| 摘要 |
PROBLEM TO BE SOLVED: To restrain the width of crack caused on a structure surface below a specific value by forming a lower layer concrete layer using ordinary Portland cement in a lower layer in the whole layer thickness of a mat, and layering a concrete layer using low heating cement on the lower layer concrete layer. SOLUTION: In a mat-like concrete main body 10, a concrete lower layer 11 using ordinary Portland cement is placed on the ground. A concrete surface layer 12 using low heating Portland cement is placed on the concrete lower layer 11. Then, the ordinary concrete layer 11 is set to a layer thickness H1, and is integrally placed on the ground. This layer 11 is continuously placed by being divided into several layers so that a horizontal placing joint is not formed. Then, the low heating concrete layer 12 is continuously placed. In that case, the concrete layer 12 is set to H2, and a ratio to the whole layer thickness H is set to 15 to 10 % to thereby sufficiently control the occurrence of surface crack and the crack width.
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