ASTM C231: Testing Air Content of Concrete With a Type B
Loss of Air Content in Pumped Concrete Click the question to reveal the answer, click the question once more to hide. Print FAQs Q About Loss of Air Content in Pumped Concrete A 1. WHAT is Air Loss in Pumping? Increasingly, specifiers are testing
17/10/2020 · Re-examining air content testing for pumped concrete Concrete durability is a foremost consideration in bridge construction because the bridge deck is where the most maintenance is required. Premature deterioration of the bridge deck is common and results in
22/4/2016 · Can concrete increase entrained air content from the on site air test to hardened air content? Equipment calibrations, cylinder weights and finishing all indicate a no air mix for this interior slab at 2-3%. 18 months later, they are witnessing delamination. Cores were
the "TESTING SCC" inter-laboratory test program. In terms of air content, density and casting of specimens the task for NICe project 02128 was to establish the best way of filling the SCC into the air content pressurmeter before testing for air content, and into
21/3/2016 · Pumped concrete can be used for most structural concrete construction but is most useful where space for construction equipment is limited or access is difficult. Concrete pumps can be either truck- or trailer mounted and range from small units, exerting pressures from 250 to 300 psi and outputs of 15 to 30 yd 3 /hr, to large units, exerting pressures of 1,000 psi and outputs up to 150 yd 3 .
12/7/2010 · Temperature can also have a significant effect on air entrainment. Air entrainment varies inversely with temperature. The same mix will entrain more air at 50 F (10C) than at 100F (38C). Air Content Control. Measurement of air content is an important checking "sensor" for the concrete user to know whether concrete will resist freeze-thaw
16/8/2011 · Air is one more method used to change the viscosity of the mix. It makes it more fluid while maintaining the same water-cement ratio. RE: Air and pumping of concrete. JAE (Structural) 10 Aug 11 08:32. Agree - and I once had a contractor add air to a lightweight mix - pumped …
Fresh concrete total air content is measured using pressurization as described by Boyle's law and standardized as ASTM C231 (2014). The air void system in hardened concrete is typically measured by examining air voids in polished concrete cross sections under a microscopeas described M …
Changes in the air content of fresh concrete that is being pumped can occur at a number of places. These locations include the initial loading of the concrete into the pump hopper, as it passes through the pump line, and when it exits the line. This synthesis reviews the findings of recent research studies which deal with air content change in pumped concrete and summarizes methods of reducing
High air content concrete with low strength could, or almost surely will, be placed in the structure if boom angles are reduced or if somewhat lower slump concrete is pumped. Research has indicated that when the loss of air content is not too high (less than about 3%), the air void system in the concrete may still be adequate for freeze-thaw resistance.
acceptance tests for consistency, air content, or potential strength. The manipulation of concrete during pumping can significantly change mix characteristics. When sam-pling from a discharge stream, di-vert the discharge into the sample c o n t a i n e r. Do not
2/1/2021 · TESTING OF CONCRETE: A third party laboratory as approved by the Contractor will be appointed to carry out tests on concrete as may be applicable as per project specification. Temperature, slump, unit weight and air content of fresh concrete shall be
Mix Design and Pumped Concrete - Civil Engineering Portal – Biggest
2/7/1994 · Concrete Pumping Effects on Entrained Air-Voids. Pumping is a frequently used method of efficiently transporting concrete from the delivery vehicles to the formwork. Unfortunately, pumping concrete can affect the air content of a concrete mix. This has caused concern about the possible loss of resistance of the concrete to freezing and thawing.
• Air Content and SAM testing after pumping may not be representative of the hardened concrete. • One should be hesitant to reject concrete for low air or high SAM Number after pumping. • It appears that sampling the concrete prior to pumpingis a good 66
Standard Details. This Reference Specification covers Testing Agency requirements for field and laboratory testing of ready mixed concrete delivered to the project. It is intended for use by specifiers, Architects, Engineers, Owners, and other groups interested in monitoring the quality of concrete used in project construction.
26/7/2018 · The bubbles do not immediately re-form when pressure is decreased, so testing fresh concrete gives the appearance of having a reduced air content. However, the dissolved air seems to reform before the concrete hardens—and it is again well-dispersed, with a …
CIP 21 - Loss of Air Content in Pumped Concrete WHAT is Air Loss in Pumping Specifications increasingly require concrete to be sampled at the discharge end of a concrete pump and tested for air content. The intent is to ensure that the specified air content is