Red Scoria Research Articles

The impact of thermal treatment on the mechanical properties and thermal insulation of building materials enhanced with two types of volcanic scoria additives

The need to substitute cement with eco-friendly building materials has increased in recent years, and attempts to enhance the mechanical and thermal insulation properties of these materials are ongoing. Therefore, the present study aims to use two different types of scoria as substitutes for cement in building materials and investigate the impact of thermal treatment on improving mechanical characteristics and thermal insulation. Black and red volcanic scoria, both before and after thermal treatment at different temperatures (600, 700, 800, and 900 °C), were utilized as cement substitutes in concrete specimens. Concrete specimens with different proportions (0–30 % wt.%) of black and red scoria were cured for different durations (14, 21, 28, and 91 days), and then tested for compressive strength. The compressive strength of specimens increased with increasing curing time, but decreased when scoria content exceeded wt.10 %. Furthermore, thermal treatment positively impacted the compressive strength of concrete specimens with red scoria, but negatively affected those with black scoria, owing to the increase in crystalline phases with increasing temperature. The specimen containing 10 % red scoria thermally treated at 900 °C and cured for 91 days yielded the highest compressive strength (60 ± 1.22 MPa). Further, the thermal insulation analysis of the concrete specimens with each type of thermally treated scoria was performed on day 28 of curing. The thermal insulation increased as the proportions of black and red scoria increased, which involved increasing the thermal treatment temperature of both scoria from room temperature to 900 °C on day 28 of curing. Additionally, the thermal insulation of concrete specimens treated with red scoria was more optimized than that of concrete treated with black scoria, particularly at high thermal treatment temperatures, and more than seven times as much as that of ordinary concrete. The lowest thermal conductivity value of the specimen was 0.157 ± 0.01 W m−1 K−1. Based on the findings, concrete with thermally treated red scoria is a suitable eco-friendly building material with high compressive strength and efficient thermal insulation properties.

The interplay between environmental and magmatic conditions in eruption style transitions within a fissure-aligned monogenetic volcanic system of Auckland, New Zealand

Recent conceptual geological frameworks of continental monogenetic volcanism highlight that the small magma volume eruptions, resulting volcanic geology and edifice architecture in such settings are sensitive to variations in external or environmental conditions. These conditions, along with fluctuations in magma flux, can change rapidly over short time frames and cause dramatic changes in eruption style. Understanding the drivers of transitions in explosive to effusive behaviour within the short timescales of eruptions at individual volcanic centres is essential to accurately assess volcanic hazards in continental monogenetic settings. Wiri Mountain Volcanic Complex is one of the largest and most complex volcanic centres in the active Auckland Volcanic Field. Despite the significant removal of much of the original volcanic deposits, present-day exposures and historical images provide a unique opportunity to examine the growth and evolution of the volcanic complex. Wiri Mountain deposited an initial basal tuff ring (covering an area of approximately 0.67 km2) by predominantly pyroclastic density currents, followed by at least two smaller tuff rings erupted through the outer flanks of the first, in a transition from phreatomagmatic to Strombolian eruptive style. A 90 m high central scoria cone was then produced within the initial tuff ring, partially capped by lava spatter, clastogenic lava flows and lava flows that mostly covered all tuff rings, the scoria cone, and the surrounding area. A high-resolution stratigraphic study of the well-exposed tuff ring to capping magmatic succession was conducted to determine the changes in eruptive style and their driving forces. The deposit architecture of Wiri Mountain can be described using three volcanic stratigraphic units: a basal unit comprised of tuff, lapilli tuff and tuff breccia deposits, a middle unit comprised of juvenile-rich transitional tuff deposits of black scoria ash and lapilli, red scoria and spatter, and a capping unit comprised of agglutinate and lava flow successions. Most volcanic materials were either fragmented and ejected at near-optimal scaled depth, or the transition between near-optimal and shallower/deeper depths. Wiri Mountain provides a striking example of a fissure eruption likely controlled by a pre-existing tectonic fault that was fed by relatively stable melt sources over a sustained period. We infer that despite eruption within a water-saturated coastal plain, the initial phreatomagmatic phase was overridden by subsequent explosive and effusive magmatic phases through the formation of an increasingly established conduit, thus allowing sustained magma flux and melt supply. The transitions, both gradual and rapid, from an initial phreatomagmatic to subsequent magmatic explosive and effusive phases fit well to the general understanding of eruption style changes over time from other larger and more complex volcanoes of Auckland, and elsewhere worldwide. Wiri Mountain showcases the fine balance between the external and internal conditions that control eruption style variations and govern the formation of complex monogenetic volcanoes.

