Setting Time Measurements Research Articles

Influence Mechanism of Accelerator on the Hydration and Microstructural Properties of Portland Cement

Shotcrete is one of the most important types of concrete used in engineering construction, and its properties are significantly influenced by accelerators. This study investigates the effects of aluminum sulfate series alkali-free accelerator (AKF) and alkali accelerator (ALK) on the strength, hydration process, characteristic hydration products, and microstructure properties of shotcrete. Techniques such as setting time measurement, isothermal calorimetry, simultaneous thermal analysis, scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM–EDS), and mercury intrusion porosimetry (MIP) were utilized. The results indicate that both ALK and AKF significantly accelerate and increase the early hydration heat release rate and cumulative hydration heat of Portland cement, producing the characteristic hydration products hexagonal plate AFm and rod AFt, respectively. This acceleration notably speeds up the setting process of Portland cement. ALK negatively impacts the later-stage microstructural development and pore structure filling of hardened cement paste, leading to average reductions of 15.3% and 19.9% in flexural and compressive strengths at 28 days, respectively. Specifically, compared to ALK, AKF shows a faster hydration heat release rate during the induction period and a more significant increase in cumulative hydration heat during the hydration process; the cumulative hydration heat is on average 18.2% higher than AKF. Furthermore, AKF does not hinder the subsequent C3S hydration and C-S-H gel densification process. After 28 days of curing, EDS analysis indicates an average Ca/Si ratio of 1.171 for the AKF-treated shotcrete; the average Ca/Si ratio shows minimal variation from the reference group and is classified as the same type of C-S-H gel as the reference group. Therefore, the strength of hardened cement paste with AKF continues to increase steadily in the later stages. At 28 days, the average flexural strength increased by 10.2%, while the compressive strength decreased by only 3.0%. These findings suggest that AKF enhances the microstructural development and strength of shotcrete, making it a more effective accelerator for engineering applications.

Hydration and Mechanical Properties of Cement Kiln Dust-Blended Cement Composite

This study aims to investigate the effects of cement kiln dust (CKD) on the hydration reactions and mechanical properties of cement, and to evaluate its potential for use as a supplementary cementitious material (SCM). The key variables are the CKD type and the replacement ratio. Cement paste and mortar specimens containing CKD were prepared to examine their effects on the cement hydration and mechanical properties. The effect on hydration was assessed using setting time measurements, heat of hydration tests, and thermogravimetric analyses (TG). In addition, compressive strength tests were conducted to evaluate the effect of CKD on the mechanical properties of the cement. The results indicated that CKD promoted early-age cement hydration and enhanced the early-age mechanical properties. However, owing to its lack of pozzolanic reactivity, it did not significantly affect long-term hydration. Given that the effects of CKD vary slightly depending on its chemical composition, careful consideration of CKD’s properties suggests that its potential use as an SCM is promising.

Hybrid Bone Substitute Containing Tricalcium Phosphate and Silver Modified Hydroxyapatite-Methylcellulose Granules.

Despite years of extensive research, achieving the optimal properties for calcium phosphate-based biomaterials remains an ongoing challenge. Recently, 'biomicroconcretes' systems consisting of setting-phase-forming bone cement matrix and aggregates (granules/microspheres) have been developed and studied. However, further investigations are necessary to clarify the complex interplay between the synthesis, structure, and properties of these materials. This article focusses on the development and potential applications of hybrid biomaterials based on alpha-tricalcium phosphate (αTCP), hydroxyapatite (HA) and methylcellulose (MC) modified with silver (0.1 wt.% or 1.0 wt.%). The study presents the synthesis and characterization of silver-modified hybrid granules and seeks to determine the possibility and efficiency of incorporating these hybrid granules into αTCP-based biomicroconcretes. The αTCP and hydroxyapatite provide structural integrity and osteoconductivity, the presence of silver imparts antimicrobial properties, and MC allows for the self-assembling of granules. This combination creates an ideal environment for bone regeneration, while it potentially may prevent bacterial colonization and infection. The material's chemical and phase composition, setting times, compressive strength, microstructure, chemical stability, and bioactive potential in simulated body fluid are systematically investigated. The results of the setting time measurements showed that both the size and the composition of granules (especially the hybrid nature) have an impact on the setting process of biomicroconcretes. The addition of silver resulted in prolonged setting times compared to the unmodified materials. Developed biomicroconcretes, despite exhibiting lower compressive strength compared to traditional calcium phosphate cements, fall within the range of human cancellous bone and demonstrate chemical stability and bioactive potential, indicating their suitability for bone substitution and regeneration. Further in vitro studies and in vivo assessments are needed to check the potential of these biomaterials in clinical applications.

