Stackelberg D.;Wilge B.;Boiko S.;
<正>New principles of monitoring the hardening and strengthening of shotcrete applied in the process of building the "Modiin - Jerusalem" railway tunnel are presented in the article.Monitoring had the primary goal to assess the time in which the concrete reaches the set level of strength to allow formwork dismantling.Shotcrete hardening and strengthening in the tunnel was estimated based on the results of continuous measurements of specific electric resistance and temperature directly in the concreted element.At the same time,the containers of additional measuring sensors were filled with concrete selected from a mixer(immediately prior to adding the accelerator) to estimate hardening in standard field laboratory conditions. Based on the results of a joint analysis of the resistivity and temperature kinetic curves, a general "Strength-Resistivity" correlation was built and the monitoring algorithm of shotcrete hardening and strengthening in its early age(within the first 24 hours) was developed This algorithm is used for the following:To estimate the time in which the required(regulated) strength is achieved directly in the concreted element mass,To estimate the work stability of the factory supplying the concrete to the building site. Originality By comparing the results of resistivity and temperature measurements carried out in standard field laboratory conditions and directly in the tunnel(at temperatures above 30℃),we were able to establish that,irrespective of the conditions of a given concrete hardening,a specific compressive strength value corresponds to a certain resistivity value.
New Principles of Monitoring Hardening and Strengthening of Shotcrete;
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