Calcrete, gypcrete and soil classification in Algeria

doi:10.1016/0013-7952(80)90028-9

Engineering Geology

Volume 15, Issues 1–2, January 1980, Pages 15-52

https://doi.org/10.1016/0013-7952(80)90028-9 Get rights and content

Abstract

Calcrete deposits are widespread in the subhumid and semi-arid zones of Mediterranean Algeria and the Sahara. They present a diversity of ages, degrees of development and weathering. Their complex history is the result of two contradictory processes: a diagenetic trend leading to hardpan formation, and a weathering trend with dissolution of calcite and its precipitation in dusty grain-size and partial leach-out from the soil profile.

Calcrete is an excellent road-paving material if used within the climatic conditions corresponding to the stability of calcite in the soil profiles. A tentative classification of calcrete gravels is proposed on the basis of the Los Angeles abrasion test results. Gypsum sands recovered from massive deposits may also be used as a paving material wherever annual precipitation is not over 100 mm.

The geotechnical characteristics of calcrete and gypsum soils make it difficult and even impossible for usual identification tests, such as the Atterberg limits, to supply reliable classification figures or estimates of important engineering properties of these soils. Other parameters must therefore be chosen in order to characterize calcrete and gypsum soils. This article considers the introduction of new soil classes into the Unified Soil Classification System (USCS). This revision is intended to strengthen the universal character of the USCS.

References (31)

AdolpheJ.P.
Obtention d'encrouˆtements carbonatés par gel expérimental
Compt. Rend. Acad. Sci. Paris
(1972)
AristarainL.F.
Clay minerals in caliche deposits of eastern New Mexico
J. Geol.
(1971)
AristarainL.F.
On the definition of caliche deposits
Z. Geomorphol.
(1971)
BoulaineJ.
Sur la formation des carapaces calcaires: accumulation de carbonates et de sulfates dans les sols bien drainés
Bull. Publ. Serv. Carte Géol. Algérie, Nouvelle Sér.
(1958)
BlountC.W. et al.
Gypsum anhydrite equilibria in systems CaSO₄3-H₂0 and CaSO₄-NaCl-H₂O
Am. Miner.
(1973)
CasagrandeA.
Classification and identification of soils
Trans. Am. Soc. Civil Eng.
(1948)
ChantereauM. et al.
Le catalogue de structures types de chaussées de la Direction des Routes
Bull. Liaison Lab. Ponts Chaussées
(1972)
ChoubertG.
Au sujet des crouˆtes calcaires quaternaires
Compt. Rend. Acad. Sci. Paris
(1948)
CoqueR.
Les crouˆtes gypseuses dans le Sud-Tunisien
Bull. Soc. Sci. Nat. Tunisie
(1955)
Corps of Engineers, U.S. Army
The unified soil classification system
Tech. Mem.
(1953)

DubiefJ.

DurandJ.H.

DutilP.

Contributionàl'étude des sole et paléosols du Sahara

Thèse Fac. Sci. Univ., Strasbourg, C.N.R.S. A.0.6

(1971)

FenzyE.

Particularités de la technique routière au Sahara

Rev. Gén. Routes Aérodromes

(1966)

GoudieA.

On the definition of calcrete deposits

Z. Geomorphol.

(1972)

