土木工程研究所专业论文演讲木工程研究所专业论文演讲土木工程研究所专业论文演讲土木工程研究所专业论文演讲.pptVIP

* * * * * * * * * * * * * * * Effects of silica powder and cement type on durability of ultra high performance concrete (UHPC) Mo Alkaysi Ph.D. Candidate at University of Michigan Sherif El-Tawil Department of Civil Environmental Engineering, University of Michigan 点击添加文本 The background 点击添加文本 Experimental program 点击添加文本 Discussion of results 点击添加文本 Conclusion Ultra-high performance concrete (UHPC) is de?ned as a cementitious material with compressive strength in excess of150 MPa. 1、The background Various versions of UHPC have been in existence for several decades . However, until recently, most existing mix formulations were proprietary, expensive and required time and labor intensive mixing. 2、Experimental program UHPC mix designs Steel ?ber reinforced concrete resist postcracking tensile stress through the composite action between the concrete and ?bers, including chemical and mechanical bonding at the interface between the two. Cylindrical specimens of 150 mm in diameter and 300 mm in height were made. Freeze-thaw resistance After air drying at 20℃ and 65% relative humidity for 24 h, the lateral surfaces of the specimens were sealed by the aluminum foil with butyl rubber. The freeze-thaw machine, as shown in Fig.2, contains ?fteen stainless steel bowls, each containing one specimen. Freeze-thaw resistance The specimen sits on four spacers so that the bottom test surface is in contact with the test liquid As can be seen in Fig. 7, mass loss for all of the specimens fell signi?cantly below the 1500 g/m2 limit de?ned by the testing standard. 3、Discussion of results * * * * * * * * * * * * * * *