Modulus Of Water Glass Research Articles

Measuring Volume Change of Alkali-Activated Slag Pastes in Early Stage by Using Helium Pycnometry

AbstractIn the present study, alkali-activated slag (AAS) pastes were prepared using slag and water glass with different modulus, and the effect of a modulus of water glass on the volume change of ...

The Solidification of Lead-Zinc Smelting Slag through Bentonite Supported Alkali-Activated Slag Cementitious Material.

The proper disposal of Lead-Zinc Smelting Slag (LZSS) having toxic metals is a great challenge for a sustainable environment. In the present study, this challenge was overcome by its solidification/stabilization through alkali-activated cementitious material i.e., Blast Furnace Slag (BFS). The different parameters (water glass modulus, liquid-solid ratio and curing temperature) regarding strength development were optimized through single factor and orthogonal experiments. The LZSS was solidified in samples that had the highest compressive strength (after factor optimization) synthesized with (AASB) and without (AAS) bentonite as an adsorbent material. The results indicated that the highest compressive strength (AAS = 92.89MPa and AASB = 94.57MPa) was observed in samples which were prepared by using a water glass modulus of 1.4, liquid-solid ratio of 0.26 and a curing temperature of 25 °C. The leaching concentrations of Pb and Zn in both methods (sulfuric and nitric acid, and TCLP) had not exceeded the toxicity limits up to 70% addition of LZSS due to a higher compressive strength (>60 MPa) of AAS and AASB samples. While, leaching concentrations in AASB samples were lower than AAS. Conclusively, it was found that the solidification effect depends upon the composition of binder material, type of leaching extractant, nature and concentration of heavy metals in waste. The XRD, FTIR and SEM analyses confirmed that the solidification mechanism was carried out by both physical encapsulation and chemical fixation (dissolved into a crystal structure). Additionally, bentonite as an auxiliary additive significantly improved the solidification/stabilization of LZSS in AASB by enhancing the chemical adsorption capacity of heavy metals.

Effect of silicate modulus of water glass on the hydration of alkali-activated converter steel slag

Converter steel slag, currently underutilized crystalline metallurgical residue, was investigated for use as a precursor for alkali activation. Water glass solution with various moduli (0.5, 1.0, 1.5 and 2.0) was used at the same Na2O dosage of 4% in order to investigate effect of modulus on hydration. Pure cement paste with the same ratio of water to binder was selected as the control sample. Results show that modulus has a significant impact on the hydration and mechanical strength development of alkali-activated steel slag. Similar to pure cement paste, alkali-activated steel slag paste has C–S–H gel and Ca(OH)2 as its main hydration products. However, alkali-activated steel slag pastes have lower hydration heat and fewer amounts of hydration products. Additional silicate has a retarding effect on the hydration of steel slag. Hydration heat, Ca(OH)2 contents and non-evaporable water contents reduce with increasing modulus. In addition, high silicate modulus fines the pore structure and improves compressive strength of the hardened paste.

Preparation and Performances of Geopolymer-Based Plant Fiber Composites

Geopolymer-based plant fiber composites were fabricated with metakaolin, alkaline sodium silicate and plant fibers. In this paper, orthogonal test and single factor analysis were used to study the influence of water glass modulus, solid liquid ratio and fiber content on bending strength. The results show that sequence of influence factors for bending strength was: solid to liquid ratio > fiber content > water glass modulus. When the water glass modulus is 1.7, the fiber content is 8% and the solid to liquid ratio is 1:1.4, the bending strength is up to 10.44MPa, which exceeds the Standard requirements (9MPa) specified by the China National Standard (GB/T 24312-2009). The micro-morphology of SEM indicates that the mix of plant fiber can enhance the toughness of geopolymer.