Physical properties of mesoporous scoria and pumice volcanic rocks

In this study, the chemical composition, crystal structure, texture properties, and thermal properties of five powdered samples of scoria and pumice volcanic rock from different Harrats were investigated. It was observed that volcanic rocks show variations in chemical compositions, crystal structure, texture, and thermal properties. All samples comprised SiO2, Al2O3, CaO, and Fe2O3 as the major elements and contained both amorphous and crystalline phases. Textural parameters such as surface area and porosity were determined using various calculation models. The surface area of scoria samples was between 0.85 and 1.71 m2 g−1 (Brunauer–Emmett–Teller and Single point model), 0.293–1.028 m2 g−1 (Barrett–Joyner–Halenda model), and 1.02–2.35 m2 g−1 (Langmuir model). While for pumice, the calculated values of the surface area were 1.67 m2 g−1 (Brunauer–Emmett–Teller and Single point model), 0.763 m2 g−1 (Barrett–Joyner–Halenda model), and 2.24 m2 g−1 (Langmuir model). The adsorption-desorption isotherm curves reveal that the scoria and pumice particles under study have mesoporous sizes between 7.89 and 9.81 nm, respectively. The differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) results of scoria and pumice samples illustrate a thermally stable material at high temperatures. TGA results show a weight gain by about 1.0% has been observed in the scoria samples in the region beyond 600 °C that may indicate a probable oxidation phenomenon with a change in color. While the DSC results of the red scoria and pumice did not show any recrystallization or oxidation, but only showed a small loss of weight in the TGA result. The diversity in molecular composition, texture, and structure of scoria and pumice volcanic rock samples provide for promising natural stable mesoporous materials that can be used in various mesoporous technologies or applications such as solar cells.

Using Structure from Motion Mapping to Record and Analyze Details of the Colossal Hats (Pukao) of Monumental Statues on Rapa Nui (Easter Island)

ABSTRACTStructure from motion (SfM) mapping is a photogrammetric technique that offers a cost-effective means of creating three-dimensional (3-D) visual representations from overlapping digital photographs. The technique is now used more frequently to document the archaeological record. We demonstrate the utility of SfM by studying red scoria bodies known aspukaofrom Rapa Nui (Easter Island, Chile). We created 3-D images of 50pukaothat once adorned the massive statues (moai) of Rapa Nui and compare them to 13 additionalpukaolocated in Puna Pau, the island's red scoriapukaoquarry. Through SfM, we demonstrate that the majority of these bodies have petroglyphs and other surface features that are relevant to archaeological explanation and are currently at risk of continued degradation.

Removal of Arsenic (V) from Aqueous Solutions Using Chitosan-Red Scoria and Chitosan-Pumice Blends.

In different regions across the globe, elevated arsenic contents in the groundwater constitute a major health problem. In this work, a biopolymer chitosan has been blended with volcanic rocks (red scoria and pumice) for arsenic (V) removal. The effect of three blending ratios of chitosan and volcanic rocks (1:2, 1:5 and 1:10) on arsenic removal has been studied. The optimal blending ratio was 1:5 (chitosan: volcanic rocks) with maximum adsorption capacity of 0.72 mg/g and 0.71 mg/g for chitosan: red scoria (Ch–Rs) and chitosan: pumice (Ch–Pu), respectively. The experimental adsorption data fitted well a Langmuir isotherm (R2 > 0.99) and followed pseudo-second-order kinetics. The high stability of the materials and their high arsenic (V) removal efficiency (~93%) in a wide pH range (4 to 10) are useful for real field applications. Moreover, the blends could be regenerated using 0.05 M NaOH and used for several cycles without losing their original arsenic removal efficiency. The results of the study demonstrate that chitosan-volcanic rock blends should be further explored as a potential sustainable solution for removal of arsenic (V) from water.

Adsorption of As(III) versus As(V) from aqueous solutions by cerium-loaded volcanic rocks.

