Performance of mortar containing alkali-activated metakaolin based binders | |
| Author | Supit, Steve Wilben Macquarie |
| Call Number | AIT Thesis no.ST-09-06 |
| Subject(s) | Mortar--Additives Binders (Materials) |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Structural Engineering, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. ST-09-06 |
| Abstract | The development of alkali-activated cements has become a new way to reduce global warming due to the ability in reducing CO₂ contents in cement production; it then called "green chemistry". In concrete technology, this product can significantly effect the early compressive strength development and durability of material. As the most effective pozzolans, metakaolin was studied to become main raw material than can be activated by using alkaline activators. In the research, cement was replaced at 20, 30 and 40% of metakaolin obtained from Ranong Province located in the Southern part of Thailand. Water to binder ratio was kept constant at 0.45. Sodium Hydroxide (NaOH), Sodium Tri-silicate (Na₂.3SiO₂) and Sodium Sulphate (Na₂SO₄) were used as alkaline activator at the interval of 2, 4 and 6 percentage by weight of binders. Mortar specimens with Ordinary Portland Cement (OPC) Type I was used as reference or control mortar. Based on the result, the most effective alkaline activator was 4% Na₂SO₄ in mortar containing 20% metakaolin replacement. The addition of NaOH and Na₂.3SiO₂ had a little influence in compressive strength development. In addition, the positive influence of alkaline activator in enhancing compressive strength can be obtained at early age than later ages. The presence of ettringgite (Aft) in MK-20 with 4% Na₂SO₄ was detected from X-ray Diffraction (XRD) test which can accelerate the depletion of Ca(OH)₂, reduces void, densifies the structure and increases the early strength of hardened mortar very si gnifi cantl y . The other feature was the optimum dosage of alkaline activator may vary depends on the percentage of metakaolin replacement. Moreover, the beneficial effect of increasing the dosage of alkaline activator on the compressive strength development is limited. On water permeability and Rapid Chloride Permeability Test (RCPT), the coefficient permeability and charge passed of chloride were reduced as increasing the dosage of alkaline activator. Since the alkali concentration affected the chloride penetration in the pore solution, the use of Na₂SO₄ with quantity 4% was accepted could contribute in forming strong binder through the hydration product thus result in delaying the chloride movement process and reduce chloride binding. According to ASTM C 1202, the metakaolin mortar containing Na₂SO₄ can be classified in very low chloride ion penetrability. |
| Year | 2009 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. ST-09-06 |
| Type | Thesis |
| School | School of Engineering and Technology |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Structural Engineering (STE) /Former Name = Structural Engineering and Construction (ST) |
| Chairperson(s) | Pennung Warnitchai;Sun Sayamipuk |
| Examination Committee(s) | Thanakorn Pheeraphan;Raktipong Sahamitmongkol |
| Scholarship Donor(s) | AIT Fellowship |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2009 |