Admixture Dosage Research Articles

Effect of Hydrophobic Water Repellent Admixture on the Compressive Strength of Concrete in Highly Aggressive Water (Dead Sea Water as a Case Study)

The compressive strength of concrete may be affected by seepage of salt water. Dead Sea water is a hazardous environment for concrete due to high concentration of salts. The aim of this study was to investigate the effect of Dead Sea water on the compressive strength of concrete containing hydrophobic water-repellent admixture, and to determine the optimum dosage of admixture to be used to reduce this effect. Three types of cement were used (Ordinary Portland Cement, Pozzolanic Cement, and Sulphate-Resisting Cement) with various dose rate of hydrophobic water repellent admixture (0%, 2%, and 4% of cement weight). An experimental approach, in which the specimens were divided based on the type of cement and the specimen’s age, was adopted. Nine control cubic specimens were cured in plain water to ensure that the required compressive strength was reached and (54) specimens were cured in Dead Sea water. The specimens cured in Dead Sea water were tested at 7 and 28 days to investigate the effect of Dead Sea water on the early and long-term strength. The results showed that a reduction in the 28-day compressive strength occurred in all specimens for the three types of cement used, but with the addition of water repellent, this reduction was alleviated, and the optimum percentage of admixture was 2% of cement weight.

Relative experimental evaluation of properties of concrete with addition of super – Plasticizers

The second most – widely used man – made material worldwide is considered to be as Concrete. Concrete is a simple construction material, produced with four basic ingredients: Cement, Fine Aggregates, Coarse Aggregates and Water. But, with the need of modification on the properties of concrete under different circumstances and various application areas, admixtures were also added while making the concrete mix. As per the latest codal provisions of IS 10262: 2019, admixtures had been added as a core ingredient, along with the four basic ingredients of concrete mix, for the determination of the quantity of each ingredient in making a concrete batch of desirable grade. With more technological advancements in the industry of cement and concrete, researchers, academicians and engineers are in a constant trend in trying to modify the properties of concrete by using various additives (such as chemical admixtures) in order to develop specialized concretes, which enhances the strength of the concrete along with the workability of concrete, thereby increasing the lifespan of the concrete – made structure. This study gives a general idea of how the different doses of chemical admixture alters the various properties of both fresh concrete and hardened concrete, such as workability and strength of concrete in compression, tension and flexure. The laboratory experiments were conducted for the determination of the characteristics of the concrete in both fresh and hardened state as per the procedures laid in Indian Standard Codal Provisions. Different dosages of chemical admixture used varies from 0% to 3% and comparable results were obtained with plain cement concrete, having 3 batch of M 20 grade concrete, each batch were tested with number of samples for getting an average value of workability and compressive strength, tensile strength and flexural strength. The result with 2% addition of admixture shows the optimum results.

The Effect of Cement Type and Granulometry on the Injectability of Suspension Grouts for Soil Improvement – A Mini Review

The safe construction and operation of many engineering projects often requires the improvement of the properties and mechanical behavior of the soil formations occurring in their area. Impregnation injections are one of the oldest methods of improving soil formations and present a wide range of applications. The injectability and penetrability of cement-based slurries are significantly affected by factors such as cement granulometry, water-to-cement ratio, grain size and degree of sand compaction, type and dosage of slurry admixtures, mixing process and the impregnation pressure. The object of this paper is to investigate the effect of cement suspensions type and granulometry on the injectability and penetrability within soil formations.

Development of a high strength cementitious grout for filling the joints of UHPC permanent formwork

