Superplasticizer Admixture Research Articles

Effect of chemical admixtures on concrete’s electrical resistivity

PurposeThe purpose of this paper is to verify the influence of superplasticizer and air entrainment admixtures (AEs) in the electrical resistivity of concrete.Design/methodology/approachTen different types of concrete have been studied. Three levels of superplasticizer and air AEs have been used (0.20, 0.35 and 0.50 per cent). Concrete samples were cast and the electrical resistivity was monitored at the ages of 28, 63 and 91 days. Compressive strength and density tests have also been executed.FindingsThe superplasticizer admixture presented an optimal level of 0.35 per cent that significantly increased the electrical resistivity. The air AEs at the same dosage caused a considerable decrease in the electrical resistivity. The concrete with air AEs showed highest resistivity/MPa ratio.Research limitations/implicationsThe results should be carefully extrapolated for other materials and admixtures.Practical implicationsThe usage of chemicals admixture in concrete is extremely common nowadays. However, only a few authors have studied the impact of such materials on the concrete’s electrical resistivity. Since many other researchers have already correlated electrical resistivity with other concrete’s properties, such as strength, setting time and corrosion probability, it is important to better understand how superplasticizers and air-entraining agents, for instance, impact the resistivity.Originality/valueThe vast majority of studies only tested the resistivity of cement paste or mortar and usually for short period of time (up to 28 days), which seems not to be adequate since the cement reaction continues after that period. This paper fills this gap and studied the impact of admixture on concrete and for a period of 91 days.

Synthesis of phosphonated comb-like copolymers and evaluation of their dispersion efficiency on CaCO3 suspensions. Part I: Effect of an increasing phosphonic acid content

Superplasticizers are admixtures widely used in the building industry for reducing the water content of concrete with a high fluidity and workability at short term, and for increasing concrete mechanical properties at long term. Polycarboxylates, which are synthetic comb-like copolymers, are the most used superplasticizer admixtures. In order to improve polycarboxylate efficiency and compatibility with use of mineral additives, high-sulfate concretes etc., various authors tried to change macromolecular architectures, including nature of anionic function. This paper is the first part of a study which presents synthesis of several macromolecular architectures of comb-like copolymers with phosphonic acid functions instead of classical carboxylic acid. Adsorption, dispersion and fluidification efficiency of these admixtures are evaluated on calcite suspensions in order to simulate early-age cement behavior. Moreover, settling behaviors are studied in order to characterize dispersion ability of synthetized polymers.

Effect of superplasticizers on Ni behaviour in cementitious environments

Nickel hydroxide solubility has been studied in this work in different cementitious systems. Our results indicate that once Glenium® 27, cement superplasticizer admixture, is added to water and then mixed with cement, this polymeric material is stabilized and not released back to the aqueous solution, with negligible effects on the mobility of nickel. Contrary to that, when Glenium® 27 is added directly in solution at high dosages, an important effect is observed on nickel behaviour. Thermodynamic calculations indicate that the effect of such component on Ni is likely the effect that other small organics could have over this element.

The development of new empirical apparatuses for evaluation fresh properties of self-consolidating mortar: Theoretical and experimental study

Self-Consolidating Concrete (SCC) and Self-Consolidating Mortar (SCMO) contain unique properties such as filling ability, passing ability, and segregation resistance, differentiating them from ordinary concretes. Little changes in SCMO and SCC ingredients bring about major changes in their workability and segregation. The behavior of fresh SCMO depends on variable factors such as water to cement ratio, gradation and moisture content of aggregates, type of mineral additives, dosage and type of superplasticizer and other chemical admixtures. In addition, evaluation of fresh properties of the SCMO requires simple and fast methods.In this study, based on the flow velocity and volume to surface ratio method, new apparatuses were developed to evaluate the fresh properties of SCMO. Mini J-ring, mini U-box, and mini L-box were used to measure passing ability parameters. Mini slump, mini Orimet, new mini V-funnel and mini V-funnel were used to measure filling ability and mini column segregation was used to measure segregation of self-consolidating mortars. The relationships between critical areas of mentioned methods are considered. The Experimental set-up method was used to record the fresh properties. In addition, 27 different mortar mixtures were prepared to verify the test methods. Results show that flow velocity and volume to surface ratio were appropriate criteria to design new apparatuses to measure fresh properties of self-consolidating mortar.

