Volcanic Aggregates Research Articles

Petro-chemical features and source areas of volcanic aggregates used in ancient Roman maritime concretes

We present and discuss data from petrographic observation at the optical microscope, electron microprobe analyses on selected glass shards, and trace-element analyses on 14 mortar aggregates collected at the ancient harbors and other maritime structures of Latium and Campania, spanning the third century BCE through the second CE, aimed at identify the volcanic products employed in the concretes and their area of exploitation.According to Latin author Vitruvius assertion about the ubiquitous use of Campanian pozzolan in the ancient Roman sea-water concretes, results of this study show a very selective and homogeneous choice in the material employed to produce the concretes for the different investigated maritime structures, evidencing three main pumice compositions, all corresponding to those of the products of the post-Neapolitan Yellow Tuff activity of the Phlegraean Fields, and a systematic use of the local Neapolitan Yellow Tuff to produce the coarse aggregate of these concretes. However, mixing with local products of the Colli Albani volcanic district, located 20km east of Rome, has been evidenced at two fishponds of Latium, in Punta della Vipera and Torre Astura. Based on these petrographic and geochemical data, we conclude that the selective use of pozzolan from Campania, rather than of unproved different chemical properties, was the consequence of a series of logistic, economic, industrial and historical reasons.

High Stiffness Concrete for Tall Buildings under Severe Conditions: Mix Design and Structural Member Test

A new type of concrete, which contains volcanic aggregate and well-graded river sand, having both high strength and ultra-high modulus of elasticity has been developed for tall buildings under severe conditions, and its properties were characterized. The structural deformation of high-rise buildings can be substantially reduced by using this type of concrete, thereby decreasing the cross-section area of the structural members and increasing the economic benefits, not to mention alleviating shrinkage and creep problems of concrete. Uniaxial compression test, static elastic modulus test and scanning electron microscope test were conducted to characterize the properties of concrete specimens with different mix proportions. The experimental results showed that volcanic rock as coarse aggregate, well-graded river sand as fine aggregate, sand ratio around 43%, silica fume content about 10% as well as some mineral admixtures such as metakaolin and nanosilica led to higher modulus of elasticity of concrete. A particular type of concrete with the compressive strength of 146 MPa and modulus of elasticity of 53.5 GPa was developed, which is much stiffer than normal concrete in the code of practice. Four concrete mixtures including C45, C80, high modulus and ultra-high modulus concrete were applied in producing structural members, verifying the advantages of utilization of high stiffness concrete.

Timing and nature of volcanic particle clusters based on field and numerical investigations

Aggregation processes are known to play an important role in volcanic particle dispersal and sedimentation. They are also a primary source of uncertainty in ash dispersal forecasting since fundamental questions, such as the timing and deposition dynamics of volcanic aggregates, still remain unanswered. Here, we applied a state-of-the-art combination of field and numerical strategies to characterize volcanic aggregates. We introduce a new category of aggregates observed with high-speed-high-resolution videos, namely cored clusters. Cored clusters are mostly sub-spherical fragile aggregates that have never been observed in the deposits nor on adhesive tape as they typically break at impact with the ground. They consist of a core particle (200–500μm) fully covered by a thick shell of particles < 90μm. The low preservation potential of cored clusters in ash deposits explains the poor documentation in the literature and the low consideration attributed so far. Cored clusters can also better explain the deposition of fine ash in proximal and medial regions and the polymodality observed in many ash deposits. In addition, numerical inversions show how cored clusters can rapidly form within 175s from eruption onset. Finally, our observations represent the first field-based evidence of the so-called rafting effect, in which the sedimentation of coarse ash in cored clusters is delayed due to aggregation.

