Setting Time and Strength Monitoring of Alkali-Activated Cement Mixtures by Ultrasonic Testing

Alkali-activated cement (AAC) is a promising binder that replaces ordinary Portland cement (OPC). In this study, the development of setting time and strength of AAC mixes were studied using ultrasonic testing method. The test results were compared with traditional Vicat setting time and compressive and flexural strengths. The findings showed that setting times and strengths have a strong correlation with ultrasonic velocity curve. The initial setting time corresponds well with the ultrasonic velocity curve’s dormant period, and the final setting time with the time it takes to reach the velocity curve’s maximum acceleration. Both setting times also showed a correlation with the value of the maximum acceleration. An exponential relation was found between the ultrasonic velocity and the compressive and flexural strengths. The effect of binder content, alkaline solid to binder ratio (AS/B), sodium silicate to sodium hydroxide solids ratio (SS/SH), and total water to total solid binder ratio (TW/TS) on the strength and setting time are also studied using Taguchi method of experimental design. AS/B ratio showed a significant influence on the setting time of AAC while TW/TS ratio showed only a minor effect. The ultrasonic velocities were able to capture the effect of the different parameters similar to the compressive strength. The velocity decreased mainly with the increase of TW/TS ratio and binder content, while AS/B and SS/SH ratios showed a lower influence.

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Effect of Binder Content and Solution/Binder Ratio on Alkali-Activated Slag Concrete Activated with Neutral Grade Water Glass

Arabian Journal for Science and Engineering ◽

10.1007/s13369-020-04666-5 ◽

2020 ◽

Vol 45 (10) ◽

pp. 8187-8197

Author(s):

Vikas Gugulothu ◽

T. D. Gunneswara Rao

Keyword(s):

Water Glass ◽

Binder Content ◽

Alkali Activated Slag ◽

Binder Ratio ◽

Activated Slag ◽

Alkali Activated

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An Innovative Admixture to Enhance the Fresh Properties of Slag Pastes

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.477-478.915 ◽

2013 ◽

Vol 477-478 ◽

pp. 915-919

Author(s):

Qun Pan ◽

Shuang Zhao ◽

Han Ying Zheng ◽

Bin Zhu

Keyword(s):

Setting Time ◽

Heat Of Hydration ◽

Fresh Properties ◽

Slag Cement ◽

Setting Times ◽

Initial Setting ◽

New Type ◽

Activated Slag ◽

Alkali Activated ◽

Initial Peak

This study reports a new type compound admixture YP developed for slag cement activated by water glass. The effect of the compound admixture on properties of slag pastes, including mini slump, setting time and heat of hydration was examined. It is found that the slump of slag paste was increased from 60 mm to 120 mm by using the admixture. Furthermore, the initial and final setting times of paste with the admixture were 96 min and 132 min, while it only took 18 min and 23 min to achieve initial setting and final setting for the paste without using the admixture. In addition, the results also indicate that the initial peak was delayed for nearly 7 hours and the heat flow of hydration was reduced from 5864 μw/g to 461μw/g, when the admixture was added. It can be concluded that the new admixture is capable of imparting a significant improvement of workability of alkali-activated slag cement with a suitable setting behavior.

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Characteristics of Wood Ash Cement Mortar Incorporating Green-Synthesized Nano-TiO2

International Journal of Concrete Structures and Materials ◽

10.1186/s40069-021-00456-x ◽

2021 ◽

Vol 15 (1) ◽

Author(s):

Bolanle Deborah Ikotun ◽

Akeem Ayinde Raheem

Keyword(s):

Compressive Strength ◽

Water Absorption ◽

Cement Mortar ◽

Setting Time ◽

Wood Ash ◽

Partial Replacement ◽

Nano Tio2 ◽

Setting Times ◽

Binder Ratio ◽

Water To Binder Ratio

AbstractThis paper presents the findings of an investigation into the influence of green-synthesized nano-TiO2 on the characteristics of wood ash (WA) cement mortar. Mortar specimens were prepared by partial replacement of cement with WA (10% by weight) and addition of 1, 2 and 3% nano-TiO2 by weight of binder; using constant water-to-binder ratio (w/b) for all mixtures. The properties evaluated are setting time of the binder and flexural and compressive strength with water absorption of the mortar. The results indicated that addition of 1 and 2% nano-TiO2 reduced setting times of WA cement paste. Also, the flexural and compressive strength of WA cement mortar were higher with the incorporation of up to 2% nano-TiO2. The water absorption of WA cement mortar was reduced when nano-TiO2 was added with 2% incorporation having the best result. The incorporation of NT in WA cement mortar improved its workability and strength characteristics.

