Moisture Content Of Mixture Research Articles

Investigation of mechanical and thermal performances and masonry quality for new raw soil-based insulating hollow bricks

ABSTRACT The development of raw soil-based insulating hollow bricks (RSIHB) provides a promising way for improving the efficiency of building energy conversation and resource utilization of construction waste soil. In this paper, the response surface method (RSM) was adopted to study the effect of multifactor on mechanical and thermal performances of modified raw soil-based samples. The results indicate that the thermal conductivity is significantly affected by the interactions between molding pressure and mixture moisture content, as well as between mixture moisture content and cement admixture. Thus, the optimal mix ratio was determined by the RSM-based regression model. The assessment based on numerical simulation demonstrates that the middle wall ribs immensely improve the stress concentration. The porous structure elongates the path of heat flow conduction, effectively enhancing the thermal resistance of the brick. In addition, bonding strength tests manifest that the mortar consistency should be within 60–80 mm for construction and plastering of the new raw soil-based insulating hollow brick. The research results have strong theoretical significance and practical value for recycling of construction waste and provide a reference for actual production and construction.

ПРИМЕНЕНИЕ МЕТОДОВ РЕГРЕССИОННОГО АНАЛИЗА И АНАЛИЗА ИЕРАРХИЙ К ВЫБОРУ ПАРАМЕТРОВ ЛИТЬЯ ОЛОВЯННОЙ БРОНЗЫ

The influence of casting technological parameters on the presence and types of defects (shrinkage sinks, shrinkage porosity, cracks) of castings from tin bronze BrO3C7C5H1 has been investigated. By the method of regression analysis it was established that the change of tin concentration in the alloy, the temperature of metal release from the furnace, the strength of the molding mixture and the duration of mold pouring in the production conditions under consideration do not have a significant effect on the defect of the casting. The type of defects and the proportion of rejects are related to the volumetric shrinkage of the alloy and the moisture content of the molding mixture, the significance of the effect of the moisture content of the molding mixture indicates the gas-shrinkage nature of porosity. Analysis of nomograms based on the obtained regression models allows us to estimate the influence of significant parameters on the number of rejected castings and the probability of defects formation in them. Thus, a 1% increase in the molding mixture moisture content and alloy volume shrinkage leads to an increase in the number of rejected castings by 2.3 and 1.2 times, respectively. When molding mixture moisture content is increased by 1%, the probability of gas sinks, shrinkage porosity or hot cracks increases by 3.3, 2.3 and 2.2 times, respectively. When the volume shrinkage of the alloy is increased by 1%, the probability of shrinkage porosity and hot cracks increases by a factor of 1.1 and 1.2, respectively. By the method of hierarchy analysis is shown that the preferred options for reducing the rejects of tin bronze castings along with the moisture content of the molding mixture are reducing the temperature of metal release from the furnace and changing the casting technology to reduce the volumetric shrinkage of the alloy.

Evaluation and Technical Requirements of the Initial Anti-Wear Performance of an Emulsified Asphalt Cold Recycled Mixture: A Case Study in Northern China

Considering the initial strength evaluation method of a cold recycled asphalt emulsified mixture, the abrasion test was selected as the evaluation method. The comparison test was designed to determine the key parameters of the test, including the molding method, the curing temperature, the curing relative humidity, and the curing time. The influence of different emulsifiers, the emulsifier dosage, the asphalt dosage, the cement dosage, and the mineral aggregate gradation on the initial anti-wear performance of the mixture was analyzed. The technical requirements for the emulsified asphalt cold recycled mixture were put forward. We analyzed the significance of different influencing factors using analysis of variance. The results shows that the abrasion test is simple and reliable. It can be used to evaluate the initial abrasion resistance of the emulsified asphalt cold recycled mixture. The curing conditions had a great impact on the abrasion loss. With the increase in temperature or the extension of the curing time, the abrasion loss gradually decreased. With the increase in relative humidity, the abrasion loss gradually increased. The testing protocols, namely 25 °C with a relative humidity of 70%, the curing time was 4 h, followed an active Chinese standard (JTG/T 5521). The results indicate that the factors that affect the initial performance of the cold reclaimed mixture of emulsified asphalt are in the following order: cement dosage, cement strength grade, emulsifier type, mineral aggregate gradation, emulsified asphalt dosage, mixture moisture content, and emulsifier dosage. The cement dosage, emulsifier type, and mineral aggregate gradation had significant effects on the initial strength of the cold recycled mixture. An abrasion loss of less than 3.5% was selected as the basis for optimizing the design of the emulsified asphalt cold recycled mixture.

