Effect Of Mix Proportions Research Articles

Effect of mix proportion on the strength and durability of plastic and sand composite for construction applications

Effect of mix proportion on the strength and durability of plastic and sand composite for construction applications

Effects of mix proportion and curing condition on mechanical properties of polyvinyl alcohol fibre ECC

With the requirements for the ductility, toughness and durability of structures increasing and the promotion of sustainable development, low-cost and high-performance building materials are highly valued by the engineering community. In this work, 12 groups of engineered cementitious composites (ECC) made with polyvinyl alcohol fibre (PVAF) were prepared. The specimens were divided into two test groups according to the origin of the PVAF: group JK-II (a well-known commercial fibre) and group CL-C (low-cost fibre). Test group JK-II was used to study the effect of waste glass powder on uniaxial tensile and thin-plate flexural properties. The CL-C test group was used to study the coupled effect of curing condition and expansion agent on uniaxial tensile and flexural properties. The PVAF-ECC prepared in this study all showed good tensile and flexural properties. The enhanced effect of JK-II fibre on the uniaxial tensile and flexural properties of the PVAF-ECC was analysed and the advantages and disadvantages of the materials used in groups JK-II and CL-C were comprehensively investigated. Future research directions and application suggestions for the PVAF-ECC are introduced.

FRESH PROPERTIES AND MIX DESIGN FOR 3D-PRINTABLE DECORATIVE CONCRETE

Statement of the problem. This paper present the rheological properties of 3D-printable decorative concrete. The effects of mix proportion on its plasticity and shape stability are presented together. It has been established that kind of cement changes plasticity of fresh mixtures and its resistance to load during the printing. Results. The fresh mixtures of 3D-printable decorative concrete with effective mix design had plastic yield value Ki 1.0 - 2.2 kPa, structural strength σ0 = 1.5 - 4.5 kPa, value of plastic deformations Δpl = 0.03 - 0.07 mm/mm. That is defined the ability of these mixtures to plastically deform without structure destruction and hold its shape, resist the deformation under compressions load during multi-layer casting.Conclusions. Shape stability of 3D-printable mixture can be changed by 2--3 times by using cement with efficient ranging of a particle size. The plasticity and shape stability of fresh mixtures can be regulated with usage of viscosity modifiers, the type of which depends on the type of cement.

Experimental and numerical study on T‐Shaped UHPFRC beams with high‐strength reinforcement

AbstractThis article experimentally and numerically investigated the flexural behavior of T‐shaped UHPFRC beams reinforced with high‐strength bars. A total of five beams were tested to study the effect of steel fiber volumetric ratio, longitudinal reinforcement ratio, and mix proportion of UHPFRC. Test results indicate that flexural stiffness and strength increased with increasing reinforcement ratio, while the effect of mix proportion was negligible. With the same shear reinforcement ratio, the failure mode of T‐shaped beams changed from shear failure to flexural failure with steel fibers. Results from finite element analyses had good agreement with test results. Future research will focus on the parametric study based on calibrated finite element models and the secondary development of ABAQUS to simulate the shear failure of UHPFRC beams.

Optimization of Technological Parameters for Preparation of Geopolymers Fabricated with Pulverized Fly Ash

Geopolymer is widely considered as an important direction for the comprehensive utilization of fly ash with its production increasing sharply year by year. The effect of mixing proportion including SiO2/Al2O3 molar ratio, Na2O/SiO2 molar ratio and water-solid ratio on the performances of geopolymer fabricated with pulverized fly ash with a median particle size of 3.3 μm was investigated by an orthogonal test in this work, and the optimum preparation technics were also obtained. Results indicated that the compressive strength of geopolymer reached the maximum of 61.0 MPa when SiO2/Al2O3 molar ratio was 3.3, Na2O/SiO2 molar ratio was 0.11 and the W/S ratio was 0.30 under the optimum preparation technics of aging time of 3h, mixing time of 3min and curing at 80℃ for 24h. Overall, Na2O/SiO2 molar ratio played the most important role on the compressive strength of geopolymer, but SiO2/Al2O3 molar ratio had a minimal impact. FTIR spectrum demonstrated that the sample with the optimum proportion exhibited a more complex asymmetric stretching vibration peak, which indicated that there were more activated silicon/aluminum monomers and dimers in fly ash depolumerized and repolymerized and tetrahedral phase transitions, and then geopolymer paste with denser microstructure was formed.

