Self Compacting Concrete (SCC) using Bromo Volcano Ash

Transcription

1 271 Self Compacting Concrete (SCC) using Bromo Volcano Ash TRIWULAN, JANUARTI J.E, PUJO A, AND ANDIKA P. Department of Civil Engineering, Faculty of Civil Engineering and Planning, Institut Teknologi Sepuluh Nopember, Surabaya, 60111, Indonesia. Abstract One of the reason the damage of concrete is the existence of honeycombs. The honeycombs occur because of imperfections pouring process, the imperfections of vibration process, and formwork that are not simple. The development of concrete technology has introduced a new mixing concrete so called self compacting concrete. The aim of the research is to use Mount Bromo s volcanic ash as apart of cement Portland to produce Self Compacting Concrete. The percentage of volcanic ash used were 0%, 10%, 15% and 20% of weight of cementitious materials. Two types of super plasticizer were used with the percentage of % of Portland cement weight. Some fresh concrete tests applied were filling ability on using slump cone, passing ability on using L-box, flow ability and segregation on using V-Funnel. Compression test was applied to hard concrete on 3, 7, 14, 21, 28 and 56 days. Microstructure of concrete were assessed with split test porosity.the results indicated that the dosage of superplastiziser was a great role in the mixture workability. The results showed that the workability of concrete was influenced by the type and amount of superplasticizer. The use of Glenium C-351 as a superplasticizer provided better workability as compared to Viscocrete 10, The amount of volcanic ash as a cement substitution had no significant effect on the workability, but plays an important role in compressive strength. The optimum compressive strength obtained if the Portland cement was replaced with 15% of volcanic ash. Keywords Self Compacting Concrete, volcanic ash, workability, Super plasticizer I.Introduction The aim of the research is to use the Bromo volcanic ash. The large amount of volcanic ash as one of materials from volcano eruption, provides an idea for researchers to take an advantage, since volcanic ash is a natural pozolanic material. The aim of this research is to assess the mechanial and physical properties of Bromo volcanic ash as cement substitution in self compacting concrete. The amount of volcanic ash used were 0%, 10%, 15% and 20% of cement weight of. Two types of superplasticizer were used with the percentage of % of Portland cement weight. The fresh concrete test conducted were filling ability on using slump cone, passing ability on using L-box, flow ability and segregation on using V-Funnel. The strength test conducted to hard concrete at 3, 7, 14, 21, 28 and 56 days, while others test were performed for porosity assessment. The amount of superplastiziser was indicated as an influential factor in workability and the strength development. II.LITERATURE REVIEW Volcanic ash is released during volcanic eruption. Physical and chemical properties of a volcanic ash could be referred to ASTM C618-93, Standard Specification for Fly Ash and Raw or Calcinated Natural Pozzolan for Use as a Mineral Admixture in Portland Cement Concrete (3).Volcanic ash could be applied for making lightweight aggregates. (1) investigated the effect of cement replacement with volcanic ash and pumice powder on the consistency and setting time of blended cement, the ash percentage varied from 0 to 50%. The normal consistency decreased by adding volcanic ash, and compressive strength decreased with the addition of volcanic ash in the mixture. III.RESEARCH METHODE

