EFFECT OF SUPERABSORBENT PARTICLE SIZE ON RHEOLOGY AND MECHANICAL PERFORMANCE OF CEMENT MORTARS

The risk of crack propagation and autogenous shrinkage pose a significant weakness for concrete structures and substantially limits its lifespan. To overbridge related issues, the smart superabsorbent polymers (SAP) can be utilized to mitigate autogenous shrinkage and promote self-healing ability. However, incorporation of highly swelling particles struggles with the workability of the fresh mixture and thus final mechanical performance. Within this paper, the effect of SAP particle size is studied and correlated with the results of flow table test to propose an optimal relationship between the amount of SAP dosage, water/cement ratio and mechanical properties in the hardened state. The reference cement mortar mixture is modified by 0.25, 0.5 and 0.75 wt.% admixture of different 3 grades of SAPs thus the fresh mixture workability, basic material properties, compressive and flexural strength parameters are determined. The obtained results provide guidelines for the efficient design of SAP modified cement mortars mixtures with desired functional properties.

Download Full-text

Application of concrete slurry waste in cement screeds

The proceedings of the 13th international conference "Modern Building Materials, Structures and Techniques" (MBMST 2019) ◽

10.3846/mbmst.2019.072 ◽

2019 ◽

Author(s):

Pavel Reiterman ◽

Martin Keppert

Keyword(s):

Bulk Density ◽

Mechanical Performance ◽

Negative Impact ◽

Environmental Risks ◽

Experimental Program ◽

Fresh Mixture ◽

Cement Replacement ◽

Additional Processing ◽

Hardened State ◽

Mineral Additives

Sedimented concrete slurry waste (CSW), containing cement, mineral additives, fine fillers, admixtures and water, is currently a waste without an additional use and has to be fully landfilled. Current CSW management is very expensive and introduces number of environmental risks due to its high pH, exceeding 11.5. This paper deals with the application of two types of CSW as cement replacement in cement screed. The evaluation was carried out in terms of workability and basic mechanical performance of the obtained composites. The applied cement replacement was up to 10 wt.% due to the negative impact on the rheology of fresh mixtures. Reduced workability consequently caused higher content of air in the fresh mixture. It was reflected by lower values of bulk density in hardened state for both studied CSW. These aspects were the reasons of decreased mechanical performance by approximately 15% per 5 wt.% of replacement. Conducted experimental program declared significant limits of CSW application in cement based composites, however additional processing of CSW could significantly modify its properties.

Download Full-text

The Contribution of Elastic Wave NDT to the Characterization of Modern Cementitious Media

Sensors ◽

10.3390/s20102959 ◽

2020 ◽

Vol 20 (10) ◽

pp. 2959 ◽

Cited By ~ 2

Author(s):

Gerlinde Lefever ◽

Didier Snoeck ◽

Nele De Belie ◽

Sandra Van Vlierberghe ◽

Danny Van Hemelrijck ◽

...

Keyword(s):

Mechanical Performance ◽

Autogenous Shrinkage ◽

Measuring Method ◽

Cementitious Materials ◽

Mechanical Tests ◽

Self Healing ◽

Destructive Testing ◽

Superabsorbent Polymers ◽

Non Destructive

To mitigate autogenous shrinkage in cementitious materials and simultaneously preserve the material’s mechanical performance, superabsorbent polymers and nanosilica are included in the mixture design. The use of the specific additives influences both the hydration process and the hardened microstructure, while autogenous healing of cracks can be stimulated. These three stages are monitored by means of non-destructive testing, showing the sensitivity of elastic waves to the occurring phenomena. Whereas the action of the superabsorbent polymers was evidenced by acoustic emission, the use of ultrasound revealed the differences in the developed microstructure and the self-healing of cracks by a comparison with more commonly performed mechanical tests. The ability of NDT to determine these various features renders it a promising measuring method for future characterization of innovative cementitious materials.

