Fineness Modulus Research Articles

DURABILITY OF HEAVY CONCRETE USING BOILER SLAGS WITH CIRCULATING FLUIDIZED BED

The results of studying the influence of boiler ash slags with a circulating fluidized bed on the freeze-thaw resistance of heavy concretes are presented. The following materials were used in the studies: Portland cement PPC 500 N, sand with the fineness modulus Mf =1.05, crushed granite fraction 5-10 mm, boiler ashes with circulating fluidized bed, hyperplasticizer «Fluid Premia-196». The study was performed using mathematical planning of the experiment. It is proved that with the replacement of sand with ashes, the freeze-thaw resistance is somewhat reduced, but the hyperplasticizer compensates the reduction of freeze-thaw resistance by reducing the W/C ratio, resulting in the formation of super-fine pore structure of concrete. Fine pores in the concrete structure compensate the ice formation stress at low ambient temperatures. The optimal cement consumption has been established in terms of freeze-thaw resistance, both at full and partial replacement of sand with ash. It was also determined that the optimum should be considered the consumption of a hyperplasticizer in the amount of 1.2-1.4% of the cement mass.

The Effect of the Material Factors on the Concrete Resistance Against Carbonation

The carbonation is one of the main factors to cause the degradation of the properties in the reinforcement concrete structures. In this study, the effect of the material factors, i.e. the type and the particle size of cement, the calcium oxide content in the fly ash, the fineness modulus of fine aggregate, the types and the dosages of superplasticizers (SPs), on the carbonation properties of the concrete was studied. The carbonation coefficient (K) values of the concrete mixtures with various material factors were obtained. The control indexes of the material to resist against carbonation of the reinforced concrete were proposed. The test results show that the type and the particle size of cement, the calcium oxide content in the fly ash and the types of SPs have the significant influence on the carbonation coefficient (K). The concrete mixture with the excellent resistance against carbonation can be prepared by using cement with the fine particle size and the high-calcium fly ash and the PCA SP of lower dosage in the concrete.

Studi Pemanfaatan Limbah Padat Industri Pengolahan Minyak Kelapa Sawit Spent Bleaching Earth sebagai Pengganti Agregat pada Campuran Beton

Palm oil refinery factory has solid waste by product called Spent Bleaching Earth (SBE). SBE consists of some chemical compounds and one of them is SiO2 up to 83,05%. SiO2 or silica fume can cause silicosis if it is exposed to the atmosphere and frequently inhaled by the workers. On the other hand, SiO2 is one of the material composition of Portland cement. Thus, it is necessary to conduct a research about the utilization of SBE. as a concrete mixture. SBE is utilized as fine aggregate substitution by the composition of 0%, 10%, 20%, 30%, and 40% of the total amount of fine aggregate. The conducted tests are fineness modulus calculation, compressive strength, setting time, and TCLP. The method used for mix design is SNI 03-2834-2000 with f’c 28,5 MPa and slump 12 ± 2 cm. This research shows that concretes with SBE substitution which achieve the planned compressive strength are 10% SBE with 34,16 MPa and 20% SBE with 29,06 MPa. Based on the TCLP test, the concentration of heavy metal substances in 10% SBE are below the standard. Thus, it is scientifically proven to conclude that concrete with 10% SBE is technically proper and safe for the environment.

Heat resistance of portland cements

Recent fire cases indicated again the importance of fire research. Fast development of construction technology requires new materials. Initiation and development of fire are strongly influenced by the choice of construction materials. In addition to their mechanical properties, their behaviour in elevated temperature is also of high importance. Residual compressive strength of concrete exposed to high temperatures is influenced by the following factors: water-to-cement ratio, cement-to-aggregate ratio, type of aggregate and water content of concrete before exposing it to high temperatures and the fire process. Therefore, mix design and composition of concrete are of high importance for high temperatures. Based on the literature, the fire resistance of concrete is influenced by the used cement type. As regards the cement type, considerable importance has been attached to the various auxiliary materials, such as slag, fly ash, trass, metakaolines and silica fume. There has been no special research devoted to the fire behaviour of pure portland cements. Pure portland cements can be made with various oxide compositions or with different grinding fineness, which increases the resistance of cements to fire. The question arises what effects grinding fineness and oxide composition have on fire resistance of cements. In my experiments, the resistance of portland cements of different composition and grinding fineness to fire (high temperature) were examined. For the test of the solidified cement paste, cement paste cubes of 30-mm edge length were prepared. The specimens were stored in water for 7 days and then in laboratory conditions for 21 days. The cubes of more than 28 days were heated to the given temperature in the furnace and then kept at the given temperature for 2 h (50, 150, 300, 500, 800 °C). Following the 2 h of thermal load, the specimens were examined once their temperature cooled down to room temperature. I have experimentally demonstrated that in case of portland cements, the grinding fineness and aluminate modulus of the cement (i.e. the oxide composition of the cement) have a significant effect on its fire resistance.

