Papers by Keyword: Superplasticizer

Abstract: Concrete is a construction material that is widely embraced worldwide with a major disadvantage of environmental unfriendliness arising from the production process of cement, one of its vital components. Recent studies have found that replacing cement with pozzolans increases compressive strength, durability, and occasionally workability, although at a low replacement percentage. The low replacement level obtained can be improved upon with the use of superplasticizer to further enhance the workability and the compressive strength. Therefore, the primary objective of this study is to determine the effects of adding Costamix 200 superplasticizer and partially replacing cement with sawdust ash (SDA) for cement on the mechanical properties of the resultant concrete. Waste sawdust was collected, dried, and then burnt in a furnace for 60 minutes at 700°C. Concrete samples were made using 150 x 150 x 150 mm³ rectangular and 100mm cylindrical molds using a 1:2:4 mix ratio, 0.55 water cement ratio, a constant dosage of 1.8% superplasticizer (Costamix 200), and SDA at 0%, 5%, 10%, 15%, 20%, and 30% SDA respectively. The concrete samples were tested at 7, 14, 21, and 28 days for bulk density, split tensile strength, and compressive strength were carried out. The outcomes of the research show that the presence of costamix 200 and SDA at 0%, 5%, 10%, 15%, and 20% cement substitution resulted in compressive strength range of 18.91 N/mm² to 25.00 N/mm² at 28 days. The optimum value of 25.00 N/mm² was recorded for 15% replacement making it ideal for use in structural applications such as beams, slab and column.

Abstract: Cementing around the casing in oil and gas wells provides proper zonal isolation, holds the casing in place, and prevents fluid migration is an important part of the completing process and well plugging for abandonment. A reliable cement rheology prediction is central to the success of oil well-cementing operations. Properties of the rheological are plastic viscosity and yield stress by using advanced shear-stress/shear-strain controlled Viscometer with using Ground Granulated Blast Furnaces Slug, and Superplasticizer investigated. The effect replacement of Class G cement according to API [1]. (American petroleum institute) classification is performed at different rates. (15%-75%) Blast Furnaces Slag (GGBFS) at intervals of 15%. Further, by using different curing conditions (moist curing and @38°C, @60°C water path curing chamber). The results show that blended cement with 45% of GGBFS has significantly increased in compressive strength more than unblended cement type G. This happened because the fine micro GGBS influences the heat of hydration through the pozzolanic reaction and the effect of superplasticizer. The double effect of GGBS and Superplasticizer on the plastic viscosity and yield point, the linear relationship between shear stress and shear rate, by using Bingham plastic Fluid Model, the slurries act as Newtonian behavior at high shear.

Abstract: Securing dense concrete structure and the intensification of cement hydration processes plays an important role in ensuring high concrete strength. The results of the applicability of dunite magnesian rocks of Central Aldan (Yakutia) for concrete production are presented. Petrographic and thermographic studies are conducted for the preliminary preparation of the charge. Pre-firing, fine intergrinding, and additional mechanical activation of the charge were applied. It is found that finely ground and pre-fired magnesium silicates act as both a micro-filler contributing to increased stone density and an active agent in forming robust crystallization structure. It is established that the use of pre-fired dunite powder with specific surface area of 8000 ± 200 cm²/kg in combination with the SP-1 superplasticizer allows obtaining autoclaved reactive powder concrete with a strength grade of up to B45.

Abstract: The self-compacting concrete (SCC) workability is usually ensured by the addition of superplasticizers in the mixture. The effect of some properties of superplasticizers was investigated by many researchers. However, in the literature, there is no study related to the effect of dry extract of superplasticizer admixture on the rheological and mechanical properties of self-compacting concrete.The objective of this work is to characterize the effects of six types of superplasticizers with various solids on the rheological properties as well as the compressive strength and elastic modulus of SCC.This experimental study shows that the dry extract of superplasticizer affects the various properties of concrete both in the fresh and hardened state: first, the dry extract allows controlling the flow properties (the lower its value, the more the concrete is self-compacting), and second, the dry extract allows the reduction of the water to cement ratio (the greater its value, the stronger the concrete). The statistical coefficients, analyzed in this work, indicate a high-level relationship between the dry extract and the rheological and mechanical behavior of SCC.

Abstract: Researchers in the field of concrete technology with the application of different admixtures are always in search of suitable admixtures to improve the workability as well as the strength of any concrete grade. An attempt was made in the present research to use chemical admixtures (superplasticizers) like sulphonated naphthalene based Apple Chemie AC-MENT-ALPHA-X5, polycarboxylic ether based Fosroc Auramix 350, sulphonated naphthalene based Fosroc Conplast SP 430, modified polycarboxylate based Du-bond DUPLAST PC P 2 and modified lignosulphate based Sika PLASTIMENT BV 40 for concrete grades M30 and M40. A literature survey revealed that all identified chemical admixtures are used for 20–25% reduced water content. A study was done to compare M30 and M40 grade concrete in both fresh and hardened states, taking water reduction into account. Experimental results showed that all admixtures demonstrate good paste-up consistency of up to 1%. As the percentage of admixtures increases, there is an increase in surface pores due to more significant air entrainment. Compressive strength results of 1% admixture content for Apple Chemie, Fosroc, and Du-bond were observed to be close to their characteristic compressive strengths for both grades, but Sika and Fosroc Auramix 350 have good compressive strength with less than 1%. As the grade of concrete improves, Conplast's effect reduces, but the Du-bond and Fosroc Auramix 350 perform excellently for split tensile strength. As the grade rises, all admixtures show increasing flexural strength levels. However, Auramix 350, with a 1.5% content for M30 grade, consistently outperforms Sika, which has a 1% content. It helped to employ up to 1% of all admixtures, but Sika reveals a cost increase of 2.5 to 7.3% for 1% and 1.5% admixture additions. The study found that Fosroc Auramix 350 could be used for both grades and still have good workability and strength.

