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The current study aims at exploring the beneficial effect of silica fume (SF) and acrylic emulsion polymer (PR) on the enhanced properties of polypropylene fiber reinforced concrete (FRC) with the supplementary cementitious binder comprised of the Portland cement, slag, silica fume and fly ash. The compressive strength and impact-abrasion resistance were used for the estimation of engineering properties while the water absorption performance, surface electricity resistance, and rapid chloride penetration resistance were used for estimation of durability. Experimental results showed that a sole addition of SF increased the compressive strengths but decreased the abrasion-impact resistances of modified FRCs, which was just opposite to the influence of a sole addition of PR. A sole addition of either the SF or PR could moderately improve the durability of modified FRCs, respectively. However, due to the beneficial effect of the complementary interaction between SF and the optimal amount of PR, the mechanical properties and durability of modified FRCs seemed to become significantly improved.

Se utilizó un detector con un fotodiodo de silicio y un «data logger» para medir radón en el suelo en la zona de falla de Chuko en el centro-sur de Taiwan. La variación temporal del radón muestra un ciclo de preparación del sismo con un aumento rápido de radón seguido de un nivel elevado sostenido, una anomalía en forma de pico y por último un decrecimiento mayor hasta alcanzar casi el nivel del fondo antes del inicio del sismo. La aproximación integrada de las medidas de radón del suelo indica que las anomalías en forma de pico son mejores precursoras y pueden utilizarse para determinar el lugar y la fecha de un sismo. Sin embargo, la geología local es un factor crítico para determinar la fecha y la localización del sismo. doi: https://doi.org/10.22201/igeof.00167169p.2002.41.4.502

Silicon photodiode detector and data logger are employed in soil gas radon measurement in Chuko fault zone in south central Taiwan. Time variation of radon shows that there is a radon earthquake preparation cycle with a fast radon build-up, then a sustaining high level, a spike-like anomaly, and then a faster decrease to near background level before the onset of an earthquake. The new integrated approach in soil gas radon monitoring reveals that the spike-like anomalies are superior precursors and could be used to delineate time and place of an earthquake. However, basement geology is a critical factor in determining time and place of earthquake. When multiple units of this system are emplaced at different locations, it is possible that the time, place, and magnitude of earthquakes could all be predicted.