Water-powder Ratio Research Articles

Study on the effect of thermoactivated conditions on the properties of hardened cement powder

The performance of thermoactivated hardened cement powder (HCP) is the basis for studying the performance of thermoactivated recycled concrete powder (RCP). Previous studies have mostly focused on thermoactivated RCP, while thermoactivated HCP is taken as the research object in this paper. The effects of different thermoactivated conditions on the mass loss rate, density, initial and final hardening time, standard consistency water powder ratio, and compressive strength of the test block made from thermoactivated HCP were studied. Furthermore, the mineral composition, microstructure, chemical elements, hydration heat, and hydration products of thermoactivated HCP made from different thermoactivated conditions were analyzed. The test results indicated that the average initial harden time of the 600, 800, 1000, and 1200 °C of thermoactivated HCP are 15, 1160, 85, and 13 min, respectively. In terms of phase change of HCP at different heating temperatures, when the heating temperature reached 800 °C, the diffraction peaks of C-S-H and CaCO3 disappear, while the diffraction peaks of C3S, β-C2S, and αC2S began to appear. AFt and Hydrotalcite are completely decomposed and C-S-H loses adsorbed water with temperature from 35.9 to 201.7 °C. Ca(OH)2 is completely decomposed with temperature from 413.3 to 457.4 °C. CaCO3 is completely decomposed with temperature from 457.4 to 731.6 °C. In terms of changes in the proportion of chemical elements after hydration of thermoactivated HCP, the values of Ca/Si of hydrated cement is 1.78. The average values of Ca/Si after hydration of 1000 and 1200 °C thermoactivated HCP are 3.32 and 3.33, respectively, while the average values of Ca/Si after hydration of 600 and 800 °C thermoactivated HCP are 2.74 and 2.6. These research conclusions provide a foundation for the application of thermoactivated HCP. HIGHLIGHTS The mass loss rate, density, and compressive strength of hardened cement powder made from different heating conditions were studied. The standard consistency water powder ratio, initial and final hardening time of hardened cement powder made from different thermoactivated conditions were analyzed. The mineral composition, microstructure, chemical elements, hydration heat, and hydration mechanism of hardened cement powder made from different thermoactivated conditions were revealed.

Strength prediction and optimization for ultrahigh-performance concrete with low-carbon cementitious materials – XG boost model and experimental validation

In recent years, supplementary cementitious materials (SCMs), as well as other unconventional materials [such as recycled glass powder (GP)], have gained much attention for the formulation of ultra-high-performance concrete (UHPC). Machine learning (ML) techniques have become more prevalent in everyday life in the current era of cutting-edge technology. Their applicability is readily evident in a wide range of areas, including civil engineering applications. This research aimed to develop, validate, and apply the novel XG Boost model to predict the characteristic compressive strength of UHPC containing recycled GP under normal moist curing conditions. Based on 309 datasets, the study developed and trained an ML model using different components, including four supplementary cementitious materials (silica fume (SF), fly ash (FA), quartz powder (QP), and glass powder (GP). The feature importance of the developed ML model was assessed using two methods (the Gini index and the SHAP values). Based on the validation datasets, the predicted-target data was within a 95% accuracy range. The optimized model was helpful tool for making accurate predictions over a wide range of data sets. It was observed from the results obtained that the most significant features were SF, water–binder ratio, water–powder ratio, and virtual packing density. The developed ML model and the tested mixtures showed a mean ratio of tested-to-predicted values of 0.956, with most data lying within a margin of error of 15%. As a result, an intuitive user interface was developed for optimizing UHPC systems, including SF, FA, QP, and GP.

