Đánh giá chất lượng silica từ tro trấu ở Thừa Thiên Huế sử dụng trong sản xuất bê tông chất lượng siêu cao

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Tác giả: VŨ TRƯỜNG SƠN LÊ, QUÝ TUẤN NGÔ, VIỆT HÙNG PHẠM, NGỌC ĐẠT TRỊNH

Ngôn ngữ: vie

Ký hiệu phân loại:

Thông tin xuất bản: Tạp chí Xây dựng, 2024

Mô tả vật lý: tr.60

Bộ sưu tập: Metadata

ID: 379540

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In comparison to conventional Portland cement concrete, Ultra-High Performance Concrete (UHPC) utilizes significantly higher amounts of binders, potentially reaching up to 1000 kg/m3, and active mineral admixtures such as silica fume, which can be as high as 250 kg/m3. This has led to increased costs for UHPC and posed challenges in the supply of these mineral admixtures in the manufacturing of UHPC, especially in developing countries like Vietnam. Finding alternative mineral admixtures with equivalent functionality to silica fume to partially replace cement in UHPC is essential. Among the active mineral admixtures used for UHPC, thermally treated rice husk ash under stringent conditions is considered a promising supply source for UHPC production. This study proposes an industrially controlled continuous pyrolysis model with an automated pyrolysis regime for producing silica-enriched amorphous rice husk ash. The experiment surveyed common rice husk sources in the Thua Thien Hue province under optimal pyrolysis conditions at 700°C, with a residence time of 1 hour in the pyrolysis chamber and a continuous production mode. XRD and SEM analysis results indicate that rice husk ash can be a substitute for part of the cement and industrial mineral admixtures in UHPC production, with potential for developing an industrial-scale model to achieve dual objectives of economic and environmental efficiency. Key words: Rice husk ash
amorphous silica
pyrolysis model
mineral admixture
UHPC.So với bê tông xi măng thông thường, bê tông UHPC sử dụng lượng chất kết dính cao hơn nhiều, có thể lên tới 1000 kg/m3, lượng phụ gia khoáng hoạt tính như silica fume có thể lên tới 250 kg/m3. Điều này đã làm giá thành bê tông UHPC tăng cao, cũng như gây khó khăn về nguồn cung vật liệu phụ gia khoáng này trong chế tạo bê tông UHPC ở những nước đang phát triển, như Việt Nam. Việc tìm kiếm nguồn phụ gia khoáng khác có chức năng tương đương với silica fume thay thế một phần xi măng trong bê tông UHPC là rất cần thiết. Trong số các phụ gia khoáng hoạt tính dùng cho UHPC, thì tro trấu nhiệt phân ở điều kiện nghiêm ngặt được đánh giá là nguồn cung triển vọng trong chế tạo bê tông UHPC. Nghiên cứu này đề xuất mô hình nhiệt phân liên tục theo hướng công nghiệp hóa được kiểm soát chế độ nhiệt phân tự động dùng để sản xuất tro trấu giàu silica vô định hình. Thí nghiệm tiến hành khảo sát các nguồn vỏ trấu phổ biến trên địa bàn tỉnh Thừa Thiên Huế ở chế độ nhiệt phân tối ưu ứng ở nhiệt độ 700oC, thời gian tro trấu lưu trú trong buồng nhiệt phân là 1 giờ, chế độ sản xuất liên tục. Kết quả phân tích XRD và SEM cho thấy tro trấu có thể là nguồn vật liệu thay thế một phần xi măng và phụ gia khoáng công nghiệp trong sản xuất bê tông UHPC và có triển vọng phát triển mô hình ở quy mô công nghiệp nhằm đạt mục tiêu “kép” về kinh tế kỹ thuật và môi trường. Từ khóa: Tro trấu
silica vô định hình
mô hình nhiệt phân
phụ gia khoáng
UHPC.

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