scholarly journals Application of the maturity method in slipforming operations

2021 ◽  
Author(s):  
Christos Anagnostopoulos
Keyword(s):  
Strength Development ◽  
Sensitivity Factor ◽  
Maturity Model ◽  
Setting Times ◽  
Concrete Layer ◽  
Maturity Method ◽  
Main Target ◽  
Initial Setting ◽  
The Times ◽  
Concrete Placement

The main objective of this thesis is to study the application of the maturity method in slipforming operations so as to provide more efficient means of the construction planning of a project. The main target of this research is to use the maturity method to establish the initial setting times and then apply those times to estimate the slipform mockup time and speed. In this research various maturity functions are compared and the most efficient one is used. The apparent activation energy (E) and the temperature sensitivity factor (B) are, examined so as to understand their effect on the maturity function and also to establish a relationship between them and the retarder dosage. Furthermore, the "FHP Strength Model (SFHP)" and the "Rate Constant Model (SkY' are used to evaluate their competence in representing the strength development of a concrete mixture in the laboratory and in the field. Also, the maturity method is used to estimate the times of mockup and then compared with the "Penetration Resistance", "2°C Temperature Increase", "Rod", and "Conductivity" methods. Furthermore, an example is presented and the mock-up times are established based on various initial concrete temperatures and slipform layer arrangements. Finally a computer program is developed to establish the mockup times, time of concrete placement, and the slipform speed during the removal process. The results of this research showed that the Carino and Tank maturity function is preferred for the calculation of the maturity indexes. Also, it is found that a linear relationship between the retarder dosage and E or B can be established. Moreover, it is shown that E or B can be estimated by the method suggested by Pinto and Hover. In addition, a new strength-maturity model is suggested. Finally, it is found that the maturity method can be used with efficiency to establish the slipform mockup times, the time of the concrete layer, and the slipform speed.

scholarly journals Application of the maturity method in slipforming operations

2021 ◽  
Author(s):  
Christos Anagnostopoulos
Keyword(s):  
Strength Development ◽  
Sensitivity Factor ◽  
Maturity Model ◽  
Setting Times ◽  
Concrete Layer ◽  
Maturity Method ◽  
Main Target ◽  
Initial Setting ◽  
The Times ◽  
Concrete Placement

The main objective of this thesis is to study the application of the maturity method in slipforming operations so as to provide more efficient means of the construction planning of a project. The main target of this research is to use the maturity method to establish the initial setting times and then apply those times to estimate the slipform mockup time and speed. In this research various maturity functions are compared and the most efficient one is used. The apparent activation energy (E) and the temperature sensitivity factor (B) are, examined so as to understand their effect on the maturity function and also to establish a relationship between them and the retarder dosage. Furthermore, the "FHP Strength Model (SFHP)" and the "Rate Constant Model (SkY' are used to evaluate their competence in representing the strength development of a concrete mixture in the laboratory and in the field. Also, the maturity method is used to estimate the times of mockup and then compared with the "Penetration Resistance", "2°C Temperature Increase", "Rod", and "Conductivity" methods. Furthermore, an example is presented and the mock-up times are established based on various initial concrete temperatures and slipform layer arrangements. Finally a computer program is developed to establish the mockup times, time of concrete placement, and the slipform speed during the removal process. The results of this research showed that the Carino and Tank maturity function is preferred for the calculation of the maturity indexes. Also, it is found that a linear relationship between the retarder dosage and E or B can be established. Moreover, it is shown that E or B can be estimated by the method suggested by Pinto and Hover. In addition, a new strength-maturity model is suggested. Finally, it is found that the maturity method can be used with efficiency to establish the slipform mockup times, the time of the concrete layer, and the slipform speed.

scholarly journals Modeling of Fatigue-Strength Development in Cold-Emulsion Asphalt Mixtures Using Maturity Method

2019 ◽  
Vol 9 (13) ◽  
pp. 2694 ◽  
Author(s):  
Kiplagat Chelelgo ◽  
Zachary C. Abiero Gariy ◽  
Stanley Muse Shitote
Keyword(s):  
Fatigue Strength ◽  
Cost Effective ◽  
Bending Test ◽  
Strength Development ◽  
Maturity Model ◽  
Reclaimed Asphalt ◽  
Bitumen Emulsion ◽  
Laboratory Characterization ◽  
Maturity Method ◽  
Cure Temperature

