Consultancy Study on asset condition review for prestressed concrete sleeper
We would like to conduct some Mechanical Testing and Concrete Testing on F27, F27VS & F40 Concrete Sleeper, Cast Iron Rail Shoulder and Prestressed Tendon Stand respectively. All the testing requirements and remarks have all been consolidated as follow.
sample 1: F27 Sleeper 2515mm length x 264mm width x 203mm thickness (at centre of rail slat) Cast Iron Rail Shoulder Prestressed Tendon Stand
sample 2: F27VS Sleeper 2515mm length x 264mm width x 203mm thickness (at centre of rail slat)
sample 3: F40 Sleeper 2420mm length x 285mm width x 200mm thickness (at centre of rail slat)
Cover Survey: Cover meter survey using Profometer 5 device or Elcometer 331B device or similar shall be carried out to detect and identify the existing reinforcement / tendon layout.
Concrete Dust Sampling: Concrete dust samples shall be taken from concrete surface of each sleeper at a minimum of 3 locations. These shall be well-spaced and taken from different faces
i.e. top, side and bottom on each sleeper so that to give a comprehensive result and
provide variations in condition of the sleeper. Four dust samples per hole shall be carefully collected for all test locations by drilling 20mm diameter holes at depth increments of 5mm-25mm, 25mm-50mm, 50mm-75mm and 75mm-100mm.
Carbonation Test:Carbonation depth shall be assessed using a chemical solution indicator to establish the pH of the concrete surfaces.
Water Permeability Test & Chloride Diffusion Test: The Contractor shall arrange for core samples to be tested for chloride diffusion (bulk diffusion or ponding test) in accordance with Nord test NT Build 443. The saturated specimen shall be, on one plane surface, exposed to a NaCl solution for a specified exposure time. Thin layers will be then ground off parallel to the exposed face and the chloride content of the layers will be measured. The Contractor shall arrange for the core samples to be tested for water permeability using pressure-induced flow method by an HOKLAS accredited laboratory. The test of permeability at pressure shall be made on concrete cores in
apparatus that permit water under pressure to be fed to the top side of the specimen, and water percolating through to be collected and measured from the underside.
Petrographic testing: The petrographical analysis shall be carried out on polished plates (thin sections) prepared from each core – 50mm section from near the outer surface of the
element (start of the core) and 50mm section from middle of the element (middle of the core).
Concrete Compressive Test: 75mm core samples to be tested for compressive strength in accordance with BS EN 12390 or HK CS1: section 21
4. sample 4: Cast Iron Rail Shoulder
Chemical Composition Test
Mechanical testing- tensile testing BS EN ISO 6892-1) or hardness test (BS EN ISO 6506 Brinell method)