Water-reducing Admixture Research Articles

PROPERTIES OF CONCRETE CONTAINING CRUSHED LIMESTONE AS TOTAL REPLACEMENT OF NATURAL SAND AND RECYCLED ENGINE OIL

The rapid growth in the construction industry at the global level has made concrete the most widely used construction material throughout the world. Accordingly, the consumption of natural sand which is one the main raw material constituent of concrete is continuously growing. The demand for river sand is highly increasing due to its scarcity in the market. Manufactured sand produced by crushed rock is being considered as an appropriate alternative to replace river sand in concrete. In recent years, there is a growing interest in the use of crushed sand obtained from limestone quarries in some countries where river sand is not widely available”. The objective of this study is to investigate the effect of total replacement of the natural sand by fine aggregates obtained from crushed limestone. However, it needs more research on the crushed stone fine aggregates to reveal its engineering properties prior to utilization in concrete. Another objective of this study is to study the effect of using the waste engine oil as partial replacement of water reducing admixture. The use of waste engine oil in concrete is beneficial for the environment. It is to be noted that some countries are recycling this used oil but others are throwing it in the sea and harming the marine life. In this paper, different combinations and grading of fine lime stone and coarse aggregates were tried in order to attain the optimal proportion that provide an acceptable concrete performance in terms of workability and compressive strength. Also, different percentages of admixture replacement ranging from zero to one hundred percent of the used engine oil were tried in the selected optimal mixture proportion. The final selected proportion using engine oil and crushed limestone could be considered as an economical solution and friendly environmental concrete product.

Concrete Water-Reducing Admixtures between Laboratory and Site.(Dept.C)

This research was planned to study the effect of water-reducing admixtures on the properties of cement paste and concrete. These properties included setting time of cement paste, consistency of fresh concrete and compressive strength of hardened concrete. The main veritables taken into consideration in this study were cement content, water/cement ratio and admixture/cement ratio. A comparison was made between the properties of concrete according to the usage of the optimum dose of the admixture as a result of the experimental test results and the properties of concrete when the dose recommended by the producer was used. Great improvement was achieved in both the workability of fresh concrete and the compressive strength of hardened concrete when optimum dose of the water-reducing admixture was used which depends on many factors among which are the cement content and water content. The initial and the final setting time of cement increase with the increase of the water-reducing admixture in the cement poste. However, the limits of the setting time recommended by the specifications have to be taken into consideration when determining the optimum dose of the admixture.

Preliminary Investigation of the Mechanical and Physical Properties of Natural Hydraulic Lime Grouts with Nano-Silica

Natural hydraulic lime-based grouts are often used in the structural consolidation of old stone masonry walls, mainly to re-establish the monolithic behaviour of masonry constructions. To ensure an adequate grouting operation, it is essential to have good fresh and hardened grout properties. The motivation of the present study was to examine the fresh and hardened properties of natural hydraulic lime grouts with nano-silica (NS) and silica fume (SF). The contribution of these materials and the dosage of a high range water reducer admixture (HRWR) were investigated on the rheological properties, water capillarity, open porosity and mechanical strength of injection grouts. The effects on rheology were analysed through plastic viscosity and yield stress. The results indicated that, even for reduced NS content, an increase in plastic viscosity and yield stress occurred, which required a higher HRWR content in order to not compromise the grout’s rheological performance. The results also showed that, when NS and SF were combined, a beneficial joint effect occurred, resulting in a substantial and positive change on the mechanical strength and microstructure of the hardened injection grouts. Taguchi’s method was used to optimize the grout’s formulation and to fulfil the required performance concerning the fresh and hardened state.