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Engineering properties and dynamic behavior of caliche deposits in a seismically active region in southern Turkey
2010, Engineering Geology
Despite the epcientral distance of 40 km significant structural damage was observed during the Adana–Ceyhan earthquake (Mw = 6.2) of 27 June 1998 in the countryside where mostly low-rise (1–2 storey) buildings are founded on caliche deposits. However, the observed damage was not uniform in that similar buildings located on other caliche sites were only slightly damaged. This study evaluates the engineering and dynamic behavior of the caliche deposits in an effort to explain the observed variation in damage. Horizontal-to-vertical spectral ratios were obtained from both microtremor measurements and strong motion records of aftershocks. Furthermore, ground amplification was modeled using one-dimensional site response analysis based on the soil profiles that were obtained from previously available geotechnical and geophysical data. The results compared with the observed damage distribution show that significant amplification does not occur on most of the caliche deposits for frequencies up to 10 Hz. Moreover, the largest amplification factor of about 5 was found at frequency of 7.5 Hz in Kılıçlı village in which mostly low-rise (1–2 storey) buildings are located. Results of 1-D linear site response analyses suggest that 1 or 2 m thick hardpan lying on top has no significant effect on soil amplification other than a slight shift in fundamental frequency. Amplification is most significantly influenced by the thickness of the softpan.
The terminology and the concepts of gypsum-rich soils
2000, Geoderma
Many terms in earth sciences, and their underlying ideas, have been developed in temperate–humid countries. Both geological and climatic reasons cause gypsum-rich soils to occur in dry lands. Soil science has paid little attention to gypseous soils, and this limited knowledge is reflected in the direct loan of customary terms of soil science that can lead to misconceptions on the composition and behaviour of soils with large proportions of gypsum. Elements for discussion on the use of sundry terms about soils containing gypsum are presented here and some of their implicit assumptions discussed. Some generic terms are examined, as well as several expressions used by organizations devoted to soil survey and classification. The transformations occurring in gypseous soils are discussed, in particular the effects from exposure. The refinements herein proposed aim to help understand the role of gypsum in local and global earth-surface processes.
Calcretic and ferricretic duricrusts of the Thar Desert, India: Their geotechnical appraisal as a road paving aggregate
1999, Engineering Geology
This paper presents the results of laboratory tests conducted to evaluate the suitability of calcrete and ferricrete as road paving aggregates. Most of these residual aggregates are gravel dominated (A-1 class) with low percentage of non-plastic fines. The maximum dry density (MDD) and optimum moisture content of these aggregates are controlled primarily by the size gradation and compaction energy. Specimens compacted using higher energy result in increase of MDD than those specimens compacted under low energy. Similarly, the California bearing ratio (CBR) also increases manifold (as much as 97.08%) when compacted under higher compaction energy. Aggregate impact values, a measure of toughness of these aggregates vary from 12.8 to 47.5%. Both calcrete and ferricrete exhibit special properties such as self-stabilization and increase in CBR after soaking. Obtained laboratory results on size gradation, CBR and aggregate impact values fulfils the Indian Road Congress (1978) specifications for the base and sub-base courses of water bound macadam (WBM) roads.
The infill of a supradetachment(?) basin: The continental to shallow-marine Upper Permian succession in the Dolomites and Carnia (Italy)
1997, Sedimentary Geology
In the Dolomites and Carnia (eastern Southern Alps), the Upper Permian succession is represented by red beds of Val Gardena Sandstone, grading upwards and eastwards into the evaporitic and carbonate deposits of the Bellerophon Formation.
An overall transgressive pattern is shown by the general trend of the depositional setting, which evolved from flashy alluvial fans, through multiple-channel bedload rivers, mixed-load sinuous rivers, terminal fans, coastal sabkha and evaporitic lagoon, to a shallow, low-gradient marine ramp. The inferred fluvial regime was subject to rapid and erratic fluctuations in discharge. Palaeosols are represented by calcic soils, and suggest a warm to hot, semi-arid or dry subhumid climate with strongly seasonal rainfall. Vertic features are associated with more inland alluvial complexes: they are missing in the terminal-fan deposits, suggesting greater aridity in lowland (coastal) areas.
The Bellerophon Fm. consists of two units: a lower evaportte-bearing unit, deposited in a barred basin, and an upper shallow-marine carbonate unit, laid down on a very low-energy, low-gradient ramp.
Five third-order sequences and the lower part of a sixth sequence, collectively showing a backstepping pattern, have been identified in the succession. Due to the presence of a very low-gradient ramp margin, and the consequent ineffectiveness of relative sea-level falls in producing large-scale erosion in coastal areas, it is suggested that, rather than eustatic changes, degradational episodes marking sequence boundaries in the red-bed succession reflect changes in the climate-modulated intrinsic variables of discharge and sediment supply, and/or tectonic uplift.
Base level rises in, red-bed sequences are recorded by upward change from thick channel-belt sandstone bodies with an often high connectedness ratio, to progressively thinner channel deposits, ranging from isolated ribbons to channel-belt sandstone bodies potentially reaching high width/thickness ratios, encased in a comparably greater volume of overbank fines. This trend is thought to reflect the change from a confined geomorphic setting, with a limited area of potential avulsion, to an unrestricted setting with rivers free to move extensively; in addition, it documents the transition from an inland fluvial system with laterally migrating perennial or semi-perennial channels, to an ephemeral network of randomly migrating and frequently avulsing small terminal-fan distributaries, through a drastic downstream decrease in channel depth and discharge.
Identification of key sequence-stratigraphic relationships within the red-bed succession was mostly aided by the presence of easily recognizable and regionally correlated marine and marginal marine bed packages, traceable landwards into alluvial deposits showing faint traces of tidal activity, interpreted as the equivalent of marine maximum-flooding sediments. They may grade upwards into progradational fluvial packages showing basinward increase in thickness.
The Upper Permian deposits of the Southern Alps are considered part of an Upper Permian-Lower Triassic, second-order, structurally controlled sequence. The location of the basin on a thickened, previously active crust, affected by thermal perturbance after the last stages of the Variscan orogeny, the relatively reduced thickness of the basin fill, and predominantly long, transverse drainage networks, mostly derived from the denuded Insubric footwall, all suggest that sedimentation took place in a supradetachment basin, with a major detachment fault located in the palaeo-Insubric belt.
Pedogenic gypcrete formation in arid central Australia
1997, Geoderma
In arid Australia, various gypsum sediments are widely distributed around salt lakes and along present and ancient drainage lines. They are primarily precipitated from saturated surface and subsurface brines and may be later transported by water or wind. When these primary gypsum sediments are exposed at the land surface and above the ground-water table, they tend to be altered by pedogenic processes, resulting in the development of a pedogenic gypcrete. Pedogenic gypcretes are white, powdery and massive and are commonly cemented to some degree, with a polygonal hardened ‘skin’ on the exposed surface. It consists of very fine (mostly < 0.1 mm) gypsum crystals, distinctively different from the underlying parent gypsum sediments which usually consist of larger (> 0.5 mm) crystals and have lacustrine, aeolian or other primary sedimentary features. A pedogenic gypcrete usually contains > 80% gypsum with minor quartz sands, clays, carbonate and heavy minerals. Various pedologic features have been developed such as channels, cutans, pedotubules and secondary carbonates. The major processes of gypcrete formation include dissolution, leaching and recrystallization. Dehydration possibly occurs, helping to break down larger crystals. However, dehydrated forms of sulphates tend to be rehydrated to gypsum when any water is available from rainfall or atmospheric moisture. The TL dating of co-occurring quartz sands in gypsum dune sequences indicates that a 0.5–1.0 m pedogenic gypcrete horizon may form in a period of up to several thousands years. In central Australia, at least three episodes of pedogenic gypcrete formation have been dated as 80–100 ka, 35–50 ka and in the Holocene. These pedogenic gypcrete formations followed major gypsum deposition episodes in salt lakes of central Australia and indicate intervals of stable land surface during which both gypsum deposition and reworking were negligible.
Desert soils
1992, Developments in Earth Surface Processes

