Hot and cold weather concreting methods linkedin slideshare. American concrete institute announces new structural. For the purposes of this data sheet, hot weather is. Cold weather, as defined in this report, usually starts during fall and usually continues until spring. Use proven local recommendations for adjusting concrete proportions, such as the use of water reducing necessary for hydration unless proper curing methods are employed. Hot weather effects on concrete for construction pros. Hot weather can lead to many problems in batching, transporting, placing, and curing of the concrete that can adversely affect the properties and service years of the concrete. Good judgment is necessary to select the most appropriate compromise of quality, economy, and practicability. Hot weather concreting problems, effects and precautions in. Aci standard 305, hot weather concreting, is summarized in this section to provide. Troubleshooting hot weather concreting national precast. Plastic shrinkage cracks are typically associated with hot weather. A special preplacement meeting is highly recommended to clarify the requirements for hot weather concreting to address the wide range of possible actions, and to define responsibilities.
R 20 guide for design of jointed concrete pavements for streets and local roads aci 330r 2008 guide for the design and construction of concrete parking lots american water works. Concreting, or low air temperature, high concrete temperature, low humidity and high wind. Planning a successful, wellrun, hotweather project is the result of thorough and careful planning. In hot weather, concrete with fly ash or slag will set a bit slower. This guide identifies problems associated with hot weather concreting and describes practices that alleviate these potential adverse effects. Gain better understanding of aci 306r10 guide to cold weather concreting be able to apply good decision making in the field learn new methodologies to ensure success in cold weather concreting.
American concrete institute guide to hot weather concreting. Aci 305r10 guide to hot weather concreting defines hot weather, discusses potential problems, and presents practices intended to minimize them. Most of these difficulties arise due to the increased rate of cement hydration at higher temperatures accelerated set times and the. The use of liquid nitrogen is one option to reduce concretes temperature during hotweather concreting. The official version of this aci document uses inchpound units. This specification governs for construction within its scope, but the contract documents govern if there is a conflict.
Introduce the aci 305 10 guide to hot weather concreting understand the effects of hot weather on concrete mixtures, concrete construction, and concrete testing learn what key steps can be taken to ensure successful hot weather concreting resources. Hotweather concreting, chapter 11 in design and control of concrete mixtures, portland cement association, skokie, il. Aci 305r guide to hot weather concreting engineering360. Hot weather concreting tips plan ahead to avoid problems caused by high temperatures and dry conditions by ward r. The protection period is defined as the amount of time recommended to prevent concrete from being. These problems can be exaggerated on projects that include architectural concrete.
Specification for hot weather concreting kindle edition by aci committee 305 pdf free product arranges the reduced mirror dialogical context, because any other behavior would violate the isotropy of space. In hot weather, the concrete bed, forms, steel reinforcement, mixing or concreting equipments etc. A link to this webinar and a pdf of the presentation. Based on my understanding on the subject which is based on some studies about the topic in books, the web as well. Aci 305, guide to hot weather concreting, outlines best practices to help minimize harmful effects on fresh and hardened concrete as a result of environmental factors in warmer months. Aug 20, 2012 hot weather concreting presents unique problems for design and construction. Hot weather issues encountered in plastic concrete include.
Guide to hot weather concreting american concrete institute. Cold weather concreting aci 306 specification west. But using admixtures to control set and slump is more common and does not lower the quality of the concrete or change its color. Oct, 2016 this ppt discuss about the concreting methods and particularly hot and cold weather concreting methods. Most aci standards and committee reports are gathered together in the annually revised aci manual of. This document, and the aci building code specifications, are included in the building code requirements of pennsylvania. Curing is the maintaining of an adequate moisture content and temperature in concrete at early ages so that it can develop properties the mixture was designed to achieve. Extra water required for the same slump concrete requires more water when it is hot than when cold. Aci 305 defines hot weather as any combination of high ambient temperature, high concrete temperature, low relative humidity, high wind speed. These practices include suggested preparations and procedures for use in general types of hot weather construction, such.
We hope this lessons learned is helpful to you on a project this summer, or on future projects. Pdf from aa 1aci 305r91 hot weather concreting reported by aci committee 305 habib m. The precautions required to ensure a quality end product will vary depending on the actual conditions during concrete placement and the specific application for. Aci 305 hot weather concreting defines hot weathers as any combination of the following conditions that tends to impair the quality of the freshly mixed or hardened concrete. This specification supplements the contract documents and provides requirements for the contractor.
A high ambient temperature is only one factor that indicates hotweather concreting conditions, according to aci 305, hot weather concreting. American concrete institute, 2005 concrete 656 pages. According to aci 305, hot weather concreting, hot weather is any combination of the following weather conditions. May 18, 2017 increase in the weather temperature increases the rate of vaporization, therefore, hot weather condition increases the water demand in concrete production. In the july 2002 issue of concrete construction stamping concrete. Although wind is not traditionally associated with hot weather, it is important to note that the effects of the first three conditions listed become. These practices include selecting materials and proportions, precooling ingredients, and batching. It is intended that the architectengineer use the checklists included in this specification to customize the project specification. Insulating blankets, for example, may be needed to cover the subgrade bef o re the pour. To ease finishing operations in cold we a t h e r, yo u may need additional equipment. Checklists are provided to assist the architectengineer in supplementing the.
