Sanyo Chemical Industries, Ltd.

Takenaka Komuten Co., Ltd.

Takenaka Doboku Co., Ltd.

Takenaka Corporation

Iwao Uchizaki

Koichi Ito

Yasuhiko Yoshioka

Masaharu Sakuta

Tsunetoshi Shioya

Yoshifumi Shimoyama

Tadahiro Kaya

Soichi Kiya

Toshio Saito

Hiroyuki Yamakawa

After a mortar layer is formed on the surface layer of placed concrete, an ultrasonic vibrator is caused to vibrate while being pressed against the mortar layer surface, and a thin surface layer is scraped off, obtaining a dense water-shielding layer. Mortar with a low water-cement ratio is spread onto the surface of the water-shielding layer, and adhesion between the mortar and the water-shielding layer is strengthened by using the ultrasonic vibrator. The pressing force of the ultrasonic vibrator is then increased to make the mortar and the water-shielding layer densely integrated together, thereby forming a hard concrete surface excelling in abrasion resistance.

Method of forming dense concrete surface layer

A cement composition is provided which has the property of being inseparable in water, having improved strength and no effect in delaying setting time or reducing strength. It is produced at a cheaper cost by reducing the amount of a polyacrylamide compound to a considerable great extent. The polyacrylamide compound is present in an amount of 0.1 to 3% by weight based on the weight of cement, when a dialdehyde is added thereto.

Cement composition for laying underwater

A concrete composition is provided which has the property of being inseparable in water and no effect in delaying setting time or reducing strength. A polyacrylamide partial hydrolysate having a molecular weight of one million or higher and a hydrolysis degree of from 0.5 to 20% moles is present in an amount of 0.5 to 4% by weight based on the cement constituent proportion.

Water-inseparable concrete composition

Growing community of inventors

Tokyo, Japan

Iwao Uchizaki