Effects of Carbonation on the Properties of Concrete Made with Crushed Sand and Admixtures | Chapter 7 | Chemical and Materials Sciences: Research Findings Vol. 5

 

Carbonation is a natural ageing process that occurs in all types of concrete. Carbonation impacts the durability of concrete, involving a reaction of carbon dioxide (CO2) with cement hydration products to reduce the pH of the concrete pore solution from around 12 to less than 9. A key implication of carbonation is the acceleration of steel corrosion caused by the phenomenon of depassivation. The goal of this research is to investigate the carbonation of quarry sand-based concrete. The concrete is made of 100% crushed sand 0/6.3, gravel 8/16, and 15/25 from the Arab Contractor quarry in Nomayos, Cameroon, with CEM II B-P 42.5 R from CIMENCAM (Cimenteries du Cameroun). The study employed two admixtures: one with a dual superplasticizing and reducing action (Sikamen) and another with a water-repellent effect (Sika liquid). The Dreux-Gorisse method was applied for mix design. Carbonation was performed on concrete samples at the following dates: 0, 7, 14, 28, 56, 90, 180 days, one year, one year and six months. Carbonated concrete (CC) and non-carbonated concrete (NCC) samples are compared firstly in terms of their physical attributes and mineralogical characteristics, secondly in microstructure terms, aspect as X Ray Diffraction (XRD) and Scanning Electron Microscope (SEM) observation. The results of this investigation reveal that after more than a year and six months of carbonation, porosity decreases and permeability increases. The microstructure becomes firmer and more resistant to hostile treatments. Despite the high fineness modulus of quarry sand, the compressive strength of quarry sand-based concrete is satisfactory. Carbonation depth is relatively high on some dates, exceeding the minimal cover value for concrete reinforcement. A reduction in water and pore space causes mass loss, which leads to an increase in elastic deformation. Sikament additive increases concrete compactness and durability while decreasing permeability. Sika water repellent mixes with the lime in cement to generate complementary crystallisations that block the mortar's capillaries, making it watertight.

 

Author(s) Details

Jacques Herve Koung à Bediang
Laboratory of Civil and Mechanical Engineering, Department of Civil Engineering, National Advanced School of Engineering of Yaounde 1, Yaounde, Cameroon.

 

Emmanuel Elat Assoua Moukete
Laboratory of Mechanics and Materials of Civil Engineering, Department of Civil Engineering, CY Cergy Paris University, Paris, France.

 

Paul Djomou Djonga
Department of Textile and Leather Engineering, National Advanced School of Engineering of Maroua, Maroua, Cameroon.

 

Michel Mbessa
Department of Civil Engineering, National Advanced School of Public Works, National Advanced School of Engineering of Yaounde 1, Yaounde, Cameroon.

 

 

Please see the book here :- https://doi.org/10.9734/bpi/cmsrf/v5/5000