Retardation effect of different alcohols on the cement coagulation in polycarboxylate- and naphthalene-based cement admixtures

Alcohol has great potential to delay the coagulation of cement. The effects of alcohol on paste fluidity and normal consistency coagulation time have been studied for polycarboxylate superplasticizer and naphthene cement admixture. Seven alcohols were combined with polycarboxylate superplasticizer and naphthene at a concentration of 0.01-0.09%, respectively, including n-propanol, methanol, sorbitol, ethylene glycol, glycerol, ethanol, and mannitol. The fluidity and normal consistency coagulation time of each cement admixture were measured. The performance of both polycarboxylate superplasticizer and naphthene cement admixtures were compared to develop cement admixture with delayed coagulation.

Plasticizer and Superplasticizer Compatibility with Cement with Synthetic and Natural Air-Entraining Admixtures

When increasing the degree of fluidity of previously aerated cementitious mixtures, there is a problem of maintaining their correct aeration. Most of the available superplasticizers cause a significant increase of the air content of concrete mixtures. The problem of compatibility of superplasticizer and air-entraining admixture increases in case of multicomponent Portland cement, due to different effects of these additives. It comes down to achieving a compatibility of the three variables mentioned in the title of the paper, due to the required air entrainment and consistency of mixture. Achieving compatibility of such a system requires a series of experimental studies that were presented in the paper together with their resulting indications. In case of previously air-entrained concrete that is made with an air-entraining cement, after the addition of new generation SP occurs very large increase in air entrainment. The air-content of mixture according to EN 480-1 may be higher than 13%.

Study of the Rheological Behavior of Mortar with Silica Fume and Superplasticizer Admixtures According to the Water Film Thickness

In the manufacture of mortar or concrete, the mixing water fills the interstitial voids between the solid particles of cement and the volume of the resulting paste should be more than sufficient to fill the voids between the fine and coarse aggregates. So we should have enough water to cover all the fine particles and enough paste to cover all aggregates. Therefore, it can be assumed that both Water Film Thickness (WFT) and paste film thickness have major effects on the rheology of the mortar. In this work, we try to apply this approach to understand the rheological properties of mortars containing various amount of Silica Fume (SF) with two types of superplasticizer using rheometer apparatus and mini cone test. The results show that the rheological behavior is governed by water film thickness and the dosage of superplasticizer. However, for high dosages water film thickness remains the only factor governing the behavior. In addition, the mixture compactness increases significantly when adjuvanted with efficient superplasticizer.

Structure and Properties of Concrete for Injection with Two-Stage Expansion

Often, when it is necessary to fill formwork space in confined working conditions with limited operational control in some engineering solutions the special materials for injection are used. In this case, it is advisable to use high-fluidity concrete mixes made with К-cement, regulator of the kinetics of structure formation, superplasticizer and gas-forming admixture. The gas-forming admixture obtains of expansion of fresh-concrete during first stage. The special sulfo-alumina additive in K-cement obtains of expansion of hardening concrete during second stage. The main regularities in the formation of the structure and properties of cement stone are considered. The dependences "composition-technology-structure-properties" for concretes with two-stage expansion are clarified. The main provisions for determination of mix proportion for concrete are proposed. The quantitative relationships between the construction properties of concretes and prescription and technological factors are obtained.

A study on the impact of cement type and heat stimulation on performance of superplasticizers

The objective of this study was to investigate the interaction of different types of cement and superplasticizer admixtures in which the Superplasticizers were stimulated by heating before addition to the mortar. To evaluate the desired impacts, tests on the fluidity and flow loss of mortar were conducted. For better considering the behavior of admixtures under heat stimulation with different cements, three types of cement and two types of superplasticizer are used, Polycarboxylic acid-based and Polycarboxylic acid-based ether. The admixtures were heated to 40EsC, 50EsC, and 60EsC for 0.5 hours and 24 hours. Generally Polycarboxylic acid-based admixtures showed higher flow improvement in 60EsC heating with all cement types especially with High Early Cement, in comparison with Polycarboxylic acid-based ether type. The flow loss of mortar was reduced by heat stimulation of admixtures, Polycarboxylic acid-based ether (the product suitable for Ready Mix Concrete) showed significant flow improvement after 15 minutes and kept it to one hour. As the result of this research, it is possible to reduce the admixture dosage and maintain the desired fluidity of mortar, or increase the mortar fluidity by applying the heat stimulation technique.

