Ảnh hưởng của kích thước khuôn đúc mẫu đến cường độ kéo khi uốn của bê tông tự lèn cốt sợi thép

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Tác giả: Việt Đức Nguyễn

Ngôn ngữ: Vie

Ký hiệu phân loại: 624 Civil engineering

Thông tin xuất bản: Tạp chí Khoa học Kỹ thuật Thủy lợi và Môi trường, 2019

Mô tả vật lý: 117-122

Bộ sưu tập: Metadata

ID: 420162

Thêm vào giỏ Liên kết toàn văn

Hỗn hợp bê tông tự lèn cốt sợi thép (BTTLCST) với mác cường độ 30 MPa được đổ vào các khuôn 100x100x400mm3 và 100x300x400mm3. Mẫu lớn sau đó được cắt ra làm 3 mẫu nhỏ như nhau 100x100x400mm3. Các mẫu được tiến hành thí nghiệm đánh giá cường độ kéo khi uốn. Thí nghiệm đã chỉ ra rằng các mẫu từ khuôn 100x100x400mm3 cho ra kết quả lớn hơn mẫu từ khuôn 100x300x400mm3 là 10%, mặc dù các mẫu thí nghiệm có kích thước như nhau. Trong khi đó, cường độ xác định trên các mẫu cắt ra từ khuôn 100x300x400mm3 cho kết quả gần giống nhau. Khi đổ hỗn hợp BTTLCST vào khuôn kích thước nhỏ, các sợi thép đã được định hướng theo dòng chảy của hỗn hợp bê tông tươi tự lèn do hiệu ứng thành ván khuôn và các đặc tính về tốc độ chảy gây ra. Hiện tượng này có thể đã không xảy ra đối với khuôn 100x300x400mm3. Đây chính là nguyên nhân chính dẫn đến sự ảnh hưởng của kích thước khuôn đúc mẫu đến cường độ kéo khi uốn của bê tông tự lèn cốt sợi thép., Tóm tắt tiếng anh, Fresh self-compacting steel fibre-reinforced concrete (SCSFRC) of strength class 30 MPa was casted into the small (100x100x400 mm3) and large (100x300x400 mm3) moulds. The large specimen was splitted into three small identical ones (100x100x400 mm3). All of the specimens were subjected to third-point bending in as-cast direction. Flexural strength of SCSFRC obtained from small specimens (100x100x400 mm3) yielded 10% higher than that from large specimens of the same size. While flexural strength defined by the small specimens (100x100x400 mm3) that were cut from the large specimens was almost the same. When pouring fresh SCSFRC into the small mould, steel fibres were orientated along with the flow of the fresh concrete due to the wall-effect and the velocity profile. Likely, this phenomenon did not occur in the case of large mould. This was the main reason why flexural strength was influenced by mould type.

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