PRODUCTS

The leading brand of mining machinery!

ONLINE MESSAGE

For More Information

dormant period concrete:

The dormant period of cement hydration (https://narcis.nl)

This period is so called the dormant period. For the building practice this period plays an important roll, because it controls the time in which the concrete is workable and placeable. The research proposal aims to explain the phenomenon of the dormant period.

Read More
(PDF) On the Origin of the Dormant Period of Cement Hydration

progressively consumed by the formation of new C-S-H nuclei and the dormant period lasts as long as . ... SO 3 and Al 2 O 3 are being used in increasing amounts in both concrete practice and ...

Read More
Cement Chemistry - The Concrete Portal

Formation of electrical double layer, and the precipitation of CH leads to the dormant period. C 3 A dissolves, and reacts with SO 4 2-to form AF t, which forms a surface barrier. C 4 AF also reacts to form AF t. Only very small % of C 2 S reacts at this stage. 2. Induction (dormant) period (first few hours):

Read More
Hydration of Cement Heat of Hydration Stages of ...

Jul 14, 2019  This is called as the Dormant Period. The existence of the dormant period allows the concrete to be transported to the construction site and placed and finished in the forms. Stage 3 - Hydration Acceleration: The end of the dormant period shows the beginning of the setting at which time the cement starts to react more rapidly with water.

Read More
Properties and effects of dormant aggregates on concrete ...

Nov 01, 2019  Aggregates used for concrete are sometimes abandoned on sites for extended periods of time. These aggregates are left dormant and exposed to harsh weather conditions before utilization. This study investigates the effect of aggregate dormancy of both fine aggregate (river sand) and coarse aggregate (gravel) on quality of concrete produced and its strength.

Read More
How Concrete is Made ( New Research) - Cement Concrete

The existence of the dormant period allows concrete to be transported to the construction site and placed and finished in the forms, the end of the dormant period represents the beginning of setting, at which time the cement again starts to react

Read More
Why Concrete Temperature Testing Is Important During ...

Mar 23, 2018  During this period fresh concrete is transported and placed. At this time, the concrete has not yet hardened and is still workable (plastic and fluid). The length of the dormant period has been shown to vary depending on multiple factors (cement type, admixtures, w/cm, etc.). The end of the dormant period

Read More
What is hydration of cement and heat of hydration - Civil Sir

2) dormant phase ( zone 2):- it is known as dormancy period of heat of hydration in which the evolution of heat gradually slow down and dramatically in this stage. And the dormancy period of concrete can last from 1 to 3 hours. during in this period concrete is in plastic stage which allows the concrete

Read More
Properties and effects of dormant aggregates on concrete ...

Aggregates used for concrete are sometimes abandoned on sites for extended periods of time. These aggregates are left dormant and exposed to harsh weather conditions before utilization. This study investigates the effect of aggregate dormancy of both fine aggregate (river sand) and coarse aggregate (gravel) on quality of concrete produced and its strength.

Read More
Types of Admixtures of Concrete Cement Chemical, Mineral

This is called the dormant period when the concrete is plastic and can be placed. At the end of the dormant period, the hydration rate increases and a lot of calcium silicate hydrate and calcium hydroxide is formed relatively quickly. This corresponds to the setting time of the concrete. Retarding admixtures delay the end of the dormant period ...

Read More
Cement - The major cements: composition and properties ...

Following the dormant period (which can last several hours), the cement begins to harden, as CH and C–S–H are produced. This is the cementitious material that binds cement and concrete together. As hydration proceeds, water and cement are continuously consumed.

Read More
Hydration of Cement Chemical Reactions in Hydration ...

Apr 08, 2020  Stage-1 corresponds to a period of rapid evolution of heat, which ceases within about 15 min.; Stage-2 corresponds to a dormant period which lasts for several hours during which the hydration is almost at halt.This is the reason why the concrete remains in plastic state for several hours. Stage-3 corresponds to acceleration period starting at the end of dormant period and lasting till the rate ...

Read More
High strength sustainable concrete using silica ...

May 01, 2017  The calorimetric results reveal that the hydration process was accelerated as a result of SNPs incorporation and the dormant period was shortening by 4 h with 2% SNPs as compared to the control. The effect of optimum dosages of SNPs addition on concrete in terms of mechanical and durability properties was studied at 0.25 w/b ratio.

Read More
An integrated macro-microscopic model for concrete ...

Dec 01, 2020  Concrete deterioration caused by external sulfate attack (ESA) is a macro-microscopically interactive expansion process, including two stages, namely a dormant period and detrimental duration. Based on ESA-induced deterioration mechanism, an integrated macro-microscopic model has been developed to describe the deterioration of concrete.

Read More
Dormont Concrete Construction Co Inc Better Business ...

Dormont Concrete Construction Co Inc. Concrete Contractors. Business Profile. ... BBB Business Profiles generally cover a three-year reporting period. BBB Business Profiles are subject to change ...

Read More
NPCA - National Precast Concrete Association

Nov 17, 2015  During the dormant period when the fresh concrete is plastic and able to be handled, prior to initial set, the action of set accelerators can last anywhere from 10 minutes in a hot mix to 2 hours for a cold mix. During the setting period, after initial set but prior to final set, accelerators can provide rapid strengthening for up to 10-12 ...