Contamination of drinking water with arsenic causes severe health problems in various world regions. Arsenic exists predominantly as As(III) and As(V) depending on the prevailing redox conditions of the environment. Most of the techniques developed for treating As(V) are not very effective for As(III), which is more toxic and mobile than As(V). In this study, novel cerium-loaded pumice (Ce-Pu) and red scoria (Ce-Rs) adsorbents were developed to remove both As(III) and As(V) ions from water. The Ce-Pu and Ce-Rs adsorbents were characterized using ICP-OES, EDX, and SEM. The experimental equilibrium sorption data fitted well Freundlich and Dubinin-Radushkevich (D-R) isotherms. The adsorption was very fast and reached an equilibrium within 2h. Both Ce-Rs and Ce-Pu showed high As(III) and As(V) removal efficiency in a wide pH range between 3 and 9, which is an important asset for practical applications. The Ce-Pu and Ce-Rs adsorbents can be recycled and used up to three adsorption cycles without significant loss of their original efficiency. Accordingly, Ce-Pu and Ce-Rs seem to be suitable for removal of arsenic from aqueous systems.

Uptake of arsenate by aluminum (hydr)oxide coated red scoria and pumice

The development of cost effective and environmentally benign adsorbents for arsenic removal is absolutely required due to arsenic contamination of water sources in many regions around the globe. The use of materials which are locally available in the affected regions is important for successful implementation of the developed technologies in rural areas. In this regard, we treated volcanic rocks (red scoria and pumice) locally available in Ethiopia with an aluminum sulphate solution and evaluated these materials for their capacity to remove As(V) from aqueous systems. The adsorbents were characterized using ICP-OES, EDX, SEM and BET. The experimental sorption data fitted well a Freundlich isotherm and the pseudo-second-order model was found to be more suitable than the pseudo-first-order model to describe the adsorption kinetics. The Langmuir maximum adsorption capacity was 0.18 mg/g for aluminum-treated red scoria (Al-Rs) and 2.68 mg/g for aluminum-treated pumice (Al-Pu). The effect of pH, adsorbent dose, initial As(V) concentration and interfering ions on arsenic adsorption were studied. The leaching of aluminum from the adsorbent during the adsorption process was also investigated. Results of column experiments indicated that Al-Pu is suitable to treat low concentration of As(V) contaminated water. The Al-Pu adsorbent is recyclable with only about 9% loss of its original efficiency after the 3rd adsorption cycle (99.5%–90.2%). The data obtained from both batch and column studies indicate that Al-Rs and Al-Pu remove As(V) effectively from aqueous systems, with the latter being more efficient.

Notes from the field: Ahu Nau Nau and Ahu Ature Huki, ‘Anakena, 1982

Notes from the field: Ahu Nau Nau and Ahu Ature Huki, ‘Anakena, 1982 Charles M. Love ‘Anakena, April 30, 1982.1 Ahu Nau Nau Routledge talks about this site to a certain extent.2 It has been excavated in part and parts have been restored, so that many things have happened here. I have no idea whether or not they will ever be recorded. The excavation and restoration that was done by a local archaeologist, Sergio Rapu,3 restored the ahu but there was little excavation done at that time. The ahu was in excellent shape.4 There are now four statues with topknots standing on the platform, each of a slightly different shape. What portions of their topknots are real as opposed to repaired or rebuilt, and what the topknots looked like in their original shape is another question. I don’t know the answer. Aside from the four standing statues with topknots, there is a vacant pedestal to the left, and then three more statues (and 3 more pedestals). All of the pedestals are composite types (I suspect all the pedestals here were reconstructed, i.e., new). Three more statues are then on the right. Very clearly, the last two on the right (out of the entire seven) were much smaller; only the base portions remain. One of the statues lacks a topknot but it appears as if the statue was designed for one. Contrary to popular local tradition, the restored ahu called Nau Nau is not the first one at this site. Off to the right, stacked in a small plaza, are fragments of other statues and topknots. It was here that fragments of worked coral were first discovered and recognized as eye for a statue. The coral pieces were found and then it was noted that they fit together.5 A number of broken statues (possibly three) are over to the right, but whether or not they belong with this particular ahu is unknown. Two lower-body pieces with the hands still visible suggests that whatever originally stood on this ahu, one of them belonged on the empty pedestal on the ahu. To return to the statues on the side, there are four bases and one head, two topknots, and several other assorted pieces, but I’m certain they didn’t all belong to Ahu Nau Nau. Immediately adjacent is the statue that was pulled along in an experiment by Heyerdahl (Heyerdahl & Ferdon 1961:Pl. 60b). It is over on the right, as one faces the sea, along with another ahu described in this report. The entire ahu had been covered by sand so that, when the moai fell, they were cushioned by it (Heyerdal & Ferdon 1961:Plate 24c). We have no record, however, as to when these statues were overturned. Some 80 burials were placed underneath them. These were excavated; it is possible they were from the smallpox epidemics as this was a mass burial. The burials seem to have been tucked underneath without context or sequence. One trench still remains out in front on the landward side at right angles to the axis of the central platform; it is about 20 meters long and goes right up to the lower part of the ramp. There are some special things about this ahu. First, the central platform is horizontal but the front landward paenga have a complete red scoria fascia. The landward paenga go up on each end, rather like the gunwales of a boat, and go out in the middle, so it looks like one half of a very long canoe. This is similar in concept to the boat-shaped houses. There is an extensively spaced poro ramp with some large blocks of bedrock or other kinds of rock in several places within the interior. Another series of paenga are at the bottom of the spaced poro ramp that forms a boundary with the spaced poro ramp; this is a non-scoria fascia. The whole was covered with small beach pebbles and red scoria pebbles. The courtyard in front (landward) is not very long. It was covered by about 30 to 50cm of sand that blew in over a red dirt-red clay base...

