2 research outputs found
Physical-mechanical characterization of blended cements manufactured with zeolite-bearing tuffs
No full textAs an integration of a study aiming to evaluate the feasibility of zeolite-rich sedimentary ricks (i.e., zeolitic tuffs) to act as pozzolanic material for manufacturing blended cements, four of the most widespread zeolite-bearing rocks, namely a chabazite-phillipsite-rich tuff, a clinoptilolite-rich tuff, an erionite-rich tuffand a phillipsite-rich tuff were used to obtain experimental blended cements, by replacing portions as high as 10%, 20% and 40% of the ordinary Portaln cement. Standard mortars, made with the mentioned blends, cured for different times, were subjected to mechanical resistance evaluation. Results were highly encouraging, because the measured compressive strength of the blends, ranging, after 28-day curing, between 35.7 and 60.4 N.mm-2, according to nature of zeolitic tuff and its substitution extent, were all included in the three classes of pozzolanic cements considered by the European Standards specification EN 197/1. This result, coupled with the excellent pozzolanic behavior demonstrated by all tuffs and thei low cost, makes very promising a possible use of zeolitic tuffs for the production of blended cements. This could also represent a valuable strategy for energy efficiency improvement and reduction of carbon dioxide emission in the cement industry
Two new species of the genus <i>Chicoreus (Siratus)</i> (Gastropoda: Muricidae) from the western Atlantic
No full textTwo new species of the family Muricidae are described. Chicoreus (Siratus) colellai, from off Veracruz, eastern Mexico, is compared with C. (S.) articulates (Reeve, 1845), and differs from this latter species in many aspects. C. (S.) caudacurta, from off Puerto Rico, is somewhat similar to C. (S.) beauii (Fischer & Bernardi, 1857), but differs in having a broad, paucispiral protoconch, a higher spire, and a shorter siphonal canal