Neural Network Prediction Model for Sinter Mixture Water Content Based on KPCA-GA Optimization

The design and optimization of a sinter mixture moisture controlling system usually require complex process mechanisms and time-consuming field experimental simulations. Based on BP neural networks, a new KPCA-GA optimization method is proposed to predict the mixture moisture content sequential values with time more accurately so as to derive the optimal water addition to meet industrial requirements. Firstly, the normalized input variables affecting the output were dimensionalized using kernel principal component analysis (KPCA), and the contribution rates of the factors affecting the water content were analyzed. Then, a BP neural network model was established. In order to get rid of the randomness of the initial threshold and weights on the prediction accuracy of the model, a genetic algorithm is proposed to preferentially find the optimal initial threshold and weights for the model. Then, statistical indicators, such as the root mean square error, were used to evaluate the fit and prediction accuracy of the training and test data sets, respectively. The available experimental data show that the KPCA-GA model has high fitting and prediction accuracy, and the method has significant advantages over traditional neural network modeling methods when dealing with data sets with complex nonlinear characteristics, such as those from the sintering process.

High-strength fuel pellets made of flour milling and coal slack wastes

Foreseeably, coal remains one of the main energy sources in the global economy. Huge amounts of hazardous coal mining wastes, coal slack may be converted to useable fuel. Producing high-strength fuel pellets from coal slack using a biomass binder presents an objective. Experimental research into combining coal wastes with wheat bran binder using products’ differential thermal analysis was undertaken. Optimum process parameters of pellet moulding were determined: mixture moisture content 16–19 wt % and wheat bran dry fraction 4–20 wt % at 120–160 °C under the pressure of 75–300 MPa. Pilot-scale implementation of the method was realized meeting moulded fuel standards.

Cellulose fiber enhances the physical characteristics of extruded biodegradable cassava starch foams

An attempt was made to assess the influence of cellulose on the physical characteristics of cassava starch foams. Cassava starch was extruded with the inclusion of cellulose fibers with 2 different particle sizes (C1: 32 μm and C2: 32–200 μm) at 0, 5, and 10% with three different moisture contents (15, 17.5 and 20%) using a twin-screw extruder. The barrel temperature was fixed at 50, 100, 140 and 140 °C for all the experiments and the extruder screw speed was varied (150, 200, and 250 rpm). Cellulose fiber content and feed moisture content of the mixture had significant impact on the cassava starch foam properties. Addition of 5% C1 and C2 led to increased expansion ratio compared to the control (without the inclusion of any cellulose fiber). The greatest expansion ratio was observed in the cassava starch foam with 5% cellulose fiber, and at 15% mixture moisture content with 250 rpm screw speed. On the other hand, the expansion ratio decreased when cellulose fiber was increased up to 10%. Scanning electron microscope images at 5% cellulose fiber also showed that cellular structure of cassava starch foam was similar for the control. The water absorption index of cassava starch foams did not change significantly, while water solubility index of cassava starch foam with C2 was significantly different.

Влияние пористости на прочность огнеупорных изделий

Improving the quality of refractories and decreasing the specific consumption of these products per a production unit through using of modern resource-saving processes is a highly relevant task in manufacturing refractory materials for metallurgical purposes. Strength and porosity are important indicators affecting operational properties of refractory materials. The object of research is refractory products made of clay from Beloe Glinishche field (Karaganda region) in a clay bond. The use of raw materials of the Kazakhstan origin reduces the product costs, decreases the import of goods, and on the condition of receiving refractory materials with higher mechanical and operational characteristics, gives the prospect of product export. The porosity of refractory products made of clays from various fields is determined. The effect of chamotte mixture moisture content on the compressive strength of refractory products is identified. It is found out that the most expedient is the following technological mode of refractory product manufacturing: pressing of samples from furnace charge for 12 seconds, (initial) pressure is 22 MPas which in 7-8 seconds has been increased up to 27 MPas. Then sintering has been carried out at the temperature of 1250-1270 °C for 12 hours. The use of the clay from Beloe Glinishche field in the composition of a clay binder allows to achieve uniform porosity and higher strength of the product.