Exploring sulphate resistance of coal mining waste blended cements through experiments and thermodynamic modelling

This study evaluates the sulphate resistance of blended cement derived from the addition of thermally activated coal waste as pozzolan, at replacement levels of 0%, 20% (CMW20) and 50% (CMW50) with a multi-method approach. The pastes were prepared at a w/b ratio of 0.5, using a water-reducing admixture in the blended pastes to compensate for their high water demand. Sulphate resistance is reduced in CMW20 pastes, while long-term benefits are observed for CMW50 pastes, although moderate signs of deterioration are observed at the beginning of the exposure. The initial damage in CMW50 pastes is attributable to the precipitation of products (mainly ettringite and monosulphoaluminate) in the small capillary pores (<0.01 μm). This is prevented in OPC and CMW20 pastes since their microstructure allow the precipitation in the macropores (>0.05 μm). The greater long-term resistance of CMW50 pastes was explained by thermodynamic calculations, which suggests that the lower calcium leachability of these cements prevented gypsum formation. This, together with the higher content of carboaluminate phases, leads to lower supersaturation levels in the pore solution with respect to ettringite, reducing stresses derived from sulphate exposure.

A Study on Durability for Rigid Pavement Against Acid Environment and Displacement Model

An acidic environment commonly found in peat soils or expansive soil will harm the quality of rigid pavement by considering its use at long-life plan, traffic load, and minimization of damage to the crossroad due to vehicle braking. As a concrete provider, chemical admixture as mixed materials today is widely used with the reasons of workability, initial strength, as well as saving of material used. This research aimed to find out the durability of concrete admixture using sika-NN and plastocrete (retarding and water reducing admixture) at the acid environment and knowing the displacement that occurred using ABAQUS software modeling. It used the laboratory experimental method and the cube concrete sample 15×15×15 cm with the compressive strength of 33.2 MPa. A total of 18 concrete samples were immersed using normal pH water and H2SO4 at pH 1 ± 1 tested at 3, 7, 14, 28, 60, and 90 days using the Duplo method. In this research, the concrete durability was carried out using, Ultrasonic Pulse Velocity Test (UPVT) to test the density, compressive test, and modeling concrete displacement on peat soils with vehicle loads in acidic environments using software ABAQUS. The mixed design results show an average setting time value of about 112 minutes. Coarse aggregate and cement decrease due to additives is approximately 24% and 18% respectively, increasing the use of fine aggregate to 16.49%, but the value of concrete density increases base on soaking time. Besides that, there is a decrease in compressive strength up to 16% at the age of 90 days. The value of displacement in the modelled pavement uses a maximum load of 8 tons each 2.994 mm for concrete with normal water and 3.045 mm for concrete with an acid environment respectively. Concrete soaked in acid water is the greatest deformation that occurred in rigid pavement using ABAQUS and indicates that acid water has an impact on decreasing concrete quality.

Assessment of cement characteristics affecting rheological properties of cement pastes

In this study, the cement-based parameters affecting CEMI portland cements-polycarboxylate ether-based high-range water-reducing (HRWR) admixtures compatibility were investigated. For this purpose, eight CEMI cements and three commercial HRWR admixtures were used. The rheological properties of 112 paste mixtures with different admixture dosages and water/cement (W/C) ratios were determined in accordance with Herschel–Bulkley model. Then after, using the experimental data, proper models were established to predict the dynamic yield stress and final viscosity of the pastes. In addition to cement characteristics (such as fineness, compound composition and equivalent alkali content), water-reducing admixture content and its solid material content as well as water/cement ratio of the pastes were considered as input data. Multivariate adaptive regression splines (MARS) and multiple additive regression trees (MART) methods were used in the models. Besides, artificial neural network (ANN) and conventional regression analysis (CRA) including linear, power, and exponential functions were applied to determine the accuracy of the heuristic regression methods. Three statistical indices, root-mean-square error, mean absolute error, and Nash–Sutcliffe, were used to evaluate the performance of the models. Modeling findings indicated that the model with the lowest error for both of the rheological variables in the testing set is the MART, followed by ANN, MARS, and CRA-Exponential methods. The most effective cement characteristics causing incompatibility, hence detraction of paste rheological properties, in decreasing order, were determined as cement fineness, C3S, C3A and equivalent alkali contents. C4AF and C2S contents of the cement were found to have less effect on the cement–admixture incompatibility. It will be possible to determine the rheological properties of mixtures containing different cements without conducting an experimental study by using the model based on MART method.

