都市におけるレデーミクストコンクリートの輸送時間に関する研究 I)

概要

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Time from mixing to placing of concrete has various effects on the property of it, and it is described in JIS (Japanese Industrial Standard) A-5308 (Ready-Mixed Concrete) that the concrete shall be delivered to the site of the work and discharge shall be completed within 1(1/2) hr. after the introduction of the mixing water to the cement and aggregates, or the introduction of cement to aggregate. Concerning this problem, the investigation of time of haul of approximately 1000 truck-mixers was carried out at 18 job-sites in Tokyo. Results of investigation were as follows : - 1) Waiting-time of truck-mixer at job-site is respectably long. (2/3) of runing-time on average of 18 sites) 2) Ratio of mean waiting-time to mean survice (i. e. placing) time is affected by ratio of mean placing time to mean interval of arrivals of trucks, i. e. traffic density. 3) Probability density of runing-time from a plant to a site is represented by follwing Erlang's function [numerical formula] where t=runing time (minute) 1/v=expectation of runing time (minute) k=phase of Erlang's function 4) Probability density of waiting time is represented as follows : [numerical formula] where t=waiting time (minute) w=expectation of waiting time (minute) Based on above consideration, calculation charts of probability of time from mixing to placing being over than specified are presented and procedure of control of time is suggested.
社団法人日本建築学会の論文
1966-02-28