02-10-2012, 02:07 PM
STRENGTH CHARACTERISTIC OF GEOPOLYMER CONCRETE CONTAINING RECYCLED CONCRETE AGGREGATE
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Abstract
Malaysian is one of the develop countries that need to face environmental pollution. Have many ways to reduce environmental pollution that causes by production of Portland cement and cause by the increasing of waste material. Geopolymer concrete incorporating with recycle concrete aggregate (RCA) is one of the method. Waste Paper Sludge Ash (WPSA) and alkaline liquid as a binder are being used to replaced the Portland cement to produce geopolymer concrete. The alkaline liquid that been used in geopolymerisation is the combination of sodium hydroxide (NaOH) and sodium silicate (Na2SiO3). In the present study, two (2) series of geopolymer concrete specimens composing two (2) different molar of sodium hydroxide (NaOH) which are 8M and 14M were adopted. There are 30 cube specimens at size 100mm x 100mm x 100mm were prepared which is 15 cubes for 8M and another 15 cubes for 14M. The compressive strength of the geopolymer concrete specimens is tested at the age of 3, 7, 14, 21 and 28 days after cured in local laboratory ambient condition. The result shows that the strength of geopolymer concrete based Waste Paper Sludge Ash (WPSA) incorporating with recycle concrete aggregate (RCA) increase by increasing the molarities of sodium hydroxide (NaOH).
INTRODUCTION
Nowadays, Portland cement (PC) concrete is the most popular and widely used building materials, due to its availability of the raw materials over the world, its ease for preparing and fabricating in all sorts of conceivable shapes. The applications of concrete in the area of infrastructure, habitation, and transportation have greatly prompted the development of civilization, economic progress, and stability and of the quality of life. However, due to the restriction of the manufacturing process and the raw materials, some inherent disadvantages of Portland cement are still difficult to overcome. There are two major drawbacks with respect to sustainability. About 1.5 tonnes of raw materials is needed in the production of every tonne of Portland cement, at the same time about one tonne of carbon dioxide (CO2) is released into the environment during the production [1]. Therefore, the production of PC is extremely resource and energy intensive process. On the other hand, the global warming also can occur because of the greenhouse gases such as carbon dioxide to the atmosphere.
PROCEDURE OF EXPERIMENT
This experiment studies the strength characteristic of geopolymer concrete that containing Recycled Concrete Aggregate (RCA). To produce geopolymer concrete in this study, materials which are Waste Paper Sludge Ash (WPSA), sodium hydroxide solution (NaOH) and sodium silicate solution (Na2SiO3), water, recycled concrete aggregate (RCA) and superplastisizer will used in this study. The Aggregate Impact Value (AIV) and Aggregate Crushing Value (ACV) for the aggregate were tested. The AIV and ACV testing are tested as accordance to BS 812-112:1990 and BS 812-110:1990 respectively [6]. Two (2) series of mix proportion with different concentration at 8 Molar and 14 Molar of sodium hydroxide solution (NaOH) mixing with sodium silicate solution (Na2SiO3) were adopted. For each series, fifteen (15) concrete specimens are being casted. The total numbers of specimens is 30. The dimension of concrete specimen is 100 mm x 100 mm x 100 mm and the detail of concrete specimens as shown in Table 1.1. After casting for 24 hours, the moulded concrete was demoulded. The demoulded concrete specimens were cured at ambient condition. The curing time varied from 4 hours to 96 hours (4 days).
RESULT AND DISCUSSIONS
If using higher concentration of sodium hydroxide it gives the higher compressive strength of the concrete because the higher concentration of NaOH will make the good bonding between aggregate and paste of the concrete. Naturally, for the normal concrete, the strength at 3 days will shows the result of the strength at 28 days which is strength at 3 days is 2/3 of the strength at 28 days but it very different with geopolymer concrete.
CONCLUSIONS
In this study, it can be concluded that:
1. The concentration (in term of molarity) of NaOH influenced the strength characteristic of geopolymer concrete. The higher concentration of sodium hydroxide (NaOH) solution, higher compressive strength of geopolymer concrete will produced because the higher concentration of NaOH will make the good bonding between aggregate and paste of the concrete.