Synthesis of high specific surface area silica aerogel from rice husk ash via ambient pressure drying

In this study, silica aerogel was synthesized from rice husk ash-derived water glass through ion-exchange, sol-gel, solvent exchange and ambient pressure drying. The physical and chemical properties of silica aerogel were fully characterized by the Brunauer–Emmett–Teller theory (BET), Field emission scanning electron microscopy (FESEM), Thermogravimetric analysis-differential thermal analysis (TGA-DTA), Fourier transform infrared spectroscopy (FTIR). The effects of processing parameters, especially, the modulus of water glass on the characteristics of the products are deeply investigated. It is found that the modulus of water glass can significantly influence the specific area and pore volume of the aerogel through changing the polymerization degree of SiO group in the water glass solution. As well as, the pH value of sol-gel process and solvent concentration during modification are of importance for the physical properties of silica aerogel. When water glass modulus was 4.26, the gelation pH was 5.0 and the volumetric ratio of Trimethylchlorosilane (TMCS) to n-hexane was 7/50, silica aerogel was obtained with optimal performances of extremely high specific surface area (945.8 m2/g), pore volume (0.889 cm3/g), low density (0.071 g/cm3) uniform pore size distribution, high heat resistance temperature as 400 °C. The presented method is promising to synthesize high specific surface area silica aerogel from rice husk ash.

Preparation and microstructural analysis of smelting waste non-ferrous metal slag geopolymer

The geopolymer samples were prepared with smelting waste slag of non-ferrous metal as the raw material and water glass as the activator. The effect of modulus of water glass and water binder ratio on the compressive strength was studied. The results show that the strength of the geopolymer activated by water glass with modulus of 1.1 and water binder ratio of 0.28 can maintain an increasing trend in the 90 curing days. Through the analyses with XRD, SEM (EDS), and FTIR, the main reaction products are found to be geopolymer gels, which bond the crystalline minerals to provide strength. The molecular chains of amorphous phase in slag become shorter after depolymerization-polycondensation.

Preparation and Microstructure Analysis of Fly Ash Geopolymer at Ambient Temperature

A high-strength geopolymer was prepared with fly ash as a raw material by mixing 25% slag and 15% cement at an ambient temperature. The influence law of water glass modulus and alkali activator dosage on geopolymer strength at an ambient temperature was systematically investigated. Results indicated that an alkali activator dosage of 7% to 8% and a sodium silicate modulus of 1.4 to 1.6 are optimal ranges to increase geopolymer strength. In addition, the microstructure of fly ash geopolymer was observed through scanning electron microscopy, X-ray diffraction, and mercury intrusion porosimetry. The relation between the microstructure and mechanical properties of the material was revealed.

Development of building material utilizing a low pozzolanic activity mineral

In this work, the effects of different activators, particle size and curing conditions on the mechanical properties and hydration progress of alkali activated Pisha mortars were studied. Four different activators (NaOH, Na2CO3, Na2SO4 and water glass) based on two different fineness Pisha were used, two kinds of curing temperature, 25 and 80°C were considerate. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG) and scanning electron microscopy (SEM) were conducted to analyze the reaction products, indentify the phase composition and observe the micro-morphology, respectively. It was found that the modulus of water glass and fineness of Pisha have significant influence on the compressive strength and hydration process of alkali activated Pisha mortars. The optimum activators were water glass, the sample (Ms=1.5, curing at 80°C) exhibited the highest compressive strength (14.4MPa) at 28days. The results of the investigation also show that the amorphous aluminosilicate gels were the main hydration products.

Influences of SiO<sub>2</sub>/Na<sub>2</sub>O Molar Ratio on Aging and Chemical Modification of Water Glass

In this paper, the content of water glass before and after adding modifying agent was measured by Trimethylsilyl-gas-chromatography. The experimental results showed that different modulus of water glass could generate different content of mono-silicate acid and oligomeric silicate acid in water glass. After a period of storage, different modulus of water glass led to decrease of silicate content at different levels. Because higher content of Na2O in water glass tended to incur the alkaline polymerization, the occurrence of depolymerization of silicate species would lead to an increase of oligomeric silicate species, resulting in a drawback of silicate species content after a period of storage. And contrary to that, lower content of Na2O in water glass tended to incur the acidic polymerization. When the modifying agent was added to the newly made water glass, the amount of mono-silicate acid and oligomeric silicate acid also decreased. In modified water glass, the change of each silicate acid species was less than that in unmodified water glass. These results showed that the modifying agent retarded the aging of water glass. It had remarkable significance on the theory and practical application of water glass chemistry.

