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Advanced materials science
Published in Paul Marsden, Digital Quality Management in Construction, 2019
For brickwork, a range of basic tests in both laboratory settings and on site include: compressive testing machines, water absorption and efflorescence tests by immersing in fresh water, and visual inspections for colour, size and shape. Certain types of Schmidt hammer can be used to test in situ strength. A digital approach can test samples using software such as WUFI (Wärme Und Feuchte Instationär,2 translated as heat and moisture transiency) developed by the Fraunhofer Institute of Building Physics to measure the risk of surface condensation, mould growth and efflorescence on internal surfaces of walls and freezing on the external surfaces. Lucideon were used as the testing consultants on the Battersea Power Station project in London to assess if the brickwork, which had been built in 1927, was still suitable for use in the modern age after the building had been refurbished into residential accommodation3 (it passed with flying colours).
Standardized joint descriptions for improved rock classification
Published in W.A. Hustrulid, G.A. Johnson, Rock Mechanics Contributions and Challenges: Proceedings of the 31st U.S. Symposium, 2020
Simple techniques are not yet available to better quantify the affect of alteration on joint surfaces. A Schmidt hammer can be used on the joint surface to determine if alteration or infilling with a strength different from that of the host rock is present on the joint surface. It is not yet known how to quantify the thickness and composition of infilling from this test. It is possible, however, to use a more systematic approach for describing joint alteration to allow easy comparison between classification systems. The NGI system goes into considerable detail in its description of joint alteration and infilling and can be used as a standard from which the alteration categories in other systems can be derived.
Silo structural assessment: A detailed approach
Published in Alphose Zingoni, Insights and Innovations in Structural Engineering, Mechanics and Computation, 2016
N. Brahimi, S. Piot, M.O. Mmusi
The Schmidt hammer test was used to evaluate the strength of the concrete. Schmidt hammer test results are sometimes unreliable (Antonio et al, 2013). In order to improve the data reliability, a concrete core sample was taken adjacent to the Schmidt hammer test. The two results were compared and adjusted accordingly.
Correlation models for utilising rebound hammer technique in evaluating weathered limestone walls
Published in Australian Journal of Structural Engineering, 2023
Tamer Eljufout, Nidal Hadadin, Assal Haddad, Fadi Alhomaidat
Based upon the above mentioned, the Schmidt hammer is a common tool for measuring the mechanical properties of rock material because it gives a quick and inexpensive assessment of surface hardness. However, a variety of factors influence the consistency and reliability of the RH test results, including hammer type; rebound normalisation; specimen size; surface smoothness; weathering and moisture content; testing and data reduction; and analysis techniques. Due to the lack of earlier studies on natural building limestones and the uncertainty involved in NDT techniques, this study aims to establish correlation models for compressive strength and modulus of elasticity based on RH values and to evaluate the impact of weathering factors on limestone walls utilising the RH test. This rock type was chosen because limestone outcrops across a large portion of the Middle East, and as a result, much construction activity is carried out on this rock type. The present study will significantly contribute to improving the reliability of evaluating existing structures made of limestones.
Machine learning techniques for estimation of Los Angeles abrasion value of rock aggregates
Published in European Journal of Environmental and Civil Engineering, 2022
Mojtaba Asadi, Abbasali TaghaviGhalesari, Saurav Kumar
The Schmidt hammer test was originally developed to measure the uniformity, stiffness and strength of concrete, mainly its surface rebound hardness. This test has also been widely used to evaluate the rock hardness due to its simplicity, repeatability, non-destructiveness and portability of the equipment. Before initiating the test, the test surface must be removed from moisture and any type of material that may interfere the readings. The instrument must be hold firmly so that the plunger is perpendicular to the test surface. If needed, a correction factor must be established to consider the direction (e.g. upward and downward) of impact. By pushing the instrument toward the test surface gradually, the steel hammer impacts a metal plunger in contact with the rock surface at a certain amount of energy. Different levels of impact energy can be applied in the testing of rock, primarily using L-type and N-type hammers. The impact energy of L-type is 0.735 N-m and the impact energy of N-type is three times higher, i.e. 2.207 N-m. After impact, the plunger can be locked in the position to maintain the pressure on the instrument and the rebound number is recorded to the nearest whole number.
Schmidt hammer rebound hardness tests for the characterization of ancient fired clay bricks
Published in International Journal of Architectural Heritage, 2019
The Schmidt hammer is a non-destructive instrument mainly used for testing concrete, rock, and more recently, brick hardness with the aim of estimating the mechanical strength of these materials. Fired clay bricks are well known to present non-heterogeneous structures, mainly influenced by the raw material, the burning process and long time exposure to climatic conditions. In the scope of building conservation, the lack of affordable technical means to simply evaluate the degree of decay of historical fired clay bricks may lead to extensive restoration campaigns, which also brings up the questions of the authenticity and compatibility of the replacement bricks. The presented study is a first step in this direction, where Schmidt hammer tests have been done on different samples from historical buildings constructed between the 18th and 20th century, considering their orientations and locations within the building’s wall. On each surface (Ee, Ei, and Ii), ten repeated impact readings were recorded at ten different points to provide the mean rebound value of the surface for each successive impact. Based on these results, a weathering index In (%) is suggested to quantitatively evaluate the degree of decay of the brick surfaces.