Dispersion and weak retardation performance of sulfate-based starch maleic acid monoesters in cement

To reduce the influence of a sulfate-based starch water-reducing agent on the setting time of cement, a novel starch-based water-reducing agent, namely sulfate-based starch maleic acid monoester (SAMAS), was designed to adjust its hydrophilicity by maleic acid monoester. Gel permeation chromatography, Fourier transform infrared spectroscopy, and 1H NMR nuclear magnetic resonance spectroscopy were used to characterize the prepared SAMAS, while Zeta potential, UV–Vis absorption, X-ray photoelectron spectroscopy, X-ray diffraction, cement paste fluidity, and setting time measurements were conducted to investigate its dispersion performance, retardation performance, adsorption behavior, and mechanism of action. SAMAS exhibited good dispersion performance and did not significantly prolong the setting time of the cement. In addition, the dispersion performance of SAMAS was found to depend mainly on steric hindrance, and its weak retardation performance originated from the hydrophilic regulation of the maleic acid monoester groups, which ensures the normal progress of the cement hydration reaction by hindering the formation of a hydration film.

Real-time implementation of an enhanced proportional-integral-derivative controller based on sparrow search algorithm for micro-robotics system

This paper presents a new approach to control the position of the microrobotics system with a proportional-integral-derivative (PID) controller. By using sparrow search algorithm (SSA), the optimal PID controller indicators were obtained by applying a new objective function namely, integral square time multiplied square error (ISTES). The effeciency of the proposed SSAbased controller was verified by comparisons made with grey wolf optimization (GWO) algorithm-based controllers in terms of time. Each control technique will be applied to the identified model using MATLAB Simulink and the experimental test facility was conducted using LabVIEW software. The simulation and experimental results show that the performance of SSA-PID controller based on ISTES cost function achieves the best performance among various techniques. Moreover, the SSA technique had the highest performance compared to GWO technique based on rising and setting time and many other performance measurements. Thus, it is recommended to apply SSA for tuning the parameters of PID as it can enhance its performance in micro-robotic systems. It was found that the amount of error is reduced by 50% using SSA than other former experiments.

The Influence of Alkali-Free Shotcrete Accelerators on Early Age Hydration and Property Development within Cement Systems.

Fluoride-containing alkali-free setting accelerators are a common type of admixture used in tunnel shotcrete but few studies in the literature focus on the effect of their fluoride compounds on the setting and hardening properties of accelerated cement paste under low environment temperatures. Tunnel shotcrete in cold regions or winter construction periods would be obviously influenced by low environment temperatures, especially for its fast setting and quick support applications. The objective of this work is to evaluate the early age hydration behavior of different accelerated cement pastes under 20 °C and 5 °C environment temperatures. In this study, setting time measurement, early age strength development, hydration ion leaching concentration, isothermal calorimetry, X-ray diffraction, and ESEM were performed on cement systems prepared with a non-fluoride alkali-free accelerator (aluminum sulfate solution with over 60% solid content) and a designed fluoride-containing alkali-free setting accelerator (aluminum sulfate and fluoride compound). The results showed that the fluorides obtained in alkali-free accelerators promote C3S dissolution and massive ettringite needles together with monosulfoaluminate (AFm) hydrate formation, thus leading to a quicker setting effect and low sensitivity to low environment temperatures than in non- fluoride groups. However, the rate of mechanical strength development of cement pastes hydrated within 24 h was decreased obviously when fluorine-containing alkali-free accelerator was used. This phenomenon is mainly related to the crystallization of thin-plate shape calcium fluoride (CaF2) formations and promoted conversion of ettringite to monosulfoaluminate hydrate in the accelerating period, thus weakening the denseness of C-S-H gel and inhibiting alite further hydration.

