scholarly journals Crossover Effect in Cement-Based Materials: A Review

2019 ◽  
Vol 9 (14) ◽  
pp. 2776 ◽  
Author(s):  
Sumra Yousuf ◽  
Payam Shafigh ◽  
Zainah Ibrahim ◽  
Huzaifa Hashim ◽  
Mohammad Panjehpour
Keyword(s):  
Compressive Strength ◽  
Construction Industry ◽  
Building Materials ◽  
Cement Hydration ◽  
Curing Temperature ◽  
Future Research ◽  
Hydration Products ◽  
Crossover Effect ◽  
Cement Based Materials ◽  
Mineral Compositions

Cement-based materials (CBMs) such as pastes, mortars and concretes are the most frequently used building materials in the present construction industry. Cement hydration, along with the resulting compressive strength in these materials, is dependent on curing temperature, methods and duration. A concrete subjected to an initial higher curing temperature undergoes accelerated hydration by resulting in non-uniform scattering of the hydration products and consequently creating a great porosity at later ages. This phenomenon is called crossover effect (COE). The COE may occur even at early ages between seven to 10 days for Portland cements with various mineral compositions. Compressive strength and other mechanical properties are important for the long life of concrete structures, so any reduction in these properties is of great concern to engineers. This study aims to review existing information on COE phenomenon in CBMs and provide recommendations for future research.

scholarly journals The influence of cement-based composite materials on the performance of bridges: modification and optimization by nano-SiO2 material

2020 ◽  
Vol 15 (3) ◽  
pp. 409-413
Author(s):  
Cheng Zhu
Keyword(s):  
Compressive Strength ◽  
Composite Materials ◽  
Flexural Strength ◽  
Building Materials ◽  
Complex Environments ◽  
Nano Sio2 ◽  
Bending Resistance ◽  
Cement Based Materials ◽  
Different Content ◽  
Compression Resistance

Abstract Cement-based materials have been widely used in bridge construction. In order to further improve their performance, this study analyzed the modification and optimization functions of nano-SiO2 materials, designed test specimens with different content of nano-SiO2 and conducted experiments on their flow performance, compression resistance, bending resistance and impermeability. The results showed that the flow performance of the materials decreased and the impermeability decreased with the increase of nano-SiO2 content. The compressive strength and flexural strength are the best when the content of nano-SiO2 is 1%. On the whole, the best content of nano-SiO2 is 1%; when the content of nano-SiO2 is 1%, all the properties of the specimens are good, which is more conducive to the construction of bridges in various complex environments. The research in this paper has made some contributions to the further application of nano-SiO2 in the optimization of building materials, which is conducive to the better development of building materials.

The Relationship of NaOH Molarity, Na2SiO3/NaOH Ratio, Fly Ash/Alkaline Activator Ratio, and Curing Temperature to the Strength of Fly Ash-Based Geopolymer

2011 ◽  
Vol 328-330 ◽  
pp. 1475-1482 ◽  
Author(s):  
M. M. A. Abdullah ◽  
H. Kamarudin ◽  
M. Bnhussain ◽  
I. Khairul Nizar ◽  
A.R. Rafiza ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Construction Industry ◽  
Curing Temperature ◽  
Test Results ◽  
Compression Tests ◽  
Naoh Solution ◽  
Alkaline Activator ◽  
Relationship Of ◽  
The Relationship

Geopolymer, produced by the reaction of fly ash with an alkaline activator (mixture of Na2SiO3 and NaOH solutions), is an alternative to the use of ordinary Portland cement (OPC) in the construction industry. However, there are salient parameters that affecting the compressive strength of geopolymer. In this research, the effects of various NaOH molarities, Na2SiO3/NaOH ratios, fly ash/alkaline activator, and curing temperature to the strength of geopolymer paste fly ash were studied. Tests were carried out on 50 x 50 x 50 mm cube geopolymer specimens. Compression tests were conducted on the seventh day of testing for all samples. The test results revealed that a 12 M NaOH solution produced the highest compressive strength for the geopolymer. The combination mass ratios of fly ash/alkaline activator and Na2SiO3/NaOH of 2.0 and 2.5, respectively, produced the highest compressive strength after seven days. Geopolymer samples cured at 60 °C produced compressive strength as high as 70 MPa.