Read More
CIVL 1101 - Part 8 - Fresh Concrete

Both are gradual changes controlled by hydration. Fresh concrete will lose measurable slump before initial set and measurable strength will be achieved after final set. Setting is controlled by the hydration of C3S. The period of good workability is during the dormant period, (stage 2).

Read More
Why Concrete Temperature is Important, Especially During ...

This is the period at which the fresh concrete is being transported and placed since it has not yet hardened and is still workable (plastic and fluid). The length of the dormant period has been shown to vary depending on multiple factors (cement type, admixtures, w/cm). The end of the dormant period is typically characterised by the initial set.

Read More
Plastic Shrinkage Cracking of Self-compacting Concrete ...

A relationship between the capillary pressure rate and the length of the hydration dormant period is defined, which can explain the cracking severity of the concrete when the volumetric ...

Read More
Why Concrete Temperature is Important, Especially During ...

This is the period at which the fresh concrete is being transported and placed since it has not yet hardened and is still workable (plastic and fluid). The length of the dormant period has been shown to vary depending on multiple factors (cement type, admixtures, w/cm). The end of the dormant period is typically characterised by the initial set.

Read More
Properties and effects of dormant aggregates on concrete ...

Aggregates used for concrete are sometimes abandoned on sites for extended periods of time. These aggregates are left dormant and exposed to harsh weather conditions before utilization. This study investigates the effect of aggregate dormancy of both fine aggregate (river sand) and coarse aggregate (gravel) on quality of concrete produced and its strength.

Read More
Types of Admixtures of Concrete Cement Chemical, Mineral

This is called the dormant period when the concrete is plastic and can be placed. At the end of the dormant period, the hydration rate increases and a lot of calcium silicate hydrate and calcium hydroxide is formed relatively quickly. This corresponds to the setting time of the concrete. Retarding admixtures delay the end of the dormant period ...

Read More
Properties and effects of dormant aggregates on concrete ...

Nov 01, 2019  This study investigates the effect of aggregate dormancy of both fine aggregate (river sand) and coarse aggregate (gravel) on quality of concrete produced and its strength. Data for the study was collected over a 3 years dormant period of the aggregates, to determine the efficiency of the aggregates and its quality on concrete production and ...

Read More
CIVL 1101 - Part 8 - Fresh Concrete

Both are gradual changes controlled by hydration. Fresh concrete will lose measurable slump before initial set and measurable strength will be achieved after final set. Setting is controlled by the hydration of C3S. The period of good workability is during the dormant period, (stage 2).

Read More
Concrete: Quizes

The dormancy period of fresh concrete is the period during which the concrete is in a plastic state and the reaction is very, very slow. This state lasts from 1 to 3 hours and allows contractors to transport concrete to the job site and consolidate it before it hardens.

Read More
NPCA - National Precast Concrete Association

Nov 17, 2015  During the dormant period when the fresh concrete is plastic and able to be handled, prior to initial set, the action of set accelerators can last anywhere from 10 minutes in a hot mix to 2 hours for a cold mix. During the setting period, after initial set but prior to final set, accelerators can provide rapid strengthening for up to 10-12 ...

Read More
An integrated macro-microscopic model for concrete ...

Dec 01, 2020  Concrete deterioration caused by external sulfate attack (ESA) is a macro-microscopically interactive expansion process, including two stages, namely a dormant period and detrimental duration. Based on ESA-induced deterioration mechanism, an integrated macro-microscopic model has been developed to describe the deterioration of concrete.

Read More
Curing Concrete Dos and Don'ts - Bob Vila

Concrete’s chemical reaction slows at 50 degrees Fahrenheit and completely stops at 45 degrees Fahrenheit, meaning that it’ll go dormant and it won’t gain strength.

Read More
Hydration of cement - SlideShare

Mar 26, 2017  This is the reason why the concrete remains in plastic state for several hours. Stage-3 :- corresponds to acceleration period starting at the end of dormant period and lasting till the rate of heat evolution reaches a maximum value.

Read More
Water-to-Cement Ratio and Aggregate Moisture Corrections

May 28, 2010  This dormant period allows for the transportation and placement of the concrete. Rather than adding additional water to increase the concrete’s workability, water-reducing admixtures can improve the dispersion of the cement particles to increase the workability.

Read More
Hardened concrete - SlideShare

Feb 20, 2015  SETTING AND HARDENING Dormant Period – time from mixing cement with water and produce plastic workable paste. The paste remain virtually unchanged. Initial set – the paste begin to stiffen to such a degree, it becomes unworkable. Initial setting time – the time required for the paste to reach the stage. ECS 256 UiTM PG W8 5.

Read More
CIVL 1101 - Part 4 - Hydration of Portland Cement

Stage 2 - Dormant period - causes cement to remain plastic (2-4 hours). The reaction slows. CH crystallizes from the solution, C-S-H develops on the surface of the C3S and forms a coating. As the thickness increases, the time it takes water to penetrate the coating increases, thus the rate of reaction becomes diffusion controlled.

Read More
QA: OSHA Regulations On Concrete Silica Dust

The U.S Department of Labor will start enforcing its new concrete silica dust ruling for construction on September 23, 2017 (moved from June 23, 2017). With those new OSHA regulations coming up, it’s important to be up to date on all the new changes regarding the OSHA standards.

Read More