The utilization of ultra-high-performance concrete (UHPC) permanent formwork could facilitate the construction of hydraulic concrete structures. However, the joints between UHPC formwork are the vulnerable parts of a whole permanent formwork system. This study aimed to develop a High Strength Cementitious Grout (HSCG) for filling these joints, integrating the formwork system, and minimizing the adverse influence on these joints. The aggregate size for the HSCG was optimized, and four kinds of admixtures (i.e., hydrophobic powder (HP), expansive agent (EA), redispersible polymer powder (RPP), and cellulose ether (CE)) and PVA fibers were used to improve the HSCG. The HSCG with different aggregate sizes, admixture dosages, and PVA fiber contents were experimentally investigated. By evaluating the compressive, tensile, flexural, and adhesive strengths of the prepared grout, the aggregate size range was recommended to be 0.15–0.30 ​mm, while the suggested contents of HP, EA, RPP, and CE were 0%, 6%, 2%, and 0.1%, respectively, by weight of binding materials. In addition, the optimal volume content of PVA fibers was 0.45%. In order to avoid the introduced foams, 0.2% of the defoamers were used in combination with the CE. After that, six combinations were tested to consider the coupled effect of different admixtures and PVA fibers on the HSCG. In consideration of the strengths, shrinkage, and abrasion resistance to water impact, the HSCG with the combination of (EA ​+ ​RPP ​+ ​CE), the aggregate size of 0.15–0.30 ​mm showed the optimal overall performance and was regarded as the most suitable HSCG for grouting.

Determining the air-entraining admixture dosage in concrete with non-traditional coal ash

Determining the air-entraining admixture dosage in concrete with non-traditional coal ash

A Comprehensive Method for the Optimization of Cement Slurry and to Avoid Air Channeling in High Temperature and High-Pressure Conditions

Air channeling in the annulus between the casing and the cement sheath and/or between the cement sheath and formation is the main factor affecting the safe operation of natural gas wells at high temperatures and pressures. Prevention of this problem requires, in general, excellent anti-channeling performances of the cement sheath. Three methods to predict such anti-channeling performances are proposed here, which use the weightless pressure of cement slurry, the permeability of cement stone and the volume expansion rate of cement sheath as input parameters. Guided by this approach, the anti-channeling performances of the cement slurry are evaluated by means of indoor experiments, and the cement slurry is optimized accordingly. The results show that the dangerous transition time of the cement slurry with optimized dosage of admixture is only 76 min, the permeability of cement stone is 0.005 md, the volume shrinkage at final setting is only 0.72%, and the anti-channeling performances are therefore maximized. The effective utilization of the optimized cement slurry in some representative wells (LD10–1-A1 and LD10–1-A2 in LD10–1 gas field) is also discussed.

Economical Robust Mix Proportioning of Self-Compacting Concrete Mixes - A Comparative Study

Concrete being the second largest consumed material after water needs attention towards sustainable construction with an increase in infrastructure. The world is moving towards innovative techniques and methodologies for sustainable and durable construction of concrete structures. The selection of suitable ingredients for making concrete and determining the relative amounts with an objective of producing a concrete of required strength and durability is the need of the hour. Standard mix proportioning of concrete should satisfy the workability requirements and also meet the requirement for mechanical properties, durability, economy, and even ecology of engineering applications. The study would focus on quality control aspects in mix proportioning the concrete as per the requirements of the industry. It includes mix proportioning of self-compacting concrete as per the standards prescribed in national construction community and Indian standards, plastic viscosity, and EFNARC based mix proportioning of self-compacting concrete. The mix proportioning would focus on utilizing various industrial and agro wastes as a suitable cement replacement material, locally available fine and coarse aggregate materials along with their alternates, appropriate dosage of admixtures, etc. The outcomes of the study include the formulation of handouts and readymade mix proportions of self-compacting concrete used in the construction of buildings and pavements along with their cost estimation. The study also provides information on some of the key points to be considered in making concrete using optimization concepts which would further reduce the cost of construction. The optimized mix proportions will be handy for the ready-mix plants especially in dealing with multiple large-scale construction activities. Mix proportioning using plastic viscosity approach was proven to be economical compared to other mix design methods.

Effect of mixed basalt fiber and calcium sulfate whisker on chloride permeability of concrete

Rapid chloride migration (RCM) test was used to determine the non-steady-state chloride migration coefficient (DRCM) of concrete mixed with calcium sulfate whisker (CSW) and basalt fiber (BF). Meanwhile, the microscopic morphology of CSW and BF in concrete was observed through scanning electron microscope (SEM), and the microstructural parameters were determined by the nuclear magnetic resonance (NMR) method. Results show that mixes with 3.0 kg/m3 CSW or BF alone outperformed in terms of chloride penetration reduction. However, by considering the strength factors comprehensively, the effect of enhancing concrete strength and chloride permeability resistance is better when 3.0 kg/m3 CSW and 4.5 kg/m3 BF are mixed. Binary problem optimal analysis results show that the optimal admixture dosage for improving the chloride impermeability and the optimum admixture dosage for enhancing the compressive strength (fc) of concrete are not consistent. According to SEM results, CSW is evenly distributed in the matrix and BF is wrapped by concrete matrix. The addition of BF and CSW to concrete reduced its porosity according to NMR tests. Increasing the content of BF would increase the contributive porosity (φ) of macro pores in concrete, while CSW could reduce the φ of macro pores. The DRCM has the strongest correlation with φ with a pore size of 100–1000 nm, followed by porosity.

Development of Non-Proprietary Ultra-High Performance Concrete Mixtures

The development of non-proprietary Ultra-High Performance Concrete (UHPC) is one way to reduce the initial cost of construction. However, workability is a major issue for which such mixtures are not practical in field conditions. Ultra-high performance cannot be achieved in field conditions if the concrete is not placed, finished, and compacted properly during placement. In this research, six UHPC mixtures were developed (three with steel fibers and three without fibers) using materials which are readily available on the local marketplace with water-to-cementitious materials ratios ranging between 0.17 to 0.30. The workability was determined using standard ASTM flow table apparatus, and specimens were prepared to determine compressive strength, splitting tensile strength, and permeable porosity. Flow table test exhibited flow values greater than 250 mm. Such high workability of the mixtures was achieved by optimizing the silica fume content and water reducing admixture dosage. These mixtures exhibited compressive strengths greater than 120 MPa and splitting tensile strengths greater than 5.10 MPa in both ambient and elevated curing temperatures. Results indicated that UHPC can be produced with a water-to-cementitious materials ratio as high as 0.30. Steel fibers helped to increase splitting tensile strength due to fiber-matrix interactions. Very low permeable porosity (1.7–16.7%) was observed which indicates superior durability due to the significant reduction of ingress of deleterious ions.

Sustainable effect of polycarboxylate ether based admixture: A meticulous experiment to hardened concrete

The manufacturing of high strength concrete uses chemicals called superplasticizers (SPs), also referred to as high range water reducers. Chemical substances known as plasticizers enable the production of concrete with a water content that is lowered by up to 15 %. Superplasticizers enable water content to be reduced by at least 30 %. If the dosage of superplasticizer increases the compressive strength also increase but excessive addition of superplasticizer disturbed the hydration process because the over dosage provides more water to mix the concrete Sometime over dosage results also the acceleration of de-flocculation of cement particle. Over dosage of admixture does not increase the strength and it only reduces the compressive strength. Experimental study focuses on effect of poly carboxylate ether-based admixture on various properties of concrete and the relation between the compressive strength, flexural strength and tensile strength along with modulus of elasticity of concrete at different amount of admixture which is based on the poly carboxylate ether. Effect of PCE on the hardened properties of concrete was performed for which sample cube of 15 cm size, beam of 500*100*100 mm and cylinder of size 15 cm diameter and 30 cm height are casted. Concrete may assist in the engineering of sustainable concrete in the building sector, offering prospects for the creation of sustainable concrete materials with resulting qualities. The experiment shows that the compressive strength increases with time but diminishes during the early days. To illustrate and contrast the impacts on tensile strength, flexural strength, and modulus of elasticity, tables and graphs were employed. To verify the findings, the non-destructive Rebound Hammer test was employed.

Ultrasonic Coda Wave Monitoring of Alkali-Silica Reactivity in Concrete Laboratory Prisms

Alkali-silica reaction (ASR) is a deleterious reaction in concrete that leads to the expansion and cracking of concrete. Laboratory approaches to monitor concrete for ASR activity are often lengthy and depend on an operator for regular measurements. The aim of this research is to develop an automated and reliable monitoring approach based on ultrasonic coda (or diffuse) wavefields, which are highly sensitive to minute and slowly occurring changes in a material—ideal for ASR. In this paper, the proposed approachis introduced along with an experimental study that compares ultrasonic coda wave monitoring data with traditional expansion measurements following ASTM C1293. A simple, fast, and robust algorithm to track a selected coda wave feature is proposed and evaluated and was applied to the recorded data. The monitored concrete prisms were designed to have three different levels of ASR activity by varying the lithium admixture dosage. The proposed approach was found to be promising. The process is automated and the monitoring of the specimens using coda wavefields was able to clearly differentiate the mixtures with varying ASR expansions.