Highly Porous Granulated Corundum Filler of Alumina-Foam Polystyrene Mixture. Part 7. Study of the Possibility of Preparing Hollow Corundum Granules1

The fraction composition of corundum granules is determined mainly by particle size analysis of a foam polystyrene nucleus, mixture moisture content, and granulation parameters. Use of high dynamic compaction loads has an unfavorable effect on product quality. Plate rotation frequency, its inclination angle, and granulation duration are established. The operating sequence for preparing hollow granules based on commercial alumina is established.

EAF Slag Aggregate in Roller-Compacted Concrete Pavement: Effects of Delay in Compaction

This study investigates the effect of delay in compaction on the optimum moisture content and the mechanical propertie s (i.e., compressive strength, ultrasonic pulse velocity, splitting tensile strength, and modulus of elasticity) of roller-compacted concrete pavement (RCCP) made of electric arc furnace (EAF) slag aggregate. EAF slag with size in the range of 4.75–19 mm was used to replace natural coarse aggregate in RCCP mixtures. A new mixing method was proposed for RCCP using EAF slag aggregate. The optimum moisture content of RCCP mixtures in this study was determined by a soil compaction method. The Proctor test assessed the optimum moisture content of mixtures at various time after mixing completion (i.e., 0, 15, 30, 60, and 90 min). Then, the effect of delay in compaction on the mechanical properties of RCCP mixtures at 28 days of age containing EAF slag aggregate was studied. The results presented that the negative effect on water content in the mixture caused by the higher water absorption characteristic of EAF slag was mitigated by the new mixing method. The optimum water content and maximum dry density of RCCP experience almost no effect from the delay in compaction. The compressive strength and splitting tensile strength of RCCP using EAF slag aggregate fulfilled the strength requirements for pavement with 90 min of delay in compaction.

Experimental evaluation of drying characteristics of sewage sludge and hazelnut shell mixtures

In this study the drying behavior of organic and agricultural waste mixtures has been experimentally investigated. The usability of sewage sludge as an organic waste and hazelnut shell as an agricultural waste was assessed in different mixture range. The paper discusses the applicability of these mixtures as a recovery energy source. Moisture content of mixtures has been calculated in laboratory and plant conditions. Indoor and outdoor solar sludge drying plants were constructed in pilot scale for experimental purposes. Dry solids and climatic conditions were constantly measured. A total more than 140 samples including for drying has been carried out to build up results. Indoor and outdoor weather conditions are taken into consideration in winter and summer. The most effective drying capacity is obtained in mixture of 20 % hazelnut shell and 80 % sewage sludge.

SEPARATING OF APRICOT PITS KERNEL USING PNEUMATIC SYSTEM

Separation of apricot kernel from shells is important processes to use the kernel and shells. In this study, some physical properties were studied for apricot kernel and shells. pneumatic separator was used and separation module performance was investigated as a function of change in air stream velocity of 9, 10, 11and 12 m/s, feeding rate of 30, 60, 90 and 120 kg/h, mixture moisture contents of 5.76, 14.46 and 21.67% w. b. and screen slope of 25 and 35o. The results revealed that, optimum operations conditions were obtained at 11 m/s air velocity, feeding rate of 120 kg/h, mixture moisture content of 14.46 % and screen slope of 25o, the separation effectiveness of 96.18 %, kernel cleanliness of 93.83 %, kernel losses of 0.69 %, kernel productivity of 40 kg/h, specific energy of 4.22 kW.h / Mg and cost of 96 L.E./Mg.

Effect of technological factors on water activity of extruded corn product with an addition of whey proteins.

