建設技術・工法 レンタル・リース i-Construction
JUST.WILL

基本情報

屋内小間番号
18-18
所在地
〒810-0022 福岡県福岡市中央区薬院2丁目2番24号 チサンマンション第3博多2F
電話番号
092-401-1424
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出展製品・サービス

A sustainable system for measuring concrete formwork removal strength based on accumulated temperature

製品・サービス説明

It is no exaggeration to say that the quality of concrete depends on quality control during the initial curing period, from the start of pouring to the removal of the formwork, as this period plays a crucial role in determining the long-term durability of the concrete.

The method of estimating concrete strength through accumulated temperature, by integrating the heat of hydration - a chemical reaction between cement and water - from the start of pouring, is now becoming the global standard. Almost all existing systems worldwide embed sensing devices inside the concrete. However, this system is different because it places the sensors outside the formwork, allowing continuous digital monitoring from pouring to formwork removal without the need for conventional compression testing. It provides real-time data visualization through graphs and color mapping while also allowing seamless real-time data sharing among key stakeholders, including the construction site, site office, branch office, headquarters, and the client. Additionally, it enables the long-term storage and management of big data for further analysis and optimization.

Furthermore, placing sensing devices on the surface side of the structure rather than at its center results in lower measured strength values compared to the core, providing a more conservative and safety-focused assessment. This IoT-driven strength management system allows for repeated use, ensuring consistent quality control throughout the entire curing process, from pouring to formwork removal.

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A sustainable system for measuring the 28-day (4-week) compressive strength of concrete based on accumulated temperature.

製品・サービス説明

In the first point of the previous section, [Product/Service Description], we stated that it is no exaggeration to say that the quality of concrete depends on the quality control during the initial curing period, from the start of pouring until the removal of the formwork. This period plays a critical role in determining the long-term durability of the concrete. However, at the time of formwork removal, the concrete has not yet reached its design standard strength. Therefore, the construction manager is obligated to verify the achieved strength 28 days after the pouring date (4-week strength).

Traditionally, the method for checking the strength after 28 days involved preparing multiple test specimens at the time of pouring and placing them in a compression testing machine after 28 days to determine whether the design standard strength had been met. However, the size and mass of these test specimens differ from actual structures, as do the hydration reactions and curing environments. As a result, the measured strength of the test specimens does not accurately reflect the strength of the actual structure. Furthermore, once the compression tests are completed, the concrete shells of the test specimens must be disposed of as industrial waste.

This system is installed outside the formwork at the time of pouring. When the formwork is removed, it is temporarily detached from the structure but is immediately reattached. It remains in place for 28 days (4-week strength) to continue collecting data.

After measuring the final achieved strength, the system is removed and can be reused multiple times. This makes it an environmentally friendly and sustainable strength verification system that supports a circular economy.

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A pressure sensor system specialized for measuring pressure during lining concrete placement in the New Austrian Tunneling Method (NATM)

製品・サービス説明

The New Austrian Tunneling Method (NATM) is the most widely used tunnel construction method.

The construction process follows these steps: excavation, muck removal, spraying of concrete (primary lining), installation of rock bolts, and pouring of lining concrete (secondary lining). The final step, the secondary lining, forms the tunnel’s inner surface, meaning it becomes the exposed part of the structure.

For the secondary lining, extra-large steel formwork that follows the arc of the tunnel cross-section is used. A steel formwork system (centering machine) exceeding 10 meters in length is utilized, and concrete is pumped by a concrete pump truck into the approximately 30cm to 40cm gap between the sprayed concrete (primary lining) and the secondary lining.

At this stage, the pumping pressure from the concrete pump truck and the self-weight of the freshly placed concrete combine to exert a significant load on the centering machine. If the pouring speed is mistimed, it could lead to the collapse of the large arch formwork and increase the risk of serious accidents. Therefore, centering machines are widely equipped with pressure sensors to manage the relationship between pouring speed and pressure.

However, despite their critical role, no pressure sensors specifically designed for tunnel construction exist, and earth pressure gauges have been used as substitutes for many years.

This pressure sensor system is an innovative solution that can measure multiple types of pressure, including instantaneous pressure from concrete pump trucks, gradually increasing self-weight pressure, and impact forces caused by collisions of coarse and fine aggregates within the concrete.

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