Comparison of extreme learning machine and deep learning model in the estimation of the fresh properties of hybrid fiber-reinforced SCC

This paper studied the estimation of fresh properties of hybrid fiber-reinforced self-compacting concrete (HR-SCC) mixtures with different types and combinations of fibers by using two different prediction method named as the methodologies of extreme learning machine and long short-term memory (LSTM). For this purpose, 48 mixtures, which were designed as single, binary, ternary and quaternary fiber-reinforced SCC with macro-steel fiber, two micro-steel fibers having different aspect ratio, polypropylene (PP) and polyvinylalcohol (PVA), were used. Slump flow, t50 and J-ring tests for designed mixtures were conducted to measure the fresh properties of fiber-reinforced SCC mixtures as per EFNARC. The experimental results were analyzed by Anova method. In the devised prediction model, the amounts of cement, fly ash, silica fume, blast furnace slag, limestone powder, aggregate, water, high-range water-reducer admixture (HRWA) and the fiber ratios were selected as inputs, while the slump flow, t50 and the J-ring were selected as outputs. Based on the Anova analysis’ results, the macro-steel fiber was the most important parameter for the results of slump-flow diameter and t50, while the most important parameter for the results of J-ring was fly ash. Furthermore, it was found that the use of more than 0.20% by volume of 6/0.16 micro-steel fiber positively influenced the fresh properties of SCC mixtures with hybrid fiber. On the other hand, the inclusion of steel fiber instead of synthetic fiber into SCC mixture as micro-fiber was more advantageous in terms of workability of mixtures as result of hydrophobic nature of steel fibers. This study found that extreme learning machine model estimated the slump flow, t50 and J-ring with 99.71%, 81% and 94.21% accuracy, respectively, while deep learning model found the same experimental results with 99.18%, 77.4% and 84.8% accuracy, respectively. It can be emphasized from this study that the extreme learning machine model had a better prediction ability than the deep learning model.

Application of Ann for Prediction of Chloride Penetration Resistance and Concrete Compressive Strength

The purpose of this paper is to present Artificial Neural Network (ANN) models to predict compressive strength and chloride penetration levels of self-consolidating concrete (SCC) mixes. The ANN models used to predict chloride penetration resistance were developed using input variables including the ratio of water to binder (w/b), and the contents of coarse aggregate, fine aggregate, fly ash, and silica fume. For prediction of concrete compressive strength, the fundamental ANN parameters considered include w/b ratio, the amount of High Range Water Reducing (HRWR) admixture, and the contents of coarse aggregates, fine aggregates, silica fume, and fly ash. Compressive strength data from published literature was used to train the developed ANN and successful models were validated using compressive strength data tested by the investigators. The trained ANN was able to predict compressive strength and chloride iron penetration levels successfully.

Selection and implementation of green materials for the sustainable development of a residential layout

The building sectors such as residential layouts are directly or indirectly contributing to the annual deterioration of an environment. Hence there is a need to contribute to sustainable development by finding more environmentally benevolent methods of construction. An initiative has been taken for the selection and implementation of green materials for the sustainable development of a residential layout through this study. Materials like Ground Granulated Blast-furnace Slag (GGBS), M−sand, water reducing admixture, Expanded Polystyrene (EPS) and foaming agent for the study were selected through a detailed literature survey. Building materials like bricks and concrete consuming more volume in a building were chosen for an experimental study. Bricks of types 1 to 4 with varying proportions of cement, GGBS, EPS, foam and M−Sand had been casted and tested for water absorption and strength. M 30 grade of concrete was considered in the study. The green concrete is produced by replacing cement by GGBS in varying proportions of 35%, 45% and 55% and was tested for compressive and flexural strengths. To conduct comparative study on green v/s conventional materials towards cost and CO 2 footprint, a residential layout with 7 types of villas was planned in Revit software to find out the quantities of materials for a selected type of villa. It was observed that type 2 bricks performed better compared to other types and higher compressive and flexural strengths were obtained at 45% replacement of cement with GGBS for the green concrete. Also the cost of green concrete was 48% cheaper than conventional concrete. It was also observed that there was 48% reduction in CO 2 footprint while adopting green bricks and green concrete in a construction project that makes it more environment friendly and sustainable alternative to conventional concrete.

