Cellular Automata Approach to Hydration Heat of Concrete Based on Equivalent Time

2020 ◽  
Vol 982 ◽  
pp. 181-188
Author(s):  
Yi Liu ◽  
Yue Ting Yang ◽  
Ling Chen ◽  
Jing Zeng
Keyword(s):  
Cellular Automata ◽  
Ambient Temperature ◽  
Temperature Rise ◽  
Concrete Slab ◽  
Hydration Heat ◽  
Slab Thickness ◽  
Adiabatic Temperature Rise ◽  
Equivalent Time ◽  
Arrhenius Function ◽  
The Relationship

Cellular automata can be used to analyze a physical system which is satisfying differential equations. A cellular automata program for a thermal analysis of hydration heat was developed. Based on the fundamental theory of cellular automata, the heat conduction equation was deduced for validating the cellular automata approach. By introduction of the concept of equivalent time, the variation of the chemical reaction rate of hydration heat with temperature was studied by use of the Arrhenius function. The relationship between the adiabatic temperature rise and equivalent time was determined by analyzing testing data．A parametric analysis of ambient temperature and concrete slab thickness was also conducted. The temperature rise of concrete increases with increasing ambient temperature and thickness of the slab.

Test of Thermal Capability to Rubber Concrete

2011 ◽  
Vol 250-253 ◽  
pp. 746-749
Author(s):  
Ling Qiang Yang ◽  
Li Wei Zhang ◽  
Rui Gao
Keyword(s):  
Thermal Conductivity ◽  
Temperature Rise ◽  
Coarse Aggregate ◽  
Bridge Pier ◽  
Adiabatic Temperature ◽  
Adiabatic Temperature Rise ◽  
The Relationship ◽  
Rubber Concrete

Through a series of tests of thermal capability to rubber concrete, we get the adiabatic temperature rise curve and hydration temperature curves with different amount rubber in concrete. It revealed the relationship between amount of rubber and thermal conductivity of rubber concrete. Large rubber pieces should be used to replace coarse aggregate in protection concrete of sluice pier and bridge pier.

An improved estimate for the critical parameter value in a thermal explosion

1981 ◽  
Vol 377 (1771) ◽  
pp. 469-476
Keyword(s):  
Ambient Temperature ◽  
Thermal Explosion ◽  
Temperature Rise ◽  
Critical Parameter ◽  
Loss Rate ◽  
Critical Concentration ◽  
Critical Value ◽  
Adiabatic Temperature Rise ◽  
Heat Loss Rate ◽  
Initial Reactant

In an earlier paper (Carter et al . 1979), estimates and bounds were derived for the critical initial reactant concentration in a thermal explosion with reactant consumption. In this paper, a greatly improved estimate for the critical concentration is obtained and its accuracy investigated. Arising from this, an excellent approximation is obtained for the relation between the critical value of the parameter a (expressing heat loss rate), the dimensionless adiabatic temperature rise B and the dimensionless ambient temperature ε. For ε = 0, this approximation is much closer to the known exact curve than any previously obtained estimates.

Thermal Characteristics of Mat Foundation with Different Lift Thickness of Mass Concrete Including Strontium-Based Latent Heat Binder

2014 ◽  
Vol 525 ◽  
pp. 461-464
Author(s):  
Kyung Lim Ahn ◽  
Qi Bo Liang ◽  
Bae Su Khil ◽  
Hyun Do Yun
Keyword(s):  
Latent Heat ◽  
Temperature Rise ◽  
Volume Fraction ◽  
Heat Of Hydration ◽  
Adiabatic Temperature ◽  
Hydration Heat ◽  
Mass Concrete ◽  
Adiabatic Temperature Rise ◽  
Concrete Foundation ◽  
Mat Foundation

This study provides analytical results for heat of hydration in the mat foundation with mass concretes to investigate the effect of lift thickness in the mat foundation on the hydration heat and crack characteristics of mat foundation with mass concrete. Mass concretes were mixed with ternary cement with 1% strontium-based latent heat binder at volume fraction and Type IV low heat cement. The mat foundation has the dimension of 15m length, 20m width and 3m depth. Lift thickness of mass concrete for mat foundation was varied from 1.0m to 3.0m. A commercial software MIDAS/Gen was used to analyze the hydration heat of mass concrete foundation. The maximum adiabatic temperature rise (K), and the coefficient of temperature rise (α) for thermal analysis were drawn from adiabatic temperature rise test. Based on the results of the finite element analysis for mat foundation with different lift thickness, the highest internal temperature and thermal stress increased with increasing with lift thickness of foundation. However, for foundation constructed with premixed strontium based latent heat binder (PSLB) concrete, this phenomenon was less remarkable compared to mass concrete foundation made with low heat cement.

