Abstract
This study presents a flow pump technique usually used for evaluating the permeability of soils, which was, for first time, applied to measure the water permeability of concrete. Additionally, a new easy-to-apply method to determine permeability is proposed, based on a modification of Valenta’s formula. In the calculations, the apparent air content of concrete mixes was taken into account. An additional purpose of the conducted research was to determine the influence of a new generation of polycarboxylate superplasticizer and chemically active admixtures on the permeability, compressive strength, and other properties of concrete. The following four types of concrete were tested: concrete without admixtures, concrete with an admixture to increase the compressive strength, concrete with a superplasticizer, and concrete containing two admixtures simultaneously. The results showed that the proposed method allows to obtain reliable measurements within a very short period of time. The obtained results confirmed that new method may be very useful in engineering practice, particularly in terms of the watertightness of hydrotechnical concretes and the properties of the concretes used in bridge construction, underground parts of office buildings, or sealed tanks.
Highlights
Concrete is one of the major construction materials widely used for infrastructure and building construction across the world
Quantitative assessment of the water permeability of concrete can be carried out by using various permeability measurement methods on cementitious materials, each of which is suitable for limited specific applications
Where k is permeability coefficient (m/s), Q is the volumetric flow rate (m3 /s), L is the length of the flow path (m), F is a cross-section of the sample exposed to water flow (m2 ), and ∆H is the drop in hydraulic potential difference (m)
Summary
Concrete is one of the major construction materials widely used for infrastructure and building construction across the world. A constant-flow permeability test is far more rapid than a conventional constant head test, and a substantial period of time—more than 40 h in soils with extremely low permeability—is needed to establish the steady state condition required for calculating permeability from Darcy’s law The advantages of this test arise from the fact that it is much easier to control small flow rates precisely than to measure them accurately. When testing a large volume of weakly permeable concrete, the limitation of this method is obtaining a flow rate through the whole sample This approach makes it possible to reproduce the test conditions that are used in measuring the depth of water penetration under pressure in accordance with EN 12390-8 [22].
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