Rheological study of cement paste with metakaolin and/or limestone filler using Mixture Design of Experiments

Several cement pastes with different amounts of metakaolin (MK) and/or limestone filler (LF) were prepared. The water/cementitious materials ratio was maintained constant at 0.3, with addition of 0.5%wt/wt of poly-carboxylate ether (PCE) superplasticizer admixture. The following parameters of the fresh cement pastes were evaluated: the slump and spread, the Marsh funnel time, the plastic viscosity, yield stress, viscoelastic properties and thixotropy. After the curing of 7day old pastes, compressive strength tests were performed according to the Brazilian standard using 50×100mm cylinder specimens. We conclude that LF alone is not able to avoid segregation or bleeding, and there is no difference between cement pastes mixed with LF and pure OPC pastes, in terms of rheology. On the other hand, if one needs low slump and low spread, the use of MK is recommended because this material creates a strong, thixotropic interconnected net inside of the paste, increasing the yield stress and the thixotropy of the cement paste. By adding 5–10%wt/wt MK, the average increase of compressive strength is approximately 45% at 7days, compared to the control (only OPC, water and PCE). The maximum recommended amount of LF or MK substitution in our case was 10%wt.

Waste glass powder as partial replacement of cement for sustainable concrete practice

Abstract Million tons of waste glass is being generated annually all over the world. Once the glass becomes a waste it is disposed as landfills, which is unsustainable as this does not decompose in the environment. Glass is principally composed of silica. Use of milled (ground) waste glass in concrete as partial replacement of cement could be an important step toward development of sustainable (environmentally friendly, energy-efficient and economical) infrastructure systems. When waste glass is milled down to micro size particles, it is expected to undergo pozzolanic reactions with cement hydrates, forming secondary Calcium Silicate Hydrate (C–S–H). In this research chemical properties of both clear and colored glass were evaluated. Chemical analysis of glass and cement samples was determined using X-ray fluorescence (XRF) technique and found minor differences in composition between clear and colored glasses. Flow and compressive strength tests on mortar and concrete were carried out by adding 0–25% ground glass in which water to binder (cement + glass) ratio is kept the same for all replacement levels. With increase in glass addition mortar flow was slightly increased while a minor effect on concrete workability was noted. To evaluate the packing and pozzolanic effects, further tests were also conducted with same mix details and 1% super plasticizing admixture dose (by weight of cement) and generally found an increase in compressive strength of mortars with admixture. As with mortar, concrete cube samples were prepared and tested for strength (until 1 year curing). The compressive strength test results indicated that recycled glass mortar and concrete gave better strength compared to control samples. A 20% replacement of cement with waste glass was found convincing considering cost and the environment.

Investigation of the effect on the physical and mechanical properties of the dosage of additive in self-consolidating concrete

The objective of this study was to investigate the effect of superplasticizer and mineral admixture contents on the properties of Self-Consolidating Concrete (SCC). Silica fume was used as a mineral admixture and polycarboxylate based third generation superplasticizer was used as a chemical admixture. In order to determine the optimum admixture dosages; trial mixes were prepared with varying admixture dosages. Nine concrete mixtures with different admixture dosages were prepared from trial mixes. Hardened concrete properties and self-compactability criteria of these series were determined and test results were compared between these SCC mixtures. It was observed that 10S1.3A (10% Silica Fume, 1.3% Superplasticizer) and 10S1.5A (10% Silica Fume, 1.5% Superplasticizer) mixtures show the best performance with regard to fresh and hardened concrete properties.

Dataset of producing and curing concrete using domestic treated wastewater.

