محمد حمودي صالح شمسة

Geopolymer concrete is considered as an environmentally friendly material due to its effect in reducing CO2 emissions to the environment. This gas is the main cause for global warming. The production of Portland cement is responsible for about 5-8 % of the global CO2 emission. This research studied the behavior of Geopolymer concrete depending on three types of source (source) materials, which are: local Metakaolin, fly ash, and granulated blast furnace slag. The effects of the mix proportions and alkaline solution on compressive strength of concrete at 7, 28, and 60 day age were investigated. The results showed that increasing the amorphous silica and alumina in the source material increases the compressive strength of the Geopolymer concrete. The presence of CaO in slag (GGBS) has a significant role in increasing the compressive strength of the slag based Geopolymer concrete.

Geopolymer is a new sustainable binding material. It was developed to reduce CO2 footprint of existing Portland cement concrete. One ton of Geopolymeric cement generates 0.18 ton of CO2 from combustion carbon-fuel. This figure is 6 times less than the emission of Portland cement manufacture. The relationship between the compressive strength of Geopolymer concrete and the percentage of amorphous silica in the source material has been studied in the present work. Six mixes with different source materials were investigated to verify this relationship. The used Pozzolanic materials were three types of Fly ash, two types of Metakaolin and one type of ground granulated blast furnace slag. Geopolymer concrete samples were cured by heating for 72 hours. The testing ages for compressive strength were 7, 14, 28, and 60 days. The results showed that a noticeable relationship between compressive strength and amorphous silica was observed. The microstructure of the six mixes was studied in detail through the SEM and XRD analysis

In this study, the effect of rapid freezing and thawing (ASTM C666 – procedure A) on three different types of Geopolymer concrete studied using three types of pozzolanic material: fly ash, metakaolin and ground granulated blast furnace slag (GGBFS). The Geopolymer concrete was prepared using 400 kg of the pozzolanic material with alkaline liquid prepared at 8 molar concentration with normal fine and coarse aggregates. The ratio of alkaline to fly ash and GGBFS was 1.5: 1 and for metakaolin was 2: 1 for workability and compressive strength requirements. Specimens (100 × 100 × 400) mm were exposed to 100, 200 and 300 cycles of freezing and thawing. The decrease in measured compressive strength was (23, 43, and 26%) for Fly ash, metakaolin and GGBFS respectively. The investigated types of concrete showed good resistance to freezing and thawing. The durability factor of these types was (77%, 68%, and 81%) for fly ash, metakaolin, and GGBFS respectively.