Name: how curing improves concrete strength
Uploaded: 2024-11-07T14:48:35.000Z
Duration: 1 min 20 s
Channel: JoVE

시멘트 수화는 시멘트 페이스트의 물로 채워진 모세관 기공에서 발생합니다.
기온, 습도 및 바람과 같은 환경 요인은 증발을 일으켜 새로 배치된 콘크리트 표면에서 물을 제거할 수 있습니다.
또는 콘크리트가 밀봉되어 있고 물-시멘트 비율이 0.5 미만인 경우 내부 건조로 인해 자유수가 손실됩니다.
양생은 수화 과정을 계속하는 데 필요한 적절한 수준의 수분과 온도를 유지하기 위해 콘크리트를 포화시켜 콘크리트에서 수분 손실을 방지합니다. 
시멘트가 최종 세트에 도달한 후 경화가 시작되고 수화 시멘트 페이스트의 모세혈관이 수화 제품으로 채워져 분절되어 콘크리트가 불침투성 및 내구성을 가질 때까지 계속됩니다.
콘크리트를 경화하지 않고 공기 중에서 건조시키면 수축이 발생하기 쉬워 표면 균열이 형성됩니다. 또한, 지속적으로 습윤 경화된 콘크리트의 압축 강도의 약 50%만 달성합니다.
마지막으로, 경화 기간이 길수록 콘크리트의 압축 강도가 높아집니다.

콘크리트의 경화

시멘트의 수화는 물로 채워진 모세관 기공 내에서 일어납니다. 그러나 환경적 요소는 콘크리트 표면에서 물을 증발시켜 이 과정을 방해할 수 있습니다. 물-시멘트 비율이 0.5 미만인 밀봉된 콘크리트는 자체 건조되어 물이 손실됩니다. 콘크리트의 물 손실은 경화를 통해 완화됩니다. 이 기술은 콘크리트를 포화 상태로 유지하여 필요한 온도와 습도 조건을 유지하고, 처음에 물이 차지했던 시멘트 페이스트의 공간을 수화 제품으로 최적으로 채우는 것을 포함합니다. 시멘트가 최종 경화에 도달한 후에 경화가 시작됩니다. 경화되지 않은 채로 건조된 콘크리트는 수축되고 균열이 생길 수 있으며 28일 동안 지속적으로 경화된 콘크리트의 강도의 절반에 불과할 가능성이 높습니다. 경화 기간은 콘크리트의 최종 압축 및 인장 강도와 직접적으로 상관 관계가 있으며, 강도뿐만 아니라 내구성, 방수성, 내마모성, 동결-융해와 같은 다른 바람직한 특성을 보장하는 데도 이 관행의 중요성을 강조합니다. 이 효과는 더 얇은 구조적 요소와 시멘트 함량이 높은 혼합물에서 더 두드러지지만, 경량 골재 콘크리트는 영향을 덜 받습니다. 게다가 공기가 포함된 콘크리트는 공기가 포함되지 않은 콘크리트보다 경화 조건의 영향을 덜 받습니다.

시멘트 수화는 시멘트 페이스트의 물로 채워진 모세관 기공에서 발생합니다.
기온, 습도 및 바람과 같은 환경 요인은 다음을 유발할 수 있습니다.

Education

교육

JoVE Core

Civil Engineering

토목공학

Unit 1

제1단원

Mixing, Placing and Curing Concrete 

콘크리트의 배합, 타설 및 양생

KEY TERMS AND CONCEPTS

주요 용어 및 개념

Curing of Concrete

how curing improves concrete strength

Curing helps concrete gain strength after it has set. It keeps the concrete moist and at the right temperature so cement hydration can continue. Hydration is the process where cement reacts with water in the water-filled capillary pores and forms the products that fill spaces in the paste.

Dry air can interrupt this process by pulling water from the concrete surface. Concrete with a water-cement ratio below 0.5 can also lose water through self-desiccation, which means internal water is used up as hydration continues. Curing reduces this water loss by keeping the surface saturated.

Curing begins after the cement reaches final set. If concrete is allowed to dry without curing, it may shrink and crack. It may also reach only about half the strength of concrete that is continuously cured for 28 days.

The length of curing affects the final compressive strength and tensile strength of concrete. It also helps improve durability, water tightness, abrasion resistance, and freeze-thaw resistance. The effect is stronger in thin structural elements and in mixes with a high cement content. Lightweight aggregate concrete is less affected, and air-entrained concrete is less influenced by curing conditions than non-air-entrained concrete.

How Curing Improves Concrete Strength

mixing concrete

Concrete Mixer Types and Capacity

Concrete mixing creates a uniform blend of cement, aggregates, and paste. The goal is to coat the aggregates evenly with cement paste. Mixers used for this job are usually grouped into two main types: batch mixers and continuous mixers. Batch mixers handle one load at a time. They mix the materials thoroughly, discharge the batch, and then receive the next one. Continuous mixers work differently. They take in a steady flow of ingredients, mix them at a constant rate, and discharge the concrete...

mixing time

Concrete Mixer Charging and Timing

Concrete mixer charging and timing are key to making a uniform concrete mix with the needed strength. Mixing begins only after all ingredients are inside the mixer. The usual charging order starts with 10% of the water, then the solid materials are added steadily, followed by 80% of the water. The last portion of water is added later, within the first quarter of the total mixing period. The minimum mixing time depends on mixer capacity. Mixers with up to 1 cubic yard of capacity need at least...