scholarly journals A Study on Relationship Between the Heat Release of Later-age Concrete and the Concrete Strength Development

2016 ◽  
Vol 10 (1) ◽  
pp. 363-368 ◽  
Author(s):  
Zhenyang Zhu ◽  
Weimin Chen ◽  
Zhiqiang Xie ◽  
Guoxin Zhang
Keyword(s):  
Heat Release ◽  
Temperature Rise ◽  
Concrete Strength ◽  
Adiabatic Temperature ◽  
Hydration Heat ◽  
Strength Development ◽  
Early Age ◽  
Testing Device ◽  
Adiabatic Temperature Rise ◽  
Early Age Concrete

The adiabatic temperature rise of early-age concrete can be precisely tested by the device. However, the insufficient accuracy of testing device can lead to inaccurate measurements of adiabatic temperature rise of later-age concrete. The purpose of this paper is to create a model to predict the hydration heat of later-age concrete. Based on the previous studies, it is known that the heat release of the concrete is accomplished with the increment of the concrete strength and concrete strength can be accurately measured. Thus, a preliminary later-age hydration heat model was established. The correction of the model was verified through experiments.

scholarly journals Effects of Steel Slag Powder and Expansive Agent on the Properties of Ultra-High Performance Concrete (UHPC): Based on a Case Study

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 683
Author(s):  
Shunkai Li ◽  
Shukai Cheng ◽  
Liwu Mo ◽  
Min Deng
Keyword(s):  
Temperature Rise ◽  
High Performance ◽  
High Performance Concrete ◽  
Steel Slag ◽  
Adiabatic Temperature ◽  
Hydration Heat ◽  
Ultra High Performance Concrete ◽  
Adiabatic Temperature Rise ◽  
Slag Powder ◽  
Steel Slag Powder

In view of the performance requirements of mass ultra-high performance concrete (UHPC) for the Pang Gong bridge steel cable tower in China, the UHPC incorporating of steel slag powder and hybrid expansive agents is optimized and prepared. The effects of steel slag powder and hybrid expansive agents on the hydration characteristics and persistent shrinkage of UHPC are investigated. The results indicate that 15 wt.% steel slag powder and 5 wt.% hybrid expansive agents can effectively reduce the drying shrinkage deformation of UHPC with a slight decrease of strength. Heat flow calorimetry results show that the incorporation of steel slag powder and expansive agents decreases the hydration heat at three days. Moreover, the obtained adiabatic temperature rise of UHPC is 59.5 °C and the total shrinkage value at 180 days is 286 με. The hydration heat release changes of large volume UHPC in the steel-concrete section of cable tower is agreed with the result of adiabatic temperature rise in the laboratory.

Effect of Shrinkage Reducing Admixture on Shrinkage and Crack Properties of Cement Based Materials

2019 ◽  
Vol 814 ◽  
pp. 387-392
Author(s):  
Yan Yao ◽  
Hao Wu ◽  
Ling Wang ◽  
Rui Jun Gao
Keyword(s):  
Calcium Hydroxide ◽  
Temperature Rise ◽  
Cement Hydration ◽  
Adiabatic Temperature ◽  
Hydration Heat ◽  
Hydration Process ◽  
Cement Pastes ◽  
Adiabatic Temperature Rise ◽  
Cement Based Materials ◽  
Shrinkage Reducing Admixture

In order to improve the dimensional stability of cement based materials, the effects of shrinkage reducing admixture (SRA) dosage on the shrinkage and crack properties of cement based materials were investigated. The hydration process of the cement pastes was tracked and monitored by hydration calorimeter and adiabatic temperature rise apparatus respectively. The action mechanism of SRA on hydration process of the cement based materials was characterized by differential scanning calorimeter (DSC). The shrinkage and crack results show that the ability of resist cracking of concrete can be effectively improved by SRA. The results of hydration calorimeter and adiabatic temperature rise indicate that the appear time of hydration temperature peak at early age was delayed and the development of hydration heat changed gently at later period by doped SRA. The results of DSC show that the release amount of hydration heat and the production of early calcium hydroxide can be delayed by SRA, however, there has no effects of SRA on the formation of cement hydration products like calcium hydroxide at the later period.