Development, characterization and optimization of polymeric mucoadhesive microcapsules containing anticancer agent using response surface method: in vitro and in vivo study

The present research work covenants the preparation, characterisation and optimisation of mucoadhesive microcapsules containing paclitaxel through ionic gelation method using 32 statistical factorial designs. The effect of mixing proportion of primary polymer sodium alginate to copolymer (X1) and speed of magnetic stirrer (X2) on the microcapsules size (Y1), efficiency of paclitaxel encapsulation (Y2), and percentage yield (Y3) was optimised. The morphology of microcapsules was characterised and evaluated by in vitro and in vivo tests to study the swelling characteristics, mucoadhesion and drug release characteristics, followed by MTT assay on human HT-29 colon cancer cell lines. The size of prepared microcapsules was within the range of 361 ± 4.50 to 931 ± 22.41; encapsulation efficiency (%) was within the range of 42.72 ± 0.43 to 98.12 ± 0.43 %. The in vitro paclitaxel released over 24 hours were in a range of 82.15 ± 3.43 % to 96.75 ± 2.41 %. The controlled release pattern of paclitaxel was observed from the in vitro drug release study of microcapsules. The prepared microcapsules that showed better mucoadhesion were in the range of 73.66 ± 1.42 to 97.85 ± 1.08 % for a period of 6 h. The in vivo pharmacokinetic study conducted in rats resulted in high Tmax, the area under the curve and mean residence time for microcapsules as compared to that of the marketed formulation. It could be concluded that the microcapsules containing povidone polymer showed superior results.

Effect of mixing proportion and mixing time on primary slurry retention and surface roughness of investment casting shells

Surface quality of investment cast parts are mainly depends upon primary slurry condition which is used to make face coat. Zircon flour (ZrSiO4) is widely used to make primary slurry. In this work different composition (75% - 25%, 70% - 30% and 65% - 35%) of zircon flour and colloidal silica is analyzed at different mixing time (at 24hrs, 48hrs and 72hrs). Viscosity, wettability, slurry retention, and surface roughness are measured and analysed. From the experimental work conclusion derived that composition with 75% zircon and 25% colloidal silica at mixing time of 72 hour gives best result in surface finish.

Effect of mix proportion on the structural and functional properties of pervious concrete paving mixtures

In recent years, pervious concrete pavement (PCP) is emerging as a novel pavement technology that is gaining a lot of attention amongst academicians due to its storm water runoff capabilities and mitigating urban heat island. This pavement technology consists of special types of concrete which has little amount of fines or no fines and interconnected voids. The different types of aggregate gradation, water-to-cement (w/c) and cement-to-aggregate, and compaction techniques with variations in efforts plays an important role in providing an optimum balance in the mixture designing of PCP mixtures. Therefore, the present study is an attempt to explore the possibility of variation of different aggregate gradation types with different proportion of w/c ratios for the production of PCP mixtures. Also, to study the effect of these mix properties on structural, functional as well as durable properties of PCP mixtures. Five aggregate gradation types and variability in w/c ratios were adopted in the present study viz. G1, G2, G3, G4 and G5, respectively. G1 and G2 consisted of larger-sized and well graded aggregates, while, G4 and G5 consisted of natural fines in proportion of 5% and 10%. Meanwhile, G3 consisted of binary blended single-sized aggregates: 30% of 10 mm and 70% of 4.75 mm. The above considered gradations were studied for porosity, density, permeability, compressive strength, flexural strength, and resistance to sulphate attack, at varied w/c ratios 0.30, 0.35, and 0.38, respectively. From an extensive laboratory investigation, it was observed that the G3 mix showed the best-balanced relation between all the afore-stated parameters, required for PCP mixtures. Hence, it can be recommended that the utilization of binary blended single-sized aggregates at a w/c ratio of 0.35 would provide an optimal solution keeping in mind the desired parameters of pervious concrete pavement mixtures are met.

Numerical simulation of co-incineration of sewage sludge and municipal solid waste in municipal solid waste incinerator

Incineration is widely used as an important method of sludge and garbage utilization and harmless treatment. The simulations of co-incineration of sludge and municipal solid waste are conducted by computational fluid dynamics method(CFD) in a MSW incinerator. The study focuses on the effect of mixing proportion, moisture content of sludge, excess air coefficient and primary and secondary air distribution ratio on the combustion progress. Simulation results indicate that the combustion temperature of furnace decreases rapidly with the increase of the mixing proportion and moisture content of sludge, which is mainly because the moisture content of sludge is higher than that of MSW as well as its low calorific value. As a result, it is recommended that the water content and mixing ratio of sludge would be controlled below 40% and 7% respectively. Therefore, the fresh sludge should be dried before entering the furnace.

