scholarly journals Autogenous and drying shrinkage of mortars based on Portland and calcium sulfoaluminate cements

2020 ◽  
Vol 53 (5) ◽  
Author(s):  
Davide Sirtoli ◽  
Mateusz Wyrzykowski ◽  
Paolo Riva ◽  
Pietro Lura
Keyword(s):  
Portland Cement ◽  
Water Demand ◽  
Ordinary Portland Cement ◽  
Rapid Evolution ◽  
Autogenous Shrinkage ◽  
Drying Shrinkage ◽  
High Water ◽  
Early Age ◽  
Volume Changes ◽  
Calcium Sulfoaluminate

Abstract Calcium sulfoaluminate (CSA) cement can be used as an alternative binder in concrete, partially or fully replacing ordinary Portland cement. While CSA cement considerably accelerates the mechanical properties development, the rapid evolution of the microstructure together with the high water demand cause rapid and large volume changes at early ages. As volume changes may lead to early-age cracking, measures to reduce them may be required In this paper, autogenous and drying shrinkage are studied in mortars prepared with Portland cement, CSA cement or a 50/50 blend as binder. Very fast self-desiccation and high autogenous shrinkage of the CSA-based mortar were observed compared to the mortar made with Portland cement. On the other hand, the early-age volume changes can be limited if a blend of the two cements is used. The blended system revealed a bi-modal trend in the evolution of self-desiccation and autogenous shrinkage, in which the initial fast self-desiccation and shrinkage enter the dormant phase after the first couple of days and again start after about 28 days.

scholarly journals Influence of Different Alkali Sulfates on the Shrinkage, Hydration, Pore Structure, Fractal Dimension and Microstructure of Low-Heat Portland Cement, Medium-Heat Portland Cement and Ordinary Portland Cement

2021 ◽  
Vol 5 (3) ◽  
pp. 79
Author(s):  
Yang Li ◽  
Hui Zhang ◽  
Minghui Huang ◽  
Haibo Yin ◽  
Ke Jiang ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
Portland Cement ◽  
Pore Structure ◽  
Ordinary Portland Cement ◽  
Autogenous Shrinkage ◽  
Drying Shrinkage ◽  
Crystal Forms ◽  
Pore Structures ◽  
Cement Based Materials ◽  
Mineral Compositions

In cement-based materials, alkalis mainly exist in the form of different alkali sulfates. In this study, the impacts of different alkali sulfates on the shrinkage, hydration, pore structure, fractal dimension and microstructure of low-heat Portland cement (LHPC), medium-heat Portland cement (MHPC) and ordinary Portland cement (OPC) are investigated. The results indicate that alkali sulfates magnify the autogenous shrinkage and drying shrinkage of cement-based materials with different mineral compositions, which are mainly related to different pore structures and hydration processes. LHPC has the lowest shrinkage. Otherwise, the effect of alkali sulfates on the autogenous shrinkage is more profound than that of drying shrinkage. Compared with the pore size distribution, the fractal dimension can better characterize the shrinkage properties of cement-based materials. It is noted that the contribution of K2SO4 (K alkali) to the promotion effect of shrinkage on cement-based materials is more significant than that of Na2SO4 (Na alkali), which cannot be ignored. The microstructure investigation of different cement-based materials by means of nuclear magnetic resonance (NMR), mercury intrusion porosimetry (MIP) and scanning electron microscope (SEM) shows that this effect may be related to the different pore structures, crystal forms and morphologies of hydration products of cement-based materials.

scholarly journals Influence of compressive strength and maturity conditions on shrinkage of ordinary concrete

2021 ◽  
Vol 13 (6) ◽  
pp. 168781402110244
Author(s):  
Olga Szlachetka ◽  
Joanna Witkowska-Dobrev ◽  
Marek Dohojda ◽  
Anna Cała
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Drying Shrinkage ◽  
Point Of View ◽  
Early Age ◽  
Volume Changes ◽  
Ordinary Concrete ◽  
Dry Conditions ◽  
Total Elimination