Abstract: Organic admixtures are an indispensable component of modern concrete. Thus, their purposeful application is not only technically and economically viable but in addition an inevitable tool to make concrete more environmentally friendly. In this context, the use of polysaccharides has increasingly gained interest in the built environment as sustainable resource for performance enhancement. However, due to its origin, biopolymers possess a vast variety of molecular structures which can result in incompatibilities with other polymers present in concrete, such as superplasticizers. The present study highlights effects of the joint application of different types of starches and polycarboxylates with respect to their influence on cement hydration and structural build-up of cement pastes.

Abstract: Composite admixtures which include active pozzolanic components and high-range water reducers, allows to obtain high-strength, particularly dense and durable concrete to achieve a reduction in resources and energy consumption of manufacturing.Zeolite, containing a significant amount of active silica, can serve as one of the alternative substances to resources and energy consuming mineral admixtures like metakaolin and silica fume. The deposits of zeolites are developed in Transcarpathia (Ukraine), USA, Japan, New Zealand, Iceland and other countries. It is known that zeolite tuffs exhibit pozzolanic properties and are capable to substitution reactions with calcium hydroxide.However, the high dispersion of zeolite rocks leads to a significant increase in the water consumption of concrete. Simultaneous introduction of zeolite tuffs with superplasticizers, which significantly reduce the water content, creates the preconditions for their effective use in high-strength concrete.Along with dehydrated (calcined) zeolite, natural (non-calcined) zeolite expresses itself as an effective mineral admixture of concrete. When using non-calcined zeolite, the effect of increasing in compressive strength at the age of 3 and 7 days is close to the effect obtained when using dehydrated zeolite: 8-10% and 10- 12%, respectively, and 28 days the strength growth is 13-22%. The use of non-calcined zeolite has a significant economic feasibility, so it certainly deserves attention. There were compared the effect of zeolite to metakaolinThe results of the research indicate that the use of composite admixtures, consisted of calcined (non-calcined) zeolite tuff of high dispersity and superplasticizer of naphthalene formaldehyde type, allows to obtain concretes classes C50…C65.

Abstract: The ethyl glycol vinyl ether polyoxyethylene ether (EPEG) is a new type of macromonomer to synthesize polycarboxylate superplasticizer (PCE), which has higher reactivity due to the unsaturated double bond and easily to polymerization. The EPEG slump retaining typed PCE can be synthesized by free radical polymerization though EPEG, acrylic acid and hydroxyethyl acrylate (HEA). The HEA had the greatest influence on slump retaining performance. High polymerization conversion rate of EPEG typed PCE was beneficial to improve the concrete performance.

Abstract: This article disclosed the influence of acid-ether ratio, n_(SH)/n_(IPEG), and n_(APS)/n_(IPEG) on adsorption and fluidity performance. The optimum synthetic parameters of acid-ether ratio, n_(SH)/n_(IPEG) and n_(APS)/n_(IPEG) were 0.5, 0.35 and 0.05, respectively. The rheology fitting equation was τ= 719.55γ+ 1834.54. And the correlation coefficient was 0.9843. The cement paste conformed to the law of pseudoplastic fluid. The preferred PCE-11 had excellent performance in freshly mixed and hardened concrete.

Abstract: Abstract: Rheology is the science that concerns the flow of liquids, and the distortion of solids under an applied force. The study of the rheology of concrete determines the properties of fresh concrete. The rheological parameters are affected by temperature, stress conditions and several other factors. The main intention of this research is to model the rheological parameters of the fly ash incorporated cement with various types of superplasticizers exposed under different temperatures using an Artificial Neural Network. Test data were generated by performing rheological tests on cement paste at three distinct temperatures (15, 27, 35°C). Mixes were prepared using OPC, fly ash (15, 25, 35%) and superplasticizers of four different families. By conducting experiments, 252 data have been generated by modifying the combination of fly-ash, superplasticizer, and test temperature. Among the 252 data, 80% has been utilized for training and 20% is utilized for predicting the model’s accuracy. The input layer of the model consists of test temperature, the amount of fly ash replaced, cement and water content, and four different groups of superplasticizers. The cement paste’s yield stress was the output parameter of the model. The model generated data has been compared with the experimentally generated data to determine the accuracy of the model.Keywords: Rheology, Fly Ash, Superplasticizer, Temperature, ANN