Properties of silica fume added pumice-concrete

Ill PROPERTIES OF SILICA FUME ADDED PUMICE-CONCRETE (PhD. Thesis) Emre SANCAK GAZI UNIVERSITY INSTITUTE OF SCIENCE AND TECHNOLOGY January 2005 ABSTRACT Large deposits of Pumice, a natural lightweight aggregate, are found in Turkey. In this study, the following properties of structural concrete produced by Pumice and normal-weight aggregate are investigated: 1) the ability to protect the embedded reinforcement against corrosion, 2) the bond strength between concrete and reinforcement, and 3) compressive strength and weight loss of Concrete with Pumice Aggregate (PAC) and Normal-weight Aggregate (NAC) after being exposed to high temperatures (20, 100, 400, 800, 1000 degrees C). To achieve these objectives, 12 different types of concrete mixtures were produced. In producing the NAC and PAC mixtures, a mineral additive, Silica Fume (SF), was used to replace the Portland cement in the ratios of 0 %, 5 % and 10 % by weight. The remaining six types of mixtures were obtained by adding Super Plasticizers (SP) to the above mixtures in the ratio of 2 % by weight. In conclusion; unit weight of PAC was 23 % lower than that of NAC. When compared to NAC, compressive strength reductions in PAC were observed to change between 48 % and 65 %. Use of SF and SP together, increased the bonding between concrete and the reinforcement in both PAC and NAC. When exposed to the temperatures of 20 °C, 100 °C and 400 °C, NAC performed better thanIV the PAC. PAC containing 10 % SF- 2 % SP, exposed to 17 cycles of wetting-drying in 7 % NaCI solution, gave the most suitable results (- 511,2 and -485,8 mV respectively) according to the half -cell potential data. The use of 10 % SF- 2 % SP together in PAC and NAC, amount of C\" ion became 2,24 % and 1,76 % respectively at a depth of 0-10 mm. The minimum loss of reinforcement weight was obtained by the addition of 10 % SF- 2 % SP to PAC and NAC, which was determined as 0,87 % and 0,85 %, respectively. When SF is used alone in NAC and PAC, carbonation depth increased. The minimum carbonation depth was obtained by the addition of 5 % SF and 2 % SP to PAC and NAC, which was determined as 1,40 mm and 1,61 mm, respectively. Science Code : 714 Keywords : Pumice-concrete, Bond strength, Reinforcement corrosion, High temperature effect Page Number : 164 Adviser : Assist. Prof. Dr. Osman ŞİMŞEK