Physical and Chemical Influence of Polyacrylate Latex on Cement Mortars

2011 ◽  
Vol 261-263 ◽  
pp. 807-811 ◽  
Author(s):  
Ye Tian ◽  
Zong Jin Li ◽  
Hong Yan Ma ◽  
Xian Yu Jin ◽  
Nan Guo Jin
Keyword(s):  
Pore Structure ◽  
Cement Hydration ◽  
Bending Strength ◽  
Mechanical Performance ◽  
Air Entrainment ◽  
Hydration Products ◽  
Cement Mortars ◽  
Cement Based Materials ◽  
Physical And Chemical ◽  
Chemical Influence

In this research, the physical and chemical influence of polyacrylate (PA) latex on cement-based materials were studied using polymer modified mortars with polymer/cement (P/C) ratios of 0%, 5% and 10%. Physically, the mechanical performance of PA latex modified mortars was investigated with compression toughness energy and bending strength. Further more, a comparison of the pore structure and porosity between PA latex modified and unmodified mortars was conducted. The chemical reactions between PA polymer and cement hydrates were clarified with thermogravimetric (TG) analysis. It can be concluded from this research that PA polymer can refine the pore structure of cement mortars and link the cement hydration products together chemically. While, at the same time, PA latex addition can cause air entrainment which will weaken the physical behavior of cement mortars. So there is an optimum P/C ratio to achieve the best mechanical properties. And in this research, the optimum P/C ratio is 5%.

scholarly journals Nanotechnology in Cement-Based Materials: A Review of Durability, Modeling, and Advanced Characterization

Nanomaterials ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 1213 ◽  
Author(s):  
Sen Du ◽  
Junliang Wu ◽  
Othman AlShareedah ◽  
Xianming Shi
Keyword(s):  
Recent Progress ◽  
Cement Hydration ◽  
Advanced Characterization ◽  
Cement Composites ◽  
Hydration Products ◽  
Cement Based Materials ◽  
Rebar Corrosion ◽  
Nanoscale Modeling

In the context of increasing applications of various nanomaterials in construction, this work reviews the renewed knowledge of nanotechnology in cement-based materials, focusing on the relevant papers published over the last decade. The addition of nanomaterials in cement-based materials, associated with their dispersion in cement composites, is explored to evaluate their effects on the resistance of cement-based materials to physical deteriorations, chemical deteriorations, and rebar corrosion. This review also examines the proposed nanoscale modeling of interactions between admixed nanomaterials and cement hydration products. At last, the recent progress of advanced characterization that employs techniques to characterize the properties of cement-based materials at the nanoscale is summarized.

Research on the Strengthening Effect of Phosphorus Slag Powder on Cement-Based Materials

2009 ◽  
Vol 405-406 ◽  
pp. 356-360 ◽  
Author(s):  
Dong Mei Liu ◽  
Kun He Fang ◽  
Hua Shan Yang
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Cement Hydration ◽  
Hydration Product ◽  
Strengthening Effect ◽  
Early Hydration ◽  
Double Excitation ◽  
Slag Powder ◽  
Cement Mortars ◽  
Cement Based Materials

The strengthening effect of phosphorus slag powder (PSP) in cement-based materials was researched by model of strengthening effect of mineral admixes, and the mechanism of strengthening effect of PSP was also studied by SEM. The results indicate that, in early hydration period, the strengthening effect of PSP on strength of cement mortars is zero. At 90 days, strengthening effect has been exerted, and increases with the amount of PSP when that is no more than 40%, but decreases with larger content of PSP. At 180 days, the strengthening effect was further enhanced, the greater the amount of PSP, the greater its effect. For compressive strength of cement mortars, the strengthening effect of PSP is more than that of PSP on flexural strength. The results analyses of SEM show that, strengthening effect of PSP mainly come from its pozzolana reaction. With double excitation of cement hydration product hydroxide and gypsum, the low alkalinity C-S-H was produced.