Effect of mix proportions on rheology and permeability of cement grouts containing viscosity modifying admixture

Abstract This paper reports the effect of mix composition of grout on the fluidity, rheological behaviour and hydro-mechanical behaviour (permeability and compressibility). Factorial design was used in this investigation to assess the combined effects of the four mix composition parameters on fluidity, rheological properties, permeability and compressibility: water/binder ratio (W/B), percentage of limestone filler as replacement of cement (LF), dosage of viscosity modifying admixture (VMA), and dosage of superplasticiser (SP). To evaluate both the rheology of the cement grout and its hydro-mechanical behaviour, mini-slump test, Lombardi plate test, and forced bleeding test, coaxial rotating cylinder viscometer were used. A two-level fractional factorial model was used to model the effect of key variables on the fluidity, the cohesion, permeability and compressibility. The predicted models are valid for mixtures made with W/B ranged from 0.35 to 0.42, LF from 12% to 45% as replacement of cement, VMA (percentage of binder) from 0.02 to 0.7%, and SP from 0.3 to 1.2%. The effects of W/B, LF, VMA and SP were analysed using polynomial regression which can identify the primary factors and their interactions on the measured properties. Prediction models were developed for mini-slump, plate cohesion meter, permeability and compressibility as function of W/B, LF, VMA, and SP. The factorial statistical approach used highlighted the effect of W/B, the dosages of SP and VMA on the various rheological properties, permeability and compressibility.

Effects of mix proportion and curing condition on shrinkage behavior of HPFRCCs with silica fume and blast furnace slag

This study investigated the effects of mixture proportion and curing condition on the mechanical and shrinkage behaviors of high-performance fiber-reinforced cementitious composites (HPFRCCs). Different water-to-binder (W/B) ratios and amounts of mineral admixtures, such as zirconium silica fume (Zr SF) and blast furnace slag were evaluated. The test results indicate that initial steam-heat curing accelerated the strength development and was sufficient to develop its full strength. The ultimate autogenous shrinkage was insignificantly affected by the curing conditions, but the heat curing accelerated the development of autogenous shrinkage. HPFRCC with a lower W/B ratio and greater amount of Zr SF exhibited higher autogenous shrinkage but lower drying shrinkage. In addition, the amount of total shrinkage of HPFRCC was more effectively reduced by providing heat curing when a higher W/B ratio and a smaller amount of Zr SF were used. There were no increases in the autogenous and drying shrinkage for HPFRCC immediately after finishing the initial heat curing, meaning that there is no possibility of shrinkage cracks forming in HPFRCC elements after the heat curing process. Finally, the autogenous shrinkage behaviors of HPFRCC were simulated with several prediction models from literature and an optimized model, considering equivalent age, was suggested.

Effect of mix proportion and processing method on the mechanical and electrical properties of cementitious composites with nano/fiber fillers

This paper studies the influence of mix proportion and processing method on the mechanical and electrical properties of nano/fiber fillers filled cementitious composites. Cementitious composites with different contents of filler, contents of superplasticizer (SP), ultrasonic energy or mixing speeds are fabricated. Experimental results indicate that the optimal content of nano-silica (NS), carbon nanotube (CNT) and carbon fiber (CF) is 0.1%, 0.1% and 1% by weight of cement, respectively, when the water/cement ratio (w/c) of composites is 0.2 and the SP content is 0.75 wt%. Compared with composites with 0.1 wt% NS/0.1 wt% CNTs, cementitious composites with 1 wt% CFs have the maximum compressive strength of 152.69 MPa and the maximum conductivity of 0.1258 s m−1. When the contents of NS, CNTs, CFs remain constant, the optimal content of superplasticizer is 1.25%, 0.75% and 0.5% for each type of composites, respectively. Additionally, the optimal ultrasonic energy for nano-fillers (NS and CNTs) is 1000 kJ l−1 while that for micro-filler (CFs) is 400 kJ l−1. The optimal mixing speed for NS, CNTs and CFs is 500 r min−1. All experiments prove that the change of conductivity is basically consistent with that of compressive strength.

