bricks (BB) to form pozzolana that would have pozzolanic activity comparable to natural pozzolanas. Four ratios of RH, BB, and SBE were burnt in the Fixed Bed Kiln (FBK). The starting ratio had 20 kg of RH, 0 kg of BB and 4 kg of SBE. The amount of BB was increased by 2 kg each to a maximum of 6 kg as the mass of SBE was kept constant. The resultant ashes were subjected to various pozzolanic tests. This included; saturated lime test and compressive strength analysis. It was observed that the calcined blend with 10: 1: 2 mix of RH: BB: SBE exhibited the highest pozzolanic activity. This sample was mixed with acetylene lime sludge (ALS) in the ratio of 2:1 pozzolana: ALS. The compressive strengths for these cements were tested at 2 and 28 days of curing. The compressive strengths of this cement met the required EN standards for Portland pozzolana cement.

Production and characterization of low-energy Portland composite cement from post-industrial waste

Abstract The utilization of post-industrial waste materials is often challenging due to environmental regulations. Additionally, the scarcity of raw materials for producing cement is generating the demand for alternate sources of materials. The current study explores the production of cement and clinker on a large scale using post-industrial waste materials from different sources. Lime sludge generated by the paper mill industry and sponge iron produced during the processing of iron are used as primary source materials for producing clinker. A large-scale vertical kiln is used for clinkering. The unburnt carbon present in the sponge iron is used as an energy source for calcining the raw materials reducing the demand on external fuel. A Portland Composite Cement (PCC) is produced by inter-grinding the clinker with waste generated by the pharmaceutical industry, silico-manganese slag and fly ash. An evaluation of the clinker and the PCC is performed and compared with a commercially available Ordinary Portland Cement (OPC). Hydration studies and characterization of the materials are performed using different analytical techniques. This work provides the fundamental basis for an environmentally sustainable utilization of post-industrial waste in the production of clinker suitable for use in construction.