Setting Time Measurement of Concrete Mixtures through Monitoring of Shear-Wave Velocity with Shear-Horizontal Waves

Setting Time Measurement of Concrete Mixtures through Monitoring of Shear-Wave Velocity with Shear-Horizontal Waves

Early-age characterisation of Portland cement by impedance spectroscopy

Alternating current impedance spectroscopy (ACIS) was used to assess the effect of different sand, anhydrite and water contents on the electrochemical response of Portland cement paste in the early stages of hydration. Potential factors that may affect impedance measurements and data interpretation are also discussed, such as the complexity of the chemical composition of cement, its physical properties and hydration kinetics, and technique limitations. The impedance data obtained were benchmarked against different supporting techniques and literature data, showing a strong relationship among hydration rates as determined by thermochemistry, setting time measurements by physical approaches, pore fluid chemistry, electrical conductivity and the observed impedance behaviour. The results demonstrate that ACIS is a sensitive technique for assessing cement paste hydration, enabling differentiation of changes in the water and cement content, hydration degree and microstructural development during the first 24 h after mixing.

Early Age Monitoring of High Cement Replacement Mixtures for Pavement

Decarbonization of concrete will require a combination of alternative binding materials and higher cement replacement rate with supplementary cementitious materials. Developing tools and methods that help engineers evaluate the properties of early age concrete pavement, such as setting time and strength gain, will be necessary to adopt new concrete mixes. Two concrete pavement test sections were constructed, a high early strength concrete mix with 25% (control) and 40% replacement of cement with fly ash (HVFAC), along with monitoring of the concrete’s setting time, saw-cut timing, and strength gain. A non-contact ultrasonic device was used to estimate setting time through measuring leaky Rayleigh wave energy transmission. The laboratory setting time of the control and HVFAC mix measured with the non-contact device was 5.5 h and 15 h, respectively, and agreed with measured isothermal calorimetry results. Further calorimeter tests showed that adding an accelerating admixture or replacing part of the cement with nano-limestone decreased the HVFAC setting time up to 4.4 h. The field setting time of the control mixture with the non-contact device measured 4.2 h, which was shorter than the laboratory estimate. Based only on the experience of construction personnel, saw-cutting for these mixtures was initiated too early and caused significant joint raveling, reinforcing the importance of in situ setting time measurement. The maturity method was successfully implemented with embedded wireless temperature sensors that rapidly and easily estimated the in-place compressive strength and improved opening time determination for concrete with high cement replacement levels, which are sensitive to the volume of supplementary cementitious materials, admixtures, and ambient conditions.

Experimental Study on Field Applicability in the Concrete Setting Time Measurement Method

Experimental Study on Field Applicability in the Concrete Setting Time Measurement Method

The Effect of Various Grinding Aids on the Properties of Cement and Its Compatibility with Acrylate-Based Superplasticizer.

The influence of grinding aids (pure triethanolamine and ethylene glycol) on the properties of cements, their compatibility with an acrylate-based superplasticizer and the rheological parameters of mortars were investigated. The presence of surfactants influences the standard properties of cements and the effectiveness of the superplasticizer. The results of the heat of hydration and setting time measurements indicate a delay in the hydration process and an increase in the induction period duration of the surfactant-doped pastes, in relation to the reference sample without grinding aids. Triethanolamine increases early-age compressive strength; the effect was observed for both standard and superplasticizer-containing mortars. The presence of grinding aids decreases the slump flow of mortars and increases rheological parameters such as yield stress (τ0) and viscosity (η).

