scholarly journals Effects of Climatic Conditions and Temperature Gradient on Jointed Plain Concrete Pavement Slabs

2021 ◽  
Vol 9 (9) ◽  
pp. 1974-1980
Author(s):  
Fathima Basha C S
Keyword(s):  
Temperature Gradient ◽  
High Performance ◽  
Concrete Slab ◽  
Plain Concrete ◽  
Climatic Conditions ◽  
Effect Of Temperature ◽  
Cement Concrete ◽  
Goods And Services ◽  
Rigid Pavements ◽  
Bituminous Pavements

Abstract: A long lasting, reliable and economical transportation system is a critical component for the continuous movement of goods and services. Rigid pavements are widely used in construction world due to its high performance and serviceability. Traditional bituminous pavements and their needs for continuous maintenance and rehabilitation operations point towards the scope for cement concrete pavements. Cement concrete slab in a rigid pavement structure are exposed to different conditions at the surface in comparison to the bottom due to daily temperature fluctuations and results in the formation of temperature gradients in the slab. Transient gradients are due to the seasonal changes to which the slabs are subjected whereas permanent gradients are due to the slab condition during the setting of slab. The objective of this study is to determine the effect of temperature gradient and climatic conditions on a jointed plain concrete (JPC) pavement slab and to establish a proper temperature gradient chart which can be referred to depending on the climatic conditions existing in Kerala. A properly designed slab can reduce the formation of cracks and hence increase the life of slab. A detailed study in this area, can help in forming some codal provisions for the design of pavement slab depending upon the climatic conditions of Kerala. Keywords: Rigid Pavements, Bituminous pavements, Jointed Plain Concrete (JPC), Permanent gradients, Temperature Gradient

Research of Zero Stress Temperature Gradient in Cement Concrete Pavement

2013 ◽  
Vol 723 ◽  
pp. 163-170 ◽  
Author(s):  
Xiang Shen Hou ◽  
Xin Kai Li ◽  
Bo Peng ◽  
Guang Hui Deng
Keyword(s):  
Temperature Gradient ◽  
Concrete Beam ◽  
Concrete Slab ◽  
Strain Sensor ◽  
Concrete Pavement ◽  
Early Age ◽  
Cement Concrete ◽  
Setting Process ◽  
Cement Concrete Pavement ◽  
Design Guidance

There is no temperature stress and temperature curling according to the present cement concrete pavement design, when the temperature gradient of cement concrete pavement in service is zero, and it does not consider the effect of Built-in curling caused in early-age setting process of cement concrete to cement concrete pavement in service. In fact, there is Built-in curling in cement concrete slab when it is after the completion of the cement concrete slab is poured, and the curling is mainly upward. It is in the setting process, when cement concrete is on the final set, the cement concrete is at the critical moment when is just able to bear load, and it exists temperature gradient but no strain in the pavement slab, the temperature gradient is known as "Built-in construction temperature gradient" in AASHTO2002 design guidance, and it is the important part of the Built-in curling. In this paper, cement concrete beam specimens were poured in outdoor and temperature sensor and strain sensor were buried in the cement concrete specimens to detect early-age internal temperature field and strain field, and then the study of Built-in curling and Built-in construction temperature gradient were carried out.

scholarly journals Experimental Investigation on Fibre Reinforced Concrete Pavement Slabs Subjected to Temperature Gradient

2021 ◽  
Vol 9 (9) ◽  
pp. 1967-1973
Author(s):  
Nandini Nair
Keyword(s):  
Reinforced Concrete ◽  
Temperature Gradient ◽  
Structural Integrity ◽  
Concrete Slab ◽  
Heavy Traffic ◽  
Ride Quality ◽  
Fibre Reinforced Concrete ◽  
Coir Fibre ◽  
Rigid Pavements ◽  
Improved Performance

Abstract: A long lasting, reliable and economical transportation system is a critical component for the continuous movement of heavy traffic. Rigid pavements are made of concrete are widely for land transportation used because of its increased life, strength and it provides efficient movement of heavy traffic. Concrete is a brittle material and its low tensile strength leads to the formation of cracks, which is one of the main reason of concrete failure. Addition of fibre prevents the crack formation because fibres are crack arresters. Fibre addition increases the structural integrity of the pavement. Concrete slab in pavement structure experiences daily temperature fluctuations and results in the formation of temperature gradients in the slab. The objective of this study is to investigate the material properties of the three different fibres used in pavement slabs subjected to temperature gradient and the fibres used is coir fibre. Reduced cracks ensure pavement durability, reduced maintenance, improved performance, improved performance and ride quality. Keywords: Rigid pavements, Fibre Reinforced Concrete (FRC), Coir Fibre, Temperature Gradient, Pavement Slab.