High performance concrete using rice husk ash

The purpose of this study is to improve the High Performance Concrete (HPC) of Grade M60 by using Supplementary cementitious substance for partial substitute for Ordinary Portland Cement (OPC) and to obtain the mix design for HPC of grade M60. Additionally, it aims to assess the effectiveness of HPC that contains additional cementitious materials like rice husk ash. Concrete cubes were prepared to have a slump between 175 and 225 mm and water-powder ratio between 0.35. The type and amount of supplemental cementitious material (SCM), such as Rice Husk Ash, were among the test variables (RHA). Ordinary Portland cement was substituted with Rice Hush Ash upto 10%. The hydration properties of concrete cubes containing SCM have also been investigate in order to realize the behaviour of HPC. For the hydration properties, concrete cubes were prepared in different series such as 2.5%, 5%, 7.5%, & 10% with water – binder ratio (w/b) of 0.35 with super plasticizer. The results confirmed that Rice Husk Ash performed better than other SCM for the strength development and bulk resistivity. Finally, the best performance was obtained for 7.5% replacement of Rice Husk Ash for OPC with w/b of 0.35 with super plasticizer and the compressive strength for this mix was found to be 66 MPa at the age of 28 days.

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.

Analysis of Hand Brewed Coffee Take Taiwan Coffee Beans as An Example

Abstract This study uses the research structure of the experimental design, taking Taiwan specialty coffee beans as an example, and selects four aspects which are a coffee grind, brewing water temperature, coffee blooming, and coffee water powder ratio that is most likely to affect the coffee extraction rate and coffee concentration. Brewing with hand brewing equipment which is easier to buy in daily life, and obtain data analysis, and then conduct experiments and comparisons with coffee beans from other countries. The results of this study found that coffee beans from different producing areas can be slightly adjusted for different brewing techniques to reduce the consumption of coffee beans and reduce costs, to provide consumers and subsequent researchers with references and suggestions. JEL classification numbers: O13, P32, Q15. Keywords: Taiwan Coffee Bean, Brew Coffee, Variation Analysis, and Gold Cup.

A new model to predict the optimal mix design of self-compacting concrete considering powder properties and superplasticizer type

This study investigated the effect of powder materials and superplasticizer type on the optimal proportion of pastes and self-compacting concrete (SCC). Nine groups of power materials containing cement, fly ash (FA), limestone powder (LP), granulated blast furnace slag (GBFS), and modified phosphogypsum (MPG) were designed. The powder materials differed in their characteristics including specific surface area, zeta potential and density. Self-compacting paste zone (SCP zone) and the optimal proportion were obtained based on the paste rheological threshold theory. Quantitative relationships between the optimal proportion and powder characteristics were obtained by the linear regression method, which can help in the optimizing process of SCC. A new powder combination was designed to validate the relationships. The optimal water‒powder ratio by volume (VW/VP) and the optimal superplasticizer dosage by mass (SP%) could be calculated considering the physical and chemical properties of the powder combination. According to the optimal mix, the search area was narrowed and the SCP zone was obtained where a good SCC was obtained, which validated the effectiveness of the powder effect model. Finally, an improved powder effect model applicable to different superplasticizer types was proposed based on a good linear relationship between the optimal VW/VP and the basic VW/VP.

The combined effect of GGBS and low volumefibres on the low-velocity impact and mechanical properties of self-compacting concrete

The primary objective of the current investigation is to evaluate the low-velocity impact behaviour and mechanical properties of low volume fibres reinforced self-compacting concrete made with 30% GGBS as a replacement of cement with a water powder ratio of 0.3. The steel, basalt and glass fibres of length 22 and 30 mm with low volume fractions of 0.25, 0.5 and 0.75% are used for this investigation. The self-compatibility of concrete is confirmed by testing the slump flow test. The addition of fibers reinforced in the concrete decreases flow as compared without fibers reinforced conrete, flow value decreased in basalt and glass as compare to steel fiber reinforced concrete. The compressive, flexural, split tensile strength and low-velocity impact resistance, shear strength were conducted after 28 days of water curing. The experimental results show that the compressive strength is only a marginal strength improvement was observed in the steel fibre reinforce self-compacting concrete mixes. The high tensile, flexural, shear strength were observed in 30% replacement of GGBS with 0.75% of steel fibres of 30 mm length. The results of the experiments express that incorporation ratio of steel fibre reinforced concrete improves the strength, remarkably tensile, flexural and shear strength as compared with the control and other fibers reinforced concrete. A significant improvement was observed in impact energy of steel fibrous reinforced concretes as compared with the control mix of self compacting concrete. The results demonstrate that use of steel fiber is reinforced in the self compacting conrete including ground granulated blast furnance slag, the impact energy and the ductility characterstics of the self compacting fiber reinforced concrete are noticeably increased.

