Setting time and strength monitoring of alkali-activated cement mixtures by ultrasonic testing
- Tekle, Biruk, Hertwig, Ludwig, Holschemacher, Klaus
- Authors: Tekle, Biruk , Hertwig, Ludwig , Holschemacher, Klaus
- Date: 2021
- Type: Text , Journal article
- Relation: Materials Vol. 14, no. 8 (2021), p. 1889
- Full Text:
- Reviewed:
- Description: 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.
- Authors: Tekle, Biruk , Hertwig, Ludwig , Holschemacher, Klaus
- Date: 2021
- Type: Text , Journal article
- Relation: Materials Vol. 14, no. 8 (2021), p. 1889
- Full Text:
- Reviewed:
- Description: 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.
Association between leg power and sprinting technique with 20-m sprint performance in elite junior australian football players
- Young, Warren, Grace, Steve, Talpey, Scott
- Authors: Young, Warren , Grace, Steve , Talpey, Scott
- Date: 2014
- Type: Text , Journal article
- Relation: International Journal of Sports Science and Coaching Vol. 9, no. 5 (2014), p. 1153-1160
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- Reviewed:
- Description: The main purpose of this study was to determine the association between leg power and sprint technique with 20-m sprint performance. Seventy-seven elite junior Australian Rules football players were assessed on a 20-m sprint test, a countermovement jump (CMJ) and a two bound test, and on a new method of quantifying sprint technique from simple video recordings. Technique assessment involved rating 14 points on a scale from 1-5. Players were median-split into faster and slower groups based on their 20-m times, and they were compared for differences in leg power and technique. The faster group was significantly better (p<0.05) in the two-bound test (5.2%) and the technique score (8.2%), but not in the CMJ (p>0.05). A multiple regression indicated that the two-bound test and technique accounted for 37.7% of the variance associated with the 20-m sprint time (p<0.05). It was concluded that the technique assessment tool captured some important characteristics of 20-m sprint performance and could potentially be used to profile or monitor athletes. Further the two-bound test is a more relevant test for developing athletes because of its specificity to sprinting, compared to the CMJ.
- Authors: Young, Warren , Grace, Steve , Talpey, Scott
- Date: 2014
- Type: Text , Journal article
- Relation: International Journal of Sports Science and Coaching Vol. 9, no. 5 (2014), p. 1153-1160
- Full Text:
- Reviewed:
- Description: The main purpose of this study was to determine the association between leg power and sprint technique with 20-m sprint performance. Seventy-seven elite junior Australian Rules football players were assessed on a 20-m sprint test, a countermovement jump (CMJ) and a two bound test, and on a new method of quantifying sprint technique from simple video recordings. Technique assessment involved rating 14 points on a scale from 1-5. Players were median-split into faster and slower groups based on their 20-m times, and they were compared for differences in leg power and technique. The faster group was significantly better (p<0.05) in the two-bound test (5.2%) and the technique score (8.2%), but not in the CMJ (p>0.05). A multiple regression indicated that the two-bound test and technique accounted for 37.7% of the variance associated with the 20-m sprint time (p<0.05). It was concluded that the technique assessment tool captured some important characteristics of 20-m sprint performance and could potentially be used to profile or monitor athletes. Further the two-bound test is a more relevant test for developing athletes because of its specificity to sprinting, compared to the CMJ.
Movement demands in Australian Rules football as indicators of muscle damage
- Young, Warren, Hepner, Jamie, Robbins, Daniel
- Authors: Young, Warren , Hepner, Jamie , Robbins, Daniel
- Date: 2012
- Type: Text , Journal article
- Relation: Journal of Strength and Conditioning Research Vol. 26, no. 2 (2012), p. 492-496
- Full Text:
- Reviewed:
- Description: The purpose of this study was to determine if there is an association between variables that describe movements in an Australian Rules football (ARF) game with muscle damage. Fourteen elite junior ARF players were monitored with a global positioning system (GPS) during a match, and muscle damage was estimated by determining creatine kinase (CK) 24 hours postmatch. The players were median split based on CK levels, into a high and low CK group, and the groups were compared with independent t-tests. The primary finding was that the group that experienced greater muscle damage (high CK group) generally covered significantly (p < 0.05) greater distances. This was the case for running speeds between 4 and 7 m·s -1 and, with the exception of high acceleration, all intensities of acceleration and deceleration. The high, as compared with the low, CK group also produced a significantly greater (42%) "player load." All of these significant differences were accompanied by large effect sizes. Group-specific Pearson (r) correlations between CK level and GPS variables suggest that a certain volume of movement is required before the elicitation of a positive relationship beyond trivial or small. Correlations between CK and running speeds >4 m·s -1 and moderate-high acceleration and deceleration were negative in the low CK (lesser volumes) group. With the exception of low-intensity acceleration/deceleration, the same relationships were positive and generally of a moderate-to-large magnitude in the high CK (greater volumes) group. It may be that a certain volume of movement is required for that movement to be strongly associated with CK levels. It was concluded that selected GPS variables obtained from ARF games can be used as indicators of muscle damage, and this information may be used to individualize recovery strategies after games. © 2012 National Strength and Conditioning Association.