scholarly journals Analysis of temperature gradient in concrete pavement

2018 ◽  
Vol 67 (4) ◽  
pp. 59-70
Author(s):  
Grzegorz Rogojsz
Keyword(s):  
Thermal Stress ◽  
Temperature Distribution ◽  
Temperature Gradient ◽  
Air Temperature ◽  
Experimental Research ◽  
Analytical Methods ◽  
Concrete Slab ◽  
Climatic Conditions ◽  
Concrete Pavement

The paper presents the results of experimental research that is the continuation of the research conducted as a part of a Ph.D. dissertation. The experimental research consisted in measuring the temperature at various depths inside a concrete slab, including its surface, and measuring the air temperature. The temperature distribution was measured on a concrete slab with dimensions similar to real road slab dimensions. The aim of the research was to determine the temperature gradient in the concrete slab in Polish climatic conditions and to verify the available analytical methods. Keywords: temperature gradient, concrete pavement, thermal stress in concrete pavement.

scholarly journals Functional response of Harmonia axyridis preying on Acyrthosiphon pisum nymphs: the effect of temperature

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yasir Islam ◽  
Farhan Mahmood Shah ◽  
Xu Rubing ◽  
Muhammad Razaq ◽  
Miao Yabo ◽  
...  
Keyword(s):  
Functional Response ◽  
High Performance ◽  
Acyrthosiphon Pisum ◽  
Harmonia Axyridis ◽  
Effect Of Temperature ◽  
Functional Responses ◽  
Aphid Control ◽  
Host Aphid ◽  
Predator Foraging

AbstractIn the current study, we investigated the functional response of Harmonia axyridis adults and larvae foraging on Acyrthosiphon pisum nymphs at temperatures between 15 and 35 °C. Logistic regression and Roger’s random predator models were employed to determine the type and parameters of the functional response. Harmonia axyridis larvae and adults exhibited Type II functional responses to A. pisum, and warming increased both the predation activity and host aphid control mortality. Female and 4th instar H. axyridis consumed the most aphids. For fourth instar larvae and female H. axyridis adults, the successful attack rates were 0.23 ± 0.014 h−1 and 0.25 ± 0.015 h−1; the handling times were 0.13 ± 0.005 h and 0.16 ± 0.004 h; and the estimated maximum predation rates were 181.28 ± 14.54 and 153.85 ± 4.06, respectively. These findings accentuate the high performance of 4th instar and female H. axyridis and the role of temperature in their efficiency. Further, we discussed such temperature-driven shifts in predation and prey mortality concerning prey-predator foraging interactions towards biological control.

scholarly journals Effect of the Geometrical Constraints to the Wenner Four-Point Electrical Resistivity Test of Reinforced Concrete Slabs

Sensors ◽  
2021 ◽  
Vol 21 (13) ◽  
pp. 4622
Author(s):  
Kevin Paolo V. Robles ◽  
Jurng-Jae Yee ◽  
Seong-Hoon Kee
Keyword(s):  
Experimental Investigation ◽  
Electrical Resistivity ◽  
Reinforced Concrete ◽  
Concrete Slab ◽  
Plain Concrete ◽  
Electrode Spacing ◽  
Concrete Slabs ◽  
Reinforced Concrete Slabs ◽  
Spacing Ratio ◽  
Geometrical Constraints

The main objectives of this study are to evaluate the effect of geometrical constraints of plain concrete and reinforced concrete slabs on the Wenner four-point concrete electrical resistivity (ER) test through numerical and experimental investigation and to propose measurement recommendations for laboratory and field specimens. First, a series of numerical simulations was performed using a 3D finite element model to investigate the effects of geometrical constraints (the dimension of concrete slabs, the electrode spacing and configuration, and the distance of the electrode to the edges of concrete slabs) on ER measurements of concrete. Next, a reinforced concrete slab specimen (1500 mm (width) by 1500 mm (length) by 300 mm (thickness)) was used for experimental investigation and validation of the numerical simulation results. Based on the analytical and experimental results, it is concluded that measured ER values of regularly shaped concrete elements are strongly dependent on the distance-to-spacing ratio of ER probes (i.e., distance of the electrode in ER probes to the edges and/or the bottom of the concrete slabs normalized by the electrode spacing). For the plain concrete, it is inferred that the thickness of the concrete member should be at least three times the electrode spacing. In addition, the distance should be more than twice the electrode spacing to make the edge effect almost negligible. It is observed that the findings from the plain concrete are also valid for the reinforced concrete. However, for the reinforced concrete, the ER values are also affected by the presence of reinforcing steel and saturation of concrete, which could cause disruptions in ER measurements

scholarly journals High-Performance Lead-Acid Batteries Enabled by Pb and PbO2 Nanostructured Electrodes: Effect of Operating Temperature