Studies on Fresh state behavior on Strength of Concrete

The water/powder ratio remains as essential descriptive statistic for today’s increasingly complex concrete mixtures. A sample of 200 SCC mixtures of various materials and proportions were fitted with linear regression models. This Demands a retrospection of well-known Abram’s Water-Cement ratio relation. With this view, as part of an ongoing research program, an investigation was taken up to study the relationship between Water-Powder ratio and compressive strength of Self Compacting Concrete.

Suitability of Gypsum from Fatha Formation for Production of Building Materials in Bazian -Takiya area, North-East Iraq

Gypsum products are one of the most widely used materials in the industry. The wide use of gypsum as a building material over a very long period of time. A number of manufacturers introduce different professional quarries, but their physical and chemical properties were still questionable. Five gypsum samples were taken for chemical and physical analysis. Chemical analysis shows that gypsum are of high purity, more than 95.25% with varying amount of impurities; SiO2 (1.49-1.87) %, Na2O (0.17-1.00) %, MgO (0.03-0.13) % Al2O3 (0.06-0.23) % and Fe2O3 (0.05-0.09) %, .This can be used for Plaster of Paris without any purification of gypsum. The (SO3 and CaO) % shows that all studied samples are suitable for gypsum production as the final coating and building gypsum. The physical analysis shows that the colors of gypsum samples are suitable for building, Plaster of Paris, final coating and Juss according to the color chart of minerals and to Iraqi standard specification. The fineness percentage is less than 8%. Thus the specifications of all samples are agreements to standard specifications for building gypsums. In terms of setting time, the sample 1 and 2 are suitable for building gypsum and plaster of Paris and classified as Borax. However, samples 3, 4, and 5 are suitable for anhydrous calcined gypsum – final coat and classified as Knee cement. Moreover, the setting time for all the samples increased with the increase of the water powder ratio.

Studies on Durability Factors of Self Compacting Concrete

The demand for high strength self compacting concrete is growing up today due to the increase of high rise structures across the globe because of its durability and ease of its place ability. It is very important to study its durability properties as it effects on economy, serviceability and maintenance. it is well known that the properties of concrete are affected by cementitious matrix, aggregate and the transition zone between the two phases. Reducing water powder ratio and addition of pozollona admixtures like Fly ash and Microsilica are often used to modify the micro structure of the matrix and to optimize the transition zone. An attempt was made to study the durability factors of High Strength Self Compacting Concrete Mixes. Durability properties have been established by exposing the concrete to Acidic and Suplhate medium.

Valorising Slags from Non-ferrous Metallurgy into Hybrid Cementitious Binders: Mix Design and Performance