Emulsion asphalts are cost-effective, environmentally friendly, and sustainable alternatives to hot-mix asphalts. Laboratory curing protocols currently used to simulate field curing of emulsion asphalts have been observed to offer conflicting predictions. This study employed the maturity method to account for the combined effects of temperature and time on fatigue-strength development in emulsion asphalts. An emulsion asphalt, composed of 55% reclaimed asphalt pavement, 45% virgin aggregates, 6.2% bitumen emulsion, and 4% pre-mix water was designed following the Asphalt Institute procedure. A total of 168 specimens from the mix were variously cured at 5 °C, 25 °C, 40 °C, and 50 °C for time intervals of 1, 3, 5, 7, 14, 21, and 28 days, before being tested for fatigue-strengths on the four-point bending test jig. It was observed that fatigue-strengths increased with an increase in cure temperature but decreased with an increase in cure duration. A parabolic hyperbolic fatigue-maturity model was developed from results of specimens cured at 5 °C, 25 °C, and 40 °C and validated with results from specimens cured at 50 °C. A strong correlation was observed between predicted fatigue-maturity and laboratory-determined fatigue-strengths at test strain levels between 125 µm/m and 200 µm/m. The study concluded that the laboratory characterization of emulsion asphalts should consider the curing history of the mix.

scholarly journals Compressive Strength Gain Behavior and Prediction of Cement-Stabilized Macadam at Low Temperature Curing

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Yongli Xu ◽  
Guang Yang ◽  
Hongyuan Zhao
Keyword(s):  
Compressive Strength ◽  
Low Temperature ◽  
Curing Temperature ◽  
Strength Development ◽  
Construction Process ◽  
Strength Gain ◽  
Estimation Model ◽  
Maturity Method ◽  
Temperature Ranges ◽  
Natural Temperature

For cement-based materials, the curing temperature determines the strength gain rate and the value of compressive strength. In this paper, the 5% cement-stabilized macadam mixture is used. Three indoor controlled temperature curing and one outdoor natural curing scenarios are designed and implemented to study the strength development scenario law of compressive strength, and they are standard temperature curing (20°C), constant low temperature curing (10°C), day interaction temperature curing (varying from 6°C to 16°C), and one outdoor natural temperature curing (in which the air temperature ranges from 4°C to 20°C). Finally, based on the maturity method, the maturity-strength estimation model is obtained by using and analyzing the data collected from the indoor tests. The model is proved with high accuracy based on the validated results obtained from the data of outdoor tests. This research provides technical support for the construction of cement-stabilized macadam in regions with low temperature, which is beneficial in the construction process and quality control.

scholarly journals Control of the setting reaction and strength development of slag-blended volcanic ash-based phosphate geopolymer with the addition of boric acid

2021 ◽  
Author(s):  
Jean Noël Yankwa Djobo ◽  
Dietmar Stephan
Keyword(s):  
Blast Furnace ◽  
Boric Acid ◽  
Blast Furnace Slag ◽  
Volcanic Ash ◽  
Strength Development ◽  
Main Process ◽  
Reaction Products ◽  
Setting Times ◽  
Granulated Blast Furnace Slag ◽  
Furnace Slag

AbstractThis work aimed to evaluate the role of the addition of blast furnace slag for the formation of reaction products and the strength development of volcanic ash-based phosphate geopolymer. Volcanic ash was replaced by 4 and 6 wt% of ground granulated blast furnace slag to accelerate the reaction kinetics. Then, the influence of boric acid for controlling the setting and kinetics reactions was also evaluated. The results demonstrated that the competition between the dissolution of boric acid and volcanic ash-slag particles is the main process controlling the setting and kinetics reaction. The addition of slag has significantly accelerated the initial and final setting times, whereas the addition of boric acid was beneficial for delaying the setting times. Consequently, it also enhanced the flowability of the paste. The compressive strength increased significantly with the addition of slag, and the optimum replaced rate was 4 wt% which resulted in 28 d strength of 27 MPa. Beyond that percentage, the strength was reduced because of the flash setting of the binder which does not allow a subsequent dissolution of the particles and their precipitation. The binders formed with the addition of slag and/or boric acid are beneficial for the improvement of the water stability of the volcanic ash-based phosphate geopolymer.