The value of water activity in extruded products constitutes a significant indicator of their quality and stability. The state, in which water is found in extruded products, is an indicator of the conducted extrusion process and the used raw material. The aim of the study was to assess water activity in extruded products made from a mixture of com grits with 12.5 and 15.0% moisture contents and different level of addition of whey proteins. It was shown that the degree of mixture moisture content did not have an effect on the value of aw in produced puffs. The greatest difference was recorded when introducing 3% proteins in comparison to aw of puffs produced solely from corn grits. Δaw = 0.023. The greater the content of whey proteins, the lower the aw value. A 3-month storage at a temperature of 18 ±0.5°C influenced aw of snacks produced from a mixture with a higher moisture content.

Stabilization of tropical peat by chemical grout

Peats have low shear strength and high deformation characteristics. Cement, sometimes with other industrial binders, is widely used for the stabilization of peats by deep mixing. However, peats lack a favorable structure for the chemical reactions, coupled with high moisture content that is acidic in nature. So, the efficiency of the binders is low making it an expensive option. This paper presents the effectiveness of using calcium chloride and kaolinite in cement-sodium silicate grout for improving the strength of tropical peat. The change in shear strength of the treated samples was evaluated by the vane shear test and moisture content test. The microstructural changes were evaluated by scanning electron microscopy and energy dispersive x-ray spectrometer analysis. Calcium chloride seemed to have different effects on the shear strength of peat and was observed to play an important role in the effectiveness of the chemical stabilizers. Experimental results showed that kaolinite (more than 10%) has a crucial rule in increasing the shear strength of peat. It was observed that sodium silicate within 3% and cement has favorable effect on the shear strength of peat and induce a decrease in the moisture content of mixtures consisting of peat and themselves and also lead to some favorable changes in the microstructure.

Residence Time Distribution of Soy Protein Isolate and Corn Flour Feed Mix in a Twin-Screw Extruder

The residence time distribution (RTD) of soy protein isolate (SPI) and corn flour mixture through a twin-screw extruder under different conditions was evaluated. A full-factorial design of experiments was used to select the variables at different levels. The feed mixture was prepared by blending corn flour and SPI in the ratio of 4:1 (20% SPI content). The effect of screw speed (75, 100 and 125 rpm), feed mixture moisture content (25, 30 and 35%) and die diameter (3 and 5 mm) were investigated. All factors were found to have a significant (P < 0.05) effect on the mean resident time and its variance (square of standard deviation). Higher screw speed, higher initial moisture content and larger die diameter resulted in a shorter mean residence time. Two conventional flow models were used to represent the RTD profile in the extruder – the frequency model (F-distribution) and the cumulative RTD model (E distribution). The parameters of these models – the half-concentration internal age and particle accumulation rate – were determined by a nonlinear regression. The parameters of these models were responsive and related to process variables and both F- and E-distributions were well predicted. Practical Applications Residence time distribution (RTD) is an important parameter that describes the time spent by particles through any continuous processing system. RTD study is important with respect to extrusion processing because the properties of extruded product depend on the shear, pressure, time and temperature history of the product in the extruder. The study is aimed at evaluating RTD of a protein-rich formulation obtained by different blends of soy protein isolates and corn flour which are prepared for producing protein-rich soy-based products. The study is important because it examines the influence of selected process and product variables on the residence time of particles in the twin-screw extrusion system.

Equilibrium moisture content of waste mixtures from post-consumer carton packaging

The manufacturing of boards and roof tiles is one of the routes to reuse waste from the recycled-carton-packaging process. Such a process requires knowledge of the hygroscopic behaviour of these carton-packaging waste mixtures in order to guarantee the quality of the final product (e.g. boards and roof tiles). Thus, with four carton-packaging waste mixtures of selected compositions (A, B, C and D), the sorption isotherms were obtained at air temperature of 20, 40 and 60°C by using the static method. This permits one to investigate which model can relate the equilibrium moisture content of the mixture with that of a pure component through the mass fraction of each component in the mixtures. The results show that the experimental data can be well described by the weighted harmonic mean model. This suggests that the mean equilibrium moisture content of the carton-packaging mixture presents a non-linear relationship with each single, pure compound.

