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Wednesday, July 29, 2020 | History

1 edition of Concrete in hot climates, admixtures and curing found in the catalog.

Concrete in hot climates, admixtures and curing

Concrete in hot climates, admixtures and curing

programme [and papers from a] one day meeting, Thursday, 10 January 1980.

  • 171 Want to read
  • 28 Currently reading

Published by Cement and Concrete Association in [London] .
Written in English


Edition Notes

In plastic envelope; includes advertising materials.

ContributionsCement and Concrete Association.
ID Numbers
Open LibraryOL19740383M

Concrete chemicals or admixtures are materials other than cement, aggregate and water that are added to concrete either before or during its mixing to alter its properties, such as workability, curing temperature range, set time or color. Some concrete admixtures have been in use for a very long time in concrete construction, such as calcium […]. Hot weather may be defined as any period of high temperature in which special precautions need to be taken to ensure proper handling, placing, finishing and curing of concrete. Hot weather problems are most frequently encountered in the summer, but the associated climatic factors of high winds, low relative humidity and solar radiation can.

Hot climates prevail in many regions of the globe. The average summer temperature of hot arid areas is in the range of °C with temperatures exceeding these values under direct solar radiation. Curing concrete in these regions may be challenging due to limited availability of suitable water for curing and/or rapid loss of curing water by evaporation. Retarding admixtures, which slow the setting rate of concrete, are used to counteract the accelerating effect of hot weather on concrete setting. High temperatures often cause an increased rate of hardening which makes placing and finishing difficult. Retarders keep concrete workable during placement and delay the initial set of concrete.

  Mineral Admixtures for Concrete. Mineral concrete admixtures include fly ash and silica fume: Fly Ash — A less-commonly used admixture, fly ash is a by-product produced when coal is burned. When added to wet concrete, it slows down the curing process, which makes the concrete pliable for a longer period. 5. Evaporation of bleed water from concrete 16 6. Curing of concrete 18 7. Hot and cold weather concreting 22 8. Cracks in concrete 24 9. Concrete delivery requirements 28 Safe handling of concrete 36 Products 38 Glossary of terms 42 Zero Harm Today Message 50 2 TABLE OF CONTENTS.


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Concrete in hot climates, admixtures and curing Download PDF EPUB FB2

Usage of admixtures: Retarding admixtures meeting ASTM CType D requirements have both water reducing and set retarding properties, and are used widely under hot weather conditions. They can be included in concrete in varying proportions and in combination with other admixtures so that, as temperature increases, higher dosages of the admixture may be.

Effect of Self-Curing Admixture on Concrete Properties in Hot Climate. Joseph P. Rizzuto1, Mounir Kamal2, Hanaa Elsayad3, Alaa Bashandy2, Zeinab Etman 2. Mohamed N. Aboel Roos2, and Ibrahim G. Shaaban1 1 Civil Engineering and Built Environment, School of Computing and engineering, University of West London.

2 Civil Engineering Department, Faculty of. There is limited published data on the performance of admixtures such as PEG self-curing agent in hot weather conditions. In this research, a series of experiments were conducted to investigate the behaviour of self curing concrete (SC) with PEGcast and cured in hot climate conditions, in comparison with conventional normal concrete (NC).Author: Joseph P.

Rizzuto, Mounir Kamal, Hanaa Elsayad, Alaa Bashandy, Zeinab Etman, Mohamed N. Aboel Roos. Hydration stabilizing admixtures are used for making more uniform and predictable high-performance concrete. Hydration stablizing admixture retard set time by controlling the hydration of Portland cement and other cementitious materials while facilitating placing and be used or curing concrete in hot weather conditions in Minnesota and Iowa.

Highlights•PEG admixture was used in concrete mixes produced for hot weather conditions.•Dry materials, mixing water and curing temperatures simulated hot weather.•Properties of PEG samples were found to be superior to the control concrete.•Results cannot to attributed only to prevention of pore water escape by PEG •A proposal was.

Hot climate concrete is when the concrete is mixed, transporting, and pured in an elevated tensile strength compared to normal concrete without using admixture. In concrete. Admixtures for Hot Weather. The laying of concrete in hot weather places extra demands on the concrete worker.

The ideal conditions for concrete curing are between C. The addition of extra heat and/or wind can have a detrimental effect on the finished product because of rapid moisture loss. The paper, after very briefly discussing the classification of world climates, considers hot climates before taking up a review of papers dealing with the effects of hot climates on the properties of both fresh and hardened concrete.