The volcanic aggregate of ancient Roman mortars from the Capitoline Hill: Petrographic criteria for identification of Rome's “pozzolans” and historical implications

Abstract We present a petrographic study of the pyroclastic-flow deposits used to produce mortar aggregates (Pozzolane Rosse, Pozzolane Nere, and Pozzolanelle), as well as dimension stones (Tufo del Palatino and Tufo Lionato) in ancient Roman times, in which we describe the characteristic textures and mineralogic assemblages of their juvenile fraction. This petrographic dataset is employed to compare and classify, through observation in thin section at the optical microscope, and complementary trace-element analyses, as well as EMP analyses on matrix glass on archaeological and bulk natural samples, the composition of the volcanic aggregate of 11 samples of ancient Roman mortars collected from several archaeological structures excavated on the Capitoline Hill. By means of the combined petrographic and geochemical identification criteria illustrated in this work, we recognize two main types of mortar aggregates characteristic of the Republican and Imperial ages, respectively, and a third type pertaining to the mediaeval epoch.

Tracing formation and durability of calcite in a Punic–Roman cistern mortar (Pantelleria Island, Italy)

Ancient hydraulic lime mortar preserves chemical and isotopic signatures that provide important information about historical processing and its durability. The distribution and isotopic composition of calcite in a mortar of a well-preserved Punic–Roman cistern at Pantelleria Island (Italy) was used to trace the formation conditions, durability, and individual processing periods of the cistern mortar. The analyses of stable carbon and oxygen isotopes of calcite revealed four individual horizons, D, E, B-1 and B-2, of mortar from the top to the bottom of the cistern floor. Volcanic and ceramic aggregates were used for the production of the mortar of horizons E/D and B-1/B-2, respectively. All horizons comprise hydraulic lime mortar characterized by a mean cementation index of 1.5 ± 1, and a constant binder to aggregate ratio of 0.31 ± 0.01. This suggests standardized and highly effective processing of the cistern.The high durability of calcite formed during carbonation of slaked lime within the matrix of the ancient mortar, and thus the excellent resistance of the hydraulic lime mortar against water, was documented by (i) a distinct positive correlation of δ18Ocalcite and δ13Ccalcite; typical for carbonation through a mortar horizon, (ii) a characteristic evolution of δ18Ocalcite and δ13Ccalcite through each of the four mortar horizons; lighter follow heavier isotopic values from upper to lower part of the cistern floor, and (iii) δ18Ocalcite varying from −10 to −5 ‰ Vienna Pee Dee belemnite (VPDB). The range of δ18Ocalcite values rule out recrystallization and/or neoformation of calcite through chemical attack of water stored in cistern.The combined studies of the chemical composition of the binder and the isotopic composition of the calcite in an ancient mortar provide powerful tools for elucidating the ancient techniques and processing periods. This approach helps to evaluate the durability of primary calcite and demonstrates the importance of calcite as a proxy for chemical attack and quality of the ancient inorganic binder.

Petrochemical Identification and Insights on Chronological Employment of the Volcanic Aggregates Used in Ancient Roman Mortars

Through the assistance of trace element and petrographic analyses on 14 samples of mortar aggregates from Roman monuments, including the Porticus Aemilia, the Temple of Concordia, the Temple of the Dioscuri, Temple B and other structures of the Area Sacra di Largo Argentina, and the Villa di Livia, we establish the source area and we investigate the chronological employment of the volcanic materials used in ancient Rome's masonry. In contrast to previous inferences, the petrochemical data presented here show that systematic exploitation of the local ‘Pozzolane Rosse’ pyroclastic deposit has occurred since the early development of concrete masonry, at the beginning of the second century bc, through the early Imperial age. Subsequently, exploitation was extended to the overlying Pozzolane Nere and Pozzolanelle deposits. Only during the early phase of development of the concrete masonry in Rome, volcaniclastic sediments outcropping near the construction sites were mixed with the sieved remains of the tuff employed as the coarse aggregate, to produce the fine aggregate. The results of the study on the investigated monuments suggest the possibility of establishing the chronological identification of three different types of mortars, as a function of the composition of the volcanic material employed in the fine aggregate, which, when implemented by future studies, may contribute to the dating of monuments and archaeological structures.

