Rheological and workability effects of bottom ash usage as a mineral additive on the cement based permeation grouting method Fatih Celik ⇑ , Osman Akcuru Department of Civil Engineering, Faculty of Engineering Nigde Omer Halisdemir University, Nigde Turkey highlights  Rheology and workability of the cement based grout treated with bottom ash (BA) were investigated.  The substitution of BA to the grout mixtures has considerable effects on the rheological and fluidity properties.  Rheological features are so critical for evaluating permeation grouting design parameters.  Water to binder ratio (w/b) is dominant factor affecting rheological and workability properties of cement based grouts. article info Article history: Received 30 March 2020 Received in revised form 28 June 2020 Accepted 7 July 2020 Keywords: Bottom ash Mineral additive Rheology of grout Workability of grout Permeation grouting abstract This study presents the effects of rheological and fluidity features of cement based grouts incorporated with bottom ash (BA) as mineral additive on permeation grouting method. In this context, some exper- imental and analytical analyses were conducted and their results were presented. In terms of rheological and workability tests, the test program included 28 different mixtures having 0% (for control purposes), 5%, 10%, 15%, 20%, 25% and 30% bottom ash content and four water to binder ratios (w/b = 0.75, 1.00, 1.25 and 1.50). Plastic viscosity, apparent viscosity, and the yield stress of the mixtures based on rheological properties were measured for all mixtures. At the same time, marsh cone flow time, plate cohesion, and mini slump diameter in terms of workability features were obtained. In second part of this study, all rhe- ological properties obtained from the mixtures were used for evaluating permeation grout method based on two analytical flow models (radial and spherical flow models). All test results showed that rheological parameters (especially plastic viscosity) and workability properties of the cement based grouts incorpo- rated with BA are very important for determining of the permeation grouting design parameters such as injection pressure. Ó 2020 Elsevier Ltd. All rights reserved. 1. Introduction Grouting method has been commonly used for soil improve- ment based on stability and deformation problems, prevention of water seepage and solving of differential settlement problems for buildings as well as different civil engineering site applications [1-4]. Three technics, which are called as permeation grouting, compaction grouting and fracture grouting, extensively used for grouting applications based on the mechanism for spreading of grout into soil [5-10]. These grouting techniques may show multi- ple complex forms during grouting diffusion into soil. However one of them presents usually different behaviors under some specific conditions. For instance, the sandy soils that have large porosity may engender less inhibitory effect during grout injection to soil. Therefore permeation grouting technique will be more favorable than other grouting methods in such conditions [11,12]. Permeation grouting method is an effective soil improvement technique that is commonly used in geotechnical works. [13]. The main principle of this method can be defined as a steady injec- tion without causing any change in the soil structure based on the pore fluid that is replaced (i.e., squeezed out) with cement based grout. The permeability of the soil is a dominant factor directly affecting grout penetration. Therefore, this technique is usually applicable for clean sands and gravel or open fills that can be pen- etrated with low-viscosity grouts [13]. The main reason of using this technique is explained as reducing soil permeability and con- trolling the seepage because of ground water flow. Moreover, it is also used for strengthen and stiffen the soil [13,14]. This method depends on stability of grout (bleeding capacity), injection https://doi.org/10.1016/j.conbuildmat.2020.120186 0950-0618/Ó 2020 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail addresses: fatihcelik@ohu.edu.tr (F. Celik), osman.akcuru@gmail.com (O. Akcuru). Construction and Building Materials 263 (2020) 120186 Contents lists available at ScienceDirect Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat