scholarly journals Influence of Combined Expansive Agent and Supplementary Cementitious Materials Against Chloride Effects in Offshore Concrete

2019 ◽  
Vol 9 (1) ◽  
pp. 3819-3825
Keyword(s):  
Performance Improvement ◽  
Drying Shrinkage ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Hardened Concrete ◽  
Nitrite Ion ◽  
Organic Salts ◽  
Chemical Action ◽  
Salt Damage ◽  
Chemical Agents

The performance of hardened concrete may be degraded by the chemical action of chlorine ions (Cl- ) or sulfate (SO4 2- ) in sea water. Thus, supplementary cementitious materials (SCMs) are used in replacement of OPC for the purpose of improving the durability of concrete, but show weaknesses such as drying shrinkage. Judging that the sole use of SCMs has limitations in designing concrete durability to cope with the environment of salt damage, this study suggests the use of aluminum-based inorganic salts (AIS) in the form of chemical agents. This study aims to select material of the highest efficiency in enhancing the durability of offshore concrete, by performing the durability evaluation of typical four SCMs and four AISs that are intermixed as single materials. There has been almost no domestic or overseas research on Al-based organic salts intermixed in the form of chemical agents for the purpose of improving resistance to salt damage and offsetting drying shrinkage. It was confirmed that mortar intermixed with Al-based chemical admixtures showed great performance improvement in the rates of length change. The mixture proportion intermixed with sulfate ion (SO4 2- ) as binding anion tended to show unfavorable reaction in terms of resistance to sulfate erosion and drying shrinkage. On the other hand, the mixture proportion set with nitrite ion (NO3 - ) as cation showed excellent performance improvement in all evaluation items, compared with non-intermixture. It is deemed that it will be necessary to highlight further and make use of the expansion properties and chloride binding performance of Al-based organic salts through the design of offshore concrete mixture proportions.

Performance of Impure Calcined Clay as a Pozzolan in Concrete

2020 ◽  
pp. 036119812095314
Author(s):  
Khashayar Jafari ◽  
Farshad Rajabipour
Keyword(s):  
Portland Cement ◽  
Drying Shrinkage ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Strength Development ◽  
Natural Pozzolan ◽  
Quartz Content ◽  
Calcined Clay ◽  
Air Content ◽  
Sand And Gravel

Supplementary cementitious materials (SCMs) are natural or industrial by-product materials which are used to improve the performance, durability, and sustainability of concrete mixtures. Motivated by the recent reports on shortage of conventional SCMs, impure calcined clays (CCs) are receiving attention as abundant alternative pozzolans for concrete. In this study, a clay slurry resulting from washing aggregates in a commercial sand and gravel pit was investigated. This source clay was dried and calcined, and the properties and pozzolanic performance of the resulting CC was evaluated. It was observed that despite having a large (>50%wt.) inert quartz content, the CC met all ASTM C618-19 (AASHTO M295) requirements for natural pozzolan. A pavement-grade concrete mixture containing 20%CC as a cement replacement (by weight) produced desired workability and fresh and hardened air content. Strength development was slightly below the control. The use of CC improved the durability of concrete with respect to chloride penetration, alkali–silica reaction, and drying shrinkage in comparison with a control (100% Portland cement) mixture. In addition, ternary limestone-calcined clay–cement and slag-calcined clay–cement mortar mixtures showed excellent strength development while replacing nearly 50% of the Portland cement.

Effect of Curing Temperature on Hardened Concrete Properties

2005 ◽  
Vol 1914 (1) ◽  
pp. 97-104 ◽  
Author(s):  
W. Micah Hale ◽  
Thomas D. Bush ◽  
Bruce W. Russell ◽  
Seamus F. Freyne
Keyword(s):  
Fly Ash ◽  
Cementitious Materials ◽  
Curing Temperature ◽  
Supplementary Cementitious Materials ◽  
Cold Weather ◽  
Strength Development ◽  
Hardened Concrete ◽  
Hardened Properties ◽  
Hot Weather ◽  
Materials Used

Often, concrete is not mixed or placed under ideal conditions. Particularly in the winter or the summer months, the temperature of fresh concrete is quite different from that of concrete mixed under laboratory conditions. This paper examines the influence of supplementary cementitious materials on the strength development (and other hardened properties) of concrete subjected to different curing regimens. The supplementary cementitious materials used in the research program were ground granulated blast furnace slag (GGBFS), fly ash, and a combination of both materials. The three curing regimens used were hot weather curing, standard curing, and cold weather curing. Under the conditions tested, the results show that the addition of GGBFS at a relatively low replacement rate can improve the hardened properties for each curing regimen. This improvement was noticeable not only at later ages but also at early ages. Mixtures that contained both materials (GGBFS and fly ash) performed as well as and, in most cases, better than mixtures that contained only portland cement in all curing regimens.

scholarly journals Implementation of natural and artificial materials in Portland cement