Experimental Investigation on Mix Designed HSC HSFRC Specimens Perfomed with Volcanic Aggregate

The selection of mix proportion is the process of choosing suitable ingredients of concrete and determine their quantities with the object of producing as economically as possible concrete of notably strength. The current paper deals with the mix design of both an HSC and HSFRC constituted by volcanic aggregates from the quarries of Eastern Sicily in Italy. The mix design was carried out on eight different concrete mixtures by using the theoretical model developed by Feret – De Larrard’s and it is capable of simulating the experimental compressive strength. The HSFRC mixtures consider different volume fractions of fibers equal to 0% (HRC), 0.5% and 2% (HSFRC). Straight Polyvinylalcohol (PVA) and hooked-end steel fibers (ACC) were the two types of fibers employed in the study. Compression and tensile tests were carried out on specimens performed according to UNI codes in order to validate the mixture proportion method adopted. The HSFRC (0.5%) mixtures did not show great differences in mechanical performance by any variation of the fiber type (steel or PVA). The mechanical properties obtained by experimental tests give back a very good accordance with the theoretical prediction of the mix design procedure adopted, and with the data reported in the literature in terms of toughness.

The Petrographical-Geochemical Properties and Industrial Availability of the Karadeniz Eregli Andesites (Zonguldak)

Aim of this study is to determine the geological properties (lithology, petrography, geochemistry) and industrial usibility of the Upper Cretaceous volcanics, seperated on the area, among Kozlu-Krd. Eregli and Ormanli, westside of Zonguldak. Volcanics, described as andesite, basaltic andesite and trachy-andesite by petrographically and geochemically, have subduction zone calk-alkaline character. Firstly, in laboratuary studies the aggregate tests (grading, specific gravity, water absorption, organic impurity, flakiness index, Los Angeles test for resistance to wear, peeling test, freezing resistance and UCS were realized on the 5 selected fresh patterns, match with the standarts (TS, ASTM, AASHO). Secondly, concrete tests (grading of the concrete aggregates, concrete preperation, slump test, specific density of concrete and UCS of the concrete) were made on the concrete patterns with volcanic aggregate additive.Statistical relationships were determined between values of the agreggate and concrete tests results. Both petrographical, chemical, physical and mechanical tests values of the agreggates and concretes are also match with the standarts, given above.As a conclusion, realized that volcanic aggregates for superstructure materials and C 25/30 concrete which made with volcanic aggregate (by using the specimen of N-4 aggregate) for rainforcement buildings, bridges, foundation walls can be used.

Use of volcanic aggregates in asphalt pavement mixes

Aggregates are one of the most important raw materials used in the construction industry. It is almost impossible to create a structure without using aggregates. The worldwide mining industry generates 16·5 billion tons of aggregates annually. An increase in domestic and industrial areas limits the regional aggregate resources, and highlights the need to find new sources of aggregate. Difficulties in using regional resources force aggregate suppliers to transport aggregate over long distances, resulting in additional time and expense, as well as rapid deterioration of highway infrastructures. Thus, it is vitally important to use available aggregate resources effectively and to find new environmentally friendly potential aggregate resources to meet the increasing demand. Therefore, aggregate samples taken from two different aggregate resources in the Afyonkarahisar–Seydiler region of Turkey were examined. In order to determine the physical properties of crushed aggregate samples, standard tests were carried out to evaluate whether the volcanic aggregate samples were suitable to use in bituminous pavement layers. In the present study, four different aggregate samples were used: volcanic aggregate 1 (V1), volcanic aggregate 2 (V2), limestone 1 (L1) and limestone 2 (L2). The V1 and V2 samples were volcanic rocks taken from the Tekerek and Kepez areas, respectively. These samples had trachy-andesite composition based on their geochemical and petrographical observations. The L1 and L2 samples were provided from quarries in the Karacaoglan and Cobanlar areas, respectively. Both L1 and L2 samples have been currently used in hot-mix asphalt pavements. The test results indicate that the sample V1 made of volcanic aggregates displayed adequate performance on a wearing course with heavy traffic. Sample V2 did not display enough deformation resistance as a bituminous mix; however, it could be used for surface courses because of its good friction properties.

