MANUFACTURE OF RC SEGMENT

PURPOSE:To obtain a product having fine surface by a method wherein an air suction port is provided on the upper part of a tightly closed form to generate negative pressure in the interior thereof and highly flowable concrete is forced and loaded from below into the form and concrete pressure therein is maintained for a certain period. CONSTITUTION:An air suction port 18 is mounted to the upper part of a tightly closed segment form A through a valve B, and a concrete casting port 17 is provided at the lower part thereof. Next the air in the form A is drawn by means of a vacuum pump G to generate negative pressure and highly flowable concrete, which does not need to be compacted, is forced and loaded into the form by means of a concrete pump E. Thereafter conctrete pressure in the form A is maintained for a certain period of time to eliminate occurrences of air pits of small diameter or water pits due to bleeding water. By this method, a fine concrete product which eliminate the need for surface finishing can be obtained.