- Authors: Young, Warren , Hepner, Jamie , Robbins, Daniel
- Date: 2012
- Type: Text , Journal article
- Relation: Journal of Strength and Conditioning Research Vol. 26, no. 2 (2012), p. 492-496
- Full Text:
- Reviewed:
- Description: The purpose of this study was to determine if there is an association between variables that describe movements in an Australian Rules football (ARF) game with muscle damage. Fourteen elite junior ARF players were monitored with a global positioning system (GPS) during a match, and muscle damage was estimated by determining creatine kinase (CK) 24 hours postmatch. The players were median split based on CK levels, into a high and low CK group, and the groups were compared with independent t-tests. The primary finding was that the group that experienced greater muscle damage (high CK group) generally covered significantly (p < 0.05) greater distances. This was the case for running speeds between 4 and 7 m·s -1 and, with the exception of high acceleration, all intensities of acceleration and deceleration. The high, as compared with the low, CK group also produced a significantly greater (42%) "player load." All of these significant differences were accompanied by large effect sizes. Group-specific Pearson (r) correlations between CK level and GPS variables suggest that a certain volume of movement is required before the elicitation of a positive relationship beyond trivial or small. Correlations between CK and running speeds >4 m·s -1 and moderate-high acceleration and deceleration were negative in the low CK (lesser volumes) group. With the exception of low-intensity acceleration/deceleration, the same relationships were positive and generally of a moderate-to-large magnitude in the high CK (greater volumes) group. It may be that a certain volume of movement is required for that movement to be strongly associated with CK levels. It was concluded that selected GPS variables obtained from ARF games can be used as indicators of muscle damage, and this information may be used to individualize recovery strategies after games. © 2012 National Strength and Conditioning Association.
Agility literature review : Classifications, training and testing
- Sheppard, Jeremy, Young, Warren
- Authors: Sheppard, Jeremy , Young, Warren
- Date: 2006
- Type: Text , Journal article
- Relation: Journal of Sports Sciences Vol. 24, no. 9 (Sep 2006), p. 919-932
- Full Text:
- Reviewed:
- Description: At present, no agreement on a precise definition of agility within the sports science community exists. The term is applied to a broad range of sport contexts, but with such great inconsistency, it further complicates our understanding of what trainable components may enhance agility. A new definition of agility is proposed: "a rapid whole-body movement with change of velocity or direction in response to a stimulus". Agility has relationships with trainable physical qualities such as strength, power and technique, as well as cognitive components such as visual-scanning techniques, visual-scanning speed and anticipation. Agility testing is generally confined to tests of physical components such as change of direction speed, or cognitive components such as anticipation and pattern recognition. New tests of agility that combine physical and cognitive measures are encouraged.
- Description: C1
- Description: 2003002129
- Authors: Sheppard, Jeremy , Young, Warren
- Date: 2006
- Type: Text , Journal article
- Relation: Journal of Sports Sciences Vol. 24, no. 9 (Sep 2006), p. 919-932
- Full Text:
- Reviewed:
- Description: At present, no agreement on a precise definition of agility within the sports science community exists. The term is applied to a broad range of sport contexts, but with such great inconsistency, it further complicates our understanding of what trainable components may enhance agility. A new definition of agility is proposed: "a rapid whole-body movement with change of velocity or direction in response to a stimulus". Agility has relationships with trainable physical qualities such as strength, power and technique, as well as cognitive components such as visual-scanning techniques, visual-scanning speed and anticipation. Agility testing is generally confined to tests of physical components such as change of direction speed, or cognitive components such as anticipation and pattern recognition. New tests of agility that combine physical and cognitive measures are encouraged.
- Description: C1
- Description: 2003002129
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