We tested the setting time of cement, slump and compressive and tensile strength of 54 triplicate cubic samples and 9 cylindrical samples of concrete with and without a Super plasticizer admixture. We produced concrete samples made with drinking water and treated domestic wastewater containing 300, 400 kg/m3 of cement before chlorination and then cured concrete samples made with drinking water and treated wastewater. Second, concrete samples made with 350 kg/m3 of cement with a Superplasticizer admixture made with drinking water and treated wastewater and then cured with treated wastewater. The compressive strength of all the concrete samples made with treated wastewater had a high coefficient of determination with the control concrete samples. A 28-day tensile strength of all the samples was 96–100% of the tensile strength of the control samples and the setting time was reduced by 30 min which was consistent with a ASTMC191 standard. All samples produced and cured with treated waste water did not have a significant effect on water absorption, slump and surface electrical resistivity tests. However, compressive strength at 21 days of concrete samples using 300 kg/m3 of cement in rapid freezing and thawing conditions was about 11% lower than concrete samples made with drinking water.

Use of treated domestic wastewater before chlorination to produce and cure concrete

Concrete samples with different amounts of cement and superplasticizer admixture produced with both drinking water and treated wastewater and cured with treated wastewater before chlorination. The 28-day compressive strength of all of the concrete samples was 93–96% of the compressive strength of the control samples. A 28-day tensile strength of all samples was 96–100% of the tensile strength of the control samples and the setting time was increased by 15min. Concrete samples produced and cured with treated wastewater did not have a significant effect on water absorption, slump and surface electrical resistivity. A one-way analysis of variance (ANOVA) at the 5% significance level indicated no significant difference between concrete samples produced and cured with treated wastewater and control samples at the age of 90days.

The Influence of Admixtures on the Technological Properties of Fresh Concrete Mixture

In this research superplasticizing (SP), air voids removing (AVR), viscosity modifying (VM) and air entraining admixtures (AE) were used. The dosage of admixtures was chosen from minimum to maximum values recommended by the manufacturers. To sum up, 7 concrete mixture compositions with SP, 6 with AVR and 6 with VM and the last 6 with AE admixture were prepared. Water and cement ratio for all the compositions was kept at the same value. According to the results obtained, the usage of SP admixture resulted in significant increase of mixture`s slump and flow however it reduced mixture`s air content and increased its density. Concrete mixture`s properties: slump and flow were almost not affected by the increase of AVR and VM admixtures, however the air content slightly decreased and the density of concrete mixture slightly increased. With the incline of air entraining admixture, mixture`s slump, flow and air content increased, but the density declined. The authors of this study wanted to express the importance of the close link between concrete mixture`s technological and rheological properties. According to the yield stress of concrete mixture it is possible to prognosticate the future problems or various outcomes during or after the concrete mixture`s casting process. DOI: http://dx.doi.org/10.5755/j01.ms.21.4.5170

Manufacture of High-Performance Concrete Made with Powdered Polyester Resin Waste and Carboxylic-Ester Based Superplasticizer

A high-performance concrete design is presented that incorporates powdered polyester resin waste as a fine aggregate material in partial substitution of sand, with additions of both a superplasticizer based on carboxylic ethers and silica fume. The potential application of the powdered polyester resin and its properties as an aggregate are both analysed as well as the mechanical behaviour, in both the fresh and the hardened states, of the concrete. Both the flexural and the compressive strength of the concrete were shown to depend on the amount of waste used in substitution of the sand. The results of the research show that the designed concrete reaches the resistances of a high performance concrete with values ​​above 50 MPa. On the other hand, the rest of its properties are equivalents, both in the fresh and hardened state, proportional to the amount of powdered polyester resin that is added. However, to achieve this, the use of superplasticizers additives and admixtures of silica fume is necessary.

