scholarly journals Maximizing Sustainability of Concrete through the Control of Moisture Rise and Drying Shrinkage Using Calcined Clay Pozzolan

2016 ◽  
Vol 2016 ◽  
pp. 1-5
Author(s):  
John Solomon Ankrah ◽  
Mark Bediako ◽  
Kwadwo Twumasi-Ampofo ◽  
Kofi Offei-Nyako ◽  
Charles Dela Adobor ◽  
...  
Keyword(s):  
Portland Cement ◽  
Negative Impact ◽  
Activity Index ◽  
Drying Shrinkage ◽  
Gravimetric Analysis ◽  
Calcined Clay ◽  
Pozzolanic Material ◽  
Experimental Works ◽  
Water Sorptivity ◽  
Peeling Off

The Ghanaian concrete industry is really a booming industry due to many infrastructural developments and the surge in residential development. However, many developmental projects that utilize concrete do suffer from the negative impact of moisture rise including paint peeling-off, bacterial and fungi growth, and microcracks as well as unpleasant looks on buildings. Such negative outlook resulting from the effects of moisture rise affects the longevity of concrete and hence makes concrete less sustainable. This study seeks to develop materials that could minimize the rise of moisture or ions through concrete medium. The experimental works performed in this study included pozzolanic strength activity index, water sorptivity, and shrinkage test. Calcined clay produced from clay was used as pozzolan to replace Portland cement at 20%. The strength activity test showed that the cement containing the calcined material attained higher strength activity indices than the control. The thermal gravimetric analysis showed that the pozzolan behaved partly as a filler material and partly as a pozzolanic material. The sorptivity results also showed that the blended mix resulted in lower sorptivity values than the control mortar. The study recommends that calcined clay and Portland cement mixtures could be used to produce durable concrete to maximize sustainability.

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.

Evaluation of Selected Durability Properties of Portland Cement Concretes Containing Ground Glass Fiber as a Pozzolan

2018 ◽  
Vol 2672 (27) ◽  
pp. 88-98 ◽  
Author(s):  
Hassan Rashidian-Dezfouli ◽  
Prasada Rao Rangaraju
Keyword(s):  
Chemical Composition ◽  
Portland Cement ◽  
Glass Fiber ◽  
Glass Fibers ◽  
Fine Powder ◽  
Drying Shrinkage ◽  
Ground Glass ◽  
Durability Properties ◽  
Pozzolanic Material ◽  
Silica Alumina

Glass fibers are produced in large quantities around the world for the production of fiber glass composites and for other reinforcement applications. However, considering the stringent quality requirements a significant quantity of waste is produced in the production process that does not meet required specifications of the final product in terms of the physical properties, although the chemical composition of the glass fiber waste is identical to that of the in-spec glass fiber. At present, this waste is largely disposed of in landfills. This glass fiber waste has the same chemical composition as the good glass fiber, and is rich in silica, alumina, and calcium oxides. Considering the requirements of a typical pozzolanic material, waste glass fiber could be ground to a fine powder for use as a pozzolan. In this study, the effect of using ground glass fiber (GGF) as a pozzolan in concrete at different cement replacement levels (10, 20, and 30% by mass) on selected durability properties of mixtures over a span of two years was investigated. For this purpose, the resistance of GGF-containing mixtures against the alkali–silica reaction, sulfate attack, and drying shrinkage was evaluated and compared with two control mixtures, including a mixture with 100% Portland cement and a mixture having 25% class F fly ash. Results of this research showed that the replacement of Portland cement with GGF resulted in significant improvements in the durability properties, and the mechanical properties were comparable with those of control mixtures.

scholarly journals CARACTERIZAÇÃO DA CINZA DA CASCA DE ARROZ VERMELHO PARA APLICAÇÃO COMO MATERIAL POZOLÂNICO

2020 ◽  
Vol 35 (1) ◽  
pp. 80-88
Author(s):  
José Ronaldo Júnior Brandão ◽  
Fernanda Fernandes de Melo Lopes ◽  
Helen Carolline Macedo Oliveira ◽  
José Neto Pinheiro Lopes ◽  
Guttemberg Silva Silvino
Keyword(s):  
Portland Cement ◽  
Activity Index ◽  
Physical And Mechanical Properties ◽  
Partial Replacement ◽  
Rice Hull ◽  
Red Rice ◽  
Rice Hull Ash ◽  
Rice Hulls ◽  
Pozzolanic Material ◽  
Controlled Burning