Effects of Modulus and Modifying Agent on Aging of Water Glass

This paper studied the content of water glass before and after adding modifying agent by TMS-GC method, it was found that different modulus of water glass led to decrease of silicate content at different levels after a period of storage, and the modifying agent could retard the aging of water glass. It has remarkable significance on the theory and practical application of water glass chemistry.

Reaction kinetics, reaction products and compressive strength of ternary activators activated slag designed by Taguchi method

This study investigates the reaction kinetics, the reaction products and the compressive strength of slag activated by ternary activators, namely waterglass, sodium hydroxide and sodium carbonate. Nine mixtures are designed by the Taguchi method considering the factors of sodium carbonate content (SCC), water to solid ratio (WSR), waterglass modulus (WGM) and waterglass content (WGC), and the experimental results are evaluated by applying the analysis of variance (ANOVA) method. The results show that ternary activators determine the reaction kinetics, sodium carbonate dominates the gel structure of reaction products, while the waterglass dosage is a determinant of the compressive strength. Based on the analyzed results, an optimal proportion of ternary alkali activators (SCC 4%, WGC 2.5%, WGM 1.1–1.5 and WSR 0.4) is proposed.

The Preparation and Characterization of Geopolymer Based Inorganic Membranes

In this work, the geopolymer based inorganic membranes, as a kind of new inorganic membranes, were synthesized with water-glass, metakaolin and deionized water. The resulting membranes were characterized by SEM, water flux and pore size. The results show that the membranes have high strength and water flux when these membranes were fabricated under the preparation condition: water-glass modulus of 1.1, Na/Al molar ratio of 0.8 and H2O/Na2O molar ratio of 18. Keywords:Geopolymer; Inorganic membranes; Preparation; Characterization

The Research on the Experiment Conditions for the Preparation of New Geopolymer by the Utilization of Tailings

Admix different tailings for preparing new inorganic mineral polymer. To explore the preparation conditions by testing the different performances of mortar specimens. The results show that, the strength performance is the best when the tailing dosage is 20%, the modulus of water glass is 1.2, water glass content (Na2O) is 4.5% and the ratio of liquid to solid is 0.6.

Effect of Dosage and Modulus of Water Glass on AC Impedance Properties of Alkali-Activated Slag Cement Mortar

Compressive strength and AC impedance of mortar made with water-glass-activated slag were investigated as a dependence of modulus (0.5-2.0) and dosage (2-6%) of the water-glass. Results shown that when the dosage of water glass is 2- 4 %, the modulus of the water glass has a little effect on the compressive strength. In the case of the dosage of water glass is beyond 4 %, when modulus of the water glass change from 0.5-1.0, the compressive strength obviously increases with increase of modulus of water glass and when modulus of the water glass change from 1.0-2.0, the modulus of the water glass has a little effect on the compressive strength. The strength increases with increase of the dosage from 2 to 6%. In the case same dosage and modulus, there is a rather good power correlation between the bulk resistance and the activated age. With increase of the dosage, the bulk resistance significantly decreases when the dosage is below 4%. The decreasing degree is small when the dosage is beyond 4%. The decreasing degree derived from the dosage increases with the activated age. The effect of the modulus on the bulk resistance depends on range of the dosage. However, it can be regarded that when the dosage is 4% and 6%, the modulus has small effect on the bulk resistance in the case of all the dosages.

The Effect of Surfactant and Alkali on the Surface Tension of Simulated Solutions of Alkali Activated Slag Cement System

Alkali activated slag cement and concrete are high strength, rapid hardening, low heat of hydration, good durability and so on. Whereas, too high viscosity and bad workability of the fresh mixture is the crux of the matter to embarrass application of alkali-activated slag cement and concrete. Development of special superplasticizer for alkali activated slag cement and concrete is a worth exploring way to solve the problem, and the study on the surface tension of simulated solutions of alkali activated slag cement system is one of the basic researches about the special superplasticizer. In this paper, the surface tension of surfactant-alkali-water was studied by Wilhelmy method. The results showed, first, water-glass had the best efficacity of several alkali activators, when the modulus of water-glass was 1.5 and dosage of water-glass by Na2O was 8%, the surface tension was reduced by 33 mN/m and reduced to 39.9mN/m; second, [CH3(CH2)9]2N(CH3)2Cl had the best efficacity of several surfactants, when the concentration of [CH3(CH2)9]2N(CH3)2Cl was 50g/L, the surface tension was reduced by 35.3 mN/m and reduced to 32.5 mN/m; finally, the effect of surfactant and alkali together on the surface tension of water was complex, surfactants had hardly effective in water glass.