The paper presents results of investigations of compressive strength and shrinkage of concrete samples made on the basis of the Portland cement CEM I 32.5R, after 2, 7, 14, 28, 90, and 365 days of maturation in four different maturation conditions. It was shown that after 28 days the samples cured according to the standard in the cuvettes with water achieved the highest compressive strength, although the early-age compressive strengths after 7 and 14 days were lower than those for the samples cured in building film and in dry conditions. A determined correlation between the compressive strength and shrinkage of the concrete proves that wet curing also allows a total elimination of the shrinkage in the first 28 days. Along with the growth of the compressive strength, the drying shrinkage reduces. Obtained results confirmed that the best way of concrete curing, among the analyzed methods, from the point of view of both compressive strength and volume changes is the wet curing.

Compressive Strength and Shrinkage Behavior of Concrete Produced from Portland Limestone Cement with Water Absorption Polymer Balls

2020 ◽  
Vol 857 ◽  
pp. 83-88
Author(s):  
Ikram F. Ahmed Al-Mulla ◽  
Ammar S. Al-Rihimy ◽  
Mushriq F. Al-Shamaa
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Water Absorption ◽  
Ordinary Portland Cement ◽  
Drying Shrinkage ◽  
Internal Curing ◽  
Early Age ◽  
Portland Limestone Cement ◽  
Limestone Cement ◽  
Shrinkage Behavior

From the sustainability point of view a combination of using water absorption polymer balls in concrete mix produce from Portland limestone cement (IL) is worth to be perceived. Compressive strength and drying shrinkage behavior for the mixes of concrete prepared by Ordinary Portland Cement (O.P.C) and Portland limestone cement (IL) were investigated in this research. Water absorbent polymer balls (WAPB) are innovative module in producing building materials due to the internal curing which eliminates autogenous shrinkage, enhances the strength at early age, improve the durability, give higher compressive strength at early age, and reduce the effect of insufficient external curing. Polymer balls (WAPB) had been used in the mixes of this research to provide good progress in compressive strength with time. Water absorption polymer balls have the ability to absorb water and after usage in concrete it will spill it out and shrink leaving voids of their own diameter before shrinking that lead to provide internal curing. The required quantity of water for the mixes were reduced due to the addition of water from the absorption polymers. Mixes produced from Portland limestone cement in this research show drying shrinkage results and compressive strength results lower than mixes made from ordinary Portland cement.

Performance of Portland Cement-Based Rapid-Patching Materials with Different Cement and Accelerator Types, and Cement Contents

2019 ◽  
Vol 2673 (11) ◽  
pp. 172-184 ◽  
Author(s):  
Shayan Gholami ◽  
Jiong Hu ◽  
Yong-Rak Kim ◽  
Miras Mamirov
Keyword(s):  
Portland Cement ◽  
Cement Content ◽  
Autogenous Shrinkage ◽  
Drying Shrinkage ◽  
High Heat ◽  
Heat Of Hydration ◽  
Early Age ◽  
Type I ◽  
Concrete Durability ◽  
Aggregate Gradation

Because of the requirements of opening pavement to traffic after placing repair concrete, it is essential for that concrete to achieve high early strength. To ensure this, a high cement content is generally used in Portland cement-based rapid-patching materials. Besides its associated high cost, high cement content tends to result in a less stable mix with high drying shrinkage, high autogenous shrinkage, high heat of hydration, and cracking potential. In addition, using chloride-based accelerators has adverse effects on concrete durability. Therefore, this paper presents an experimental assessment to improve rapid-patching concrete mixtures by reducing cement content through optimizing aggregate gradation. A non-chloride-based accelerator was also sought to replace the chloride-based accelerator when the accelerators are associated with two different series of patching materials using Type I and III cement, respectively. Fresh, early-age, mechanical, and permeability tests were conducted on each specific mixture design. As an important outcome, patching materials employing lower cement content together with an optimized aggregate gradation can meet the general requirements, which were found from the observation of several key parameters, including early-age strength, setting times, surface resistivity, and heat of hydration. Furthermore, the non-chloride-based accelerator showed promising behavior as an alternative accelerator when it is blended with the proper cement type and content.