Avaliação de jazidas de areia quartzosa para a produção de concreto a base de cimento portland

Os parâmetros granulométricos das jazidas de areia que exercem maior influência nas propriedades mecânicas do concreto são o módulo de finura e o coeficiente de uniformidade. Areias com elevados valores destes índices tendem a produzir concretos com maior resistência mecânica à compressão. Nesse sentido, o presente trabalho avaliou as propriedades granulométricas de três jazidas comerciais do Rio Paraná na região do município de Alto Paraíso (PR). Para analisar a influência da granulometria na produção de concreto foram confeccionados corpos de prova de 100 mm de diâmetro por 200 mm de altura com classe de resistência de 20 MPa. A seguir foram determinadas a resistência à compressão e a consistência no estado fresco. As três amostras testadas obtiveram resistência aos 28 dias superior a resistência de dosagem mínima de 26,6 MPa. A amostra 3 em relação com a amostra 1 teve resistência superior em 32 % e em relação com a amostra 2 o aumento foi de 12 %. Isso se deve pelo maior coeficiente de uniformidade que aumenta o embricamento entre as partículas, diminui o volume de vazios e, por fim, aumenta a resistência à compressão; e com maior módulo de finura menor é a superfície especifica dos grãos, menor é a área de recobrimento da pasta de cimento e por conseqüência maior a resistência mecânica para uma mesma quantidade de areia.

Physical quality characteristics of the microwave-dried breadfruit powders due to different processing conditions

Production of breadfruit powder has been an option to make easy its uses in various food processing. Accordingly, there is a need recently to apply advanced drying method, i.e. microwave drying, for improving quality since conventional methods produced highly variable product quality and required longer process. The present work was aimed to study the effect of microwave power and grinding time on physical quality of breadfruit powders. The experiment was done initially by drying breadfruit slices in a microwave dryer at power level of 420, 540, and 720 W and then grinding for 3, 5, and 7 min to get powdery product of less than 80 mesh. The physical quality of breadfruit powders were measured in terms of fineness modulus (FM), average particle size (D), whiteness (WI), total color difference (ΔE), water absorption (Wa), oil absorption (La), bulk density (ρb) and consistency gel (Gc). The results showed that physical quality of powders and its ranged-values included the FM (2.08-2.62), D (0.44-0.68 mm), WI (75.2-77.9), ΔE (7.4-10.5), Wa (5.5-6.2 ml/g), La (0.7-0.9 ml/g), ρb (0.62-0.70 g/cm3) and Gc (41.3-46.8 mm). The experiment revealed that variation of microwave power and grinding time affected significantly the quality of the breadfruit powders. However, microwave power was more dominant factor to affect quality of breadfruit powder in comparison to the grinding time.

Development of an optimum mix design method for self-compacting concrete based on experimental results

The main objective of this study is to develop an optimum mix design method for self-compacting concrete (SCC) based on experimental results. For this purpose, mix design of self-compacting concrete is formulated as an optimization problem. Given the importance of manufacturing costs of concrete, the total cost of one cubic meter of self-compacting concrete is considered as the objective function in the optimization problem, which must be minimized. Limitation of the 28-day compressive strength and slump flow of self-compacting concrete are considered as the main inequality constraints. To ensure that sum of concrete components makes unit volume, an equality constraint is considered. To formulate the self-compacting concrete mix design optimization problem based on experimental data, forty-two different mix designs of self-compacting concrete are presented and three cylinder specimens are made and tested for each of them. Two mathematical models are developed to estimate the strength and the slump of the concrete and used to define the main constraints in the mix design optimization model. The concrete specimens are prepared in a construction site in Sanandaj in Iran. Considering importance of sand grading on the compressive strength of self-compacting concrete, stone powder is used to improve sand fineness modulus. The sequential quadratic programming is employed to solve the optimal mix design problem of self-compacting concrete based on proposed model. In order to verify the proposed method, the mix design problem is solved for several case studies and then the final optimal mix designs are made in laboratory and mechanical properties of specimens are evaluated. The results show that the proposed method satisfies the mechanical characteristics of the self-compacting concrete, besides minimizing the cost of the concrete and automating the mix design process.