THE INFLUENCE OF INITIAL MATERIALS ON THE COMPRESSIVE STRENGTH OF GEOPOLYMER SOILS

2014 ◽  
Vol 1 (1) ◽  
Author(s):  
Hong Chan Nguyen ◽  
Anh Tuan Nguyen ◽  
Namshik Ahn
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Sodium Silicate ◽  
Alkaline Solution ◽  
Building Materials ◽  
Clay Content ◽  
Carbon Dioxide Production ◽  
Environmental Benefits ◽  
Curing Temperature ◽  
Low Carbon

In recent years, geopolymers have received significant attention because they show environmental benefits, such as a reduction in the consumption of natural resources and a decrease in the net production of CO2. In addition, as green material, soil has low carbon dioxide production emissions compared to other building materials. In this research, soil was combined with activator alkaline to produce hardening materials as geopolymer soils. An alkaline solution with sodium hydroxide, sodium silicate and fly ash was used. The influence of clay content on the geopolymer soils’ compressive strength was investigated. The best strengths were obtained from 5% to 12% clay content. SEM photos were also taken from specimens to investigate the structure of geopolymer soils. When combined with soil and fly ash in geopolymerization, fly ash reacted to the alkali solution quickly. The relationships between many variables such as clay content, fly ash, alkaline solution, curing time, and curing temperature were investigated by using a statistical analysis program with over 100 initial parameters. These results also indicate that the use of soils in geopolymer soil should have been limited. Additionally, increasing the sodium silicate in the alkaline liquid affected the geopolymerization reaction significantly. However, the suitable Si on the alkaline solution and soil should be limited.

Improvement of Wood-Cement Composition Properties with Microsilica Additive

2020 ◽  
Vol 992 ◽  
pp. 162-167
Author(s):  
E.Yu. Gornostaeva ◽  
N.P. Lukuttsova ◽  
D.I. Dryazgov
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Silicon Dioxide ◽  
Cement Hydration ◽  
Cement Stone ◽  
Hydration Products ◽  
Maximum Increase ◽  
Calcium Hydrosilicates ◽  
Calcium Silicates ◽  
Composition Properties

The properties and microstructure of wood-cement compositions (WCC) with microsilica (MS) additive for the manufacture of small-pieces wall products are studied. The extreme dependences of mean density, thermal conductivity and compressive strength on the content of microsilica additive are established. The mechanism of microsilica effect on wood-cement compositions is offered. Two interrelated factors (chemical and physical) could be distinguished at that. The first factor includes mainly the interaction of silicon dioxide with lime having released during hydration of calcium silicates, i.e. pozzolatic process. The second factor lies in the compaction of wood-cement compositions and the cement stone structure by means of cement hydration products and silica particles. It is established that introducing 20% of microsilica in the composition results in the maximum increase in ultimate compression strength (3 times). It can be explained not only by forming calcium hydrosilicates, uniformly and densely covering the wood aggregate, but by compacting effect of spherical microsilica inclusions, filling the space between the new cement stone formations and wood aggregate.

scholarly journals Modern trends in the development of the construction industry in the production of building materials

Technobius ◽  
2021 ◽  
Vol 1 (3) ◽  
pp. 0003
Author(s):  
Aliya Aldungarova ◽  
Kapar Aryngazin ◽  
Vladimir Larichkin ◽  
Assem Abisheva ◽  
Kamilla Alibekova
Keyword(s):  
Compressive Strength ◽  
Construction Industry ◽  
Power Plants ◽  
Building Materials ◽  
Moisture Absorption ◽  
Thermal Power ◽  
Thermal Power Plants ◽  
Ash And Slag Waste ◽  
Slag Waste ◽  
Construction Product