The Influence of Composition and Recipe Dosage on the Strength Characteristics of New Geopolymer Concrete with the Use of Stone Flour

Currently, considering global trends and challenges, as well as the UN sustainable development goals and the ESG plan, the development of geopolymer binders for the production of geopolymer concrete has become an urgent area of construction science. This study aimed to reveal the influence of the component composition and recipe dosage on the characteristics of fine-grained geopolymer concrete with the use of stone flour. Eleven compositions of geopolymer fine-grained concrete were made from which samples of the mixture were obtained for testing at the beginning and end of setting and models in the form of beams and cubes for testing the compressive strength tensile strength in bending. It was found that the considered types of stone flour can be successfully used as an additive in the manufacture of geopolymer concrete. An analysis of the setting time measurements showed that stone flour could accelerate the hardening of the geopolymer composite. It was found that the addition of stone waste significantly improves the compressive strength of geopolymers in comparison with a geopolymer composite containing only quartz sand. The maximum compressive strength of 52.2 MPa and the tensile strength in bending of 6.7 MPa provide the introduction of potassium feldspar in an amount of 15% of the binder mass. Microstructural analysis of the geopolymer composite was carried out, confirming the effectiveness of the recipe techniques implemented in this study.

Mechanical and Morphological study of Copper slag admixtured cement mortar under different curing media

The hydration of ordinary Portland cement was measured on the respect of the setting time, compressive strength and morphology measurements in the presence of 0%, 10%, 20% and 30 wt% copper slag. These samples were cured in distilled water, seawater and groundwater. The results show that the replacement rates of copper slag (0%, 10%, 20% and 30 wt.%) raises the compressive strength and brings down the setting time. Both these findings suggest that at an early stage, seawater accelerates cement hydration but slows the later stage of hydration.

Effect of different mixture parameters on the setting time of fly ash/rice husk ash-based geopolymer mortar

The present study investigated the effects of different mixture parameters on the setting time of fly ash/rice husk ash – based geopolymer mortars. Mortar mixtures were prepared using fly ash and rice husk ash as the raw material, activated using a blended alkali activator solution consisting of sodium hydroxide (SH) and sodium silicate (SS). The concentration of SH was varied from 10M to 14M, while the SS/SH ratio was varied to 1.0, 1.5 or 2.0. The ratio of alkali activator solution to binder (A/B) was also varied from 0.45 to 0.55. Fresh mortar mixtures were subjected to setting time measurement at curing temperatures of 80 °C. Cubes of 50 mm size were also prepared and subjected to compressive strength testing at different ages. Results showed that increases in both parameters comprising SS/SH ratio and SH concentration resulted in reduction of setting time, while rise in A/B ratio led to increase in setting time of mortars.

Effect of casting and curing temperature on the interfacial bond strength of epoxy bonded concretes

The effect of casting and curing temperature on concrete-epoxy-concrete interfacial bond strength was evaluated. To cover a wide range of climatic conditions, six different temperature values from 5 to 55 °C were considered. The interfacial bond strength of the composites was experimentally assessed using pull-off, wedge splitting and bi-surface shear tests. The individual materials, epoxy and cement paste, were also characterized by means of viscosity, shore D hardness and setting time measurements. Results show that the casting and curing temperature dramatically impacts the mechanical properties of the epoxy bonded concretes. Indeed, increasing temperature from 5 to 55 °C leads to a decrease in bond strength up to 65%. The significant drop in setting time of epoxy compared to cement at high temperature, the inferior epoxy mechanical properties, as well as the reduction in epoxy thickness due to material loss in pores and microcracks can explain this decrease.

Setting time of geopolymer binder based on Umeanyar slate stone powder

This study aims to determine the effect of precursor and activator proportion on the setting time of the geopolymer binder. The precursor used was Umeanyar slate stone powder containing SiO2 (49%), Al2O3 (11%), CaO (11.2%). While the activator used was a mixture of 14 M sodium hydroxide (NaOH) solution and sodium silicate (Na2SiO3). The proportion of precursor: activator (P/A) in the geopolymer binder were 70%: 30%; 75%: 25%; 80%: 20% and those of Na2SiO3 : NaOH (SS/SH) were 1:1; 1.5:1; 2:1, by weight. The setting time of the binders was tested according to the SNI 2049: 2015. Measurement of setting time using vicat test equipment and based on normal consistency. The measurement of the setting time was carried out every 15 minutes until the initial bonding time was reached. The initial and final setting time result of the geopolymer binder decreased to 75 minutes and 100 minutes when P/A, as well as, SS/SH increased.

