Effect of Alkali Concentration on Physico -Chemical and Mechanical Properties of Slag Based Geopolymer Cement.

Abstract

In this article we studied the effects of sodium hydroxide pellets (SH) and sodium silicate liquid (SSL) as an activator on the physico chemical and mechanical Properties of ground granulated blast furnace slag (GGBFS) geopolymer pastes. Various mixes are prepared using different liquid/solid ratios (L/S) by weight. The hydration characteristics of the various mixes have been tested through determination of total porosity, compressive strength, bulk density, chemically combined water, and XRD analysis at different time intervals from 2 days up to 90 days under relative humidity 100%. The results elucidated that as the quantity of alkali activator increases up to (15% SSL, and 15% SH), the compressive strength increases up to 90 days. The combined water content of all mixes increases up to 90 days. Also the bulk density raises and the total porosity minimizes, this is due to the addition of the pozzolanic materials. All mixes showed good stability of its compressive strength values in 5 % MgSO4 solution. The data showed that mix S6 (100% GGBFS) activated by (15% SSL, and 15% SH) is the most appropriate binding material (geopolymer cement) that has good properties so it can be used as alternative binding materials to the ordinary Portland cement.

Keywords

• geopolymer cement
• sodium silicate
• slag
• mechanical properties
• and sulphate resistance.