Download Full-text

Characterization of Steel Slag Filler and Its Effect on Aging Resistance of Asphalt Mastic with Various Aging Methods

Materials ◽

10.3390/ma14040869 ◽

2021 ◽

Vol 14 (4) ◽

pp. 869

Author(s):

Minghua Wei ◽

Shaopeng Wu ◽

Haiqin Xu ◽

Hechuan Li ◽

Chao Yang

Keyword(s):

Particle Size ◽

Surface Characterization ◽

Steel Slag ◽

Self Healing ◽

Limestone Filler ◽

Asphalt Mastic ◽

Pore Characterization ◽

Asphalt Mastics ◽

Healing Property

Steel slag is the by-product of the steelmaking industry, the negative influences of which prompt more investigation into the recycling methods of steel slag. The purpose of this study is to characterize steel slag filler and study its feasibility of replacing limestone filler in asphalt concrete by evaluating the resistance of asphalt mastic under various aging methods. Firstly, steel slag filler, limestone filler, virgin asphalt, steel slag filler asphalt mastic and limestone filler asphalt mastic were prepared. Subsequently, particle size distribution, surface characterization and pore characterization of the fillers were evaluated. Finally, rheological property, self-healing property and chemical functional groups of the asphalt mastics with various aging methods were tested via dynamic shear rheometer and Fourier transform infrared spectrometer. The results show that there are similar particle size distributions, however, different surface characterization and pore characterization in the fillers. The analysis to asphalt mastics demonstrates how the addition of steel slag filler contributes to the resistance of asphalt mastic under the environment of acid and alkaline but is harmful under UV radiation especially. In addition, the pore structure in steel slag filler should be a potential explanation for the changing resistance of the asphalt mastics. In conclusion, steel slag filler is suggested to replace limestone filler under the environment of acid and alkaline, and environmental factor should be taken into consideration when steel slag filler is applied to replace natural fillers in asphalt mastic.

Download Full-text

Performance of Lime-Metakaolin Pastes and Mortars in Two Curing Conditions Containing Kaolin Wastes

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.668.419 ◽

2015 ◽

Vol 668 ◽

pp. 419-432 ◽

Cited By ~ 3

Author(s):

Aline Figueirêdo Nóbrega de Azerêdo ◽

Givanildo Azeredo ◽

Arnaldo Manoel Pereira Carneiro

Keyword(s):

Hydrated Lime ◽

Microstructural Characteristics ◽

Curing Conditions ◽

Pozzolanic Material ◽

Cement Mortars ◽

Lime Mortars ◽

Moist Environment ◽

Hardened State ◽

Hydrated Products ◽

Hardened Properties

Many works have shown that metakaolin is very good pozzolanic material for using in lime mortars and Portland cement mortars. Alternatively, many studies also have shown that kaolin wastes, after some treatment, can become a high quality pozzolans. Most of these studies have discussed about the microstructural characteristics and hardened properties of pastes, mortars or concretes mixes containing metakaolin or kaolin wastes cured in moist environment. In this work pastes and mortars made of metakaolin and hydrated lime (L-MK), which the metakaolin was obtained from the kaolin production waste, were assessed in their hardened state. Two curing conditions were considered: dry and moist environment; and three ages of curing (28, 90 and 180 days) were studied. Pastes were assessed by XRD and TG/DTG. In pastes according to the XRD and TG/DTG results, the main hydrated products found were strätlingite, in moist curing, and monocarboaluminate, in dry curing. Properties like flexural and compressive strengths, water absorbed capillarity and loss mass variation were studied in mortars. The results showed that mortars in dry curing presented lower strengths than one in moist curing. In moist curing mortars presented compressive strength values around 12 MPa and in dry curing this value reached 6 MPa. This fact indicate that the strätlingite maybe is responsible for the high strengths in mortars in moist curing when compares with the strengths of mortars cured in dry environment. Further the results showed that mortars in dry curing presented higher water absorbed and mass loss variation than mortars in moist curing.

Download Full-text

Design and Evaluation of an Ultrahigh-Strength Coral Aggregate Concrete for Maritime and Reef Engineering

Materials ◽

10.3390/ma14195871 ◽

2021 ◽

Vol 14 (19) ◽

pp. 5871

Author(s):

Jinming Liu ◽

Boyu Ju ◽

Wei Xie ◽

Huang Yu ◽

Haiying Xiao ◽

...

