The article is focused on the medium-term negative effect of groundwater on the underground grout elements. This is the physical-mechanical effect of groundwater, which is known as erosion. We ...conduct a laboratory verification of the erosional resistance of grout mixtures. A new test apparatus was designed and developed, since there is no standardized method for testing at present. An erosion stability test of grout mixtures and the technical solutions of the apparatus for the test's implementation are described. This apparatus was subsequently used for the experimental evaluation of the erosional stability of silicate grout mixtures. Grout mixtures with activated and non-activated bentonite are tested. The stabilizing effect of cellulose relative to erosion stability has been also investigated. The specimens of grout mixtures are exposed to flowing water stress for a certain period of time. The erosional stabilities of the grout mixtures are assessed on the basis of weight loss (WL) as a percentage of initial specimen weight. The lower the grout mixture weight loss, the higher its erosional stability and vice versa.
This book was proposed and organized as a means to present recent developments in the field of testing of materials and elements in civil engineering. For this reason, the articles highlighted in ...this editorial relate to different aspects of testing of different materials and elements in civil engineering, from building materials to building structures. The current trend in the development of testing of materials and elements in civil engineering is mainly concerned with the detection of flaws and defects in concrete elements and structures, and acoustic methods predominate in this field. As in medicine, the trend is towards designing test equipment that allows one to obtain a picture of the inside of the tested element and materials. Interesting results with significance for building practices were obtained.
This book was proposed and organized as a means to present recent developments in the field of testing of materials and elements in civil engineering. For this reason, the articles highlighted in ...this editorial relate to different aspects of testing of different materials and elements in civil engineering, from building materials to building structures. The current trend in the development of testing of materials and elements in civil engineering is mainly concerned with the detection of flaws and defects in concrete elements and structures, and acoustic methods predominate in this field. As in medicine, the trend is towards designing test equipment that allows one to obtain a picture of the inside of the tested element and materials. Interesting results with significance for building practices were obtained.
In order to create the grout curtain for the Ermenek hydropower plant in Turkey, grouting measures were designed in karstified limestone. Based on the geological model, detailed investigations were ...carried out in advance of construction into the location and nature of the anchoring of the grout curtain into impermeable rock. Eventually, the water head of about 220 m will be grouted from four grouting galleries arranged vertically above one another with a separation of 70 m in each case, and connected from the lowest gallery at a maximum 250 m deep into impermeable layer. The overall height of the grout curtain will thus be about 470 m and the area approx. 680,000 m2. The design intends a single‐row grout curtain with drillings spaced at 1.5 m, with denser spacing at some locations in the course of construction. In the immediate vicinity of the dam, the grout curtain is to have two rows for structural reasons, combined with a drainage curtain. Consolidation grouting in the foundation area of the arch dam will be carried out in the course of concreting. The injection pressures and the success criteria for each injection will be described.
Detailed investigations into the grout were performed for the implementation of the grouting measures. The determination of the injection steps and the closer spacing of the injection pattern required in places will be discussed, also regarding the karst features encountered.
The impounding of the 4,600 m m3 reservoir, which will take about 5 years, will be started while the dam is still being concreted.
Für die Herstellung des Dichtschirms des Kraftwerks Ermenek in der Türkei wurden Injektionsmaßnahmen im verkarsteten Kalkgestein geplant. Basierend auf dem geologischen Modell gingen der Ausführung detaillierte Untersuchungen über die Lage und die Art der Einbindung des Dichtschirms in den undurchlässigen Untergrund voran. Schlussendlich wird die etwa 220 m hohe Wassersäule über vier vertikal übereinander angeordnete Injektionsstollen mit einem Abstand von jeweils 70 m injiziert und von der tiefsten Galerie maximal 250 m tief bis zum undurchlässigen Untergrund angeschlossen. Die Gesamthöhe des Dichtschirms beträgt somit etwa 470 m und weist eine Fläche von ca. 680.000 m2 auf. Die Planung sieht einen einreihigen Dichtschirm mit Bohrungen im Abstand von 1,5 m vor, der im Zuge der Ausführung örtlich verdichtet wurde. Im unmittelbaren Bereich der Talsperre ist aus Standsicherheitsgründen der Dichtschirm in zwei Reihen vorgesehen, der mit einem Dränageschirm kombiniert ist. Konsolidierungsinjektionen in der Aufstandsfläche der Bogenstaumauer werden im Zuge des Betonierens durchgeführt. Die zu verwendenden Injektionsdrücke und zu erzielenden Injektionserfolge werden erläutert.
Für die Ausführung der Injektionsmaßnahmen wurden detaillierte Untersuchungen des Injektionsguts durchgeführt. Die Festlegung der Injektionsschritte und die erforderliche lokale Verdichtung des Bohrrasters – auch in Hinblick auf die angetroffenen Karsterscheinungen – werden diskutiert.
Mit dem Aufstau des 4.600 Mio. m3 fassenden Reservoirs, der etwa fünf Jahre benötigen wird, wird während der Betonierung des Sperrenbauwerks begonnen.
•Commercially available grouts for post-tensioning applications were characterized.•Flow cone test should not be used as a screening test for post-tensioning applications.•Increase in fineness can ...increase the flow retention & bleed resistance of PT grouts.•Increase in fineness is critical for enhancing the fillability in post tensioned systems.•Mixing speed and ambient temperature significantly influence the grout performance.
In grouted post-tensioned (PT) systems, cementitious grouts are supposed to completely fill the interstitial spaces between the strands and act as the ‘last line defence system’ against corrosion. However, use of poor quality grout materials and grouting practices result in voided grout systems, ultimately leading to premature failure of tendons in many bridges around the world. To ensure an intact system, the grout must have excellent fresh properties, in particular the flow properties. Such high-performance grouts are not available in many developing countries, where grouting for post-tensioned structures is still a nascent technology. In this research, a two-stage test program was carried out to evaluate the fresh and hardened properties of seven commercial grouts, which includes three Pre-Packaged Grout mixes (PPG); three Site-Batched Grout mixes (SBG) and one standard Ordinary Portland Cement grout mix (PCG). Further, one PPG mix and SBG mix were chosen and their properties were evaluated for three levels of mixing speed and two ambient temperature conditions. Fresh properties such as wet density, efflux time and its retention, standard bleed, wick-induced bleed and pressure bleed, as well as set/hardened properties such as setting time, compressive strength and volume change were evaluated. Three batches of grout were tested for each grout material, to ensure reliability of results. The influence of binder fineness on the performance of grouts was also evaluated. The study serves as a strong evidence in substantiating that the most commonly used grout materials for PT system in developing countries, fail to meet the standard requirements and even the manufacturer’s own specifications. It is also found that the performance of the grout is influenced by mixing speed, ambient temperature, and fineness. The study emphasises that the evaluation of the grout behaviour under simulated field conditions is essential to ensure void free and durable PT systems.
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