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4/28/2017
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Injection of liquid nitrogen into concrete truck As a global leader in advancing concrete knowledge, ACI’s goal is to keep concrete industry professionals up to date with the latest information. For example, here’s a recent exchange from ACI’s Q&A section: Q. “What are the ACI building code requirements for placing concrete in a tropical climate? Some people in our office say we should specify a maximum permissible concrete temperature of 90 ºF (32 ºC). Others say a temperature higher than 90 ºF (32 ºC) is allowable if the concrete contains a set-retarding admixture.” A. ACI 301-16 “Specifications for Structural Concrete” and ACI 305.1-14 “Specification for Hot Weather Concreting” limit the maximum concrete temperature to 95 °F (35 ºC) at the time of discharge. This limit is for general types of hot weather construction such as pavements, bridges, and buildings, not mass concrete. Hot weather concreting is defined by ACI as “one or a combination of the following conditions that tends to impair the quality of freshly mixed or hardened concrete by accelerating the rate of moisture loss and rate of cement hydration, or otherwise causing detrimental results: high ambient temperature; high concrete temperature; low relative humidity; and high wind speed.” Various adverse effects on the properties and serviceability of concrete are brought on by hot weather. Just one of those is the effect on strength—concrete mixed, placed, and cured at elevated temperatures normally develops higher early strengths than concrete produced and cured at lower temperatures. Hot Weather Concrete webinar scheduled for May 9 at 1 pm EST. Sign up now and reserve your spot! https://t.co/rNpfqyrjXx pic.twitter.com/g4mNZpngXy— AmericanConcreteInst (@ConcreteACI) April 20, 2017 Damage to concrete caused by hot weather can never be fully alleviated. Potential deficiencies to concrete in the hardened state can include decreased strengths resulting from higher water demand, and decreased durability resulting from cracking. Typical hot weather concrete evaporation protection measures include fogging; evaporation retarders; wet burlap; wind breaks; and protection of quality control specimens. An upcoming May 9 webinar will cover best practices and examples from projects where pre-cooling measures, moisture controls, mixture adjustments, and admixture technologies have been implemented to reduce adverse effects to the concrete under hot, drying conditions. Add to your knowledge by signing up for: Hot Weather Concrete – Best Practices and Lessons Learned On-Demand Course. ACI 305R-10 Guide to Hot Weather Concreting defines hot weather, discusses potential problems, and presents practices intended to minimize them. These practices include selecting materials and proportions, precooling ingredients, and batching. Other topics discussed include length of haul, consideration of concrete temperature as placed, facilities for handling concrete at the site, and, during the early curing period, placing and curing techniques, and appropriate testing and inspection procedures in hot weather conditions. Hot weather concreting can be a challenge – to minimize the disadvantages, and make your next hot weather concreting project a success, use ACI’s resources, including ACI University online courses, free online education presentations, publications, and journal articles. View all ACI resources on Hot Weather Concreting. As part of its strategic plan, ACI strives to add value for its members, chapter members, and customers by providing the most up-to-date information for the concrete industry.
Injection of liquid nitrogen into concrete truck
As a global leader in advancing concrete knowledge, ACI’s goal is to keep concrete industry professionals up to date with the latest information.
For example, here’s a recent exchange from ACI’s Q&A section:
Q. “What are the ACI building code requirements for placing concrete in a tropical climate? Some people in our office say we should specify a maximum permissible concrete temperature of 90 ºF (32 ºC). Others say a temperature higher than 90 ºF (32 ºC) is allowable if the concrete contains a set-retarding admixture.”
A. ACI 301-16 “Specifications for Structural Concrete” and ACI 305.1-14 “Specification for Hot Weather Concreting” limit the maximum concrete temperature to 95 °F (35 ºC) at the time of discharge. This limit is for general types of hot weather construction such as pavements, bridges, and buildings, not mass concrete.
Hot weather concreting is defined by ACI as “one or a combination of the following conditions that tends to impair the quality of freshly mixed or hardened concrete by accelerating the rate of moisture loss and rate of cement hydration, or otherwise causing detrimental results: high ambient temperature; high concrete temperature; low relative humidity; and high wind speed.”
Various adverse effects on the properties and serviceability of concrete are brought on by hot weather. Just one of those is the effect on strength—concrete mixed, placed, and cured at elevated temperatures normally develops higher early strengths than concrete produced and cured at lower temperatures.
Hot Weather Concrete webinar scheduled for May 9 at 1 pm EST. Sign up now and reserve your spot! https://t.co/rNpfqyrjXx pic.twitter.com/g4mNZpngXy— AmericanConcreteInst (@ConcreteACI) April 20, 2017
Hot Weather Concrete webinar scheduled for May 9 at 1 pm EST. Sign up now and reserve your spot! https://t.co/rNpfqyrjXx pic.twitter.com/g4mNZpngXy
Damage to concrete caused by hot weather can never be fully alleviated. Potential deficiencies to concrete in the hardened state can include decreased strengths resulting from higher water demand, and decreased durability resulting from cracking.
Typical hot weather concrete evaporation protection measures include fogging; evaporation retarders; wet burlap; wind breaks; and protection of quality control specimens.
An upcoming May 9 webinar will cover best practices and examples from projects where pre-cooling measures, moisture controls, mixture adjustments, and admixture technologies have been implemented to reduce adverse effects to the concrete under hot, drying conditions. Add to your knowledge by signing up for: Hot Weather Concrete – Best Practices and Lessons Learned On-Demand Course.
ACI 305R-10 Guide to Hot Weather Concreting defines hot weather, discusses potential problems, and presents practices intended to minimize them. These practices include selecting materials and proportions, precooling ingredients, and batching. Other topics discussed include length of haul, consideration of concrete temperature as placed, facilities for handling concrete at the site, and, during the early curing period, placing and curing techniques, and appropriate testing and inspection procedures in hot weather conditions.
Hot weather concreting can be a challenge – to minimize the disadvantages, and make your next hot weather concreting project a success, use ACI’s resources, including ACI University online courses, free online education presentations, publications, and journal articles.
View all ACI resources on Hot Weather Concreting.
As part of its strategic plan, ACI strives to add value for its members, chapter members, and customers by providing the most up-to-date information for the concrete industry.
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