Optimizing of chemical admixtures for 3D printable cementitious materials by central composite design

Printability of 3D printable cementitious materials is related to material rheological properties, and is affected and controlled by modern concrete chemical admixtures. In this work, the influence of several chemical admixtures including superplasticizer, retarder, and accelerator on the rheological characteristics of printable materials was investigated using central composite design (CCD). Twenty test points with varying dosages of chemical admixtures were performed to evaluate the primary effects of chemical admixtures and their combined interactive effects on the rheological properties. The results indicate that with the increase of retarder or superplasticizer dosage, all rheological parameters decrease while accelerator possesses an opposite impact. The rheological properties are negatively proportional to the combined interactive effect of retarder and accelerator. The combined interactive effect of retarder and superplasticizer positively affects dynamic yield stress, plastic viscosity, and thixotropy, while it negatively impacts static yield stress. The combined interactive effect of accelerator and retarder positively affects the yield stress, whereas it negatively influences the plastic viscosity and thixotropy. The results indicate that the CCD is an efficient method to find the desirable formulation within a given boundary.

Experimental study on effect of fly ash content on self-compacting concrete

Self-compacting concrete (SCC), concrete flows by its own weight, is a recent innovation in concrete industry. In recent times, the usage of self-compacting concrete was increasing. Self-compacting concrete will be form, if it had sufficient binder content and required water content. The strength of concrete majorly depending on water to powder ratio. However, there were workability problems associated while fixing the water powder ratio as per target mean strength when SCC was made, especially for design mix for low strength and high strength of concrete. Apart from this, binder content and mineral admixture will also responsible for strength of concrete. As mineral admixture content increases the strength will reduce. If a relationship between compressive strength and mineral admixture content was found, mix proportions of SCC can be made easily. In this area more research has to be focused. This research is an attempt to assessing the grade of concrete with respect to fly ash content and relationship was developed between fly ash content and compressive strength of concrete. IS 10262-2019 and EFNARC guidelines are used in mix design. A water content of 200 kg/m3 and water powder ratio = 0.4 is kept as constant. Cement was partially replaced with fly ash at proportions of 10%, 20%, 30%, 40%, and 50%. In this research the fresh properties, mechanical properties, and Sulphate attack test of each proportion were tested. The workability properties are measured under different chemical admixture levels, such as 0.5%, 0.6%, and 0.8%. Strength properties are determined with a chemical admixture dosage of 0.6%. The fresh properties of concrete were measured by slump flow test, L–box test, and V–cone test. Mechanical properties such as compressive strength, flexure strength and split tensile strength were determined. Sulphate attack test also conducted by immersing cube specimens in 5% of H2SO4. Further, correlation study was done between compressive strength & fly ash content and also correlation between compressive strength & flexure strength.

Study on the effect of VMA admixture for concrete cured under different conditions on air permeability and sorptivity

• Application of VMA resulted in a decrease in compressive strength of concrete in most cases. • VMA resulted in an increase in sorptivity with increasing admixture dosage regardless of the specimen curing applied. • The effect of VMA application on concrete air permeability is negative in most cases. • The use of the plasticiser cause an elongation of initial setting time resulting from retardation of hydration processes. • In general, the same kinds of hydration products were identified in all the hardened samples after long time of hydration. The main goal of this research was to determine the effect of viscosity modifying agent admixture and specimen curing conditions on air permeability, sorptivity and mechanical properties of concrete and determining the effect of the admixture on the intensity of early cement hydration and the phase composition of the hardened cement paste. Used admixtures decreases 28 day compressive strength and the reduction depends on the kind of cement and curing conditions. VMA admixture did not significantly affect the sorptivity of the CEM I series, while in the case of the CEM III series, the sorptivity increased with increasing admixture dosage. The effect of VMA application on concrete permeability is negative in most cases and is most evident in the specimens tested after drying at 65 °C. The rate of heat release during hydration and the related parameters depend primarily on the type of cement, and in the case of admixtures, the use of plasticiser has a much greater effect than VMA. In general, the same kinds of hydration products were identified in all the hardened samples after long time of hydration. The quantitative composition of hardened cement paste depends mainly on the kind of cement used. It was found that the presence of admixtures had a greater impact on the quantitative composition of the cement paste in the case of samples made with CEM I.