The environmental impact of ordinary Portland cement (OPC) can be decreased by using alternative precursors, such as non-ferrous metallurgy slags (NFMS), which can be alkali-activated to form an inorganic polymer binder (IP). However, an IP demands the use of a high molarity alkali-solution, which is expensive, has a relative high environmental footprint and limits the use of superplasticizers. In order to tackle these challenges, hybrid binders are proposed, which consist mainly of NFMS, a minor amount of OPC and are activated with a low molarity NaOH solution, in which the superplasticizers can be used effectively. A self-compacting hybrid paste with high early-age strength was developed step-by-step by investigating the effect of different amounts of raw materials on the reactivity, identified by semi-adiabatic calorimetry, and strength development. The obtained optimal hybrid binder formulation was (in wt%) 70 NFMS, 10 ground granulated blast furnace slag, 10 OPC, 8 limestone, 0.9 NaOH, 0.8 plasticizer and 0.3 bassanite; for a water-powder ratio of 0.19, the compressive strength was 20, 41 and 61 MPa at 1, 7 and 28 days, respectively. This study demonstrated that a hybrid binder can be produced from mainly NFMS, which can increase their valorisation potential.

Efficacy of Ca2+- or PO4 3--conjugated mesoporous silica nanoparticles on dentinal tubule occlusion: an in-vitro assessment.

BackgroundMaintaining a long-term biological effect of dental materials on dentinal tubule occlusion is one of the great technical challenges in dental clinics. In addition to physical treatment, chemical treatment to produce insoluble precipitates to seal dentinal tubules has been used. As dentin is mostly composed of calcium and phosphate complexes, in this study, we have developed a novel tubule-occluding material [Ca2+/PO43−@mesoporous silica nanoparticles (MSNs)] by separately conjugating either Ca2+ or PO43− with MSNs.MethodsThe shape and structure of the MSNs were examined using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The surface morphology and chemical compositions of Ca2+@MSNs/PO43−@MSNs and Ca2+/PO43−@MSNs were examined using SEM and X-ray fluorescence (XRF). The element distribution of Ca2+/PO43−@MSNs was detected using energy dispersive spectrometer (EDS). The sustained release ability of Ca2+@MSNs/PO43−@MSNs was detected using inductively coupled plasma atomic emission spectrometry (ICP-AES). The efficacy of Ca2+/PO43−@MSNs on dentinal tubule sealing was evaluated using SEM, and the results were analyzed by Image-Pro software to determine the best water-powder ratio. We also compared the sealing efficacy between Ca2+/PO43−@MSNs and NovaMin, which is currently used in clinics, under the simulated conditions of oral acidic corrosion and mechanical friction.ResultsCa2+/PO43−@MSNs are a new type of tubule-occluding material with sustained release properties. The ratio of Ca2+@MSNs: PO43−@MSNs: H2O =0.015 g: 0.015 g: 150 µL exhibited an excellent sealing effect on dentinal tubules as well as resistance to oral acid corrosion and daily oral friction.ConclusionsThe novel dental material Ca2+/PO43−@MSNs demonstrates potential long-term effectiveness in sealing dentinal tubules and reducing dentin sensitivity, which is one of the most important problems in dental clinics.

Assessment on Workability and Strength Properties of SCC using Quarry Rock Dust and different bases of Super Plasticizers & VMA

SCC is a concrete which has the ability to flow like liquid. This flowability of concrete is achieved by limiting the size of coarse aggregate content. Also 20% of the coarse aggregate is replaced by utilizing flyash inorder to increase the percentage of powder content..And due to the scarcity and unavailability of sand, an alternate is choosen to measure the rate of workability of SCC using quarry rock dust. The main property and strength of SCC depends on its workability[1] Hence workability tests and its relative compressive strength have been conducted to measure SCC specimens with fine aggregate and quarry rock dust. Fluidity of the paste can be improved by increasing the content of water-powder ratio and by adding super plasticizers. Segregation and blockages can be avoided by reducing the coarse aggregate content. A viscosity modifying agent (VMA) helps to reduce the changes in concrete properties[2]. Thus, relative proportions of ingredients need to be carefully determined to impart self leveling and self compacting properties to SCC in the fresh stage. Thus SCC specimens have been casted with quarry rock dust and fine aggregate using three different bases of superplasticizers(HRWRA) such as polycarboxyl, naphthalene and melamine bases and VMA. And its workability and strength properties have been evaluated by conducting different tests.

