| Title |
Development of Quality Restoration Agent and Properties of Elapsed Time of Concrete by Long Distance Delivery |
| Authors |
Han Cheon-Goo ; Yang Seong-Hwan ; Hwang Yin-Seong |
| Keywords |
Long Distance Delivery ; Elapsed Time ; Fluidity ; Air Content ; Quality Restoration Agent |
| Abstract |
This paper is to discuss the quality variation of ready mixed concrete due to long distance delivery and the development of quality restoration agent. According to test results, fluidity exhibited a sharp drop after 1 hour since mixing. After 3 hours, no fluidity was observed. For air content, elapse of time resulted in a decrease in air content caused by loss of AE and entrapped air. Setting time was shortened with elapse of delivery time. Compressive strength increased with proportion to elapse of age within 3~4 hours. Deteriorated concrete during long term delivery for 3 hours caught up with target slump with 150±15mm when adding 0.2% of superplasticizer. The use of 0.05×10-2% of AE agent and 0.02% of retarding agent respectively overcame the air content and setting time. Recovered concrete enhanced compressive strength as much as 17% compared with control concrete. It shows that the combination of superplasticizer, AE agent and retarding agent with 1:0.0025:0.1 enables deteriorated concrete by long term delivery to recover the quality as well as enhance compressive strength. |