Synthesis of the VPEG Polycarboxylate Superplasticizer with Controllable Activity and Its Properties

This paper focuses on the synthesis of a kind of VPEG polycarboxylate superplasticizer with controllable activity with 4-hydroxybutyl vinyl polyoxyethylene ether (VPEG), acrylic acid (AA) and fumaric acid (FMA) as the main raw materials. Through the experimental results, it can be found that the optimum process conditions are as follows: the water-reducing admixture has ideal fluidity and workability in concrete, with the temperature of 20°C, the reaction system concentration of 40%, the mass ratio of acid to ether of 9.2%, and the initiator and the chain-transfer agent respectively accounting 0.3% and 0.09% of the total mass.

Workability maintenance of water-reducing admixtures in high-performance pastes produced with different types of Portland cement

This work evaluated the efficiency and workability manteinance of a polyfunctional (lignosulfonate-based) and a superplasticizer (polycarboxylate-based) admixture in high-performance pastes (water/cement ratios of 0.30, 0.33 and 0.36) produced with two types of Portland cement (one pozzolanic and one high early strength). The workability of the pastes was evaluated by the mini slump test immediately after mixing, and after 20 and 40 minutes. Furthermore, the mechanical strength of pastes with fixed w/c ratio (0.36) and mini slump (130 mm), produced with the different combinations of cements and admixtures, was evaluated. The results showed that the CP IV+lignosulfonate and CP V-ARI+polycarboxylate mixes presented the best workability maintenance over time. The pastes produced with CP V-ARI presented 28-day strengths about 22% higher than those produced with CP IV, for both admixtures. In turn, the lignosulfonate-containing pastes showed strengths about 10% higher than those produced with the polycarboxylate-based admixture. Overall, it was possible to obtain the same workability for high-performance Portland cement pastes produced with both admixtures and cements; however, the workability mantainance and mechanical strength highly depends on the combination of cement and admixture used.

Effects of Water-Reducing Admixture on the Compressive Strength of Concrete Using Crushed Mangima Stone as Fine Aggregate

Crushed Mangima stone as an alternative concrete aggregate has been studied and found to provide concrete with comparable compressive strength to that of the conventional concrete. This study investigated the effect of water-reducing admixtures in concrete production using crushed Mangima stone as fine aggregate. Waterreducing admixture with a variance of 0.5, 1.0, and 1.5% by weight of cement was added to the concrete mixture. A water-cement ratio of 0.57 was used for this study. Samples were cured at seven, 14, and 28 days and tested for compression after each curing period. The compressive strength of concrete using water-reducing admixtures showed an early strength and passed the minimum requirement of 3,000 psi. Results revealed that through the use of admixtures, compressive strength obtained from all samples was higher than the control mixture. This means that using crushed Mangima stone has its potential to be used as fine aggregate in a structural concrete mixture with the addition of water-reducing admixture.

Effect of nonionic side chain length of polycarboxylate-ether-based high-range water-reducing admixture on properties of cementitious systems

Despite the large variations in the behaviors of water-reducing admixtures upon changes in their structures, most previous reports on the cement-admixture compatibility did not provide sufficient information on the structure of the admixture. Hence, the evaluation and generalization of the reports on the cement-admixture compatibility are challenging. In this study, three different polycarboxylate-ether-based water-reducing admixtures with the same free nonionic content, anionic/nonionic molar ratio, and main chain length and different side chain lengths were produced. The compatibility of these admixtures with a CEM I 42.5 R-type cement was investigated. In addition, an analysis of variance was performed on the experiment results to evaluate the contributions of the admixture type, admixture/cement ratio, and elapsing time to the Marsh funnel flow time, mini-slump, slump flow, and compressive strength. The water-reducing admixtures having long or short side chains reduced the initial flow characteristics of the cementitious systems. However, the admixture having the shortest side chain was better with regard to flow retention. The side chain length of the admixture did not have significant effects on the compressive strength and water absorption capacity of the mortar mixtures and mini-slump performances of the cement paste mixtures. Regarding the behaviors of the admixtures in the cementitious systems, an optimal admixture side chain molecular weight is proposed.