Study on effect of strength and durability parameters and performance of Self Compacting Concrete replacement with GGBS at different dosages

To investigate experimentally, the behavior of exterior beam-column joint and strength characteristics of Self Compacting Concrete (SCC) containing Viscosity Modifying Admixture (VMA), and Ground Granulated Blast Furnace Slag (GGBFS). Since there is no standard method of mix design is available for SCC. Hence mix design was arrived as per the rules of European Federation of National Associations Representing for Concrete (EFNARC). Marsh cone test was used to find the saturation of various kind of cements by adding the dosage of super plasticizer accordingly. In this investigation SCC was made by usual ingredients such as cement, fine aggregate, coarse aggregate, water and ground granulated blast furnace slag at various replacement levels (10%, 20%, 30%, 40%, and 50%), with that the Super Plasticizer (Glenium B233) and viscosity modifying agent (Glenium Stream 2) was used in appropriate amount for achieving the better flow in the concrete. The experiments were carried out by maintaining a constant water-powder ratio of 0.45. At various replacement levels the performance of freshly prepared SCC is checked by conducting tests such as slump flow, T50 slump flow, U-tube, L-box and V-funnel tests. Mechanical characteristics like Compressive, Split-tensile and Flexural strength examined. Also, the durability study for SCC after 28, 56 and 90 days curing was done by conducting a number of the tests like saturated water absorption, porosity, carbonation depth and alkalinity measurement

Mechanical and durability properties of self-compacting concrete with marble fine aggregate

Abstract Self-compacting concrete (SCC) enhances qualities and working conditions due to the elimination of compaction during construction. The usage of river sand in concrete affects natural resources and groundwater. This the paper deals the different testing methods to test high-flow ability, resistance against segregation, and passing ability of self- compacting concrete for M60 grade of concrete with a partial replacement of marble waste as a fine aggregate. Slump flow, V-funnel, L-box and U-box tests were carried out to examine the performance of fresh state SCC. In hardened state, the tests were conducted and cured at different periods to find compressive strength, tensile strength and flexure strength test with the replacement of marble fine aggregate percentage of 0%, 25%, 50% and 100% in SCC for 14, 28 and 56 curing days. The chemical admixture super plasticizer master Glenium sky 8233 and the viscosity modifying agent are used. The specimens are cast with 0.28 water-powder ratio. And also durability of SCC is tested by RCPT, WPT, chemical attack tests like acid and sulphate attack are conducted at the age of 28 and 56 days in SCC specimens. The results are compared with the conventional SCC and found satisfied up to 25% of partial replacement of fine aggregate as a marble aggregate for 28 and 56 curing days.

Lightweight Self-Compacting Concrete Incorporating Industrial Rejects and Mineral Admixtures: Strength and Durability Assessment

By the recent global research developments, a lot of natural and artificial materials that are normally discarded and landfilled, are continually investigated for potential construction applications. In this study, the mechanical and durability properties of lightweight self-compacting concrete produced using pumice, ground granulated blast furnace slag (GGBS), rice husk ash (RHA) and precipitated silica, was investigated. A detailed experimental design was performed, which entailed reducing the water powder ratio, and use of viscosity modifying admixture, for enhancing the fresh SCC quality. The experimental process involved assessment of mechanical and durability properties of concrete mixtures. The results have shown that compressive and flexural strength of SCC made with lightweight aggregate are improved using mineral blended cement. Also, same mix, but with pumice as coarse aggregate gave higher split-tensile strength than other mixtures. This study deduced that pozzolanic reactivity and filler action of supplementary cementitious materials used, enhanced the resistance of the mixtures to deterioration when exposed to aggressive environment.