2020 ◽  
Vol 74 (3) ◽  
pp. 147-161
Author(s):  
Pero Dabic ◽  
Damir Barbir
Keyword(s):  
Portland Cement ◽  
Cementitious Materials ◽  
Environmental Benefits ◽  
Supplementary Cementitious Materials ◽  
Hardened Concrete ◽  
Cement Composites ◽  
Artificial Materials ◽  
Waste Container ◽  
Almost All ◽  
The Impact

For the preparation of modern cement and concrete, supplementary cementitious materials (SCM) have become essential ingredients. The technical, economic and environmental advantages of using SCM have become unquestionable. The main technical reasons for their use are the improvement of the workability of fresh concrete and durability of hardened concrete. Actually, SCM affect almost all concrete properties, while environmental and economic reasons may be more significant than technical reasons. These ingredients can reduce the amount of Portland cement used in cement composites, resulting in economic and environmental benefits. In addition, many of the SCM are industrial by-products, which can otherwise be considered as waste. This paper presents a literature review of the present knowledge on the impact of natural zeolite, waste construction brick and waste container glass on physical, chemical and mechanical properties of Portland cement as the most commonly used cement in the world.

scholarly journals Influence of Rice Husk Ash Density on the Workability and Strength of Structural Concrete

2017 ◽  
Vol 2 (3) ◽  
pp. 36 ◽  
Author(s):  
John Kamau ◽  
Ash Ahmed ◽  
Fraser Hyndman ◽  
Paul Hirst ◽  
Joseph Kangwa
Keyword(s):  
Compressive Strength ◽  
Rice Husk ◽  
Water Demand ◽  
Rice Husk Ash ◽  
Concrete Strength ◽  
High Water ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Hardened Concrete ◽  
Structural Applications

Supplementary cementitious materials (SCMs) have been known to improve the properties of fresh and hardened concrete, and at the same time enhance the sustainability of concrete. Rice husk Ash (RHA), is one such material, but has neither been widely studied nor applied in practice. This work investigated the effect of the density of RHA on the workability and compressive strength of fresh and hardened RHA-replaced concrete respectively. Cement was replaced with RHA in concrete by weight (RHA-W) and by volume (RHA-V) at steps of 0%, 5%, 7.5%, 10%, 15%, 20%, 25% and 30%. The 0% replacement was used as the reference point from which performances were measured. Results showed that unlike the characteristic of other established pozzolans, RHA significantly reduced the workability of wet concrete and the rate of compressive strength gain over curing time due to a high water demand that is caused by the increased volume of replaced concrete, which results from its low density. Workability reduced with increased replacement for both RHA-W and RHA-V. Replacements of above 15% were not possible for the RHA-W due to the high water demand. However, replacements of up to 30% were achieved for the RHA-V. RHA-W specimens achieved lower compressive strengths and were observed to gain strength at a lower rate over the 28 to 91-days period of curing compared to RHA-V specimens. This behavior was attributed to the shortage of water that is necessary for the hydration of cement and subsequent pozzolanic reaction, which is the basis of the contribution that is made to the strength and performance of concrete by SCMs. However, the compressive strengths achieved were above the study’s target concrete strength of class C32/40 at 91 days, which is among those classes that are listed as being durable and suitable for structural applications. A conclusion that RHA should supplement cements by volumetric replacement rather than simple substitution by weight was drawn.

scholarly journals Experimental Study of Blended Binders with Metakaolin

2021 ◽  
Vol 13 (19) ◽  
pp. 10548
Author(s):  
Christian Cremona ◽  
Stéphanie Vildaer ◽  
Maxim Cadillac
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Autogenous Shrinkage ◽  
Rheological Behaviour ◽  
Mineralogical Composition ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Hardened Concrete ◽  
Flash Calcination ◽  
Creep Measurements

Three metakaolins are evaluated for use as supplementary cementitious materials in cement-based systems. The metakaolins vary in mineralogical composition and in fabrication (traditional and flash calcination), but are quite similar in their surface area (16–19 m2/g), but are quite similar in mineralogical composition. Performance of metakaolin mixtures will be compared to two control mixtures (standard concrete for foundation C40/50 and high performance concrete C60/75). In this study, the properties of fresh concrete and the mechanical and durability properties of hardened concrete will be examined. The rheological behaviour are aimed to determine the effect of metakaolin on mixture workability. Compressive, tensile and flexural strength and elastic modulus will be measured at various concrete ages. The influence of metakaolin on durability is assessed through rapid chloride migration and carbonation measurements. For high performance concrete mixtures, drying and autogenous shrinkage will be monitored and creep measurements are performed and compared.

scholarly journals Synthesis of a New Polycarboxylate at Room Temperature and Its Influence on the Properties of Cement Pastes with Different Supplementary Cementitious Materials

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Shuncheng Xiang ◽  
Yingli Gao ◽  
Caijun Shi
Keyword(s):  
Room Temperature ◽  
Autogenous Shrinkage ◽  
Drying Shrinkage ◽  
Cementitious Materials ◽  
Heat Evolution ◽  
Hydration Heat ◽  
Supplementary Cementitious Materials ◽  
Cement Pastes ◽  
Binder Ratio ◽  
Water Binder Ratio