BUILDING MATERIALS OF THE THEATRE OF MARCELLUS, ROME*

The building materials of the Theatre of Marcellus, 44–11 bce, reflect Roman builders' careful selections of tuff and travertine for dimension stone and volcanic aggregates for pozzolanic concretes. The vitric–lithic–crystal Tufo Lionato tuff dimension stone contains a high proportion of lava lithic fragments, which increase its compressive strength and decrease water sorption, enhancing durability. Sophisticated installations of travertine dimension stone reinforce the tuff masonry, which is integrated with durable concrete walls and barrel vaults. The pozzolanic mortars of the concretes contain harenae fossiciae mainly from the intermediate alteration facies of the mid-Pleistocene, scoriaceous Pozzolane Rosse pyroclastic flow. They have pervasive interpenetrating pozzolanic cements, including stratlingite, similar to high-quality, imperial era mortars. Concrete walls are faced with refined Tufo Lionato opus reticulatum and tufelli, and opus testaceum of fired, greyish-yellow brick. The exploratory concrete masonry, which includes some of the earliest examples of brick facings and stratlingite cements in Rome, and the integration of these materials in complex architectural elements and internal spaces, reflect the highly skilled workmanship, rigorous work-site management and technical supervision of Roman builders trained in republican era methods and materials.

Toughness increase of self compacting concrete reinforced with polypropylene short fibers

Increases in bending tests by the addition of low volume fractions of Polypropylene (PP) Short Fibers PP. These toughness increases are similar to those attained by Fiber Reinforced Concrete (FRC) referred elsewhere as Engineered Cementitious Composites (ECC), having some ductility and strain hardening in direct tensile and flexural tests. Concretes mixtures were manufactured using natural pozzolanic blended Portland cement, volcanic crushed coarse aggregates and fine sand from Sahara desert dunes (0-1 mm) from Canary Islands quarries and sand reservoirs, respectively, besides ordinary siliceous sand (0-4 mm) and fly ash from an anthracite-coal heat generator.

Physico-chemical characterization of mortars as a tool in studying specific hydraulic components: application to the study of ancient Naxos aqueduct

Mortars and plasters from the ancient aqueduct on the island of Naxos, Greece, were studied with regard to mineralogical and chemical composition, grain size distribution, raw materials and hydraulic properties, in order to assess their characteristics and design compatible repair mortars. The authentic materials contained lime, crushed-brick, siliceous and calcitic aggregates, in different proportions according to mortar type. Crushed-bricks fired at low temperatures and lightweight volcanic aggregates contained amorphous phases, which upon reaction with lime yielded hydraulic components capable of protecting the construction from the continuous presence of water. Hydraulic calcium silicate/aluminate hydrates, the proportions and the perfect packing of the raw materials, along with the diligent application justify the longevity and durability of the studied samples. The hydraulic properties of samples were pointed out through (a) the well-established CO2/H2O ratio derived from the thermogravimetric analysis and (b) by introducing two powerful indices issued from the chemical analysis, namely CaOhydr and soluble SiO2 hydr. These indices improved the clustering of hydraulic mortars and provided better correlation between mortars, plasters and their binders. By comparing grain size distribution and hydraulicity indices it was possible to distinguish among the construction phases. Based on this study, repair mortars were formulated by hydraulic lime, siliceous sand, calcareous and crushed-brick aggregates, with the optimal water content, ensuring optimum workability and compatible appearance with the authentic ones.

