Eksperimen ini dijalankan untuk mengkaji kesan perbezaan kaedah merawat sampel konkrit berkekuatan tinggi yang mengandungi silica fume. Silica fume adalah bahan pozzolanic yang mampu memberi impak kepada sifat-sifat mekanikal dan kekuatan sampel konkrit. Untuk penyelidikan ini, sejumlah dua adunan telah dihasilkan daripada simen biasa sebagai adunan kawalan dan 10% silica fume yang mana menggantikan simen biasa sebagai adunan berkekuatan tinggi. Nisbah air kepada simen adalah tetap iaitu 0.44. Kajian eksperimen telah dijalankan untuk mengkaji kekuatan mampatan (compressive strength), belahan tegangan (splitting tensile), perubahan pemanjangan (change in length), tahap kekenyalan (modulus of elasticity), lenturan (flexural), halaju dedenyut bunyi (UPV), keliangan dan serapan air (porosity and water absorption) dan ketumpatan konkrit. Kekurangan tahap rawatan kepada sampel konkrit boleh menyebabkan kecacatan seperti plastic shrinkage, keretakan (cracking) dan excessive drying shrinkage. Keretakan menyebabkan kenaikan ketelapan kembali dan pengurangan kekuatan mampatan seterusnya mengakibatkan kekuatan konkrit terjejas. Sampel dirawat oleh 5 cara seperti menengelamkan di dalam air, semburan air, rawatan stim pada tekanan biasa pada suhu 60 0C selama 16 jam dengan penangguhan selama 3 jam pada suhu bilik, suhu sejuk 10 0C dan rawatan kebiasaan pada suhu bilik 28 0C. Keputusan menunjukkan bahawa rawatan stim kepada sampel konkrit yang mengandungi silica fume memberi kekuatan mampatan yang tinggi pada permulaan tetapi sebaliknya berlaku kepada sampel konkrit yang dirawat di dalam air dan semburan pada usia 28 hari. Secara umumnya, penyelidikan ini mencadangkan agar rawatan stim dapat digunakan untuk mempercepatkan perkembangan kekuatan produk konkrit terutamanya di dalam pengeluaran precast konkrit. Sampel yang mengandungi silica fume harus dirawat menggunakan air untuk mencapai sifat-sifat yang bagus.
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This experiment is done to study of influence of different curing conditions on high performance concrete (HPC) containing silica fume. Silica fume is pozzolanic material that exhibits a considerable influence in enhancing the mechanical and durability properties of concrete. In this experiment, total of two mixes were made of Ordinary Portland Cement (OPC) as a control mix and OPC replaced with 10% silica fume as a HPC. The water to a binder ratio was kept constant at 0.44. An experimental program was performed to study the compressive strength, splitting tensile strength, change in length, modulus of elasticity, flexural strength, ultrasonic pulse velocity (UPV), water absorption, porosity, and hardened density tests. Insufficient curing can also lead to serious defects such as plastic shrinkage, cracking, and excessive drying shrinkage. These cracks increase in return permeability and decrease the compressive strength; as a result, it causes a decrease in concrete durability. Samples are curing by five methods such as immersing specimens in water, spraying specimens with water (fog room), steam curing at an ordinary pressure at 60 0C temperature for 16 hours with a delay period of 3 hours at room, cold weather curing was applied at 10 0C, and natural weather curing was applied at 28 0C as an average to cure the cube, prism and cylinder specimens until the day of testing. Test results indicate that steam cured concrete containing silica fume shows higher compressive strength at the early age but lower than immersing specimens in water and fog curing methods at 28 days. In general findings of this study suggest that Steam curing is a heat treatment method which has been used to speed up the strength development of concrete products, especially in producing precast concrete. The samples are containing silica fume should be cured by water curing to achieve well hardened properties.
Influence of different curing conditions on high performance concrete containing silica fume_Nabeel Abed Farhan_A9_2011_875000494_NI