Three polycarboxylates with different comb structures (i.e., the same degree of polymerization in side chains but different main chains) were synthesized via radical polymerization reaction at room temperature. The effect of polycarboxylates on the surface tension and the flowability in cement pastes was determined. The best product was selected to study its effects on the hydration heat evolution, compressive strength, autogenous shrinkage, and drying shrinkage of cement pastes with different kinds and contents of supplementary cementitious materials. The results showed that with the increase of molar ratio between AA and TPEG to 6 : 1, we could synthesis the best product. When the water-binder ratio was 0.4, with the increase of polycarboxylates, the cement hydration heat evolution had been slowed down, and the more the dosage was, the more obvious the effect was. Adding supplementary cementitious materials to cement under the same experimental conditions also played a mitigation role in slowing down the hydration heat. When the water-binder ratio was 0.3, supplementary cementitious materials could increase the strength of cement by 24.5% in maximum; its autogenous shrinkage and drying shrinkage could be decreased, respectively, by 60.1% and 21.9% in the lowest.

A Review on the Effects of Various Supplementary Cementitious Materials on Physical Properties of Hardened Concrete

2014 ◽  
Vol 905 ◽  
pp. 287-291
Author(s):  
Salim Barbhuiya ◽  
Hamid Nikraz
Keyword(s):  
Physical Properties ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Hardened Concrete ◽  
Granulated Blast Furnace Slag ◽  
Current Trends ◽  
Fuel Ash ◽  
Treatment And Disposal ◽  
Furnace Slag ◽  
By Products

The global development and current trends in social attitude are resulting in an increase in the amount of waste generated by society, the treatment and disposal of which are becoming a serious problem. Therefore, waste management is one of the most important aspects in ensuring sustainable development in todays world. Some of the industrial by-products, such as pulverised-fuel ash (PFA), ground granulated blast-furnace slag (GGBS) and microsilica (MS) can be used in concrete to improve its properties. In this paper the influence of various by-products on the physical properties of concrete is reviewed.

scholarly journals Use of Rice Husk Ash (RHA) as a Supplementary Cementitious Material in Producing Normal Concrete

2019 ◽  
Vol 271 ◽  
pp. 07007
Author(s):  
Kazi islam ◽  
Zahid Hossain
Keyword(s):  
Rice Husk ◽  
Rice Husk Ash ◽  
Construction Material ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Hardened Concrete ◽  
Type I ◽  
Continuous Increase ◽  
Material Sources ◽  
By Products

With the continuous increase of scarcity of the natural construction material sources and environmental awareness, utilization of wastes/by-products in the construction industry has become an attractive field of study. Several industrial by-products produced from different manufacturing processes have been considered for various usages in the construction field. This paper briefly describes the potential use of Rice Husk Ash (RHA) as Supplementary Cementitious Materials (SCM). Here, three different grades of RHA (600-RHA, 150-RHA, and 44-RHA) in two different percentages (10 % and 20 %) of replacement of Type I Ordinary Portland Cement (OPC) were investigated. Laboratory tests on the fresh concrete mix as well as the mechanical properties of the hardened concrete were performed. It was observed that coarser RHA-modified concrete (600-RHA and 150-RHA) showed reduced strength properties while finer RHA (44-RHA) exhibited improved concrete properties. Moreover, the incorporation of RHA in concrete was found to be effective in mitigating alkaline expansion.

scholarly journals Efficiency Concepts and Models that Evaluates the Strength of Concretes Containing Different Supplementary Cementitious Materials

2019 ◽  
Vol 5 (1) ◽  
pp. 18 ◽  
Author(s):  
Rahul Biswas ◽  
Baboo Rai
Keyword(s):  
Fly Ash ◽  
Silica Fume ◽  
Research Work ◽  
Cementitious Materials ◽  
Mineral Admixture ◽  
Supplementary Cementitious Materials ◽  
Hardened Concrete ◽  
Effective Utilization ◽  
Natural Pozzolans ◽  
Quantitative Understanding

The usage of Supplementary Cementitious Materials (SCM) is very much acknowledged due to the several improvements possible in the concrete composites, and because of the general economy. Research work till date suggests that utilization of SCMs enhance a significant number of the performance characteristics of the hardened concrete. The idea of efficiency can be utilized for comparing the relative performance of different pozzolans when incorporated into concrete. The efficiency concept, which was initially developed for fly ash, can be effortlessly connected to other advantageous s as well, such as silica fume, slag and natural pozzolans. A quantitative understanding of the efficiency of SCMs as a mineral admixture in concrete is essential for its effective utilization. The paper reviews the literature pertaining to the different efficiency concepts and models present to date that evaluates the strength of concretes containing different SCMs. This short survey demonstrates that there is a need for a superior comprehension of the SCMs in concrete for its powerful usage. Also, it is an effort directed towards a specific understanding of the efficiency of SCMs in concrete.

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