Performance evaluation of concrete made with sands from selected locations in Osun State, Nigeria

It is common practice among most local contractors in Nigeria to produce concrete with any available sand, disregarding its attendant effect on concrete performance. Sands obtained from popular quarries in Osun State, Nigeria were investigated to determine their suitability for concrete production. The sands were labelled A, B, C, D and E. Physical and chemical properties as well as grading characteristics of the sand samples were determined using standard procedures. Impurities in the sands were equally evaluated. Strength and water demand of the concrete produced from these sands were also examined. The results showed that all the sands contained high silica with traces of alumina in almost the same quantity except Sand E that had relatively low silica but higher alumina. Particle size distribution of the sands indicated that Sand A had more fine particles with fineness modulus of 1.95 while sand D was coarser (2.79) and other sands (B, C and E) were within the range of 2.7 and 2.6. The specific gravities of the sands fell in the range of 2.5–2.7 except Sand A, which was 2.2. The strength of the concrete made from each of the sands equally differed significantly, with Sand E having the highest strength (23.5 N/mm2). Water absorption results indicated that Sands A and C may pose durability challenges due to higher water absorption compared to other sands. The study concluded that the selected sands had influence on the performance of concrete and it was recommended that all except Sand A, could be used for specific construction application.

The influence of filler type and gradation on the rheological performance of mastics

This paper present a laboratory study on the influence of filler type on the rheological properties of mastics. Mastic is the main component that undergoes any deformations in asphalt structure. Low shear resistance can lead to susceptibility to permanent deformations. The type of filler used in mastic can highly influence its rheological properties. The main objective of the study was to evaluate different types of mineral fillers and their stiffening effect on unmodified and modified mastics in terms of permanent deformations. During this study performance of three mineral fillers, namely Jelsa granite, Portland cement and Aggersund limestone were investigated. The fillers used in this study were evaluated according to common filler characteristics, such as Rigden voids (RV), density, specific surface area, fineness modulus and others. Dynamic shear rheometer was used for testing mastics under repeated shear stress with multiple stress creep recovery test method. Mastics performance was tested under three different temperature conditions. Analysis of the results showed that limestone filler provide best stiffening effect. The main factors affecting that is its fine gradation, high percentage of RV and high specific surface value. This subsequently results in high amount of bitumen being as fixed one. Granite filler with low value of RV showed poor performance.

The effect of dryer air temperature on fineness modulus and moisture content of cassava flour in pneumatic dryer process

One of drying method applied in flour milling industry is pneumatic drying. Various kinds of variable both dried materials and drying process condition strongly influence the quality of drying result. Fineness Modulus (FM) and Water Rate are significant variables in defining the flour quality. The aim of this study is to identify the influence of dryer air temperature on FM and Moisture Content in pneumatic dryer process condition. Both variables have sufficiently big coefficient of determination value; therefore, it can be employed to predict well the fineness modulus and water rate of the flour.

Technology of soil stabilization with cement-sand grouting mortar with optimal aggregate grading

This article studies technological, physical and technical properties and corrosion resistance of cement-sand slurry. Comparative data of the strength of test samples made on mortars of equal mobility with a composition of 1:1 (C: S) using river sand with fineness moduli (Mf): 1.50; 1.35; 1.25, showed the best results in the latter case. The use of the "Mylonaft M1" plasticizer in the solution in an amount of 0.5 % of the mass of the cementing with sand with Mf = 1.25 allowed to keep the mobility of 200 mm at W/C ratio = 0.6 without loss of the mixture homogeneity. Investigation of the corrosion resistance of sample mortars with the introduction of 1 % Na2SO4 into it during the process of its preparation made it possible to achieve stability in aggressive sulfate media at low (T = 20 °C) and normal temperatures (T = 5 ° C). In order to mechanize the work on strengthening the loess soils with cementing slurry the traditional equipment used in the production (stationary solution station with a compressor and a pump) has been compared with the advanced mobile unit UNB-125 × 50 SO on the basis of KamAZ 363501.