Reolojik Parametreleri Ölçülebilen Farklı C3A Oranına Sahip Hamur Karışımlarında Optimum Su Azaltıcı Katkı Dozajının ve Su Muhtevasının Belirlenmesi

C3A ratio is one of the parameters that greatly affects the rheological properties of cementitious systems. With the increase in the C3A ratio, the water reducing admixtures and/or water requirement increases to achieve the target spread. Some parameters are taken into account such as the type of rheometer, application of the method, the homogeneous preparation of the mixture and the water reducing admixture content in determining the water/cement (w/c) ratio and water reducing admixture requirement in the mixtures produced for the measurement of the rheological parameters of paste mixtures. The mixture produced should not be too solid (it may exceed the measuring capacity of the rheometer / the mixture may not be homogeneous) and excessively fluid (there may be a risk of segregation). For this reason, it is of great importance to determine the optimum water reducing admixture requirement and water/cement (w/c) ratio in mixtures where rheological measurements can be taken. In this study, optimum polycarboxylate-based water reducing admixture (PCE) dosage and w/c ratio were investigated in paste mixtures having different C3A ratios. For this purpose, CEMI 42.5R type portland cement with 4 different C3A ratios as 2%, 3%, 6% and 9% was used. A total of 80 different paste mixtures with 4 different w/c ratios (0.30, 0.32, 0.35 and 0.40) were prepared by adding PCE (0, 0.05, 0.10, 0.15 and 0.20% by weight of cement) in 5 different dosages. According to the results, it was observed that the admixture requirement and w/c ratio increased with the increase in the C3A ratio of the mixtures. On the other hand, it was determined that the segregation tendency increased with the increase of PCE dosage and w/c ratio in mixtures with low C3A ratio. As a result, the optimum PCE dosage was determined as 0%, 0.10% and 0.15% in terms of rheological parameters in paste mixtures. Also, the optimum w/c ratio was obtained between 0.32 and 0.35.

Use of Modified Andreassen Curve in Optimizing Mixes

Particle packing optimization is a philosophy that has evolved over the years. Its use in concrete proportioning has helped in creating denser and stronger mixes. Numerous packing theories and models have evolved over the course of time to optimize the concrete. Out of which the Modified Andreassen curve has found its practical application in optimizing high-performance concrete. The main objective of the study was to study different particle packing theories and their effects on the mortar mixes and to design the most optimized material which gives the maximum strength. In this paper, the use of quartz sand and Modified Andreassen packing theory has been adopted for the concrete proportioning. This paper also deals with the changes in density and compressive strength in concrete after the application of the Modified Andreassen curve. The EMMA software whose algorithm is based on the Modified Andreassen curve is used for proportioning the concrete. In addition, the effects of admixture dosage on strength have been discussed in the paper. An attempt has been made to create an Ultra-High-Performance Concrete (UHPC) by applying Modified Andreassen Curve and using quartz aggregates. For this a thorough literature review was done, a precast site where the high strength concrete was required was identified and the various tests were conducted on the site itself. The results obtained from this study are quite interesting as 16 % cement was replaced by metakaoline and silica fume and phenomenol strength of 96.18 MPa.
 HIGHLIGHTS
 
 Particle packing optimization is a philosophy that has evolved over the years
 The main objective of the study was to study different particle packing theories and their effects on the mortar mixes and to design the most optimized material which gives the maximum strength
 Ultra-High-Performance Concrete (UHPC) was created by applying Modified Andreassen Curve and using quartz aggregates. For this a thorough literature review was done, a precast site where the high strength concrete was required was identified and the various tests were conducted on the site itself. The results obtained from this study are quite interesting as 16 % cement was replaced by metakaoline and silica fume and phenomenol strength of 96.18 MPa was achieved
 
 GRAPHICAL ABSTRACT

Effect of Partial Replacement of Sand By Glass Powder with Calcium Nitrite as Admixtures On the Properties of Concrete