INFLUENCE OF WATER-CEMENT RATIO AND WATER REDUCING ADMIXTURES ON THE REBOUND NUMBER OF HARDENED CONCRETE

In this paper, effect of water-cement ratio (w/c) and type of water reducing admixtures (WRA) on the Schmidt hammer rebound number (RN) were investigated. Concrete of mix ratio 1:2:4 was prepared at the w/c of 0.45, 0.50, 0.55 and 0.60 and with each of the three WRA at the w/c of 0.45. Concrete cubes of size 150 mm were cast and cured in water for 3, 7 and 28 days. RNs of the cubes were determined and the compressive strengths (fc) corresponding to the RNs obtained from the conversion graph supplied by the manufacturer were compared with the compressive strengths obtained from crushing machine (CM). The results showed that as the w/c increased, the RN increased up to when w/c was 0.5 and began to drop, while there was no significant effect of all the WRA on the RN. It was also found that fc obtained from CM and those obtained using the conversion graph differed considerably. A new correlation graph was therefore proposed, which showed a correlation coefficient of 0.96, while coefficient of determination obtained for the regression equation between RN and fc, was as high as 0.92. The study concluded that w/c had effect on RN and that the equation developed could be used to determine fc, once RN is known.

Effects of anionic monomer type of water-reducing admixture on fresh properties, compressive strength and water adsorption of self-compacting concrete

In this study, the effects of anionic monomer functional group type of the water-reducing admixture (WRA) on the fresh properties and compressive strength of self-compacting concrete (SCC) mixtures were investigated. Nine types of polycarboxylate ether-based high-range WRAs with the same main chains but different anionic monomers linked to the main chain were synthesized and used in different dosages to provide the desired slump-flow value in SSC mixtures. For this motivation, in addition to the control admixture consisted of 100% carboxylate functional group, 5, 10, 20 and 30% of carboxylate functional group was replaced by either phosphate or sulfonate group. Test results revealed that the admixtures containing sulfonate and phosphate anionic monomer improved the fresh properties of SCC mixtures compared to those of the control admixture. However, anionic monomer exchange in the structure of the WRA did not significantly affect the compressive strength and water absorption capacity of the SCC mixtures.

Study on the Determination Method of the Adsorption of Water Reducer on Cement Surface Based on Total Organic Carbon Analyzer

At present, most of the methods for testing the amount of Water-reducing admixture adsorbed on the surface of the cement particles use the total organic carbon method (TOC method), but various literatures describe the pre-treatment of the test method as ambiguous and poor operability. In view of the above problems, this paper carried out a study on the pre-treatment conditions of the test for the adsorption of Water-reducing admixture on the surface of cement particles by total organic carbon method, and explored the effects of stirring time, standing time, and standing temperature on the adsorption of Water-reducing admixture on the surface of cement particles. The study determined the pre-treatment and test conditions of the TOC method, and provided reference for the research on the adsorption behavior of the water reducer on the surface of cement particles. The correlation coefficients of the standard curve of Water-reducing admixture obtained by this method are all greater than 0.999, the relative error of the results of the 10 parallel experiments of the method is less than 0.005%, and the relative standard deviation (RSD) is 0.7706%.

Influence of segregation on the permeability of self-consolidating concrete

Segregation resistance of Self-Consolidating Concrete (SCC), concerning the cause of Water-Reducing Admixture (WRA) over dosage and vibration, was characterized by bulk density and image analysis first. Then, the influence of segregation on the permeability of SCC was investigated by the Total Charge Passed (TCP) obtained by integrating current–time curve. Meanwhile, porosity obtained under 50 °C and 105 °C was measured, and the relationship between TCP and porosity was discussed. Research results show that both the over dosage of WRA and vibration will lower the segregation resistance of SCC, and the effect of the later is more significant than that of the former; both bulk density distribution analysis and image analysis can be an effective way for evaluating the segregation resistance of SCC. Segregation will decrease the permeability of SCC, and there is power function relationship between bulk density and TCP, showing the significant influence of segregation on the permeability of SCC. Enhance the sand to paste volume ratio (STPVR) in the mix proportion of SCC benefits the segregation resistance of SCC on the effect of WRA over dosage, however, the increase of STPVR increases the permeability of SCC. Relationship between TCP and porosity showed that the porosity obtained under 50 °C (capillary porosity) is more appropriate than the porosity obtained under 105 °C (permeable porosity) for evaluating the permeability of SCC.

