Recycled geopolymer aggregates as coarse aggregates for Portland cement concrete and geopolymer concrete: Effects on mechanical properties

2020 ◽  
Vol 236 ◽  
pp. 117571 ◽  
Author(s):  
S. Mesgari ◽  
A. Akbarnezhad ◽  
J.Z. Xiao
Keyword(s):  
Mechanical Properties ◽  
Portland Cement ◽  
Geopolymer Concrete ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Coarse Aggregates

Dispersion of Multi-Walled Carbon Nanotubes in Portland Cement Concrete Using Ultra-Sonication and Polycarboxylic Based Superplasticizer

2015 ◽  
Vol 802 ◽  
pp. 112-117 ◽  
Author(s):  
Ali Yousefi ◽  
Norazura Muhamad Bunnori ◽  
Mehrnoush Khavarian ◽  
Taksiah A. Majid
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Portland Cement ◽  
Cement Matrix ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Uniform Dispersion ◽  
Multi Walled Carbon Nanotubes ◽  
Sonication Technique ◽  
Walled Carbon Nanotubes

The potential properties of carbon nanotube-cement based materials strongly depend on the dispersion of carbon nanotubes (CNTs) within the cement matrix and the bonding between CNTs and the hydrated cement. The homogeneous dispersion of CNTs in the cement matrix yet is one of the main challenges due to strong van der Waals forces between nanotubes. In this study, a polycarboxylic ether based superplasticizer and ultra-sonication technique was used for dispersion of multi-walled carbon nanotubes (MWCNTs). Portland cement concrete specimens with different concentrations of MWCNTs (0.04 and 0.1 % by the weight of cement), with and without the presence of superplasticizer were investigated. Compressive strength test results revealed a significant improvement in mechanical properties of sample containing 0.1 % MWCNTs and 0.2 % superplasticizer. Moreover, field emission scanning electron microscopy (FESEM) images of fractured surfaces of hardened specimens showed a good dispersion of MWCNTs within the cement matrix. This method was developed to facilitate the uniform dispersion of MWCNTs in the cementitious concrete for better reinforcement in nanoscale and mechanical properties enhancement by transfer of load between the nanotubes and matrix.

scholarly journals Durability Study on High Calcium Fly Ash Based Geopolymer Concrete

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Ganesan Lavanya ◽  
Josephraj Jegan
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Sodium Hydroxide ◽  
Ordinary Portland Cement ◽  
Geopolymer Concrete ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
High Calcium ◽  
High Calcium Fly Ash ◽  
Ordinary Portland Cement Concrete

This study presents an investigation into the durability of geopolymer concrete prepared using high calcium fly ash along with alkaline activators when exposed to 2% solution of sulfuric acid and 5% magnesium sulphate for up to 45 days. The durability was also assessed by measuring water absorption and sorptivity. Ordinary Portland cement concrete was also prepared as control concrete. The grades chosen for the investigation were M20, M40, and M60. The alkaline solution used for present study is the combination of sodium silicate and sodium hydroxide solution with the ratio of 2.50. The molarity of sodium hydroxide was fixed as 12. The test specimens were150×150×150 mm cubes,100×200 mm cylinders, and100×50 mm discs cured at ambient temperature. Surface deterioration, density, and strength over a period of 14, 28, and 45 days were observed. The results of geopolymer and ordinary Portland cement concrete were compared and discussed. After 45 days of exposure to the magnesium sulfate solution, the reduction in strength was up to 12% for geopolymer concrete and up to 25% for ordinary Portland cement concrete. After the same period of exposure to the sulphuric acid solution, the compressive strength decrease was up to 20% for geopolymer concrete and up to 28% for ordinary Portland cement concrete.