Use of industrial waste as partial fine aggregate replacement in SCC

In the current scenario, SCC is used in the variety of massconcreting applications. But SCC involves usage of more quantities of binder and fine aggregate content compared to conventionally vibrated concrete (CVC). The availability of basic constituent materials required for preparing the concrete in the entire world is facing a majorcrisis. For example, the construction industry has faced the non-availability of river sand since it is the principal ingredient that contributes the homogeneity in concrete. The experimental investigation was planned with the total of ten SCC mixes using industrial wastes namely copper slag (CS) and steel slag (SS) from 0% to 50% (with an increment of 10%) as fine aggregate replacement along with one control SCC (SCC0). The water-powder (w/p) ratio of 0.38, the dosage of Super plasticizer (SP) as 1.5% by the weight of cement and viscosity modifying agent VMA as 0.15% by the weight of cement were arrived based on the laboratory test trials. The fresh property tests were conducted in greener SCC according to EFNARC guidelines. The mechanical properties(compressive strength and split-tensile) were determined after 28 days of curing. Keywords: Compressive strength; copper slag; self-compacting concrete; splitting tensile strength; steel slag.

Prediction of fresh and hardened properties of self-compacting concrete using support vector regression approach

This article presents the feasibility of using support vector regression (SVR) technique to determine the fresh and hardened properties of self-compacting concrete. Two different kernel functions, namely exponential radial basis function (ERBF) and radial basis function (RBF), were used to develop the SVR model. An experimental database of 115 data samples was collected from different literatures to develop the SVR model. The data used in SVR model have been organized in the form of six input parameters that covers dosage of binder content, fly ash, water–powder ratio, fine aggregate, coarse aggregate and superplasticiser. The above-mentioned ingredients have been taken as input variables, whereas slump flow value, L-box ratio, V-funnel time and compressive strength have been considered as output variables. The obtained results indicate that the SVR–ERBF model outperforms SVR–RBF model for learning and predicting the experimental data with the highest value of the coefficient of correlation (R) equal to 0.965, 0.954, 0.979 and 0.9773 for slump flow, L-box ratio, V-funnel and compressive strength, respectively, with small values of statistical errors. Also, the efficiency of SVR model is compared to artificial neural network (ANN) and multivariable regression analysis (MVR). In addition, a sensitivity analysis was also carried out to determine the effects of various input parameters on output. This study indicates that SVR–ERBF model can be used as an alternative approach in predicting the properties of self-compacting concrete.

Effect of non-adsorbed superplasticizer molecules on fluidity of cement paste at low water-powder ratio

Non-adsorbed superplasticizer molecules increase the fluidity of cement paste with low water-powder ratio, but their function is unclear. The authors used superplasticizers having different molecular structures to investigate the influence of non-adsorbed superplasticizer on the fluidity of cement paste. The paste consisted of low-heat Portland cement, ultra-fine silica particle, and polycarboxylate-based superplasticizer solution. First, a superplasticizer having moderate molecular length was added to the paste, and the adsorption saturated. Subsequently, another superplasticizer was added to the paste. The subsequent additions of shorter superplasticizers decreased the adsorption of the first superplasticizer but the fluidity did not change. The subsequent additions of moderately long superplasticizers did not change the adsorption but increased the fluidity. In contrast, the subsequent additions of longer superplasticizers decreased the fluidity. The authors consider that the fluidity is related to the size of the subsequent superplasticizer, i.e. small superplasticizer molecules intercalate between the particles and aid in dispersion.

The effect of magnetically treated water on some physiomechanical properties of a local plaster (plaster of Paris)

Magnetically treated water was used for the determination of the physiomechanical properties (setting time, water/powder ratio (W/P) and compressive strength) of a local plaster of Paris. The results were compared with that of ordinary, and non-treated water to determine the same properties. It was found out that through using magnetically treated water, setting time has decreased by an average of (15.3 %); water powder ratio (W/P) has increased by an average of (2.4 %) and compressive strength has decreased by an average of (22.5 %) compared with the results of ordinary water. Thereforemagnetically treated water may be considered as an accelerator for the plaster of Paris rather than a retarder.