Raw materials for concrete are discussed, where the adverse and positive effects of C3A and gypsum contents of Portland cement, thermal movement of concrete. For many years self-curing admixtures were recommended as an alternative to water curing, however, limited studies have been conducted on their performance in hot weather conditions.

In this investigation, the effects of a hot climate on the fresh and hardened properties of self-curing (SC) concrete and normal conventional concrete (NC) in hot. In general, if fresh concrete is poured over a hardened concrete surface, there is a chance of failure of fresh concrete surface due to weak bond with old surface.

To make the bond stronger, bonding admixtures are added to cement or mortar grout which is applied on the concrete surface just before placing fresh concrete. This chapter discusses the important aspects of the physical, chemical, durability, and mechanical characteristics of cement paste and concrete that may be influenced by admixtures.

Concrete, a composite material made with: (1) cement, (2) aggregates, (3) admixtures, and (4) water, comprises in quantity the largest of all man-made materials. Concrete applications may be considered hot weather concrete at temperatures ranging from 77 to 95 degrees Fahrenheit depending on the specific application.

Precautions should be planned in advance to counter the effects of high temperature well in advance of execution to counter these effects. Generally, if concrete strengths are satisfactory and curing practices are sufficient to avoid undesirable drying of surfaces, durability of hot weather concrete will not differ greatly from similar concrete placed at normal temperatures.

The presence of a desirable air-void system is needed if the concrete is going to be exposed to freezing. As per IS –concrete should not be cured less than 7 days for ordinary Portland Cement, & it must be at least 10 days for concrete with mineral admixtures or blended cement.

In case of hot weather and arid temperature conditions, the curing should not be less than 10 Days for OPC and 14 days for concrete with blended cement. Concrete admixtures can greatly improve the strength, manageability, setting time, and quality of your mix. Consider using hot weather admixtures, like recycled plastic additives, that will make your mix easier to work with, and increase its setting time so it can cure to a greater strength.

Concrete poured in hot weather, low humidity, or high wind can suffer adverse effects if proper adjustments are not made to the process. Any time hot and/or dry conditions are present when pouring concrete, it is important to schedule the work during the coolest part of the day, if possible, and to have plans in place to keep the concrete cool.

Fifty-two concrete mixes were prepared, and prisms were made and exposed to natural weather after a day period of laboratory curing (water and/or air curing).

Parameters investigated included water-to-cement ratio, type of cement, type of admixture and dosage, type of pozzolanic material, water curing period, and type of curing aid and. Retarding admixtures are essentially the opposite of accelerators.

They increase the amount of time it takes concrete to cure, in other words, they slow down the setting time of the cement paste. Retarding admixtures are typically used in hot weather.

By using retarders in hot weather, less water is required to cure the concrete mix. Others say a temperature higher than 90 ºF (32 ºC) is allowable if the concrete contains a set-retarding admixture. ACI “Specifications for Structural Concrete” and ACI “Specification for Hot Weather Concreting” limit the maximum concrete temperature to 95 °F (35 ºC) at the time of discharge.

The following are admixtures that help concrete cure quickly and reach adequate strength when cold weather is present: Accelerators– Calcium chloride admixtures are the most common type of accelerators and are used to speed the curing process by increasing the rate of cement amount added to cement mixture will depend on ambient conditions.

Hot weather conditions can lead to problems in mixing, placing and curing hydraulic cement concrete that can adversely affect the properties and serviceability of the concrete. If precautions are not effectively implemented during hot weather, the concrete may be damaged through plastic-shrinkage cracking, thermal cracking and decreased day.CHAPTER 9 Finishing Concrete pages 26–27 CHAPTER 10 Curing Concrete pages 28–30 CHAPTER 11 Joints in Concrete pages 31–33 CHAPTER 12 Hot and Cold Weather Concreting pages 34–35 CHAPTER 13 Surface Finishes on Concrete pages 36–39 CHAPTER 14 Defects in Concrete pages 40–43 CHAPTER 15 Removing Stains from Concrete pages 44–Part 3 Construction in hot climates: quality assurance/quality control for concrete in hot climates; problems of unsupervised quality control in ready-mixed concrete plants in Saudi; the selection of hydraulic cements to satisfy the requirements for concrete construction in hot climates; performance evaluation of curing membranes; durability of.