New Metakaolin-Based Geopolymers with the Addition of Different Types of Waste Stone Powder

The search for new alternative raw materials and their subsequent use supports the sustainability of natural resources. This article describes the use of waste stone powder (WSP) in geopolymer synthesis. Five different types of WSP (feldspar, limestone, marlstone, dolomite, marble) were comprehensively characterized and their influence on the resulting properties (especially mechanical and textural properties, setting time and structure) of metakaolin-based geopolymer composites was investigated. Their comparison with a geopolymer composite containing only quartz sand has revealed that WSP additions have a small but positive effect on the mechanical or textural properties of geopolymers. Moreover, setting time measurements have shown that waste stone powders can be used as an accelerator of geopolymer reaction solidification. The results demonstrated that the mentioned types of WSP, previously landfilled, can be used for the preparation of geopolymers. This can help reduce the environmental burden.

Evaluation of the Hydration Characteristics and Anti-Washout Resistance of Non-Dispersible Underwater Concrete with Nano-SiO2 and MgO

In this paper, the effect of nano-SiO2 (NS) and MgO on the hydration characteristics and anti-washout resistance of non-dispersible underwater concrete (UWC) was evaluated. A slump flow test, a viscosity test, and setting time measurement were conducted to identify the impacts of NS and MgO on the rheological properties of UWC. The pH and turbidity were measured to investigate the anti-washout performance of UWC mixes. To analyze the hydration characteristics and mechanical properties, hydration heat analysis, a compressive strength test, and thermogravimetric analyses were conducted. The experimental results showed that the fine particles of NS and MgO reduced slump flow, increased viscosity, and enhanced the anti-washout resistance of UWC. In addition, both NS and MgO shortened the initial and final setting times, and the replacement of MgO specimens slightly prolonged the setting time. NS accelerated the peak time and increased the peak temperature, and MgO delayed the hydration process and reduced the temperature due to the formation of brucite. The compressive results showed that NS improved the compressive strength of the UWC, and MgO slightly decreased the strength. The addition of NS also resulted in the formation of extra C–S–H, and the replacement of MgO caused the generation of a hydrotalcite phase.

Evaluation of stiffening behavior of concrete based on contactless ultrasonic system and maturity method

This study proposes an innovative contactless ultrasonic system (CUS) for monitoring the hardening behavior of concrete under accelerated curing, without any penetration or embedment of measurement devices. Two different concrete mixtures types were tested under several temperature-controlled environments, and the maturity method was used to calibrate the temperature effect on setting times. The conventional Penetrometer test results were compared with those of CUS. The equivalent ages as per the Penetrometer test and CUS results showed maximum differences of 8 h and less than 1.6 h, respectively. The CUS demonstrated promising results regarding hardening behavior without sampling procedures, which has advantages regarding accelerated curing. It is thus a potential alternative to the existing setting time measurement methods regarding practicality and accuracy.

The analysis of accelerator concentration effect on setting time and morphology surface impression materials made of brown algae Sargassum sp

ObjectiveTo analyze the accelerator concentration on alginate impression material setting time made of brown algae Sargassum sp. MethodThis study was an experimental laboratory using samples of impression material made of brown algae Sargassum sp. Measurement of setting time using stopwatch and morphological surface analysis using Scanning Electron Magnetic (SEM). ResultThe average setting time for the fastest calcium sulfate accelerator is 3.11min (17g) and the longest is 6.13min (15g). As for the fastest potassium titanium fluoride accelerator material the timeline setting is 3.81min (4g) and the longest is 5.73min (2g). SEM analysis showed that alginate printing impression materials with accelerator materials of calcium sulfate 17g and potassium titanium fluoride 4g showed the smaller, finer denser and more homogenous surface morphology. ConclusionImpression material made of Sargassum sp. with accelerator calcium sulfate 17g and potassium titanium fluoride 4g has a better setting time and surface morphology.