Environ Earth Sci (2013) 69:1299–1332 DOI 10.1007/s12665-012-2008-1 SPECIAL ISSUE Petrographical and petrophysical properties of sandstones: statistical analysis as an approach to predict material behaviour and construction suitability H. Stu¨ck • R. Koch • S. Siegesmund Received: 10 June 2012 / Accepted: 12 September 2012 / Published online: 25 October 2012 Ó The Author(s) 2012. This article is published with open access at Springerlink.com Abstract Most studies dealing with material properties of of pore radii distribution, cementation and degree of sandstones are based on a small data set. The present study alteration. Sandstones showing a maximum of capillary utilizes petrographical and petrophysical data from 22 pores and micropores (bimodal) exhibit a distinct hygric selected sandstones and *300 sandstones from the litera- dilatation and low salt resistance. These sandstones are ture to estimate/predict the material and weathering highly immature sublitharenites–litharenites, characterized behaviour of characteristic sandstones. Composition and by altered unstable rock fragments, which show pointed- fabric properties were determined from detailed thin sec- elongated grain contacts, and some pseudomatrix. Quartz tion analyses. Statistical methods applied consist of data arenites and sublitharenites–litharenites which are strongly distributions with whisker plots and linear regression with compacted and cemented, show unimodal unequal pore confidence regions for the petrophysical and weathering radii distributions, low porosity, high strength and a high properties. To identify similarities between individual salt resistance. The presence of swellable clay minerals in sandstones and to define groups of specific sandstone types, sublitharenites–litharenites leads to a medium to high principal component and cluster analyses were applied. hygric dilatation, whereas quartz arenites show little hygric The results confirm an interaction between the composi- dilatation. Sandstones with unimodal equal pore radii dis- tion, depositional environment, stratigraphic association tribution mostly belong to weakly compacted and cemen- and diagenesis, which leads to a particular material ted mature quartz arenites. These are characterized by high behaviour of sandstones. Three different types of pore radii water absorption and high porosity, low to medium distributions are observed, whereby each is derived from strength and a low salt resistance. The data compiled in this different pore space modifications during diagenesis and is study are used to create a sandstone quality catalogue. associated with specific sandstone types: (1) bimodal with Since material properties are dependent on many different a maximum in capillary and micropores, (2) unimodal parameters of influence, the transition between different unequal with a maximum in smaller capillary pores and (3) lithotypes is fluent. unimodal equable with a maximum in larger capillary pores. Each distribution shows specific dependencies to Keywords Sandstones Á Pore space Á Prediction Á water absorption, salt loading and hygric dilatation. The Weathering behavior Á Compressive strength strength–porosity relationship shows dependence on the content of unstable lithic fragments, grain contact and type Introduction H. Stu¨ck (&) Á S. Siegesmund Geoscience Centre of the University Go¨ttingen, Due to their great availability, sandstones are commonly Goldschmidtstr.3, 37077 Go¨ttingen, Germany used as a natural stone for buildings, monuments and e-mail: [email protected] sculptures. The wide variety of different applications increases the need to understand their characteristic mate- R. Koch University of Erlangen, GeoCentre Northern Bavaria, rial properties. Complex sedimentary processes are Lo¨wenichstr.28, 91054 Erlangen, Germany involved in the origin of sandstones. These include the 123 1300 Environ Earth Sci (2013) 69:1299–1332 source material, transport processes, the depositional Sedimentary processes as a key to understanding environment and diagenesis. Characterizing and predicting material behaviour of sandstone the material properties of sandstone requires detailed investigations of sedimentological, petrographical and The path from unconsolidated sediment to lithified sand- petrophysical parameters (Koch and Sobott 2008;Morales stone suitable for construction is controlled by complex Demarco et al. 2007;Ru¨drich et al. 2010). Thereby, the sedimentary and diagenetic processes (Tucker 2001). The characteristics of the pore space such as porosity, permeability mineralogical composition of sandstone (compositional and pore geometry are most important for the weathering maturity) and the textural maturity are dependent on sed- behaviour of porous sandstones (cf. Fitzner 1988; Fitzner and imentological parameters (e.g. transport, depositional Snethlage 1982; Putnis et al. 1995; Putnis and Mauthe 2000; environment), which contribute to the petrophysical prop- Ru¨drich et al. 2010). In this context, a linear correlation erties, and to a certain degree the weathering behaviour. between porosity and compressive strength and flexural Diagenesis begins immediately after/with deposition and strength as well as water balance and storage properties has includes processes of compaction, pressure solution, been reported by Ru¨drich et al. (2010). recrystallization, dissolution, replacement/alteration, clay However, most of these studies are based on a small data set mineral and feldspar authigenesis as well as cementation of samples and parameters. Therefore, general statements by varying mineral phases (Burley et al. 1985; Morad et al. covering a wide stratigraphic range and different sandstone 2000; Tucker 2001; Koch and Sobott 2008). Diagenetic types of varying depositional environments and diagenetic realms include eo-, meso- and telogenetic processes development cannot be made. A statistical analysis of the (Choquette and Pray 1970) acting from shallow to deep parameters such as grain size, compositional and textural burial conditions depending on the chemistry of pore water maturity, cementation and fabric, which essentially control present. The development of pore space geometry through the material properties of sandstones, is lacking. time together with the alteration of grain contacts are Therefore, the aim of the present study is to establish parameters of special importance. Cements and compaction criteria and systems, which aid in predicting the weathering lead to the reduction of the primary intergranular pore behaviour of various sandstone types. This is based on a space. Eogenetic cements also shelter the rock against later statistical analysis of a large data set that includes most of compaction during deeper burial (Worden and Morad the parameters generally used when analysing the quality 2000). Some cement is dissolved by processes forming a of a sandstone. The study is based on a large amount of late-stage secondary porosity. petrographical and petrophysical data collected from 300 Clay material as a primary matrix, pseudomatrix and/or sandstones described in the literature. Twenty-two of the later infiltration into open pore spaces is a significant total samples analysed represent important sandstones used problem of sandstones with regard to their weathering in Germany. These sandstones were investigated in detail stability, since they considerably influence porosity and by petrographic analysis, determining the fabric charac- permeability (Houseknecht and Pittman 1992). Neofor- teristics, measuring the petrophysical properties and com- mation, transformation and alteration of different clay bining all these data using statistical analyses. minerals under varying conditions (temperature, pressure When using data from the literature, it has to be taken and water access) define clay minerals as a special into account that the data might not be complete in regard parameter in sandstones that requires careful analysis when to petrographical analyses and petrophysical measure- characterizing the material behaviour of a sandstone. ments. Commonly, just single samples are taken when analysing a quarry, and thus the samples collected may not represent the wide variety of facies types present. For Methods sandstones frequently used, this might be less problematic because only certain qualities are generally regarded. To support this investigation, a large data set was taken Further possible sources of error may be caused by dif- from the literature (Fig. 2; Table 1) dealing with the pet- ferent approaches during sampling, preparation of samples, rographical and petrophysical analysis of sandstones different methods and the apparatus used for analysis (Rac (Bartelsen 2008; Seidel 2004; Chitsazian 1985; David and Chernyshev 1970). Data found on the Internet or from 2006; Fitzner 1970; Grimm 1990; Holzwarth 1996; Kirsten company brochures need to be used with caution, since the 2009; Mosch and Siegesmund 2007). Basic parameters information may only reflect the optimum quality but not such as porosity, density, water uptake and strength are the natural variations of quality in a quarry. Therefore, the included for the sandstones from all over the world, par- data utilized in the present study originates from scientific tially originating from the natural stone industry and from non-commercial sources, which deal with material testing the data collected in detailed studies dealing with German and/or research. sandstones. 123 Environ Earth Sci (2013) 69:1299–1332 1301 Petrographical and petrophysical