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Calcrete, gypcrete and soil classification in Algeria

Abstract

Obtention d'encrouˆtements carbonatés par gel expérimental

Compt. Rend. Acad. Sci. Paris

Clay minerals in caliche deposits of eastern New Mexico

J. Geol.

On the definition of caliche deposits

Z. Geomorphol.

Sur la formation des carapaces calcaires: accumulation de carbonates et de sulfates dans les sols bien drainés

Bull. Publ. Serv. Carte Géol. Algérie, Nouvelle Sér.

Gypsum anhydrite equilibria in systems CaSO43-H20 and CaSO4-NaCl-H2O

Am. Miner.

Classification and identification of soils

Trans. Am. Soc. Civil Eng.

Le catalogue de structures types de chaussées de la Direction des Routes

Bull. Liaison Lab. Ponts Chaussées

Au sujet des crouˆtes calcaires quaternaires

Compt. Rend. Acad. Sci. Paris

Les crouˆtes gypseuses dans le Sud-Tunisien

Bull. Soc. Sci. Nat. Tunisie

The unified soil classification system

Tech. Mem.

Contributionàl'étude des sole et paléosols du Sahara

Thèse Fac. Sci. Univ., Strasbourg, C.N.R.S. A.0.6

Particularités de la technique routière au Sahara

Rev. Gén. Routes Aérodromes

On the definition of calcrete deposits

Z. Geomorphol.

Gypsum anhydrite equilibria in systems CaSO₄3-H₂0 and CaSO₄-NaCl-H₂O