Performance Characteristics of Concrete Produced with Fluidized Bed Combustion Ash Residue

1988 ◽  
Vol 136 ◽  
Author(s):  
A. E. Bland ◽  
C. E. Jones ◽  
J. G. Rose ◽  
J. L. Harness
Keyword(s):  
Fluidized Bed ◽  
Performance Characteristics ◽  
Strength Development ◽  
Fluidized Bed Combustion ◽  
Portland Cement Concrete ◽  
Conventional Concrete ◽  
Setting Times ◽  
Pulverized Fuel ◽  
Tennessee Valley ◽  
Pulverized Fuel Ash

ABSTRACTOver the last five years, the Kentucky Energy Cabinet (KEC) and the Tennessee Valley Authority (TVA) have developed and demonstrated the production of concrete from atmospheric fluidized bed combustion (AFBC) spent bed (SB) ash, and pulverized fuel ash (PFA). This AFBC concrete contains no cement and relies on the reaction of residual lime in the SB ash to react with the pozzolan PFA to form cementitious products. The SB ash is prehydrated in order to reduce exothermic lime hydration reactions and minimize molar volume expansion. Laboratory tests were conducted to establish the performance characteristics of AFBC concretes relative to conventional concrete. AFBC concretes exhibit slower strength gain characteristics, but long term (60 day), unconfined compressive strengths of 5,000 psi have been documented. This slow strength development is typical of pozzolanic concretes. AFBC concrete is more flexible and less brittle than conventional Portland cement concrete, as evidenced by its much lower modulus of elasticity. Setting times for AFBC concretes are extended, requiring the use of accelerators under certain applications. Field demonstrations of the AFBC concretes in ready mix concrete, masonry units, and road base applications have indicated excellent workability and finishing characteristics and confirm the laboratory performance characteristics.The paper describes the results of the testing program with emphasis on the ash chemistry/conditioning, the performance characteristics and field demonstrations.

scholarly journals Comparative Analysis and Strength Estimation of Fresh Concrete Based on Ultrasonic Wave Propagation and Maturity Using Smart Temperature and PZT Sensors

Micromachines ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 559 ◽  
Author(s):  
Tareen ◽  
Kim ◽  
Kim ◽  
Park
Keyword(s):  
Phase Transition ◽  
Compressive Strength ◽  
Wave Propagation ◽  
Ultrasonic Wave ◽  
Penetration Resistance ◽  
Strength Development ◽  
Early Age ◽  
Ultrasonic Wave Propagation ◽  
Maturity Method ◽  
Concrete Maturity

Recently, the early-age strength prediction for RC (reinforced concrete) structures has been an important topic in the construction industry, relating to project-time reduction and structural safety. To address this, numerous destructive and NDTs (non-destructive tests) are applied to monitor the early-age strength development of concrete. This study elaborates on the NDT techniques of ultrasonic wave propagation and concrete maturity for the estimation of compressive strength development. The results of these comparative estimation approaches comprise the concrete maturity method, penetration resistance test, and an ultrasonic wave analysis. There is variation of the phase transition in the concrete paste with the changing of boundary limitations of the material in accordance with curing time, so with the formation of phase-transition changes, changes in the velocities of ultrasonic waves occur. As the process of hydration takes place, the maturity method produces a maturity index using the time-feature reflection on the strength-development process of the concrete. Embedded smart temperature sensors (SmartRock) and PZT (piezoelectric) sensors were used for the data acquisition of hydration temperature history and wave propagation. This study suggests a novel relationship between wave propagation, penetration tests, and hydration temperature, and creates a method that relies on the responses of resonant frequency changes with the change of boundary conditions caused by the strength-gain of the concrete specimen. Calculating the changes of these features provides a pattern for estimating concrete strength. The results for the specimens were validated by comparing the strength results with the penetration resistance test by a universal testing machine (UTM). An algorithm used to relate the concrete maturity and ultrasonic wave propagation to the concrete compressive strength. This study leads to a method of acquiring data for forecasting in-situ early-age strength of concrete, used for secure construction of concrete structures, that is fast, cost effective, and comprehensive for SHM (structural health monitoring).