Effect of Silica Fume on two-stage Concrete Strength

Two-stage concrete (TSC) is an innovative concrete that does not require vibration for placing and compaction. TSC is a simple concept; it is made using the same basic constituents as traditional concrete: cement, coarse aggregate, sand and water as well as mineral and chemical admixtures. As its name suggests, it is produced through a two-stage process. Firstly washed coarse aggregate is placed into the formwork in-situ. Later a specifically designed self compacting grout is introduced into the form from the lowest point under gravity pressure to fill the voids, cementing the aggregate into a monolith. The hardened concrete is dense, homogeneous and has in general improved engineering properties and durability. This paper presents the results from a research work attempt to study the effect of silica fume (SF) and superplasticizers admixtures (SP) on compressive and tensile strength of TSC using various combinations of water to cement ratio (w/c) and cement to sand ratio (c/s). Thirty six concrete mixes with different grout constituents were tested. From each mix twenty four standard cylinder samples of size (150mm×300mm) of concrete containing crushed aggregate were produced. The tested samples were made from combinations of w/c equal to: 0.45, 0.55 and 0.85, and three c/s of values: 0.5, 1 and 1.5. Silica fume was added at a dosage of 6% of weight of cement, while superplasticizer was added at a dosage of 2% of cement weight. Results indicated that both tensile and compressive strength of TSC can be statistically derived as a function of w/c and c/s with good correlation coefficients. The basic principle of traditional concrete, which says that an increase in water/cement ratio will lead to a reduction in compressive strength, was shown to hold true for TSC specimens tested. Using a combination of both silica fume and superplasticisers caused a significant increase in strength relative to control mixes.

Mechanical and thermophysical properties of lightweight aggregate concretes

In this study, experimental investigation is performed for producing new cement-based with relatively high strength, low density and good thermal properties for energy efficient buildings. Different types of concretes containing silica fume (SF), superplasticizer (SP) and air-entrained admixtures are prepared with a constant water–cement ratio, and normal aggregates replaced by lightweight aggregates (LWAs) including pumice (PA), expanded perlite (EPA) and rubber aggregates (RA) at different volume fractions of 10%, 20%, 30%, 40% and 50%. 102 samples with different materials and compositions are produced, and their characteristics are tested in accordance with ASTM and EN standards. Based on the experimental results, equations are presented to determine the relation between the thermophysical properties of composite samples. The investigation revealed that the addition of PA, EPA and RA reduced the material bulk density and compressive strength, and improved the insulation characteristics of the composite concretes. Furthermore, it was found out that the reductions in thermal conductivity and diffusivity of the produced samples reached to 82% and 74%, respectively.

PERILAKU MEKANIS BETON MUTU TINGGI DENGAN VARIASI PENGGUNAAN SUPERPLASTICIZER

Concrete itself is quite popular in terms of usage in the field of construction (bridges, buildings, and dams). In large projects and unconditioned special (extreme) as the long-span bridge construction in the middle of the sea, pier construction, buildings and retaining walls high sea waves need to use high-quality concrete. To be able to make high strength concrete required fas value (water-cement ratio) is low, ranging from 0.20 to 0.30 (ACI, 1998). In high quality concrete workmanship in the field, to facilitate construction of concrete because considering using a little water, then a superplasticizer admixture materials needed to facilitate mixing concrete. This study was conducted to determine the performance of each in terms of value Slump superplasticizer, concrete compressive strength and split tensile strength of concrete. Calculation of SNI 03-6468-2000 material refers to the weight ratio of cement: fine aggregate: coarse aggregate of 1.00: 1.67: 2.15 with water cement factor of 0.317. Used to test a cylindrical specimen with a diameter of 150mm and height of 300mm which for the life of the test was made three (3) pieces of the specimen. Preparation and treatment of test specimens performed by standard procedures. The results showed that the use of superplasticizer type Napthalene Formaldehyde Sulphonate deliver results better compressive strength than the type superplasticizer Aqueous Solution Of Modified Polycarboxylate Copolymers is equal to 7.70%, but when viewed in terms of tensile strength and slump value (kelecakan) type superplasticizer Aqueous Solution Of Modified Polycarboxylate Copolymers provide better value Napthalene Formaldehyde Sulphonate when compared with that of 4.04% for split tensile strength and 22.22% for the slump value.

Vpliv dodatka superplastifikatorja na parametre mehanskega zloma betona

Vpliv dodatka superplastifikatorja na parametre mehanskega zloma betona