Gillmore Needle Apparatus

Gillmore Needle Test Procedure Using the Gillmore Needle Apparatus

Gillmore Needle Apparatus is used to determine initial and final set times of Portland cement, masonry cement, hydraulic hydrated lime, and certain mortars in accordance with ASTM C266 and other standards. The adjustable support has horizontal arms to guide two weighted needles with flat-end cylindrical stainless steel tips. The base has an ample flat shelf for positioning specimens. In testing the molded specimen for the time of setting, the initial-set needle is 1/4lb (113.4g) and 1/12in (2.12mm) diameter. Final-set needle is 1lb (453.6g) and 1/24in (1.06mm) diameter.

Features:

• Meets several ASTM and AASHTO test methods for set-time testing

• Includes initial and final-set needles

• Large base to position specimens

Meets Test Methods:

AASHTO Test Methods T 154 , ASTM C266 , ASTM C414 , ASTM C150/150M , ASTM C91/91M

The Gillmore needle apparatus is a widely used tool in cement testing to determine the initial and final setting times of cement. It provides valuable information about the time required for cement paste to transition from a plastic, workable state to a hardened state. This information is essential for various construction applications, as it helps determine the optimal time for various operations, such as mixing, placing, and finishing concrete.

The Gillmore needle apparatus consists of two needles—a reference needle and a test needle—and a needle holder. The cement paste, prepared by mixing cement with water according to specified proportions, is placed in a mold and leveled. The needles are then placed on the surface of the paste. The test needle is released and allowed to freely penetrate into the paste, while the reference needle remains stationary. The penetration depths of both needles are measured and recorded at regular time intervals.

The initial setting time is defined as the time at which the test needle ceases to make a perceptible impression on the cement paste. It indicates the point at which the portland cement begins to lose its plasticity and starts to harden. The final setting time is the time at which the test needle fails to penetrate the paste, indicating the completion of the hardening process.

The results obtained from the Gillmore needle apparatus help engineers, researchers, and manufacturers evaluate the setting characteristics of different cement types, assess the impact of various factors such as temperature and admixtures, and optimize concrete mix designs. It aids in quality control during portland cement production, enables the selection of appropriate cement for specific applications, and ensures compliance with industry standards and specifications.

In summary, the Gillmore needle apparatus is a valuable tool in cement testing, providing critical information about the initial and final setting times of cementitious materials. It allows for precise timing of construction operations, assists in quality control, and contributes to the performance and durability of concrete structures.

The Gillmore needle apparatus is a cornerstone in the realm of portland cement testing, specifically designed to determine the initial and final setting times of various cement types. This test method covers the use of Gillmore needles to measure the setting of hydraulic cement paste, including Portland cement, masonry cement, and hydraulic hydrated lime. By assessing the setting characteristics of these materials, the apparatus plays a crucial role in ensuring that portland cement complies with specification limits on setting times. Understanding these setting times is vital for various construction applications, as it helps in planning and executing operations like mixing, placing, and finishing concrete. In this section, we will delve into the significance of the Gillmore needle apparatus in cement testing and its application across different types of cement.

The test method for determining the setting time of hydraulic-cement paste using Gillmore needles is meticulously outlined in ASTM C266-21. This method covers the use of the apparatus to measure the setting of hydraulic cement paste, ensuring precise and reliable results. The apparatus itself comprises two horizontal arms, an adjustable support, and two weighted needles—the initial set needle and the final set needle.

To begin the test, a portland cement paste is prepared with a specific water cement ratio and molded into a test specimen. The initial set needle, which is lighter, is gently placed on the surface of the specimen. The time is recorded when this needle ceases to penetrate the cement paste, indicating the initial setting time. Following this, the final set needle, which is heavier, is used to determine the final setting time by recording when it no longer penetrates the paste.

This test method is performed in accordance with AASHTO test methods and requires adherence to regulatory limitations prior to use. It is crucial for users to establish appropriate safety and health practices, as fresh hydraulic cementitious mixtures are caustic and can cause chemical burns upon prolonged exposure. Therefore, the use of gloves, protective clothing, and eye protection is strongly recommended to ensure safety during the testing process.

By following this procedure, engineers and researchers can accurately determine the setting characteristics of hydraulic cement, aiding in quality control and ensuring compliance with industry standards.