2021 ◽  
Vol 11 (14) ◽  
pp. 6357
Author(s):  
Roberto Luigi Oliveri ◽  
Maria Grazia Insinga ◽  
Simone Pisana ◽  
Bernardo Patella ◽  
Giuseppe Aiello ◽  
...  
Keyword(s):  
High Performance ◽  
Active Material ◽  
Active Surface ◽  
Effect Of Temperature ◽  
Active Surface Area ◽  
Polycarbonate Membrane ◽  
Nanostructured Electrodes ◽  
Lead Acid Batteries ◽  
Improved Stability ◽  
Lead Acid

Lead-acid batteries are now widely used for energy storage, as result of an established and reliable technology. In the last decade, several studies have been carried out to improve the performance of this type of batteries, with the main objective to replace the conventional plates with innovative electrodes with improved stability, increased capacity and a larger active surface. Such studies ultimately aim to improve the kinetics of electrochemical conversion reactions at the electrode-solution interface and to guarantee a good electrical continuity during the repeated charge/discharge cycles. To achieve these objectives, our contribution focuses on the employment of nanostructured electrodes. In particular, we have obtained nanostructured electrodes in Pb and PbO2 through electrosynthesis in a template consisting of a nanoporous polycarbonate membrane. These electrodes are characterized by a wider active surface area, which allows for a better use of the active material, and for a consequent increased specific energy compared to traditional batteries. In this research, the performance of lead-acid batteries with nanostructured electrodes was studied at 10 C at temperatures of 25, −20 and 40 °C in order to evaluate the efficiency and the effect of temperature on electrode morphology. The batteries were assembled using both nanostructured electrodes and an AGM-type separator used in commercial batteries.

Pursuit of Operational Excellence

2016 ◽  
Vol 3 (2) ◽  
pp. 21-34
Author(s):  
Christine Welch ◽  
Tammi Sinha ◽  
Nigel Ward
Keyword(s):  
Change Management ◽  
Continuous Improvement ◽  
High Performance ◽  
Effective Leadership ◽  
Value Systems ◽  
Goods And Services ◽  
Team Working ◽  
Performance Teams ◽  
Operational Excellence

Operational Excellence (OE) is achieved when high performance teams are seeking for continuous improvement in well-designed processes, using appropriate tools and technologies. Excellence is underpinned by a philosophy in which problem-solving, team-working and effective leadership combine to focus upon customer needs, and all employees are empowered to act to maintain optimal flows of value. OE is clearly a desirable quality of organizations seeking both effectiveness and efficiency in their production of goods and services for customers. OE is underpinned by concepts such as team-working, effective leadership and change management, and depends upon effective flows of value. Systems Thinking (ST) is consequently at the heart of genuine excellence. This paper was conceived in the context of a Community of Practice of business improvement professionals, who took Operational Excellence as their agenda for inquiry during sessions in 2015. Reflection upon practice discussed at these meetings, together with the literature of change management and continuous improvement, have led to development of a systemic ‘landscape' model for pursuit of Operational Excellence. The elements of this model are set out, showing how they can contribute to OE.

scholarly journals The Effect of Cooling Agent on Stress and Deformation of Charge-loaded Cast Pallets

2017 ◽  
Vol 17 (4) ◽  
pp. 13-18
Author(s):  
A. Bajwoluk ◽  
P. Gutowski
Keyword(s):  
Heat Transfer ◽  
Heat Treatment ◽  
Temperature Gradient ◽  
Effect Of Temperature ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Cooling Conditions ◽  
Cooling Agent ◽  
Stress And Deformation ◽  
A Charge

Abstract The results of research on the effect of the type of cooling agent used during heat treatment and thermal-chemical treatment on the formation of temperature gradient and stress-deformation distribution in cast pallets, which are part of furnace accessories used in this treatment, are disclosed. During operation, pallets are exposed to the effect of the same conditions as the charge they are carrying. Cyclic thermal loads are the main cause of excessive deformations or cracks, which after some time of the cast pallet operation result in its withdrawal due to damage. One of the major causes of this damage are stresses formed under the effect of temperature gradient in the unevenly cooled pallet construction. Studies focused on the analysis of heat flow in a charge-loaded pallet, cooled by various cooling agents characterized by different heat transfer coefficients and temperature. Based on the obtained temperature distribution, the stress distribution and the resulting deformation were examined. The results enabled drawing relevant conclusions about the effect of cooling conditions on stresses formed in the direction of the largest temperature gradient.

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