01555037

Component

Sustainable utilizations of industrial waste materials to construction field have been given considerable worldwide attention. Geopolymer is a novel binding material produced from the reaction of aluminosilicate solid materials with an alkaline solution. In this study, Class C fly ash and bentonite as precursor, together with alkaline solution and steel fibers from waste tires are used to synthesize Geopolymer cement. The influence of bentonite content, sodium hydroxide concentration and content of steel fibers recycled from waste tires, on the short term properties of the geopolymer mortar is studied. The experimental results show that geopolymer mortar using fly ash and NaOH of 9 M possesses the highest compressive strength of 31.6MPa and 35.9 MPa at 3 and 7 days, respectively. As the content of bentonite increases from 25 to 50%, the compressive strength of the geopolymer mortar decreases from 12 to 0.2 MPa and the failure behavior changes from brittle and split model to split + shear failure. Besides, the increase of steel fiber content from 2 to 6 wt%, the 7-day compressive strength of the geopolymer mortar is found to decrease from 24.2 to 1.2 MPa. However, the bridge effect of steel fibers is found in the geopolymer mortar, helps to prevent the crack propagation in the mortar and shear off. The interfacial transition zone (ITZ) is identified using the Scanning Electron Microscope equipped with an Energy Dispersive X-ray (SEM-EDX), features the thickness of ~ 25 μm for the geopolymer mortar containing 100% fly ash, and 10–12 μm for the mortar containing 50% fly ash, respectively. The EDX results additionally demonstrate the low concentration of major elements in the ITZ, implying the low formation of the gels. This leads to weak bonding and cracking in the ITZ.

This paper was sponsored by TRB committee AFN10 Basic Research and Emerging Technologies Related to Concrete. Alternate title: Mechanical and Microstructure Characterizations of Geopolymer Mortars Containing Industrial Waste Materials

01550057

15-4880

English

19p

2015

Transportation Research Board 94th Annual Meeting

Digital/other

Figures; References; Tables

Bentonite; Cement mortars; Compressive strength; Fly ash; Geopolymer concrete; Mechanical properties; Microstructure; Steel fibers; Thickness; Wastes

Interfacial transition zone; Scanning electron microscopy

Bridges and other structures; Design; Highways; Materials; I22: Design of Pavements, Railways and Guideways; I24: Design of Bridges and Retaining Walls; I30: Materials

Transportation Research Board Annual Meeting 2015 Paper #15-4880

TRIS, TRB, ATRI

Dec 30 2014 1:37PM