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New Rapid Setting Alkali Activated Cement Compositions

MRS Proceedings ◽

10.1557/proc-179-203 ◽

1989 ◽

Vol 179 ◽

Cited By ~ 7

Author(s):

D. M. Roy ◽

M. R. Silsbee ◽

D. Wolfe-Confer

Keyword(s):

Mechanical Property ◽

Alkali Activation ◽

X Ray Diffraction ◽

X Ray ◽

Blended Cements ◽

Setting Times ◽

Rapid Setting ◽

Alkali Activated ◽

Alkali Activated Cement

AbstractThe advantage of utilizing blended cements for many applications has been well documented. However, the use of these materials has been limited by the longer setting times associated with the use of these materials. This report discusses the development of formulations employing alkali activation to shorten the setting times. The results of characterization of these materials using calorimetry, microscopic, x-ray diffraction, and mechanical property techniques are discussed.

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IMPLEMENTATION OF FELDSPAR AS PARTIALLY REPLACEMENT MATERIAL IN CEMENT MORTAR (EXPLORATION AND APPLICATION)

Istrazivanja i projektovanja za privredu ◽

10.5937/jaes0-31694 ◽

2021 ◽

pp. 1-9

Author(s):

Walid Edris ◽

Mahmoud Al-Tamimi ◽

Mohammed Aldelgawy

Keyword(s):

Compressive Strength ◽

Elevated Temperatures ◽

Cement Mortar ◽

Setting Time ◽

Raw Material ◽

Replacement Ratio ◽

Cement Replacement ◽

Residual Compressive Strength ◽

Setting Times ◽

Compressive And Flexural Strengths

This paper aims to explore and evaluate the use of Jordanian Feldspar as a natural resource partially replacement material for each of cement and sand in cement mortar. First, Al-Jaishia area was explored through a global positioning system (GPS) navigation to gather site samples of Feldspar raw material. Afterward, cement and sand were partially replaced by Feldspar with substitution ratios of 5%, 10%, 15%, 20%, and 25% for each. The study included the effect of cement replacement on normal consistency and setting time for cement paste. The water content along with initial and final setting times increased via the increment of cement replacement ratio. Moreover, mechanical properties (compressive, flexural, and residual compressive strengths) of cement mortar due to both cement and sand replacement were evaluated. The compressive and flexural strengths after 3, 7, and 28 days of curing were examined for both cement and sand replacement. While, residual compressive strength for cement replacement after 28 days was measured at elevated temperatures of 400°C, 600°C, and 800°C. The compressive and flexural strengths decreased by increasing the Feldspar replacement ratio for both cement and sand at all specimen ages. Whereas, heat resistance properties were improved by cement/Feldspar replacement. The best result for residual compressive strength was obtained at 15% replacement ratio and 400°C temperature.

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Understanding the relationship between composition and rheology in alkali-activated binders

Journal of Physics Conference Series ◽

10.1088/1742-6596/2124/1/012004 ◽

2021 ◽

Vol 2124 (1) ◽

pp. 012004

Author(s):

N I Kozhukhova ◽

I M Shurakov ◽

M I Kozhukhova ◽

M Yu Elistratkin ◽

N I Alfimova

Keyword(s):