Factors Influencing the Strength of Alkali-Activated Slag Cement

In this paper, water glass was chosen as activator to prepare Alkali-activated slag(AAS) cement. Effects of modulus and dosage of water glass, and admixture (fly ash, slag and silica fume) on the strength of AAS cement was investigated. It was found that the modulus of water glass had great effect on the strength of AAS cement when the mixing amount of water glass was less than 12%. With the incorporation of fly ash or slag, the strength of AAS cement decreased, however the incorporation of silica fume could promote the flexural and compressive strength of AAS cement slightly.

Study on Sulfate-Attack of Slag-Based Geopolymer Concrete

Geopolymer has been attracted world attention as a potentially revolutionary material that is one of the ideal substitutes of portland cement. Fundamental studies on geopolymer are increasing rapidly because of its potential commercial applications. However, little work has been done on its erosion resistance of sulfate. In this paper, slag and metakaolin as source materials, different modules of water-glass as activator were used to prepare slag-based geopolymer which was then prepared to make slag-based geopolymer concrete. Linear expansion rate and mass loss of concrete were used as indicators to explore different erosion rules of slag-based geopolymer concrete which was long-term immersed in the 5% ( by mass ) Na2SO4 solution. Comparative experiments were also done between slag-based geopolymer concrete and ordinary cement concrete. The results showed that geopolymer concrete had excellent sulfate resistance performance, linear expansion rate and mass loss rate of geopolymer were 0.024% and 0.58% respectively at the soaking age of 49d as the water glass modulus was 1.4 and the water-glass content was 4%. It was also found that the anti-sulfate ability of geopolymer concrete is much better than that of ordinary concrete with the same strength grade.

Fireproof Water Glass Composite Based on Mechanically Activated Alumina

The effect of the silica modulus of water glass, functional additives, and mechanical activation of the filler on the composition of a fireproof composite is described. At temperatures up to 700°C one can decrease thermal diffusivity by the formation of a heat-insulating layer frothed by water vapor dehydrated from water glass. Within the high-temperature range heat-insulating properties are improved by the synthesis of nepheline in the reaction between sodium silicate and alumina. Mechanical activation of alumina improves this effect. Introduction of carbamide and boric acid additives improves the fireproof properties of the gaseous medium.

Effects of dosage and modulus of water glass on early hydration of alkali–slag cements

This paper examines the early hydration of alkali–slag cements activated with water glass with different n moduli and sodium metasilicate (Na 2SiO 3·5H 2O) in solution at 25 °C. The early hydration of alkali-activated blast furnace slag cements has been studied using isothermal conduction calorimetry. The cumulative heat of hydration increases by increasing the n modulus as well as the dosage of water glass, but is still lower than that of Portland cement. The compressive strength of normal-cured water glass slag cements is higher than Portland cement mortars. Drying shrinkage of alkali–slag cements is considerably higher than that of Portland cement. Consequently, industrial use of alkali–slag cement needs better understanding of the hardening mechanism and requires further research based on presented observations and results.

Investigation on some factors affecting the characteristics of alkali-phosphorus slag cement

Alkali-slag cements are of higher strength, and their other properties are also better than those of Portland cement. In this paper, the authors studied how the properties of alkali-phosphorus slag cement were influenced by the modulus of water glass (Na 2O:nSiO 2), soluble phosphates, water to solid ratio and the fineness of the slag when water glass and granulated phosphorus slag (GPS) were used to make alkali-GPS cement. The experimental results indicated that the modulus of water glass had great influence, but soluble phosphates had little influence on the properties of the cement. If the water to solid ratio was increased, it was not helpful both to the early hydration or to the strength of the cement. There would be a critical fineness after some days. If the fineness was larger than the critical value, the fineness hardly affected the strength of the cement.