Stone use and avoidance on Easter Island: Red scoria from the topknot quarry at Puna Pau and other sources

AbstractThe paper presents new observations on the use and avoidance of different red scoria rocks on Easter Island (Rapa Nui), made during fieldwork. It describes the different facies of the rock, their origins, their nature and their context of quarrying and use. From the latter, it is inferred that, for the prehistoric Rapanui, the meaning of red scoria transcended practical utility. A combination of stone context and ethnographic analogy suggests what this meaning or these meanings might be. Stone use on the Island is presented as a model against which the stone use of other prehistoric cultures might be measured.

Partial anhysteretic remanent magnetization in magnetite 2. Reciprocity

[1] One necessary condition for successful determination of relative paleomagnetic field intensity using anhysteretic remanent magnetization (ARM) methods is reciprocity: a partial ARM, produced by a steady field H applied over a narrow interval (2, 1) of alternating field (AF), must demagnetize over the same interval (2, 1). Experimentally, we find that partial ARMs of single-domain (SD) and pseudosingle-domain (PSD) grains demagnetize mainly between 2 and 1, whereas >50% of partial ARMs of large PSD and multidomain (MD) grains are erased below 1, giving a low-field tail in the coercivity distribution. Natural pumices, granites, and oceanic basalts violated reciprocity, but lake sediments, gabbros, andesite, and red scoria had relatively small low-coercivity tails and are better candidates for paleointensity work. Using total ARM to simulate natural remanence, we carried out pseudo-Thellier paleointensity determinations for coarse PSD and MD grains. ARM demagnetization outweighed partial ARM acquisition at the same AF step, resulting in convex-down curves of ARM remaining versus partial ARM gained (pseudo-Arai plot). Pseudo-Arai plots predicted from experimentally determined distributions of blocking and unblocking fields agreed well with measured pseudo-Thellier results, in particular explaining convex-down MD curves.

Archaeological stone of Easter Island

AbstractWith the scarcity of other resources, stone assumed great importance in the culture of Easter Island. The volcanic rocks display a compositional continuum paralleled by changes in physical characteristics. The most abundant rock type, porphyritic hawaiite, was the least useful as it is poorly jointed and difficult to work. Mugearites and benmoreites usually have a flaggy structure and were used as dressed stone in the early ahu, in the houses of Orongo and in stone implements. Rhyolitic obsidian was used for scrapers, knives, and a variety of weapons, especially the tanged mataa. Statue carving reached its zenith on Easter Island largely because of the availability of a suitable rock type, the Rano Raraku tuff. The tuff was not erupted from the present Rano Raraku crater but from another vent southeast of the surviving portion of the cone. Red scoria from Puna Pau was quarried for the topknots. © 1993 John Wiley & Sons, Inc.

Symbolic stratigraphy: Rock art and the monolithic statues of Easter Island

Abstract Recent field work on Easter Island, East Polynesia, has collected new data on monolithic statue sites, rock art design motifs and the ideological significance of their temporal and spatial relationships. This paper details what is currently known about the re‐use of statue sites post A.D. 1500, and describes the occurrence of rock art on statue, ceremonial architecture (ahu) and quarry sites. In particular, it is postulated that the superimposition of a limited range of design motifs ('boat’ forms) on the red scoria of statues and ahu constitute an ideologically significant site re‐use which links statue cult practices with subsequent birdman cult ideology.