The Influence of Slab Concreting Sequence on a Continuous Composite Girder Bridge

2016 ◽  
Vol 691 ◽  
pp. 96-107
Author(s):  
Tomas J. Zivner ◽  
Rudolf B. Aroch ◽  
Michal M. Fabry
Keyword(s):  
Concrete Slab ◽  
Transverse Cross Section ◽  
Slab Thickness ◽  
Slab Width ◽  
Composite Girder ◽  
Steel Members ◽  
Composite Bridge ◽  
Bridge Girder ◽  
Girder Bridge ◽  
Main Girder

This paper deals with the slab concreting sequence and its influence on a composite steel and concrete continuous highway girder bridge. The bridge has a symmetrical composite two-girder structure with three spans of 60 m, 80 m, 60 m (i.e. a total length between abutments of 200.0 m). The horizontal alignment is straight. The top face of the deck is flat. The bridge is straight. The transverse cross-section of the slab is symmetrical with respect to the axis of the bridge. The total slab width is 12 m. The slab thickness varies from 0.4 m on main girders to 0.25 m at its free edges and 0.3075 m at its axis of symmetry. The center-to-center spacing between main girders is 7 m and the slab cantilever on either side is 2.5 m long. Every main girder has a constant depth of 2800 mm and the thicknesses of the upper and lower flanges are variable. The lower flange is 1200 mm wide whereas the upper flange is 1000 mm wide. The two main girders have transverse bracing at abutments and at internal supports and at regular intervals in every span. The material of concrete slab is C35/45 and of steel members S355. The on-site pouring of the concrete slab segments is performed by casting them in a selected order and is done after the launching of the steel two girder bridge. The paper presents several concreting sequences and their influence on the normal stresses and deflections of the composite bridge girder.

scholarly journals Changes in ambient temperature increase hospital outpatient visits for allergic rhinitis in Xinxiang, China

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Jianhui Gao ◽  
Mengxue Lu ◽  
Yinzhen Sun ◽  
Jingyao Wang ◽  
Zhen An ◽  
...  
Keyword(s):  
Allergic Rhinitis ◽  
Ambient Temperature ◽  
Positive Association ◽  
Ambient Air ◽  
Ambient Air Pollution ◽  
Hospital Outpatient ◽  
Distributed Lag ◽  
Outpatient Visits ◽  
Daily Data ◽  
The Relationship

Abstract Background The effect of ambient temperature on allergic rhinitis (AR) remains unclear. Accordingly, this study aimed to explore the relationship between ambient temperature and the risk of AR outpatients in Xinxiang, China. Method Daily data of outpatients for AR, meteorological conditions, and ambient air pollution in Xinxiang, China were collected from 2015 to 2018. The lag-exposure-response relationship between daily mean temperature and the number of hospital outpatient visits for AR was analyzed by distributed lag non-linear model (DLNM). Humidity, long-time trends, day of the week, public holidays, and air pollutants including sulfur dioxide (SO2), and nitrogen dioxide (NO2) were controlled as covariates simultaneously. Results A total of 14,965 AR outpatient records were collected. The relationship between ambient temperature and AR outpatients was generally M-shaped. There was a higher risk of AR outpatient when the temperature was 1.6–9.3 °C, at a lag of 0–7 days. Additionally, the positive association became significant when the temperature rose to 23.5–28.5 °C, at lag 0–3 days. The effects were strongest at the 25th (7 °C) percentile, at lag of 0–7 days (RR: 1.32, 95% confidence intervals (CI): 1.05–1.67), and at the 75th (25 °C) percentile at a lag of 0–3 days (RR: 1.15, 95% CI: 1.02–1.29), respectively. Furthermore, men were more sensitive to temperature changes than women, and the younger groups appeared to be more influenced. Conclusions Both mild cold and mild hot temperatures may significantly increase the risk of AR outpatients in Xinxiang, China. These findings could have important public health implications for the occurrence and prevention of AR.

scholarly journals Study on the Relationship between Electrical Tree Development and Partial Discharge of XLPE Cables

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Chaofei Gao ◽  
Yanlong Yu ◽  
Zan Wang ◽  
Wei Wang ◽  
Liwei Zheng ◽  
...  
Keyword(s):  
Statistical Characteristics ◽  
Time Frequency ◽  
Experimental Platform ◽  
Equivalent Time ◽  
Electrical Tree ◽  
Electrical Trees ◽  
Insulation Breakdown ◽  
The Relationship ◽  
Frequency Diagram ◽  
Tree Development

Based on the slice materials of 35 kV and 110 kV XLPE cables, an experimental platform is built to study the relationship between electrical tree and PDs in XLPE with different voltage levels. There are three significant statistical characteristics of the PDs during the growth of electrical trees. The analysis of the results shows that each growth stage has certain characteristics. Different features existed between the growth of the electrical trees and the PD in the insulation of the 35 and 110 kV cables. Evident characteristics such as large spans of time and frequency were present as the electrical trees grew violently in the equivalent time-frequency diagram at every stage. These results could provide criteria for the identification of the deterioration using PD to monitor cables in service at rated voltages. The results are important for the identification of defects in cable insulation in order to provide an early warning of insulation breakdown in the cables.

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