Use of natural pozzolan in stabilising lightweight volcanic aggregates for roadbase construction

The aim of this study was to explore whether marginal materials like lightweight volcanic aggregates (LVA) could economically and effectively be stabilised using natural pozzolan so as to conform to roadbase specifications. The combinations of natural pozzolan with lime; natural pozzolan with natural activator (natural gypsum); and natural pozzolan, lime and natural activator mixes were examined for their binding capabilities. Three types of natural pozzolan and two types of LVA materials from Arusha region in Tanzania were studied. Standard tests on physical, chemical and mineralogical properties of both the virgin materials and the stabilised mixes were carried out. Laboratory test results and statistical analyses show that natural pozzolan–lime binder could stabilise LVA to achieve roadbase strength requirements at a dosage of less than 2% of lime with between 10 and 30% (by mass) of natural pozzolan. Natural pozzolan–gypsum–lime binder mixes were found to develop a significantly higher unconfined compressive strength (UCS).

Development of volcanic pumice based cement and lightweight concrete

The results of investigations on the suitability of using volcanic pumice (VP) as cement replacement material and as coarse aggregate in lightweight concrete production are reported. Tests were conducted on cement by replacing 0–50% of cement by mass and on concrete by replacing 0–100% of coarse aggregate by volume. The physical and chemical properties of VP were critically reviewed to evaluate the possible influence on both fresh and hardened properties of cement and concrete. The standard tests on different mixtures of Portland cement and volcanic pumice powder (VPP) mixtures provided encouraging results, comparable to those for blended Portland fly ash cement, and showed good potential for manufacturing Portland volcanic pumice cement with higher setting time and low heat of hydration using up to 15% of VPP. The properties of volcanic pumice concrete (VPC) using different percentages of volcanic pumice aggregate were evaluated by conducting a comprehensive series of tests on workability, strength, shrinkage and permeability. It is concluded that VPC has sufficient strength and adequate density to be accepted as structural lightweight concrete. Design charts are presented to evaluate mix design parameters of VPC.

Alkali release by volcanic aggregates in concrete

Selective leaching techniques that dissolve hardened cement paste in concrete while leaving aggregate particles intact, reveal mass transfer from the aggregate to the hydrated phases during concrete hardening. Leaching techniques based on selective cement dissolution with alkaline EDTA-TEA were applied to experimental mortars. Results are presented for two solvents whose only difference lies in the choice of cation: MET, the Li +, NH 4 + version, and TET, the tetramethyl-ammonium (TMA)-version. TET, which features large cations providing limited exchange capability, attacks alumine-silicates the least while dissolving clinker and paste faster. In contrast to dacite and phonolite, which reduce the level of alkali, some basalts release large amounts of alkali into the pore solution of concrete, especially when the aggregate considerable amounts of fine material and the water-cement ratio ( w c ) is high. The alkali release during the first 6 months ranges from about 1%Na 2O equivalent for a rapidly cooled fresh basalt with poorly crystallised feldspars to about 0.1% for a well crystallised basalt. It follows that, despite the use of low-alkali cement, sufficient alkali can be released from some aggregates to initiate alkali-aggregate reaction.

Comparison of Granitic and Volcanic Aggregates for Making High Strength Concrete in Hong Kong

Both granitic and volcanic aggregates are being used for concrete in Hong Kong. Granitic aggregate is more common because of historical reasons. With the advent of high strength concrete, however, it is gradually realized that the relatively low intrinsic strength of the granitic aggregate is a limiting factor for concrete strength. The volcanic aggregate, which is generally stronger, may be better for producing higher strength concrete. In this study, parallel tests on the two types of aggregates are carried out to investigate the effects of using the different aggregates on concrete strength, and to determine the highest concrete strength achievable with each of them. Certain problems with the volcanic aggregate are identified and possible improvements in concrete properties by overcoming these problems are investigated.