ready mixed concrete

How Ready-Mixed Concrete Is Delivered

Ready-mixed concrete is prepared at a centralized plant and then delivered by truck to a construction site. It arrives ready for placement, which makes it different from concrete mixed entirely on site. Ready-mixed concrete includes three main forms: central-mixed, truck-mixed, and shrink-mixed. Central-mixed concrete is fully mixed at the plant and carried to the site in agitator trucks. These trucks rotate at 2 to 6 rpm, which helps keep the concrete in motion during transport. Truck-mixed...

pumped concrete

Concrete Pumping for Hard-to-Reach Sites

Concrete pumping moves large amounts of concrete through pipes to places that are hard to reach. It is used for sites such as deep foundation pits and other inaccessible locations. The system includes a hopper, a pump, and pipelines that carry the concrete to the placement point. Direct-acting pumps use a piston to move the concrete. Concrete enters the pump through the inlet valve by gravity and by suction created as the piston moves. The forward movement of the piston then pushes the...

placing concrete

Concrete Placement Methods and Compaction

Concrete placement methods focus on keeping the mix in a uniform shape and position. The concrete is placed as close as possible to its final location to reduce segregation, which is the separation of ingredients. It is then fully compacted to remove trapped air. The next layer is added while the layer below is still plastic, or soft enough to shape. The rate of placing and compacting concrete is kept equal. Concrete is laid in uniform layers, and hand shoveling is avoided. Moving concrete...

vibrating concrete

Concrete Compaction with Vibrators

Concrete compaction with vibrators helps newly poured concrete settle inside formwork and around reinforcement bars. The goal is to remove trapped air pockets and create a dense concrete mass. Mechanical vibration is a key part of that process. One common method uses an internal vibrator, also called a poker vibrator or immersion vibrator. It is quickly inserted through the full depth of the fresh concrete and slightly into the layer below, which is still in a plastic state. The vibrator is...

shotcrete

Shotcrete for Vertical and Overhead Surfaces

Shotcrete is a concrete spraying method used on vertical and overhead surfaces. It uses mortar or small aggregate concrete with a high cement content. The material is sprayed at high velocity, and the impact helps compact it so it can cling without sagging. Builders place shotcrete in layers until it reaches about 4 inches thick. The quality depends strongly on the operator’s skill in managing the nozzle. Careful nozzle control helps the material land evenly and build up properly. Shotcrete...

preplaced aggregate concrete

Concrete Placement for Tight Spaces

Preplaced aggregate concrete is used when a construction site is hard to reach. The process starts by wetting gap-graded coarse aggregates. This helps remove dirt from the stones. The aggregates are then placed in the form and compacted. Next, a mortar mix is pumped under pressure through slotted pipes to fill the spaces between the aggregates. The mortar usually contains Portland cement, pozzolan, fine aggregates, water, and a fluidizing aid. The pozzolan reduces bleeding and segregation and...

finishing concrete

Concrete Surface Finishing Steps

Concrete surface finishing begins right after the concrete has been placed and consolidated. The first step is screeding, which levels the surface by removing extra material until it is even with the top of the formwork. A screed is a straight edge used for this leveling step. After screeding, a bull float or darby is used to smooth the surface further. These tools help lower high spots, fill low areas, and push larger aggregate particles deeper into the concrete. This preparation should...

curing of concrete

Curing helps concrete gain strength after it has set. It keeps the concrete moist and at the right temperature so cement hydration can continue. Hydration is the process where cement reacts with water in the water-filled capillary pores and forms the products that fill spaces in the paste. Dry air can interrupt this process by pulling water from the concrete surface. Concrete with a water-cement ratio below 0.5 can also lose water through self-desiccation, which means internal water is used up...

curing methods

Concrete Curing for Moisture Retention

Concrete curing for moisture retention helps fresh concrete keep the water it needs as it hardens. For members with a small surface-to-volume ratio, the forms are often oiled and moistened before the concrete is placed. These forms may stay in place for a long time to reduce moisture loss. If the form material can be wetted, it can also be kept damp. When forms are removed early, the concrete member is moistened and then covered with polythene sheets. Large horizontal concrete surfaces in dry...

accelerated curing of concrete

How Concrete Gains Strength Faster

Concrete can gain strength faster when heat and extra moisture speed up cement hydration. This faster hydration helps the concrete build early strength sooner than normal curing. The process is used when quicker hardening is needed after casting. One common method is steam curing. Concrete products may move through a chamber on a conveyor belt, or they may be encased in plastic so steam at atmospheric pressure can circulate around them. Steam curing starts with moist curing for about 3 to 5...

key terms and concepts

Learn how curing keeps concrete moist after final set, supports hydration, and improves strength, durability, water tightness, and crack resistance.

How Curing Improves Concrete Strength | JoVE K12

JoVE Core Civil Engineering offers a foundational exploration of essential construction materials such as bricks, stones, steel, wood, and concrete, along with fluid mechanics topics like flow over immersed bodies, open channel flow, and dimensional modeling. It also covers key surveying concepts, including leveling, traverse adjustments, curve design, topographic mapping, and geospatial technologies (GPS & GIS). Science-in-action videos showcase laboratory research on materials, fluids, and surveying practices in real-world engineering systems.

civil engineering

How Curing Improves Concrete Strength

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