Experimental Study of Recycled Concrete Aggregate for Cement-Stabilized Macadam

The merits of recycled concrete aggregate used in cement-stabilized macadam have been demonstrated, and the influence of recycled concrete aggregate on strength and deformability of cement-stabilized macadam was studied, while the recycled aggregate was used as a replacement of equal gradation for original aggregate. The results show that the optimum moisture content of mixture was increased with the increment of recycled aggregate content within a certain range, but maximum dry density and drying shrinkage strain were decreased. The unconfined compressive strength was first increased and then decreased, and the splitting tensile strength was first increased and then gradually stabilized. Recycled aggregate with a reasonable content is beneficial for improving the pavement performance of cement-stabilized macadam.

Formation Conditions, Water‐vapor Permeability, and Solubility of Compression‐molded Whey Protein Films

ABSTRACT: Films based on whey protein isolate (WPI) were formed using compression molding. Compression molded films could be formed using 30% to 50% moisture content or glycerol content WPI at 104 °C to 160 °C for 2 min. Films made from water‐WPI mixtures were brittle and insoluble and had water‐vapor permeability values independent of starting water‐WPI mixture moisture content, molding temperature, or molding pressure. Gly‐WPI films produced at 104 °C were flexible and partially soluble. Gly‐WPI films produced at 140 °C were also flexible but nearly insoluble. Glycerol content and molding temperature and pressure had little effect on water‐vapor permeability values of Gly‐WPI films over the range of conditions studied.

Liquid penetration rate into submerged porous particles: theory, experimental validation and implications for iron ore granulation and sintering

A two-stage model has been developed to describe the penetration of liquid into a submerged porous particle. In the first stage liquid flow is driven by capillary pressure and resisted by viscous losses and the pressure of the air trapped inside the pores. This initial flow ceases when the trapped air pressure equals the capillary pressure. In the second stage the pressurized air slowly dissolves and diffuses through the pore liquid into the bulk fluid; this continues until all the air has dissolved. Novel but simple experiments were performed to measure directly the time required for liquid to soak into porous iron ore particles. The trends of the measured penetration times supported the predictions of the model. Quantitatively, however, the model under-predicted the penetration times. This is probably due to the heterogeneous nature of the pore networks in the iron ore particles, which are poorly described by a single, average pore diameter. The results show that the time taken for iron ore particles to saturate with liquid can be of the order of hours—much longer than the typical residence time during drum granulation in sinter plants. This provides a plausible explanation of why some pre-wetted ores require a higher total mixture moisture content to agglomerate satisfactorily than partially dried ores.

Composting Process Design Computer Model

A user-friendly computer package, COMPOST, was developed as a design, management, and educational tool to assess composting system requirements. The user enters ingredient characteristics along with critical operational parameters. Output includes the quantity of amendment required to supply the energy needed, the quantity of recycled compost required to adjust the initial moisture content, the mixture moisture content, and the carbon-to-nitrogen ratio of the mixture. The volume required for active composting and curing is calculated along with air flow rates for oxygen supply, moisture removal, and temperature control. The calculations in COMPOST are based on the assumption of a continuous, completely mixed system where ingredients are continuously added and product is continuously removed. However, calculations for mixtures of residue, amendment, and recycled compost and water also apply to batch systems. Peak air flow is calculated to reflect the requirement for a batch system.

Sewage Sludge Composting Process by Static Pile Method

This paper reports the results of experiments on the static pile composting process undertaken in different conditions. The experiments have revealed the following:–In order to compost dewatered sludge with polymer without any bulking agents, we used recycled compost to adjust the moisture content of dewatered sludge.When the moisture content of feed mixture, which was dewatered sludges and recycled composts, was lowered to approximately 50%, the raw sludge could be composted by either natural ventilation or intermittent aeration.–When the BOD of feed mixture was lower than 50 g/kg-DS, the fermentation temperature did not reach 60°C and the moisture content of the mixture was not lowered during composting period.–The required composting time was approximately 50 days for natural ventilation (at an average temperature of 10°C or 24°C) and approximately 35 days for intermittent aeration (at an average temperature of 10°C to 24°C), when the moisture content and the BOD of finished compost was 40% or less and 30 g/kg-DS or less, respectively.–There was a highly positive correlation between the amount of water evaporated and the amount of BOD removed. This result suggested that the amount of water evaporation could be deduced from the amount of BOD removed.