Hot weather concreting national precast concrete association. This and other problems can be avoided with precautionary steps. Specification for hot weather concreting kindle edition. The american concrete institute aci, relies on the work of over 3,000 volunteers who serve on committees to develop the latest codes and reports related to concrete, including a committee on hot weather concrete practices. Managing initial set times, joe nasvik wrote the definitive guide, advocating. The success of many hotweather concreting operations depends on the steps taken to slow the cement hydration reactions within the concrete and to minimize the rate of evaporation of. Portland cement association pca hotweather concreting, chapter in design and control of. Aci 305r91, hot weather concreting is a very useful and practical document.
Aci committee 305, hot weather concreting, american concrete institute, farmington hills, mi hot weather concreting, design and control of concrete mixtures, portland cement association, 5420 old orchard road, skokie, illinois. Jan 01, 2010 305r10 guide to hot weather concreting paperback january 1, 2010 by aci committee 305 author. Aci 305 defines hot weather as any combination of high ambient temperature, high concrete temperature, low relative humidity, high wind speed, and excessive solar radiation that can impair the quality of fresh or hardened concrete. Any combination of high ambient temperature, low relative humidity, solar radiation and wind defines hot weather, according to aci 305. Hot weather resource guide american concrete institute. Aug 22, 2016 active documents of aci committee 305 hot weather concreting include 305r10. Hot weather concrete specification choices to achieve. Hot weather concreting in tropical countries, such as india, air temperatures may rise up to 4050 deg. According to aci 305, if the initial 24hour curing is at 100 degrees f, the 28day compressive strength of the test specimens may be 10to15% lower. This reduces strengths and increases drying shrinkage. Detailed planning for hot weather concrete is essential. High temperature also accelerates cement hydration and contributes to the potential for thermal cracking in thicker concrete sections.
Adapted from aci standard 30678 and usdibr concrete manual. Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. Specifies requirements for hot weather concreting that the architectengineer can apply to any construction project involving hot weather concreting by citing it in the project specification. Weather conditions can have a dramatic effect on both the setting time and concrete placing, finishing and protection systems that must be followed for proper concrete placement.
R 2002 standard specification for cold weather concreting aci 325. Economic necessity to continue work in extremely hot weather. Atlantic testing laboratories hot weather concreting. Planning for hot weather conditions is essential because of the potential effects on fresh and recently placed concrete. Care has been taken to ensure that the conversion is correct. The webinar will address changes to the specification, calculation of evaporation rate to mitigate plastic shrinkage cracking, and will provide an overview of the current state of the art of hot weather concrete. For a 1hour delive r y time, conc rete in a white drum will be. National ready mixed concrete association cip12 hot weather concreting. Hot weather concreting concreting in hot weather the. Guide to hot weather concreting describes how environmental factors, such as high ambient temperature, low humidity, high wind, or both low humidity and high. Hot weather concreting effects of placing concrete in hot.
This specification covers requirements for hot weather concrete construction. Specification for hot weather concreting, 06 specification for hot weather concreting, 14. Cold weather concreting objectives for todays presentation. Other challenges of hot weather concreting can be summarized as. Hot weather concreting conditions typically include. Guide to cold weather concreting is one of many numerous, valuable resources on cold weather concrete practices by the american concrete institute aci. Hot weather concreting problems, effects and precautions. The specification was developed in order to address the fluctuating environmental and marine conditions that pose unique challenges for the florida construction industry. Cold weather concreting aci 306 specification west valley city 1. Such temperatures combined with high wind velocity andor low humidity enhance the rate of evaporation of the water, increase the rate of hydration of cement, which factors reduce the setting time of the concrete considerably and this is apt.
Environmental factors affect concrete properties and the construction operations of mixing. Aci 305 10 guide to hot weather concreting pca design and control of concrete mixtures. Guide to hot weather concreting reported by aci committee 305 aci 305r10 environmental factors, such as high ambient temperature, low humidity, high wind, or both low humidity and high wind, affect concrete properties and the construction operations of mixing, transporting, and placing of the concrete materials. This reference specification provides requirements for hot weather concreting that the architectengineer can apply to any construction project involving hot weather concreting by citing it in the project specification.
Complete disaster full interior car detailing transformation. American concrete institute guide to cold weather concreting. The american co n c r ete institute aci defines cold weather as t h r ee successive days in which the ave r age daily air tempera t u r e dro p s. The most common problem is with having the concrete freeze andor go through freezethaw cycles before acquiring adequate strength. Hot weather concreting, aci305, aci specification, metric. Specifications for structural concrete, aci 30105, with selected aci references. Provide expansion and control joint width indicated in drawings. Aci 306r defines cold weather to exist when the air temperature has fallen to, or is expected to fall, below 40o f during the protection period. Aci manual of concrete practice, a fivevolume document containing numerous reports and standards on concrete practices and procedures. Sets quickly concrete setting is a chemical reaction. See aci 305 standards on hot weather concreting, or aci 306 standard on cold weather concreting. Rapid evaporation of moisture from exposed surfaces may cause plastic shrinkage cracking and crazing, see also main entry cracking and subsequent subheadings.
Hot weather introduces problems in mixing, placing and curing concrete. Planning a successful, wellrun, hot weather project is the result of thorough and careful planning. Specifications for structural concrete, aci 30105, with. The laying of concrete in hot weather places extra demands on the concrete worker. Hot weather concreting a high ambient temperature increases the temperature of the fresh concrete, resulting in more rapid hydration of the cement and leading to accelerated setting.