Development of Very High Strength Concrete for Hong Kong

In order to explore the feasibility and means of producing very high strength concrete (with mean cube strength > 100 MPa) in Hong Kong, extensive trial mixing and testing have been conducted. The conditions adopted for the very high strength concretes described here are that only locally available materials and conventional production and curing methods can be used and that the heat of hydration and shrinkage should not be excessive. To satisfy these conditions, all ingredients were obtained from the local market and the mixes were designed to have a binder paste volume of not more than 35%. Because of the high strength requirement, volcanic aggregates, which are generally stronger, were used instead of the more commonly used granitic aggregates. In the testing programme, the effects of various mix parameters including binder paste volume, fine to total aggregates ratio, dosage of condensed silica fume, and combined usage of condensed silica fume and pulverized fuel ash etc. were studied. Based on the test results, several selected mixes which may be considered for the production of Grade 90–100 concrete are recommended.

The aerodynamic behaviour of volcanic aggregates

A large proportion of solid material transported within the atmosphere during volcanic eruptions consists of particles less than 500 mum in diameter. The majority of these particles become incorporated into a wide range of aggregate types, the aerodynamic behaviour of which has not been determined by either direct observation or in the laboratory. In the absence of such data, theoretical models of fallout from volcanic plumes make necessarily crude assumptions about aggregate densities and fall velocities. Larger volcanic ejecta often consists of pumice of lower than bulk density. Experimental data are presented for the fall velocities of porous aggregates and single particles, determined in systems analogous to that of ejecta falling from a volcanic plume. It is demonstrated that the fall of aggregates may be modelled in identical fashion to single particles by using a reduced aggregate density dependent on the porosity, and a size corresponding to an enclosing sphere. Particles incorporated into aggregates attain a substantially higher fall velocity than single particles. This is due to the larger physical dimensions of the aggregate, which overcomes the effect of lower aggregate density. Additionally, the internal porosity of the aggregate allows some flow of fluid through the aggregate and this results in a small increase in fall velocity. The increase in fall velocity of particles incorporated into aggregates, rather than falling individually, results in the enhanced removal of fine material from volcanic plumes.

Alkali-Silica Reactivity: Some Reconsiderations

Abstract Numerous instances have been recorded where the use of low alkali cement with certain volcanic aggregates has failed to prevent deleterious alkali-silica reactivity. Present testing using the ASTM Test for Potential Alkali Reactivity of Cement-Aggregate Combinations (Mortar-Bar Method) (C 227) may fail to identify this reactivity because testing is normally done with only high alkali cements. It is recommended that concurrent testing be done, using a range of both high and low alkali cements, to determine that maximum safe cement alkali level for each aggregate in question. Although the traditional limit of 0.60% alkali has prevented alkali aggregate reaction with many reactive aggregates, there are certain volcanic aggregates that require even lower alkali or the use of suitable pozzolanic materials to avoid alkali aggregate reactivity or both.

On the Origin of the Gypseous and Saliferous Marls of the New Red Sandstone

For years past I have had great difficulty in accounting for the marls of the new red sandstone, and as none of the explanations yet given appear to me sufficient, or satisfactorily account for the * absence of molluscous and zoophytous remains in these beds, and still less for that of the numerous plants entombed above and below them, I propose in the following observations to attempt to explain these phenomena, in the hope, to use the words of Sir H. Delabeche, of arriving at the “knowledge of the true causes which have produced” the remarkable aggregates in question. In examining the district of Bleadon with a view to account for the phenomena of trap rocks presented in the railway cutting, I observed in the superficial coating of soil on the northern flank of the hill above Weston-super-Mare, such abundant fragments of vesicular trap, some of them having the aspect of recent volcanic scoriæ, others containing spherical kernels of decomposing calcareous spar and hæmatitic iron, that I entertained no doubt whatever that I was standing on a dyke of ancient lava. The occurrence of these fragments for about seventy-five yards, in an east and west direction, indicated its strike, and rendered it probable that the same appearance would recur in the neighbouring coast cliffs. Those brown, strange-looking rocks, therefore, with whose aspect I had been long familiar, were volcanic aggregates, and were, in fact, two of the most interesting and instructive of the large number which had fallen under my notice.