Effects of Consumption of Cement in Mechanical Properties of Lightweight Concrete Containing Brazilian Expanded Clay

2013 ◽  
Vol 368-370 ◽  
pp. 925-928 ◽  
Author(s):  
Andressa Fernanda Angelin ◽  
Lubienska Cristina L.J. Ribeiro ◽  
Marta Siviero Guilherme Pires ◽  
Ana Elisabete P.G.A. Jacintho ◽  
Rosa Cristina Cecche Lintz ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Portland Cement ◽  
Building Materials ◽  
Lightweight Concrete ◽  
Construction Materials ◽  
Lightweight Aggregates ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Conventional Concrete ◽  
New Techniques

Concrete is one of the oldest building materials known to humankind. From 1824, with the advent of Portland cement, concrete assumed a prominent place among the construction materials, due to large amounts of strength, durability and versatility it offered compared to other products, allowing the molding of various forms architectural. Until the early 80s, the concrete remained only as a mixture of cement, aggregates and water, however, in recent decades, due to the development of new techniques and products, the concrete has been undergoing constant changes. The concrete with lightweight aggregates have been used since the beginning of the last century, with low values of density (< 2000 kg/m3), demonstrating the great potential of using this material in several areas of construction [. With the objective of analyzing the influence of the consumption of cement in conventional concrete and light, were molded, tested and compared body-of-evidence containing two different amounts of cement consumption: a) 350 kg/m3 and b) 450 kg / m3. The results were compared with those obtained by other researchers, as well as with [ and [.

scholarly journals Sulfuric acid corrosion of geopolymer concrete with mineral additives from wastes

2019 ◽  
Vol 6 (3) ◽  
Author(s):  
Nadezhda Eroshkina ◽  
Mikhail Chamurliev ◽  
Mark Korovkin
Keyword(s):  
Corrosion Resistance ◽  
Sulfuric Acid ◽  
Portland Cement ◽  
Geopolymer Concrete ◽  
Acid Solutions ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Demolition Waste ◽  
Sulfuric Acid Solutions ◽  
Mineral Additives

The effect of mineral additives such as crushed ash and individual building demolition waste on the corrosion resistance of geopolymer concrete based on screening the crushed granite and blast furnace slag in an environment of sulfuric acid solutions was studied. The corrosion resistance of concrete was evaluated by the kinetics of reducing the mass and strength of samples in sulfuric acid solutions with a concentration of 2,5 and 5 % for 10 days. It was shown that replacing 50 % of granite powder with ground crushed bricks or ash significantly increases the corrosion resistance of geopolymer materials. It was established that due to the formation of poorly soluble products of the interaction of sulfuric acid and concrete in the pores of a geopolymer stone, an interface is formed between the undestructed material and the zone subjected to destructive processes, which impedes the penetration of the corrosive medium into the material. The study also conducted comparative studies of the corrosion resistance of Portland cement concrete with various water-cement ratios. The research results showed that under the influence of sulfuric acid in Portland cement concrete this border does not form and a rapid loss of mass and strength occurs in the samples. The established feature of the process of destruction of geopolymer concrete in a solution of sulfuric acid is the reason for its higher resistance in comparison with cement concrete.

scholarly journals Structural analysis of composite metakaolin-based geopolymer concrete

2018 ◽  
Vol 11 (3) ◽  
pp. 535-543 ◽  
Author(s):  
F. PELISSER ◽  
B. V. SILVA ◽  
M. H. MENGER ◽  
B. J. FRASSON ◽  
T. A. KELLER ◽  
...  
Keyword(s):  
Portland Cement ◽  
Concrete Beam ◽  
Rupture Strength ◽  
Geopolymer Concrete ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Two Samples ◽  
Geopolymer Cements ◽  
Geopolymer Cement ◽  
Nonlinear Numerical Model

Abstract The study of alternative binders to Portland cement, such as geopolymer cements, offers the chance to develop materials with different properties. With this purpose, this study evaluated experimentally the mechanical behavior of a geopolymer concrete beam and compared to a Finite Element (FE) nonlinear numerical model. Two concrete beams were fabricated, one of Portland cement and another of metakaolin-based geopolymer cement. The beams were instrumented with linear variable differential transformers and strain gauges to measure the deformation of the concrete and steel. Values for the compressive strength of the geopolymer cement concrete was 8% higher than the Portland cement concrete (55 MPa and 51 MPa, respectively) and the tensile rupture strength was also 8% higher (131 kN) for the geopolymer concrete beam in relation to Portland cement concrete beam (121 kN). Distinct failure mechanisms were verified between the two samples, with an extended plastic deformation of the geopolymer concrete, revealing post-fracture toughness. The geopolymer concrete showed higher tensile strength and better adhesion in cement-steel interface.

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