3D Printing ◽

Setting Time ◽

Experimental System ◽

Mixture Flow ◽

Binding System ◽

Setting Times ◽

Torsional Loads ◽

Alkaline Activator ◽

Alkali Activated Binders ◽

Alkali Activated

Abstract Based on the knowledge that exists today, it is generally accepted that there are basic parameters and characteristics to obtain effective mixtures for their use in 3D printing. Rheological behavior and setting time (initial and final) are those characteristics that determine workability, as well as the speed and nature of hardening of the molded pastes and, as a result, the final framework and the integrity of the resulted structure. Among the promising options for 3D printing, the literature often contains information on alkali-activated binders. In this work, an alkali-activated binding system based on electrometallurgical slag, as well as citrogypsum, a waste of the industrial production of citric acid, was studied. Some rheological characteristics of experimental binders were considered: the nature of the mixture flow under the action of torsional loads and their initial and final setting times. It was found that the joined use of both components in the experimental system “slag - water”: an alkaline activator and citrogypsum, promotes the transition of the character of the system from thixotropic to mixed: dilatant-thixotropic (for the Na2SiO3 activator) and dilatant (for the NaOH activator). It was found that the addition of alkaline activators and citrogypsum to the binding system separately in both cases helps to reduce the initial and final setting times from 18 and 22 hours to 1 hour and 1.5 hours. Also, experimental results have shown that the jointed action of both components: an alkaline activator and cytogypsum, has a synergistic effect on the setting time.

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Effect of Ca(OH)2 Addition on the Engineering Properties of Sodium Sulfate Activated Slag

Materials ◽

10.3390/ma14154266 ◽

2021 ◽

Vol 14 (15) ◽

pp. 4266

Author(s):

Xiaodi Dai ◽

Serdar Aydın ◽

Mert Yücel Yardımcı ◽

Karel Lesage ◽

Geert De Schutter

Keyword(s):

Sodium Sulfate ◽

Setting Time ◽

Engineering Properties ◽

Main Reaction ◽

Phase Identification ◽

Reaction Products ◽

Alkali Activated Slag ◽

Setting Times ◽

Activated Slag ◽

Alkali Activated

Alkali-activated slag is considered as a sustainable construction material due to its environmentally friendly nature. To further promote the sustainable nature of alkali-activated slag, a sodium sulfate activator is suggested to be used since it can be obtained naturally and generates lower greenhouse gas emissions. However, the mixtures activated by sodium sulfate exhibit low early strength and very long setting times. This study investigates the effects of calcium hydroxide (Ca(OH)2) addition on some engineering properties such as rheology, setting time, mechanical properties, porosity, and microstructure of sodium sulfate activated ground granulated blast furnace slag (GGBFS). Furthermore, the changes of chemical groups in reaction products and phase identification have been evaluated by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction. Test results showed that Ca(OH)2 addition can substantially increase the reaction rate and the compressive strength at early ages. In addition, the very long setting times of the sodium sulfate-activated mixtures were shortened by the addition of Ca(OH)2. SEM analysis confirmed that the incorporation of excessive amounts of Ca(OH)2 could lead to a less well-packed microstructure although the reaction degree of GGBFS remained the same at later ages as compared to the sodium sulfate mixture. It was also revealed that in case of the Ca(OH)2 addition into sodium sulfate activator, the main reaction products are chain-structured C-A-S-H gels and ettringite.

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Novel Geopolymers Incorporating Wollastonite and Recycled Mixed Plastics

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1129.39 ◽

2015 ◽

Vol 1129 ◽

pp. 39-48

Author(s):

S.F. Wong ◽

S.K. Ting ◽

M. Lin ◽

M. Shamini ◽

B.K. Tay

Keyword(s):

Thermal Properties ◽

Water Absorption ◽

Magnesium Oxide ◽

High Density Polyethylene ◽

Setting Time ◽

High Density ◽

Molar Ratio ◽

Binder Ratio ◽

Monopotassium Phosphate ◽

Compressive And Flexural Strengths

This paper reports a study on novel geopolymers, focusing on chemically bonded composites, by incorporating wollastonite and recycled mixed plastics. Magnesium oxide and monopotassium phosphate were used as binders; while the recycled mixed plastics consisted of high-density polyethylene and polystyrene at different volume ratios. The effects of molar ratio (magnesium-to-phosphorus ratio), wollastonite-to-binder ratio and recycled mixed plastics content were investigated. The performance of geopolymers was evaluated based on their setting time and water absorption, compressive and flexural strengths as well as thermal properties.

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