2 272 Fig 1: Flow chart of research methods The method of research is described in Flow chart in Fig.1 A.The Materials In this research, ordinary Portland Cement,was from local cement industry; Course aggregates with maximum diameter 20mm were from Mojosari, and fine aggregates were from Lumajang.Volcano ash were taken from Mount Bromo with area size 75 micrometer. Two polycarboxilyte superplasticizer, were Viscocrete 10 and Glenium C-351.All test conducted in concrete laboratory of ITS using ASTM standart. Table 2: Mix design of SCC No Cement Volcanic Ash Water Gravel Sand Superplasticizer (% ) (kg) (% ) (kg) (kg) (kg) (kg) (% ) (ml) Type Viscocrete Viscocrete Viscocrete Viscocrete Viscocrete Viscocrete Viscocrete Viscocrete Glenium Glenium Glenium Glenium IV.TESTS RESULTS B.Chemical composition of Bromo volcano ash Table 1: chemical composition of Bromo volcano ash No compounds Percentsage 1 SiO 2 35,70 % 2 Na 2 O 22,00 % 3 Fe 2 O 3 15,80 % 4 Al 2 O 3 9,90 % 5 CaO 8,32 % 6 K 2 O 3,37 % 7 TiO 2 1,50 % 8 SO 3 1,30 % 9 MgO 1,00 % C.Mix proportion of materials Concrete mix design was based on DOE (Departemen of Environment) standart,with Indonesian standart SK.SNI.T and adjusted to European Guidelines for SCC The course aggregate were not more than 50% of concrete volume Ratio of fine aggregate to course aggregate was 55% : 45% The superplasticizer dosage used were 0.8% and 1.0 % by Portland cement weight. A.Slump Cone Test (T50) Slump Cone Test was used to determine flowability SCC indicated by Slump Flow Time (T50). The time is observed to have mixture that reaches a diameter of 500mm between 2 6 second. Fig. 2-Baseplate (EFNARC 2005) Mix design of SCC is shown in Table 2

3 273 Fig. 3- Graph of Slump Cone Test T50 Fig. 4-Slump Flow test Based on the Fig. 3, the more superplasticizer were added, the sooner concrete mixture to achieve a diameter of 50 cm. It is due to the reaction of superplasticizer that causes fluidity to the mixture and than increase the flowability. (7) Furthermore, the more volcano ash were used, the longer T50 were achieved. The reason is because the texture of the ash tends to be more sharper and rough. Fraction formed by phreatomagmatic eruption often have a particularly angular shape resulting from the great explosive interaction between magma and water (3). The use of superplasticizer from C-351 Glenium gives better flowabilty results as compared to those of Viscocrete 10. It is caused by branch polymer of Glenium as graft chain / side chain and length to better disperse in the cement particles better. B.Slump Flow Test (SF) The flow test was used to determine the flowability of SCC indicated by Slump Flow Spread (SF). The value target was shown by maximum diameter between mm correspond to European Guidelines for SCC (EFNARC 2005) Fig. 5- Graph of Slump Flow Test (SF) Based on Fig. 5, the more superplasticizer were added, the greater the diameter of the final mixture can be achieved. It is because of the reaction of the superplasticizer causes fluidity of mixture, so it increases the flowability. While the connection of ash as addition cement replacement, has lest effect on concrete flowability C. V-Funnel Test (Tv) V-Funnel test was conducted to assess determine the flowability concrete mixture, indicated by the length of flowing (Tv), the flow of mixture must be less than 25 seconds

4 274 Fig. 6-V-Funnel test (EFNARC 2005) Concrete Fig. 8-L Box was poured test in tool to (EFNARC the L- Box 2005) test equipment, then measured of H 1 and H 2 was.; The result was indicated in graph below PL = H2 H1 H1 = The height of concrete mixture that could not passed the net of reinforcement H2 = The height of concrete mixture that gap. Fig. 7-Graph V-Funnel Test (Tv) It is shown in Fig. 7. The flow time of each specimen. It is not affected by volano ash content of ash conten. The different ash content and superlasticizer give les effect in terms of vertically fillingability. However, if fly ash used as cement replace material, the more fly ash conten, the less time for fillingability (7). The aplication of superplasiticizer from Glenium C-351 has more influence in terms of fillingability.the using of Glenium C-351 has less time for fillingability.it is due to Glenium C-351 has longer branch of polymer (graft chain / side chain) and more numerous, which is easy to disperse in the cement particles. D.L-Box Test (PL) L-Box Test was conducted to determine the value of passing ability indicated by Passing Ratio (PL) must be more than 0,80 Fig. 9-Graph of L - Box Test (PL) Based on Fig.9 concrete mixer using superplastisizer from Viscocrete 10. Shows that the greater amount of superplasticizer inducing the passing ratio (PL). the resulting in mixture passing better, it is adjusted to. European Guidelines However the more the ash was in, the longer passing abilities will be achieved. Volcanic ash having mesh of 200, mixed in large volumes will increase the viscosity of the mixture. It can also be seen in the result of slump cone test. This condition