Effect of Adjusting for Particle‐Size Distribution of Cement on Strength Development of Concrete

The massive construction projects such as nuclear power plants and gas storage plants operate their own batch plants for appropriate supply of a massive amount of ASTM Type I cement. The batch plants have difficulty responding to diversifying consumer requirements such as early strength development of concrete under the current limited production line of cement. In order to respond to the needs, this study collected several sizes of cement particles from different filters at a cement plant, and conducted the adjustment of cement particle‐size distribution to enhance the properties of concrete based on ASTM Type I cement. This paper shows the chemical properties and physical tests such as setting time and compression tests considering the effects of the distribution of cement particles. Also, the classification based on cement particle‐size distribution was defined as FMC (fineness modulus of cement). As FMC increased, compressive strength was relatively low at early age but the difference became smaller for later age. The test results show the effects of the adjusted mix proportion considering particle‐size distribution of cement on strength development of concrete. Therefore, it is possible to see that customized cement or concrete can be manufactured in response to various consumer requirements by introducing such method that by‐passes and collects fine or coarse cement in the cement‐crushing process and then re‐mixes them with OPC ASTM Type I cement depending on FMC.

Effect of Pharmaceutical Wastes Usage as Partial Replacement of Cement on the Durability of High-Performance Concrete

This paper reports an experimental study of the influence of ash produced from incinerated hospital wastes used as partial substitute for Portland cement (PC) on the mechanical properties and durability of high performance concretes. The analysis of the experimental results on concrete at 10% content of ash resulting from incineration of pharmaceutical wastes with a fineness modulus of 8000 cm2/g, in a chloride environment, showed that it contributes positively to the perfection of its mechanical characteristics, its durability with respect to migration of chloride ions and oxygen permeability. On the basis of the experiments performed, it can be concluded that the ash is suitable for formulation of high performance concretes (HPC) and their properties are significantly better compared to the reference concrete (RC). This paper points out the directions for the proper uses of ash of pharmaceutical wastes in concrete.

The influence of fine aggregates on the 3D printing performance

Influences of nature Particle, size, grain shape and fineness modulus of fine aggregates on the 3D printing performance of cement-based mortar were investigated. Results showed that the working performance of the mortar is not only dependent on the fineness of the aggregate, but also the gradation and grain size of the aggregate. And the mechanical properties of the mortar are increasing with the increase of Mx in the same test condition. The research shows that it is effective to choose different properties of materials for different design requirements, and the fluidity of mortar must be decreased under assuring construction quality and the pumpability of 3D printing materials.

The physical and mechanical properties of recycled gypsum and potential application of pre-molded panels

This study analyses the physical properties of recycled gypsum and mechanical performance of pre-molded gypsum panels made of recycled gypsum. A compatation with commercial gypsum physical properties and mechanica behavior of pre-molded commercial gypsum panels is also carried out. After collection, recycling and grinding gypsum residues, the quality of the powder produced was evaluated in terms of units of mass and fineness modulus. Additional tests of the dry paste were conducted for assessment of hardness, water absorption, and compressive strength of recycled gypsum. The commercial potential of the material was evaluated by the bending strength testing pre-molded panels. The results demonstrate that gypsum recycling is sustainable, ecologically correct and feasible for the production of pre-molded elements with great potential use in civil construction. Keywords: gypsum panels, mixed pastes, sustainable, gypsum pastes.

Physical and Chemical Character of Fly Ash of Coal Fired Power Plant in Java

Quality of fly ash is varying widely in the field, it depends on the combustion process and the quality of the basic ingredients, namely coal. It will affect the physical and mechanical properties of the concrete mixtures used. This study used 12 samples of fly ash. The physical and chemical properties and finesse modulus were analyzed. The fly ash was mixed with OPC (Ordinary Portland Cement) with the proportion of 20% fly ash and 80% OPC. The specimens were form with mortar dimension of 5cm x 5 cm. The test was affected by the correlation of fly ash fineness modulus to compressive strength, correlation density of fly ash to compressive strength, and correlation of carbon content to the compressive strength.

Studying the representative volume of concrete using the entropy weight–grey correlation model

The representative volume element (RVE) plays an important role in the study of concrete properties. Meanwhile, RVE size determination itself is an issue that needs further study. For the first time, the problem of determining RVE size based on several factors is regarded as a multi-objective decision-making problem. A new method, the entropy weight–grey correlation model, is proposed, by comprehensively considering the influence of coarse aggregate content, aggregate average particle size and the aggregate fineness modulus. A two-dimensional concrete aggregate specimen, randomly generated by numerical simulation with an aggregate size of 5–20 mm, is taken as a case study, and the RVE size is determined as 6–7 times the maximum aggregate size. Then the finite-element method is used to verify its mechanical properties. This new method has the advantage of depending less on variable data compared to the traditional method, indicating a wider range of applicability. Additionally, the model is applied to determine the RVE size of three-dimensional concrete, which is similar to two-dimensional concrete. It provides a new comprehensive insight for the study of concrete RVE size, which could also be extended to apply to determining the RVE of other composite materials.

Multigraded linear series and recollement

Given a scheme Y equipped with a collection of globally generated vector bundles E_1, ldots , E_n, we study the universal morphism from Y to a fine moduli space {mathcal {M}}(E) of cyclic modules over the endomorphism algebra of E:={mathcal {O}}_Yoplus E_1oplus cdots oplus E_n. This generalises the classical morphism to the linear series of a basepoint-free line bundle on a scheme. We describe the image of the morphism and present necessary and sufficient conditions for surjectivity in terms of a recollement of a module category. When the morphism is surjective, this gives a fine moduli space interpretation of the image, and as an application we show that for a small, finite subgroup Gsubset {{mathrm{GL}}}(2,mathbb {k}), every sub-minimal partial resolution of {mathbb {A}}^2_mathbb {k}/G is isomorphic to a fine moduli space {mathcal {M}}(E_C) where E_C is a summand of the bundle E defining the reconstruction algebra. We also consider applications to Gorenstein affine threefolds, where Reid’s recipe sheds some light on the classes of algebra from which one can reconstruct a given crepant resolution.

Study of Permeability of Glass-Sand Soil

Abstract The drainage consolidation method has been efficiently used to deal with soft ground improvement. Nowadays, it has been suggested to use a new sand soil which is a composite of sand and recycled glass waste. The permeability performance of glass-sand soil was explored to judge the feasibility of glass-sand soil backfilled in the drainage consolidation of sand-drained ground. For comparison purposes, different mix proportions of recycled glass waste, fineness modulus, and glass particle size were analyzed to certify the impact on the permeability coefficient and the degree of consolidation. The numerical results show that adding a proper amount of recycled glass waste could promote the permeability performance of glass-sand soil, and the glasssand soil drain could be consolidated more quickly than a sand drain. Experiments showed that glass-sand soil with the a 20% mix of recycled glass waste reveals the optimum performance of permeability.

EXPERIMENTAL STUDY OF CREEP AND SHRINKAGE STRAINS IN FINE- AGGREGATE CONCRETES

The paper studies creep and shrinkage processes running in fine-aggregate concretes with plasto-elastic properties (deformations) under short-time loading are different from those of standard heavy concretes. Experimental studies of creep and shrinkage strains in fine-aggregate concretes that are based on sands with different fineness moduluses permit to compare prestress losses resulting from the creep and shrinkage of concrete. Usually these factors produce an aggregate effect, which makes the study of the processes that run in concrete under long-time influence noticeably complicated. There paper contains analysis results obtained by experimental studies of concrete prisms at different initial strains in the range of , with loading age of t= 14 or 28 days and different properties of concrete mixes. Concrete mix properties were modified by using sands with different fineness modulus. Likewise in order to determine creep and shrinkage deformations due to long-time loads the samples were tested under stress during 14, 73 and 180 days. All experimental data have been systematized in tables and are represented by diagrams. The analysis has helped to investigate the effects of relative stains on the creep deformation in concrete and to define the boundary line between linear and non-linear creep with relation to the stresses in concrete. Analytical description of non-linear deformations was performed with the help of N.H.Arutyunyan’ and I.I.Ulitsky methods. The resultant calculations formed a basis for the recommendations to simplify problem solving methods considering non-linear creep of concrete.