Additivity effect on properties of cemented coal fly ash backfill containing water-reducing admixtures

Cemented coal fly ash backfill (CCB), a flowable structure of coal fly ash, binding agent and mixing water, has been often employed in mining operations to offer ground support as well as waste disposal solutions. An appropriate CCB mass should have sufficient rheological (e.g., workability) and mechanical (e.g., strength and stability) characteristics. Chemical admixtures are well known to greatly enhance the pumpability and strength properties of cementitious materials. Thus, this work provides the effect of water-reducing admixtures (namely, Sikament MR 50 W and Sikament FFN) on characteristics of CCB materials manufactured at a constant slump value. The role of admixtures in CCB mix is to reduce the cement-related costs, to modify the properties of the hardened backfills, and to ensure the quality of the backfill during mixing, transporting, placing, and curing. These admixtures were used at a dosage of 1% and 2% by weight of anhydrous material on cement. Several laboratory tests including slump, setting time, uniaxial compressive strength, scanning electron microscopy and mercury intrusion porosimetry were undertaken on CCB samples to understand their fresh and hardened performance. Experimental results show that the admixtures used ensure the slump required to deliver CCB at low water/cement ratios, improve short- and long-term backfill strengths up to 33%, and decrease the total porosity of the tested CCB. The findings of this study also show that the admixture use in CCB leads to a significant decrease in the considered cement content and a remarkable increase in the mechanical strength. As a result, understanding the actual fresh and hardened properties of CCB remains crucial for the choice of the greatest acting backfill admixture and for a fruitful change from capable experimental results to the in-situ conditions.

Effect of main and side chain length change of polycarboxylate‐ether‐based water‐reducing admixtures on the fresh state and mechanical properties of cementitious systems

AbstractIn this study, the effect of both main and side chain length changes of the admixtures on some properties of cementitious systems were investigated. Three different polycarboxylate‐ether‐based water‐reducing admixtures (WRA) having constant molecular weights and different main and side chain lengths were synthesized. Single type of raw material and carboxylate functional group were used in all WRAs. The molecular weights, free nonionic contents, and anionic/nonionic ratios of the admixtures were kept constant. Test results showed that degree of fluidity was observed in cement paste and mortar mixtures in case the admixture main and side chain length is more or less than a critical value. This negative effect is thought to be due to the weakening of the adsorption ability by the chain length change of the admixtures, the being tendency of polymers to intertwine and the adsorbing of admixture on several cement particles simultaneous. Admixtures having excessive long or short main chain and side chain improved the time‐dependent slump‐flow retention of the mortar mixtures. The admixtures with short main and side chains had insufficient adsorption ability and the admixture with excessive long main and side chains had the interlacing risk of polymers. In both cases, time‐dependent behavior improved because the amount of free admixture in solution increased. The change in the chain lengths of the WRAs affected the 1‐day compressive strength of the mortar mixtures.

Constitutive Modeling of New Synthetic Hybrid Fibers Reinforced Concrete from Experimental Testing in Uniaxial Compression and Tension

Hybridization of fibers in concrete yields a variety of applications due to its benefits compared to conventional concrete or concrete with single type-fiber. However, the Finite Element (FE) modeling of these new materials for numerical analyses are very challenging due to the lack of analytical data for these specific materials. Therefore, an attempt has been made to develop Hybrid Fiber Reinforced Concrete (HyFRC) materials with High Range Water-Reducing Admixture (HRWRA) during the concrete mixing process and conduct experimental study to evaluate the behavior of the proposed materials. Constitutive models for each of the materials are formulated to be used as analytical models in numerical analyses. The acquired data are then used to formulate mathematical equations, governing the stress–strain behavior of the proposed HyFRC materials to measure the accuracy of the proposed models. The experimental testing indicated that the Ferro with Ferro mix-combination improved the performance of concrete in the elastic stage while the Ferro with Ultra-Net combination has the highest compressive strain surplus in the plastic stage. In tension, the Ferro with Ferro mix displayed the highest elastic behavior improvement while the Ferro with Ultra-Net designs proved superior in the plastic range, providing additional toughness to conventional concrete.