5 275 was inversely proportional to the previous study on fly ash, where mixture containing fly ash as a cement substitute materials (6,7). Greater amount of fly ash induces an increase of PL. The used Glenium C-351 could accelerate the value of fillingability rather than the use of Viscocrete 10. The use of volcanic ash in a larger amount still gives little effect on the passing ratio, because the form of volcanic ash which tends to be rougher and sharper than the fly ash. Fig. 12- Compressive strength test of specimens containing 1,0 % viscocrete 10 (a) Fig. 10. a - SEM Fly Ash X, b - SEM volcanic ash X (Research Center ITS) (b) E.Testing Of Hard Concrete e1.compressive Strength Test Compresive strength tests were conducted at 7, 14, 21, 28 and 56 days for 3 identical specimens, having size of 150in diameter and 300 mm in height. Fig. 13- Compressive strength test of sspecimens containing 0,8 % Glenium Fig Compressive strength test of specimen 0,8% viscocrete 10 Fig. 14- compressive strength comparison of specimen at the age of 28 days It is not easy to evaluate the compressive strength progress of concrete containg volcanic ash. For example, at concrete having 10% of volcanic ash, the compressive strength tend to decline, conversely

6 276 by using 15% of volcanic ash, the compressive strength increases. This condition occurs also in previous studies on normal concrete with volcanic ash reported by. (1 ) he found that the compressive strength decreased with the increase in volcanic ash conten.the result from his research indicated that there were no real correlation between the volume of volcanic ash and compressive strength. e2.split Tensile Strength Test Split tensile strength testing on SCC was cconducted for specimen 28 days. Each testing performed on 3 identical samples. Fig. 16- The Porosity of viscocrete 0,8% Fig. 17- The Porosity of viscocrete 1,0 % Fig. 15-tensile strength of SCC (Mpa) The development of tensile strength of SCC almost equal to the trend of compressive strength. With using 10% of Glenium, the tensile strength tend to decrease and tends to increase b thy using of 15% Glenium. e3.porosity Test The concrete porosity test was conducted at the age of 28 days, for obtaining closed, apparent and total porosity Fig.18- The Porosity of Glenium 0,8 %

7 277 Fig. 19- The Comparison of Total Porosity The porosity of the mixture using a various plasticizer has a similar trend, In general, the total porosity is inversely proportional to the results of compressive strength. There for, compressive strength is connected with microstructur properties shown by porosity 2. Triwulan, Ekaputri,Januarti J, Adiningtyas,Tami (2007). Analisa Sifat Beton Geopolimer Berbahan Dasar Fly Ash Dan Lumpur Porong Kering Sebagai Pengisi Jurnal Teknologi dan Rekayasa Sipil TORSI November 3. Siddique, R (2008) Waste material and by- Product in concrete, Springer,USA 4. SK.SNI.T (2003) Tata cara pembuatan beton normal, Departemen Pekerjaan Umum. 5. The Self Compacting Concrete European Project Group. (2005). The European Guidelines For Self-Compacting Concrete. U.K Hamka, A,Triwulan (2008) Sifat Fisik dan Mekanik Self Compacting Concrete (fc 60 MPa) Campuran V.CONCLUSION - Dosage and type of superplasticizer, influence the workability, flowability, passing ability of mixture. - In general, the addition of volcanic ash as a cement replacement have no significant effect on the workability of SCC - The volcanic ash content has no real correlation with compressive strength. However, concrete containing 15% of volcanic provides an optimum at compressive strength \- Porosity that occurs in the SCC is inversely proportional to the compressive strength, and development of porosity values tend to support the value of compressive strength REFFERENCES 1. Hossain, KMA, (2003) Blended cement using volcanic ashand pumice, Cement Concrete Research 33: