Measurement of thermal conductivity in lightweight concrete produced with ground stone residue

With the advancement of concrete production technologies, such as the development of additives, use of different aggregates, dosing methods, mixing and application equipment, they have contributed to the emergence of concrete with special characteristics, as is the case with light concrete. Given the above, this research continues the experimental studies of structural lightweight concrete with expanded clay (coarse aggregate) developed by Lucas and Azambuja (2020). This research presents the results of mechanical properties at older ages, 28 days 214 days for Trait 1 (AN100%) and Trait 2 (AB20%) compared to the results of 7 days of age, however, the main contribution was the measurement of thermal conductivity with construction of a low-cost prototype in accordance with NBR 15220-4:2005, using the protected hot plate method. The results showed compressive strength values ​​of a minimum of 17,8 MPa at 7 days of age and a maximum of 28,6 MPa at 214 days, values ​​above 17 MPa established by NBR NM 35:1995 at 28 days, as well as the tensile strength by diametrical compression, which also presented values ​​that served as a basis for framing concrete as lightweight and structural. The evaluation of thermal conductivity was performed using a hot plate, in which the results were satisfactory between 0,44 and 0,71 W/(m.k), appropriate values ​​to answer the question of thermal performance, thus as well as complying with the established by ABNT NBR 15220-2:2008.

An Archaeological Study of Early Farming Settlements on Iresi Hills

Recent Investigation of an archaeological site in southwest Nigeria during the Late Stone Age revealed additional information about the cultural development of the area. On Iresi Hills two rock shelters (Ajaye and Cherubim & Seraphim) were investigated in two seasons from 2017 to 2018 during which pottery, ground stone axes and microlithics were excavated. Although there is no clear break in the stratigraphy, the findings show clear demarcation between two cultural layers. The upper layer contains pottery, microlithics and ground stone axes, and ochre while the lower layer is characterized by microlithics only. The site presented a date of about Cal 5653 BP which coincides with a short dry period in the area. Tis paper reports the occupation in Iresi, in southwest Nigeria with a view to fill the gap in the chronology and to interrogate the evidence for Late Stone Age in terms of the culture that existed in between 12000YBP of Iwo Eleru and 2000YBP of Itaakpa and the influence of a change in environment of southwest Nigeria and West Africa in general.

Climate-Driven Dietary Change on the Colorado Plateau, USA, and Implications for Gender-Specific Foraging Patterns

Complementary archaeological and paleoenvironmental datasets from North Creek Shelter (Colorado Plateau, Utah, USA) are analyzed using the diet breadth model, revealing human dietary patterns during the early and middle Holocene. Abundance indices are derived from botanical and faunal datasets and, along with stone tools, are used to test the prediction that increasing aridity caused the decline of high-return resources. This prediction appears valid with respect to botanical resources, given that high-ranked plants drop out of the diet after 9800 cal BP and are replaced with low-ranked, small seeds. The prediction is not met, however, with respect to faunal resources: high-ranked artiodactyls are consistently abundant in the diet. The effects of climate change on dietary choices are also examined. Findings show that increased aridity coincides with greater use of small seeds and ground stone tools but not with increases in low-ranked fauna, such as leporids. The patterns observed from the North Creek Shelter botanical and faunal datasets may reflect different foraging strategies between men and women. This would explain why low-ranked plant resources became increasingly abundant in the diet without a corresponding decrease in abundance of high-ranked artiodactyls. If so, then archaeological records with similar datasets should be reexamined with this perspective.

Wild cereal grain consumption among Early Holocene foragers of the Balkans predates the arrival of agriculture

Forager focus on wild cereal plants has been documented in the core zone of domestication in southwestern Asia, while evidence for forager use of wild grass grains remains sporadic elsewhere. In this paper, we present starch grain and phytolith analyses of dental calculus from 60 Mesolithic and Early Neolithic individuals from five sites in the Danube Gorges of the central Balkans. This zone was inhabited by likely complex Holocene foragers for several millennia before the appearance of the first farmers ~6200 cal BC. We also analyzed forager ground stone tools for evidence of plant processing. Our results based on the study of dental calculus show that certain species of Poaceae (species of the genus Aegilops) were used since the Early Mesolithic, while ground stone tools exhibit traces of a developed grass grain processing technology. The adoption of domesticated plants in this region after ~6500 cal BC might have been eased by the existing familiarity with wild cereals.

Direct Evidence for Geophyte Exploitation in the Wyoming Basin

In the Wyoming Basin, archaeological sites dating from the Early Archaic to Late Prehistoric are often found associated with or adjacent to dense populations of Cymopterus bulbosus (springparsley), a nutritious geophyte that would have been an important food source for prehistoric humans living in the region. Experimental data have shown that the caloric return rates of C. bulbosus were enough to support seasonal exploitation by foragers, yet there has been no direct evidence for the use of this geophyte from the archaeological record. In this study, we examine starch granules from 10 ground stone tools excavated from two stratified, multicomponent archaeological sites in the Wyoming Basin to determine if C. bulbosus was collected and consumed in the past. Taproots of C. bulbosus were collected from two populations in the immediate vicinity of the archaeological sites in order to develop a modern starch reference. Identification of Cymopterus starch granules is based on a systematic study of those reference granules. The presence of Cymopterus starch on the ground stone artifacts suggests that prehistoric foragers were collecting and consuming these geophytes. These findings support previous hypotheses about geophyte use in southern Wyoming and therefore have implications for increasing human populations as well as settlement and subsistence decisions.