Keyword(s):

Mechanical Performance ◽

Autogenous Shrinkage ◽

X Ray Diffraction ◽

Early Hydration ◽

X Ray ◽

Ultrahigh Strength ◽

Marine Concrete ◽

Marine Engineering ◽

Reactive Powder ◽

Economical Alternative

In this paper, an ultrahigh-strength marine concrete containing coral aggregates is developed. Concrete fabricated from marine sources is considered an effective and economical alternative for marine engineering and the construction of remote islands. To protect sea coral ecosystems, the coral aggregates used for construction are only efflorescent coral debris. To achieve the expected mechanical performance from the studied concrete, an optimal mixture design is conducted to determine the optimal proportions of components, in order to optimize the compressive strength. The mechanical properties and the autogenous shrinkage, as well as the heat flow of early hydration reactions, are measured. The hydration products fill up the pores of coral aggregates, endowing our concrete with flowability and self-compacting ability. The phases in the marine concrete are identified via X-ray diffraction analysis. The 28-day compressive and flexural strength of the developed marine concrete achieve 116.76 MPa and 18.24 MPa, respectively. On account of the lower cement content and the internal curing provided by coral aggregates, the volume change resulting from autogenous shrinkage is only 63.11% of that of ordinary reactive powder concrete.

Download Full-text

The Effect of Different Thermal Treatment on the Allotropic fcc↔hcp Transformation and Compression Behavior of Polycrystalline Cobalt

Materials ◽

10.3390/ma13245775 ◽

2020 ◽

Vol 13 (24) ◽

pp. 5775

Author(s):

Michal Knapek ◽

Peter Minárik ◽

Patrik Dobroň ◽

Jana Šmilauerová ◽

Mayerling Martinez Celis ◽

...

Keyword(s):

Grain Size ◽

Yield Strength ◽

Performance Optimization ◽

Fracture Strain ◽

Mechanical Performance ◽

Effective Means ◽

Basic Material ◽

Phase Content ◽

Compression Behavior ◽

Fcc Phase

Pure polycrystalline cobalt is systematically thermally treated in order to assess the effect of the microstructure on the compression behavior. Isothermal annealing of the as-drawn material leads to recrystallization and grain growth dependent on the annealing temperature (600–1100 ∘C). Consequently, the yield strength decreases and the fracture strain increases as a function of rising grain size; the content of the residual fcc phase is ~6–11%. Subsequent thermal cycling around the transition temperature is applied to further modify the microstructure, especially in terms of the fcc phase content. With the increasing number of cycles, the grain size further increases and the fraction of the fcc phase significantly drops. At the same time, the values of both the yield strength and fracture strain somewhat decrease. An atypical decrease in the fracture strain as a function of grain size is explained in terms of decreasing fcc phase content; the stress-induced fcc→hcp transformation can accommodate a significant amount of plastic strain. Besides controlling basic material parameters (e.g., grain size and texture), adjusting the content of the fcc phase can thus provide an effective means of mechanical performance optimization with respect to particular applications.

Download Full-text

Influence of Different Types of Fine Aggregate on Cement Composites Resistance to High Temperatures

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1000.126 ◽

2014 ◽

Vol 1000 ◽

pp. 126-129 ◽

Cited By ~ 1

Author(s):

Tomáš Melichar ◽

Jiří Bydžovský

Keyword(s):

Mineralogical Composition ◽

Mechanical Tests ◽

Basic Material ◽

Fine Aggregate ◽

Cement Composites ◽

Cement Mortars ◽

Different Types ◽

Natural Aggregates ◽

The Impact

The paper discusses the impact of several selected aggregates on the basic material characteristics of cement composites. Both artificial and natural aggregates (four types in total) with different mineralogical composition were evaluated. The specimens were exposed to environments with the temperature up to 1000°C and then subjected to physico-mechanical tests. For the follow-up development of polymer-cement mortars, we selected two types of aggregates – fly ash aggloporite (FAA) and amphibolite (AMA).

Download Full-text

Mechanical Performance Research on Modified Cement Concrete with Recycled Plastic Particles

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.450-451.650 ◽

2012 ◽

Vol 450-451 ◽

pp. 650-654

Author(s):

Jian Hong Di ◽

Zhan Liang Liu ◽

Jun Jun Li

Keyword(s):

Bending Strength ◽

Mechanical Performance ◽

Research Result ◽

Basic Material ◽

Fine Aggregate ◽

Cement Concrete ◽

Performance Indexes ◽

Mechanical Strengths ◽

Performance Research ◽

Addition Amount

In order to improve the concrete performance and research the greenmaterial, the recycled ABS/PC plastic particles will be added into the cement concrete as a modifier. In this research, the C30 cement concrete was taken as the basic material, the fine aggregate in cement concrete was substituted by different amounts of recycled plastic particles. The change law of mechanical performance indexes（including cubic compressive strength. Splitting tensile strength，bending strength）were researched. The research result showed the recycled plastic particles, as a modifier, can improve mechanical performance of the cement concrete greatly. In the five addition amounts，including 0%, 2%, 5%, 8%, 11%，the three mechanical strengths will all increases at first then decreases with the addition amount increasing. When the addition amount is 5%, the three mechanical strength indexes will all reach the maximum.

Download Full-text

Effect of Zeolite on Shrinkage and Crack Resistance of High-Performance Cement-Based Concrete

Materials ◽

10.3390/ma13173773 ◽

2020 ◽

Vol 13 (17) ◽

pp. 3773

Author(s):

Nguyen Cong Thang ◽

Nguyen Van Tuan ◽

Keun-Hyeok Yang ◽

Quoc Tri Phung

Keyword(s):

Particle Size ◽

Crack Resistance ◽

High Performance ◽

Autogenous Shrinkage ◽

Shrinkage Strain ◽

Shrinkage Behaviour ◽

Proposed Model ◽

Zeolite Content ◽

Humidity Measurements ◽

Improved Model

This study examined the effectiveness of zeolite addition to reduce the autogenous shrinkage of high-performance cement-based concrete (HPC). The zeolites were replaced up to 15% of the cement content by weight and their mean particle size varied from 5.6 to 16.7 µm. To evaluate the crack resistance of HPC containing zeolites, the ring tests and internal relative humidity measurements were performed at different ages. The compressive strengths were determined at 3, 7, 28 and 90 days of curing. Test results confirmed that the addition of zeolite was promising and favourable in enhancing the compressive strength, crack resistance and reducing the autogenous shrinkage of HPC due to synergistic pozzolanic and internal curing effects. The autogenous shrinkage tended to decrease with the increase in zeolite content and its particle size. In addition, the extent of the autogenous shrinkage development at the early ages decreased with higher zeolite content replaced. Furthermore, to predict the autogenous shrinkage of HPC containing zeolite, an improved model has been proposed, in which the conventional ultimate autogenous shrinkage strain and time function were modified by introducing new parameters accounting for the zeolite content and its particle size. It appeared that the proposed model was able to capture the autogenous shrinkage behaviour of HPC with or without zeolite, while the fib 2010 model underestimated the autogenous shrinkage of HPC containing less than 10% zeolite replacement.

Download Full-text

Mechanical Recovery of Cracked Fiber-Reinforced Mortar Incorporating Crystalline Admixture, Expansive Agent, and Geomaterial

Advances in Materials Science and Engineering ◽

10.1155/2019/3420349 ◽

2019 ◽

Vol 2019 ◽

pp. 1-14 ◽

Cited By ~ 1

Author(s):

Abdul Salam Buller ◽

Fahad ul Rehman Abro ◽

Kwang-Myong Lee ◽

Seung Yup Jang

Keyword(s):

Water Flow ◽

Mechanical Performance ◽

Water Flow Rate ◽

Self Healing ◽

Test Results ◽

Fiber Reinforced ◽

Dissipation Energy ◽

Expansive Agent ◽

Strength Recovery ◽

Crack Sealing

This research is sought to characterize the stimulated autogenous healing of fiber-reinforced mortars that incorporate healing agents such as crystalline admixtures, expansive agents, and geomaterials. The effects of the healing materials on mechanical performance and water permeability were evaluated experimentally. Furthermore, microscopic and microstructural observations were conducted to investigate the characteristics and physical appearance of healing products within healed cracks. Test results are presented herein regarding index of strength recovery (ISR), index of damage recovery (IDR) and index of dissipation energy gain (IDEG) in relation to crack healing, and reduction of water flow rate. The self-healing capability of the mortars was greater in terms of resisting water flow rather than recovering mechanical performance likely because water flow depends on surface crack sealing, whereas mechanical performance depends on bonding capacity as well as full-depth healing of cracks; thus, mechanical performance may further be improved after longer healing duration.

Download Full-text