The paper describes the technology of manufacturing a construction product by vibrocompression using ash and slag waste from thermal power plants in the Pavlodar region. The task of the experimental research was to obtain a hollow wall stone based on ash and slag waste with a strength grade that is not inferior to products made according to the traditional recipe. The obtained samples with different ratios of components in the mixture were investigated for compressive strength, moisture absorption, frost resistance. It has been established that when ash and slag waste are added to the composition of the concrete mixture in an amount of up to 35 % of the mass of dry components, the strength characteristics of the hollow wall stone correspond to the selected brand

scholarly journals Effect of Curing Temperature on the Mechanical Strength of Alkali Activated Laterite Geopolymeric Samples

2021 ◽  
Author(s):  
Ahmad Fahmi ◽  
◽  
Alireza Babaeian amini ◽  
Yaser Marabi ◽  
Sohrab Rafati Zavaragh ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Mechanical Strength ◽  
Sodium Hydroxide ◽  
Building Materials ◽  
Sodium Hydroxide Solution ◽  
Low Cost ◽  
High Strength ◽  
Curing Temperature ◽  
Green Materials ◽  
New Type

A huge amount of carbon dioxide is released in the Portland cement production process. A large quantity of greenhouse gases is produced because of the significant amount of energy consumption via making bricks through firing. Using the pozzolanic sources containing the aluminosilicate and alkaline reagents, a new type of green materials called geopolymeric materials are produced with quite lower environmental hazards. The use of laterite as an iron-rich aluminosilicate material has a high potential for building materials. In this study, the effect of the curing temperature and characteristics of the alkaline reagent including the concentration of sodium hydroxide solution and the water-glass to sodium hydroxide mass mixing ratio on the mechanical strength of the laterite-based, oven-cured geopolymer samples was investigated. The results showed that the curing temperature had a significant effect on the compressive strength of the laterite-based geopolymer samples so that with a 15°C change at the curing temperature, the compressive strength of the samples could be multiplied and a sharp increase in the mechanical strength could occur. Also, according to the results of this study, the 6 M sodium hydroxide is recommended for the construction of the laterite-based geopolymer materials with low cost and relatively high strength, and for the construction of higher-strength building materials, the 14 M sodium hydroxide is recommended.

scholarly journals Waste Foundry Sand Usage for Building Material Production: A First Geopolymer Record in Material Reuse

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Neslihan Doğan-Sağlamtimur
Keyword(s):  
Compressive Strength ◽  
Building Material ◽  
Building Materials ◽  
Curing Temperature ◽  
Unit Weight ◽  
Wall Material ◽  
Sieve Analysis ◽  
Foundry Sand ◽  
Building Wall ◽  
Waste Foundry Sand

In order to bring a solution to the problem of waste foundry sand (WFS) in the foundry sector and achieve its reuse, geopolymer building material (as a cementless technology) was produced from the WFS for the first time in the literature in this study. The physical and mechanical characteristics of this material were determined. In the first part of the experimental step, the sieve analysis, loose/tight unit weight, and loss of ignition of the WFS were obtained as well as the ultimate analysis. In the second step, the water absorption percentage, porosity, unit weight, and compressive strength tests were conducted on the WFS-based geopolymer specimens activated by chemical binders (sodium hydroxide: NaOH and sodium silicate: Na2SiO3). As the unit weights of all the produced samples were lower than 1.6 g/cm3, they may be considered as lightweight building materials. The minimum compressive strength value for building wall materials was accepted as 2.5 MPa by national standards. In this study, the maximum compressive strength value was measured as 12.3 MPa for the mixture incorporation of 30% Na2SiO3 at the curing temperature of 200°C in 28 days. It was concluded that this geopolymer material is suitable for using as a building wall material.

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