Prediction of the Strength Development of Fly Ash Concrete

2010 ◽  
Vol 150-151 ◽  
pp. 1026-1033 ◽  
Author(s):  
Ming Hui Liu ◽  
Yuan Feng Wang
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Concrete Strength ◽  
Strength Development ◽  
Standard Temperature ◽  
Development Models ◽  
Fly Ash Concrete ◽  
Strength Tests ◽  
Maturity Method ◽  
Predicted Model

The effect of fly ash in improving the mechanical properties of concrete is investigated and the existing concrete strength development models are studied. Based on the chemic reactivity properties between fly ash and cement, an appropriate concrete strength model are chosen, and a new model for the fly ash strength factor combing Maturity method is built up and the factors are regressed by existing experimental datum. A total of 24 concretes, including two concretes were produced with two partial fly ash replacement ratios (23.7%, 32.7%). The cubic samples produced from ash fly concrete were demoulded after a day, and cured at standard temperature ( in GB/T 50081-2002) with 100% relative humidity until 28 days, then cured in water. The compressive strength tests were carried out on the cubic specimens at different ages. The compressive strength with time was evaluated by using the new predicted model. It was found that the calculated results by new method are fit the experimental data well.

scholarly journals A Study on Initial Setting and Modulus of Elasticity of AAM Mortar Mixed with CSA Expansive Additive Using Ultrasonic Pulse Velocity

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4432
Author(s):  
Gum-Sung Ryu ◽  
Sung Choi ◽  
Kyung-Taek Koh ◽  
Gi-Hong Ahn ◽  
Hyeong-Yeol Kim ◽  
...  
Keyword(s):  
Modulus Of Elasticity ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Static Modulus ◽  
Setting Times ◽  
Initial Setting ◽  
Expansive Additive ◽  
Static Modulus Of Elasticity ◽  
Initial Reactivity

This study investigated the hardening process of alkali-activated material (AAM) mortar using calcium sulfoalumiante (CSA) expansive additive (CSA EA), which accelerates the initial reactivity of AAMs, and subsequent changes in ultrasonic pulse velocity (UPV). After the AAM mortar was mixed with three different contents of CSA EA, the setting and modulus of elasticity of the mortar at one day of age, which represent curing steps, were measured. In addition, UPV was used to analyze each curing step. The initial and final setting times of the AAM mortar could be predicted by analyzing the UPV results measured for 14 h. In addition, the dynamic modulus of elasticity calculated using the UPV results for 24 h showed a tendency similar to that of the static modulus of elasticity. The test results showed that the use of CSA EA accelerated the setting of the AAM mortar and increased the modulus of elasticity, and these results could be inferred using UPV. The proposed measurement method can be effective in evaluating the properties of a material that accelerates the initial reactivity.

scholarly journals Slurry Preparation Effects on the Cemented Phosphogypsum Backfill through an Orthogonal Experiment

Minerals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 31 ◽  
Author(s):  
Xibing Li ◽  
Yanan Zhou ◽  
Quanqi Zhu ◽  
Shitong Zhou ◽  
Chendi Min ◽  
...  
Keyword(s):  
Orthogonal Experiment ◽  
Dominant Role ◽  
Solid Content ◽  
Strength Development ◽  
Range Analysis ◽  
Setting Times ◽  
Stirring Time ◽  
Binder Ratio ◽  
Four Levels ◽  
Slurry Preparation

The cemented phosphogypsum (PG) backfill technique provides a new method for massive consumption of PG, and therefore alleviating the environmental pollution of PG. This study considered the effects of slurry preparation on the performance of cemented PG backfill. A L16(44) orthogonal experiment was designed to analyze four factors, namely the solid content, phosphogypsum-to-binder ratio (PG/B ratio), stirring time and stirring speed, with each factor having four levels. According to the range analysis, the solid content played the dominant role in controlling the bleeding rate, while the setting times strongly depended on the PG/B ratio. In terms of strength development of the backfill, the PG/B ratio was shown to be the most significant factor determining the unconfined compressive strength (UCS), followed by the solid content, stirring time and stirring speed. Furthermore, the results showed that the slurry preparation affected the environmental behavior of impurities that originated in PG. By analyzing the concentrations of impurities in the bleeding water of the slurry as well as the leachates of the tank leaching test, the results showed that the release of F− and SO42− was aggravated clearly with the increase in the PG/B ratio, while the release of PO43− always remained at relatively low levels.

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