Modeling moisture transport at the surface layer of fatigue-damaged concrete

This study investigates the moisture transport at the surface layer of concrete damaged by uniaxial tensile fatigue loading. In particular, a theoretical model for calculating the surface factor of drying concrete was established and verified with laboratory testing. The effect of mix proportion (e.g. water-to-binder ratio, supplementary cementitious materials) and level of fatigue damage on the moisture desorption at the concrete surface were studied. The results show that the surface factor of drying concrete increases as the environmental temperature or wind speed increases, but seldom changes with the mix proportion and fatigue damage. However, the fatigue loads (up to 30% of the ultimate tensile load) can accelerate the concrete surface water transfer by a factor of 1.05–1.60 times in the initial drying process, mainly due to enlarged surface mass transfer area.

Effects of Mix Proportion on the Strength and Elasticity of Concrete Subjected to High Temperatures up to 800C

This paper presents the results of an experimental study on the strength and elasticity of concrete subjected to high temperatures up to 800C carried out to determine the effects of exposure temperature and the effects of mixture proportion of concrete. Cylinders made of 4 mixture of normal-weight concrete with the W/C of 50 and 60% and slump of 50 and 210mm were subjected to 13 phases of temperatures from 20 to 800C without seal at the age of 91 days. Exposure term was 91 days for exposure up to 300C, 60 days for 400C and 24 hours for higher temperatures above 500C. After temperature exposure, cylinders were tested for weight loss, compressive strength, dynamic and static moduli of elasticity and Poisson's ratio at room temperature.Weight loss increased with exposure temperature, indicating greater loss below 110C and smaller loss above 300C. Compressive strength did not decline monotonously with temperature rise between 20 and 110C, but showed 10 % reduction at 35 to 50C and recovery at 80 to 110C, indicating the minimal and maximum points. The minimal point was associated with intermediate weight loss of 4 to 5 %. At temperatures higher than 400C, residual compressive strength showed greater reduction with temperature rise for smaller weight loss.As for the effects of mixture proportion, concrete with higher W/C and higher water content showed greater weight loss and greater strength reduction below 300C, while those with higher cement content showed greater strength reduction above 500C.Both dynamic and static modulus of elasticity declined monotonously with temperature rise, indicating higher reduction rate than compressive strength. And the relationship between the two moduli of elasticity was in good correlation. Poisson's ratio did not show monotonous change with temperature, but showed discontinuity between elevated and high temperatures, indicating downward peaks at about 80C which associated with 2 to 5 % weight loss, and an upward peak at 200 to 300C, which was associated with about 7 % weight loss, and a rapid increase at higher temperature of 700 to 800C.

Extended Strength Development Model of Cement-Treated Clay

Cement stabilization is a well-established technique involving the addition of cement to increase shear strength of soft soils. Studies on the prediction of cement-treated slurry clay generally do not cover a comprehensive suite of experiments to develop a more in-depth strength-development model, and applicability is often limited to their specific database. This paper presents a large database of unconfined compressive strength tests of cement-treated marine clay over a wide range of mix ratios and curing ages. An improved predictive strength-development model is proposed that considers the effect of mix proportions and curing duration. The actual and predicted strength values are found to agree with a correlation coefficient of 0.997. The model is also shown to be applicable to several clay and cement types; the good fit to experimental data is indicated by correlation coefficients exceeding 0.95, which is superior to existing classic prediction models.

SP제 및 물시멘트비 영향을 고려한 초유동 콘크리트의 흐름 실험 및 해석

ABSTRACT In this research, flow experiments and simulation of highly flowable concrete has been attempted using a viscoplastic particle method varying with dosages of SP admixture and water-cement (W/C) ratios. Rheological and flow characteristics of flowable concrete manufactured in domestic products of cement, aggregates, and SP admixtures were investigated by experimental programs varying with mix proportions. From experiment, the predictive model of rheological characteristics of flowable concrete has been newly proposed considering with the effects of the W/C ratio and the dosage of SP admixture, and the effect of mixing proportion has also been incorporated into shear stress and strain rate curve of flowable concrete in the current method. A series of L-box flow test of highly flowable concrete varying with dosages of SP admixture and W/C ratios was compared with the proposed model. Keywords : highly flowable concrete, particle method, water-cement ratio, SP admixture, L-box flow test

