scholarly journals On effect of superplasticizers and mineral additives on shrinkage of hardened cement paste and concrete

2018 ◽  
Vol 196 ◽  
pp. 04018 ◽  
Author(s):  
Grigory Nesvetaev ◽  
Yulia Koryanova ◽  
Tatiana Zhilnikova
Keyword(s):  
Portland Cement ◽  
Cement Paste ◽  
Autogenous Shrinkage ◽  
Drying Shrinkage ◽  
Hardened Cement ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Hardened Cement Paste ◽  
Mineral Additive ◽  
Mineral Additives

A model describing the variation in autogenous shrinkage and drying shrinkage of portland cement concrete, depending on the volume of aggregates and the shrinkage of hardened cement paste, is presented. The equation to calculate shrinkage of concrete as a function of the volume of aggregates and shrinkage of a hardened cement paste was proposed. Formulas are proposed that describe the change in the shrinkage of hardened cement paste as a function of water/cement. The results of studies of the effect of superplasticizers and mineral additives on the autogenous shrinkage and the drying shrinkage of hardened cement paste are presented. Concretes made with superplasticizer and mineral additive may have the potential lower the value of drying shrinkage. The shrinkage value can be lowered from 30% till 70%. Concretes containing superplasticizers and mineral additives can potentially have the autogenous shrinkage reduced to 75%, or increased to 180%.

Mechanical Properties of Alite-Calcium Barium Sulphoaluminate Cement Concrete

2008 ◽  
Vol 400-402 ◽  
pp. 121-124
Author(s):  
Zong Hui Zhou ◽  
Ling Chao Lu ◽  
Xing Kai Gao ◽  
Xin Cheng
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Portland Cement ◽  
Cement Paste ◽  
Early Age ◽  
Hardened Cement ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Hardened Cement Paste ◽  
Sulphoaluminate Cement

In this paper, preparation and mechanical properties of Alite-calcium barium sulphoaluminate (Alite-C2.75B1.25A3 ) cement concrete were studied. The results showed the compressive strength of Alite-C2.75B1.25A3 cement concrete was much higher than that of Portland cement concrete, especially the early-age compressive strength. The 24-hour compressive strength of Alite-C2.75B1.25A3 cement concrete could reach 22.81Mpa for w/c=0.45, 17.29Mpa for w/c=0.50 and 17.04Mpa for w/c=0.55 respectively. They were about 50 to 65 percent higher than those of Portland cement concrete. The 7-day compressive strength could reach about 80 to 90 percent of 28-day strength for Alite-C2.75B1.25A3 cement concrete. The 28-day strength could reach 55.85Mpa for w/c=0.45, 48.01Mpa for w/c=0.50 and 44.21Mpa for w/c=0.55 respectively. The results of SEM showed the interfaces between the hardened cement paste and aggregates in Alite-C2.75B1.25A3 cement concrete were more compact than those in Portland cement concrete. Distribution of particulate bulk was more uniformity and a majority of clinker particles was wrapped by hydrated gel in Alite-C2.75B1.25A3 concrete. And, the structure of Alite-C2.75B1.25A3 cement concrete was much more compact than that of Portland cement concrete.

Hardening Cement Conglomerates by Mining Industries Waste

2021 ◽  
Vol 316 ◽  
pp. 1061-1066
Author(s):  
Lilia V. Ilina ◽  
Irina N. Mukhina ◽  
Mariya M. Semenova
Keyword(s):  
Cement Paste ◽  
Hardened Cement ◽  
Hardened Cement Paste ◽  
Period Increase ◽  
Complex Additive ◽  
Nonlinear Mathematical Models ◽  
Study Results ◽  
Cement Strength ◽  
Heat And Moisture ◽  
Mineral Additives

About 3.5 billion tons of mining waste is generated annually in Russia. The task of their utilization is urgent in connection with the accumulation of large-tonnage waste of simultaneously mined rocks, enrichment waste and crushing screenings. The problem can be solved by using these wastes as mineral additives to artificial cement-based conglomerates. According to the study results it was found, that the compressive strength of hardened cement paste increased during all hardening periods, when finely dispersed mining wastes were introduced. In the early stages of hardening, limestone had a predominant effect. Introduction of diopside led to the greatest hardening together with the hardening period increase. Linear and nonlinear mathematical models, describing the dependence of cement strength on the type and amount of mineral additives, were constructed. The highest strength values of hardened cement paste, both after hardening under normal conditions for 28 days, and after heat and moisture treatment could be achieved with 7% dispersed diopside. At the same time, the hardening effect (increase in the strength of cement by 35–40%) was retained when 1/3 of the diopside in the complex additive was replaced by dispersed limestone. An increase in the content of limestone in the complex additive composition over 1/3 was impractical.

EXPLORATORY STUDY ON THE MECHANICAL AND PHYSICAL PROPERTIES OF CONCRETE CONTAINING SULFUR

2015 ◽  
Vol 77 (32) ◽  
Author(s):  
David Yeoh ◽  
Koh Heng Boon ◽  
Norwati Jamaluddin
Keyword(s):  
Portland Cement ◽  
Physical Properties ◽  
Ordinary Portland Cement ◽  
Cement Content ◽  
Drying Shrinkage ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Complete Replacement ◽  
Mechanical And Physical Properties ◽  
Ordinary Portland Cement Concrete

This research is an exploratory experiment into sulfur concrete used not as a complete replacement of cement but as an additional material in percentage of the cement content. The aim of this research was to explore the possible appreciation of mechanical and physical properties of concrete containing sulfur with percentages of 1%, 5% and 10% of the cement content. The sulfur used here was not heat-activated, hence the binding effect in sulfur was absent. The experimental results revealed that concrete containing sulfur did not perform better in their strength properties, both compressive strength and flexural strength. The physical properties such as water penetration and water absorption for concrete containing sulfur also showed poor performance in comparison to ordinary Portland cement concrete. Such phenomena are very likely due to the sulfur not being activated by heat. Carbonation test did not show good results as a longer term of testing is required. Drying shrinkage property was found to be encouraging in that concrete containing 10% sulfur had quite significant reduction in drying shrinkage as opposed to ordinary Portland cement concrete. 

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.

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