Influence of Early Age Volume Changes on Long-Term Concrete Shrinkage

1998 ◽  
Vol 1610 (1) ◽  
pp. 28-32 ◽  
Author(s):  
Erika E. Holt ◽  
Donald J. Janssen
Keyword(s):  
Concrete Slab ◽  
Drying Shrinkage ◽  
Early Age ◽  
Volume Changes ◽  
Test Procedures ◽  
Cracking Behavior ◽  
Concrete Shrinkage ◽  
Cracking Potential ◽  
Partially Restrained

Volume changes can occur in concrete during the first 24 hr and are generally missed in laboratory shrinkage evaluations. Unfortunately these early age volume changes are present in real pavements and structures and can contribute to the cracking behavior of the concrete at later ages. Early age volume changes can occur in two forms: drying shrinkage before the start of curing and autogenous volume changes. Although these early age volume changes are often dismissed as being insignificant, recent work in Europe has identified magnitudes for early age volume changes of some concretes that are equal to or greater than 28-day drying shrinkage measurements. Expansions have also been identified in some cases. The results of some investigations of volume changes in concrete during the first 24 hr under both drying and nondrying conditions are presented. An example of potential long-term cracking under partially restrained conditions (concrete slab-on-grade modeled by a concrete ring cast around a hollow steel ring) is used to illustrate the magnitude of influence of early age volume changes on concrete cracking. Both test procedures employ nonstandard methods to quantify the cracking potential of concrete.

Alkali Activation of Granulated Blast Furnace Slag

2010 ◽  
Vol 158 ◽  
pp. 1-11 ◽  
Author(s):  
Zi Qiao Jin ◽  
Xian Jun Lu ◽  
Shu Gang Hu
Keyword(s):  
Compressive Strength ◽  
Blast Furnace ◽  
Portland Cement ◽  
Blast Furnace Slag ◽  
Ordinary Portland Cement ◽  
Hydration Product ◽  
Early Age ◽  
Hydration Products ◽  
Granulated Blast Furnace Slag ◽  
Furnace Slag

In order to stimulate the potential cementitious property of granulated blast furnace slag (GBFS), the ground GBFS sample (Wei Fang Iron and Steel Corporation, China) was activated by lime and gypsum under different dosages. The results showed that lime is an effective activator for the slag, and the optimum dosage of lime is about 10% (w/w) of the slag. At the optimum dosage of lime, the 28 days compressive strength of the lime-slag paste is higher than that of 32.5 ordinary Portland cement (OPC). But, the early age strength (3 and 7 days compressive strength) of the lime-slag paste is lower than that of the OPC. Addition of gypsum can effectively improve the early age strength of the lime-slag paste. At the ratio of gypsum:lime:slag of 8.2:9.2:82.6 (w/w), both the early and long-term compressive strengths of the gypsum-lime-slag paste are higher than that of the OPC. According to XRD, TG-DTA and SEM detections of the hydration products of the lime-slag paste, the gypsum-lime-slag paste and the OPC paste, it reveals that the hydration process of the GBFS-based cementitious material is different from the ordinary Portland cement and the presence of ettringite (AFt) contributes to the early age strength of the pastes. The major hydration product of the OPC paste (<7 days) were measured as ettringite (AFt), but the AFt phase was not detected in the hydration product of the lime-slag paste and the major hydration product of the lime-slag paste was determined as amorphous CSH gel. However, AFt was detected in the hydration products of the gypsum-lime-slag paste in the early stages of hydration, and the formation of AFt is favorable for the early strength improvement of the material.

Effects of ordinary Portland cement on the early properties and hydration of calcium sulfoaluminate cement

2018 ◽  
Vol 186 ◽  
pp. 1144-1153 ◽  
Author(s):  
Junjie Zhang ◽  
Guoxin Li ◽  
Wenting Ye ◽  
Yuzhen Chang ◽  
Qingfeng Liu ◽  
...  
Keyword(s):  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Calcium Sulfoaluminate Cement ◽  
Calcium Sulfoaluminate

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. 

Sign in / Sign up

Export Citation Format

Share Document