薄板モルタル供試体を用いた中性化環境評価の影響要因に関する基礎的検討

It is known that environmental condition affects carbonation progress of concrete. The effects of environmental condition on carbonation rate are not the same in the same structure. Therefore, the depth of carbonation at various points is not same even in the same structure. It is important to evaluate the effect of environmental condition on the carbonation progress. The purpose of this study is to evaluate the influence of environmental conditions on the carbonation process of concrete structure. Exposure tests of mortar thin plate for 3 months were conducted 4 times a year on various points in two bridges and four structures in water purification plants. The effects of mix proportion and exposure season were studied. After exposure, the amount of CaCO₃ and water content in the plate specimen were measured. The carbonation depth in each part of the structure was closely related with the amount of CaCO₃ in the specimen exposed at the same point. Furthermore, the carbonation depth can be predicted from the amount of CaCO₃ in the mortar thin plate specimen. The conclusions obtained in this study are as follows. （1）The effect of environmental condition on carbonation progress can be evaluated using mortar thin plate specimen is exposed to the part where is not affected by rainfall. （2）Mix proportion that is higher carbonation rate is suitable to evaluate carbonation progress. （3）When mortar thin plate specimens were exposed to actual environment in period with little rainfall, the accuracy of evaluation of carbonation environment is better than exposure test in period with large rainfall.本研究では、環境条件がコンクリート構造物の中性化の進行に及ぼす影響を評価するため、薄板状の小型モルタル供試体を2つの橋梁および浄水場施設の4構造物に貼り付けて暴露し、実構造物の異なる部位における環境条件の影響を評価した。また、モルタルの配合および暴露時期が中性化環境評価に及ぼす影響について検討した。その結果、雨掛かりの無い環境条件下では、薄板供試体によって中性化環境評価が可能であることが確認できた。また、短期間の暴露試験によって長期供用された構造物中性化深さを評価するには、中性化しやすい配合で供試体が乾燥しやすい時期の暴露が適していることが確認できた。

Effect of Mix Proportion on Strength and Permeability of Pervious Concrete for Use in Pavement

A study to achieve high-strength, high porosity and permeability pervious concrete pavement was carried out. Mix proportions in terms of cement content, coarse aggregate-cement ratio (CA/C) and water-cement (W/C) ratio were varied. A mix proportion providing the optimal combination of strength and porosity was chosen, and polymer superplasticizers were added to examine their effect on the strength and porosity. Results showed that a water-cement ratio of 0.2 resulted in a dry and brittle mix that led to compressive strength less than 15MPa but a high permeability rate of approximately 20mm/s. A mix with w/c ratio of 0.3 and CA/C ratio of 4.25 resulted in compressive strength of 13.9MPa, flexural strength of 3MPa and high porosity of more than 20%. The use of high cement content of 495kg/m3 in the mix resulted in high compressive strengths of 51.8MPa, flexural strength of more than 4MPa, however permeability was reduced to approximately 1mm/s.

Study on the Coexistence of Porous Ecological Concrete with Plants

The effects of mix proportions on the properties of porous ecological concrete, and its coexistence with plants are discussed in this paper. In conclusion, the strength of porous ecological concrete is governed simultaneously by water cement ratio and cement content. Permeability is increased with any increment in aggregate gradation and any decrease in cement paste content. The thicknesses of concrete blocks and topsoil affect the growth of plants.

Effect of mix proportions, seawater curing medium and applied voltages on corrosion resistance of concrete incorporating mineral admixtures

Most reinforced concrete structures suffer durability problems during their service. The major durability problem is the corrosion of reinforcing steel which results in cracking and spalling of concrete. Nowadays, mineral admixtures, such as silica fume and metakaolin are used to enhance the corrosion resistance of reinforced concrete structures. In this research work, accelerated corrosion tests were carried out on reinforced concrete specimens made with plain, silica fume and metakaolin blended cements. The mineral admixtures were incorporated in the mixtures as a partial replacement by weight. The replacement percentages were 10%, 15%, and 25% of cement content by weight. Three types of cement were used in the program which were type I, type II, and type V Portland cement as classified by ASTM C150. Cement content of 350 and 450 kg/m 3 were used in concrete mixes with 0.40 and 0.50 water-binder ratios (w/c m). The curing mediums of specimens were potable water and seawater medium. Also, the effect of applied voltage on the accelerated test was studied. The current intensity, visible cracking time, and critical time up to 2 mm crack width were recorded during testing. The weight loss of the steel was also determined after testing. The observed superior resistance performance of silica fume and metakaolin blended cement concrete as compared to plain cement concrete in terms of cracking time, critical time, weight loss, and corrosion intendancy factor was monitored. Also, concrete mixes made with type I Portland cement have a good corrosion resistance compared with that of type II and type V Portland cement concrete mixes both cured in potable water and sea water medium.