AASHTO R 115-2023
Mechanical Mixing of Hydraulic Cement Pastes and Mortars of Plastic Consistency
- Standard No.
- AASHTO R 115-2023
- Release Date
- 2023
- Published By
- American Association of State Highway and Transportation Officials US / AASHTO
- Latest
- AASHTO R 115-2023
- Introduction
Standard Overview and Technical Background
AASHTO R115-231, "Standard Practice for Mechanical Mixing of Hydraulic Cement Grouts and Mortars of Plastic Consistency," is a key technical standard developed by the U.S. Association of State Highway and Transportation Officials. It specifically regulates the mechanical mixing process of hydraulic cement grouts and mortars. This standard, which was reclassified but not revised in 2023, remains fully consistent with ASTM C305-20 and reflects the level of standardization in the United States in the field of cement material testing.
The standard primarily applies to the preparation of hydraulic cement grouts and mortars in a laboratory environment, ensuring comparability and repeatability of test results between different laboratories. Through strict control of equipment specifications and operating procedures, the impact of human factors on test results is effectively reduced.
Detailed Explanation of Equipment Technical Requirements
The standard sets strict technical requirements for mixing equipment to ensure the standardization and repeatability of the mixing process.
Mixer core parameters
The mixer must use an electric mechanical agitator, which is a revolving gear system type and can provide planetary motion and rotational motion at the same time. The equipment must have at least two speeds, controlled by a certain mechanical method, and the use of a rheostat for speed regulation is prohibited.
Speed gear Blade speed (r/min) Planetary motion speed (r/min) Application stage Low speed 140±5 About 62 Initial mixing stage Medium speed Standardized operation of the mixing procedure
Cement slurry mixing procedure
The cement slurry mixing procedure is divided into five key steps, each of which has strict time control:
- Add all the mixing water to the bowl
- Add cement and let it stand for 30 seconds for water absorption
- Stir at low speed for 30 seconds
- Stop stirring for 15 seconds and scrape off the attachments on the bowl wall
- Stir at medium speed for 60 seconds
Mortar mixing procedure
The mortar mixing procedure is more complicated and includes seven steps:
Steps Operation content Time control Speed requirement 1 Add water and cement - - 2 Mix at low speed 30 seconds 140±5 r/min 3 Add sand slowly 30 seconds Keep low speed 4 Mix at medium speed 30 seconds 285±10 rpm 5 Standstill Scrape 90 sec Stop Mixing 6 Final Mix 60 sec 285±10 rpm Environmental Control and Quality Management
Temperature and Humidity Control Requirements
The standard requires strict control of indoor temperature, humidity, and mixing water temperature in accordance with Section 4 of the M201 standard to ensure a consistent testing environment. Dry materials must remain within the room temperature range to avoid temperature differences that may affect material properties.
Equipment Calibration and Maintenance
Mechanical mixing devices must be inspected and verified for compliance at least every 2.5 years. Laboratories should establish a quality management system that complies with the R18 standard to ensure the reliability and accuracy of test results.
Standard Implementation Recommendations and Precautions
Equipment Selection Recommendations
When selecting mixing equipment, focus on speed accuracy, gap adjustment functionality, and material requirements. The mixing paddle and mixing bowl must be made of stainless steel to ensure corrosion resistance and long-term stability.
Operational Precautions
Operators should note: When using aggregate coarser than standard sand, it may be necessary to adjust the gap adjustment bracket to provide a wider gap than specified in the standard to avoid serious damage to the paddle and bowl. Scrapers should be made of semi-rigid rubber to ensure they can effectively remove debris without damaging the equipment.
Quality Control Key Points
During implementation, complete equipment documentation should be established, recording all calibration and maintenance activities. Critical parameters such as speed and gap should be regularly verified to ensure consistent compliance with the standard. Laboratories should participate in proficiency testing activities to continuously improve their testing capabilities.
Technological Evolution and Standard Value
The predecessor of this standard, T162, was first published as a standard practice in 2023, reflecting the continuous development and improvement of cement testing technology. Through a unified mechanical mixing method, the consistency and comparability of test results between different laboratories have been significantly improved, providing a reliable technical basis for the quality control and performance evaluation of cement materials.
The implementation of the standard not only standardizes laboratory operating procedures, but more importantly, establishes a traceable quality assurance system, providing solid technical support for the quality of engineering construction. With the continuous development of new materials and new technologies, this standard will continue to be updated to meet the needs of industry development.
AASHTO R 115-2023 Referenced Document
- AASHTO M 201 Standard Specification for Mixing Rooms, Moist Cabinets, Moist Rooms, and Water Storage Tanks Used in the Testing of Hydraulic Cements and Concretes*， 2025-01-01 Update
AASHTO R 115-2023 history
- 2023 AASHTO R 115-2023 Mechanical Mixing of Hydraulic Cement Pastes and Mortars of Plastic Consistency
Topics on standards and specifications
Standard and Specification
ASTM C305-06 Standard Practice for Mechanical Mixing of Hydraulic Cement Pastes and Mortars of Plastic Consistency ASTM C305-99e1 Standard Practice for Mechanical Mixing of Hydraulic Cement Pastes and Mortars of Plastic Consistency ASTM C305-99 Standard Practice for Mechanical Mixing of Hydraulic Cement Pastes and Mortars of Plastic Consistency ASTM C305-12 Standard Practice for Mechanical Mixing of Hydraulic Cement Pastes and Mortars of Plastic Consistency ASTM C305-11 Standard Practice for Mechanical Mixing of Hydraulic Cement Pastes and Mortars of Plastic Consistency ASTM C305-20 Standard Practice for Mechanical Mixing of Hydraulic Cement Pastes and Mortars ASTM C305-13 Standard Practice for Mechanical Mixing of Hydraulic Cement Pastes and Mortars of Plastic Consistency ASTM C305-14 Mixing of Hydraulic Cement Pastes and Mortars of Plastic Consistency KS L 5109-2012 Testing method for mechanical mixing of hydraulic cement pastes and mortars of plastic consistency
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Update: Sat, 02 May 2026 04:38:45 +0000