Every year, millions of tonnes of waste glass are produced across the world. Glass is disposed of as garbage in landfills, which is unsustainable since it does not breakdown in the environment. Silica is the main component of glass. The use of milled (ground) waste glass as a partial replacement for cement in concrete might be a significant step toward the creation of environmentally friendly, energy-efficient, and cost-effective infrastructure systems. When waste glass is ground down to micron-sized particles, it is called micro glass. It is believed that it would undergo pozzolanic reactions with cement hydrates, resulting in secondary Calcium Silicate Hydrate (C–S–H). Chemical characteristics of clear and tinted glass were assessed in this study. The X-ray fluorescence (XRF) technique was used to analyse the chemical composition of glass and cement samples, and it revealed slight changes in composition between clear and tinted glasses. Flow and compressive strength experiments on mortar and concrete were conducted by adding 0–25% ground glass, with the water to binder (cement + glass) ratio being constant for all replacement levels. With the inclusion of glass, mortar flow rose somewhat, with a small influence on Further experiments were undertaken using the same mix parameters and a 1% super plasticizing admixture dosage (by weight of cement) to analyse the packing and pozzolanic effects, and usually observed an improvement in compressive strength of mortars with admixture. Concrete cube samples were made and evaluated for strength in the same way as mortar samples were (until 1 year curing). When compared to control samples, the compressive strength of recycled glass mortar and concrete was found to be higher. The financial and environmental benefits of replacing 20% of cement with waste glass were determined to be compelling.

Mix design methods for pervious concrete based on the mesostructure: Progress, existing problems and recommendation for future improvement

High porosity endues pervious concrete with outstanding performances as water permeability, pollutant removal, and noise reduction, which make pervious concrete a sustainable material for wide application fields, but a uniform mix design method for pervious concrete is not established yet. This review is conducted to integrate the useful findings in the publication and search the efficient method for the mix design of pervious concrete. The quantitative relationships between the mechanical and hydraulic properties and the mesoscopic parameters of pervious concrete provides the foundation for the property estimation during the mix design of pervious concrete, and the existing model could quantitatively characterize the mesostructure of pervious concrete consisting of cement paste and aggregate. The paste thickness is an important parameter to the final mesostructure of pervious concrete. The film-forming ability test provides an effective approach to select the suitable W/C and dosage of chemical admixture. Based on the previous finding in the publications, the mixture of pervious concrete could be quantitatively controlled from fresh to hardened state, and a systematic mix design method for pervious concrete is suggested. The suggested method would conduce to better control the quality of pervious concrete and greatly reduce the number of trail batching.

Study on strength characteristics of concrete by replacement of fine aggregates and fibre addition to cement using SCC

The present investigation is on strength characteristic of hardened concrete with materials re-placement of fine aggregates and addition of fibre by using self-compacting concrete method which is an advanced technology used in improving the construction methodology. The SCC requires an admixture like Poly Carboxylate Ether (PCE) based super – plasticizer (Master Glenium SKY 8630) used as curing compound to improve the efficiency of self-compacting concrete SCC in terms of its performance. As the nominal fine aggregate cost is increasing the re-placement of fine aggregates is done by by-products of steel industry and query dust. Grade of concrete, dosage of admixtures, self-curing compounds, and time of curing are parameters to be considered for investigation. The performance studies include water retention, compressive test and split tensile test. The result analysis shows that crusher dust and foundry sand show increase in tensile and flexural strength at 0.2% of fibre addition. The grade of concrete is M30 is taken for investigation.

Investigation of the Efficiency of Ultra High Range Water Reducing Admixture in Roller Compacted Concrete Production

In this study, roller compacted concretes were produced by using polycarboxylate-based third generation high-performance mortar and concrete admixture, which provides ultra-high range water reduction and long workability time. In roller compacted concrete production, the chemical admixture dosage was 1%, which was the maximum dosage recommended by the manufacturer, and the amount of water used was reduced by 10, 20, 30 and 40% compared to the concrete produced without the use of concrete admixture. The physical and mechanical properties of the roller compacted concrete specimens were investigated. When the ultra-high range water reducer was used as 1% of the cement weight in the production of roller compacted concrete, optimum values in terms of unit weight, compressive strength, water absorption, ultrasonic pulse velocity and dynamic modulus of elasticity were obtained by reducing the mixing water by 10%. Although the water/cement ratio decreased, further reduction in water amount resulted in a decrease in compressive strength and affected the concrete quality negatively.