CARACTERIZAÇÃO DA CINZA DA CASCA DE ARROZ VERMELHO PARA APLICAÇÃO COMO MATERIAL POZOLÂNICO   JOSÉ RONALDO BRANDÃO JÚNIOR 1, FERNANDA FERNANDES DE MELO LOPES2, HELEN CAROLINE MACEDO OLIVEIRA3, JOSÉ PINHEIRO LOPES NETO 4, GUTTEMBERG DA SILVA SILVINO5   1 Mestrando no PPG em Engenharia Agrícola - UFCG, Rua Aprígio Veloso, nº 882, Bloco CK, bairro Universitário, CEP 58429-900, Campina Grande, PB, Brasil. [email protected] 2 Professora do Departamento de Solos e Engenharia Rural – UFPB. Rodovia PB-079, s/n, CEP 58397-000, Areia, PB, Brasil. [email protected] 3 Engenheira Agrônoma – UFPB. Rodovia PB-079, s/n, CEP 58397-000, Areia, PB, Brasil. [email protected] 4 Professor da Unidade Acadêmica de Engenharia Agrícola - UFCG, Rua Aprígio Veloso, nº 882, Bloco CK, bairro Universitário, CEP 58429-900, Campina Grande, PB, Brasil. [email protected] 2 Professor do Departamento de Solos e Engenharia Rural – UFPB. Rodovia PB-079, s/n, CEP 58397-000, Areia, PB, Brasil. [email protected]   RESUMO: Um dos principais problemas na produção do arroz está centrado na quantidade de resíduo gerado nessa atividade, cerca de 20% corresponde a casca, que na maioria das vezes é descartada de forma inadequada. A cinza oriunda da queima controlada da casca do arroz pode fornecer um material pozolânico rico em sílica, que quando aplicado na elaboração das argamassas pode melhorar suas propriedades físicas e mecânicas, além de contribuir com a durabilidade da argamassa. Objetivou-se com esse estudo avaliar a viabilidade da utilização da casca de arroz vermelho na obtenção de cinza pozolânica e o seu desempenho quando adicionadas na argamassa, em substituição parcial ao cimento Portland. As cascas foram calcinadas em três temperaturas (500, 600 e 700°C) e períodos de tempo (2, 4 e 6 horas); após a calcinação as cinzas obtidas foram caracterizadas através da tonalidade, rendimento, índice de atividade pozolânica, termogravimetria (TGA) e térmica diferencial (DTA). A influência da pozolanicidade das cinzas na resistência mecânica das argamassas foi determinada através da comparação de corpos-de-prova, elaborados com e sem substituição parcial de 10% de cimento Portland por cinzas. Com os dados encontrados observou-se que a queima controlada a temperatura de 600°C por 4 horas apresentou as melhores características de pozolanicidade estudadas e a argamassa com a incorporação de 10% de cinza da casca de arroz vermelho apresentou resistência à compressão superior à argamassa sem substituição.   Palavras chave: Oryza, resíduo, calcinação, pozolanicidade.   CHARACTERIZATION OF RED RICE SHELL ASH FOR APPLICATION AS POZZOLANIC MATERIAL   ABSTRACT: The main problem in rice production is centered on the amount of residue generated in this activity, about 20% corresponds to bark, which is most often discarded inappropriately. The ash from the controlled burning of the rice husk can provide a pozzolanic material rich in silica, which when applied in the preparation of the mortars can improve its physical and mechanical properties, besides contributing to the durability. The objective of this study was to evaluate the viability of the use of red rice hulls in obtaining pozzolanic ash and their performance when added to the mortar, in partial replacement with Portland cement. The peels were calcined at three temperatures (500, 600 and 700 ° C) and time periods (2, 4 and 6 hours); After calcination the ashes obtained were characterized by tonality, yield, pozzolanic activity index, thermogravimetry (TGA) and differential thermal (DTA). The influence of the ash pozzolanicity on the mechanical strength of the mortars was determined by comparing specimens made with and without partial replacement of 10% Portland cement by ash. With the data found, it was observed that the controlled burning at 600 ° C for 4 hours showed the best characteristics of pozolanicity studied and the mortar with the incorporation of 10% of red rice hull ash showed superior compressive strength to the mortar without replacement.   Keywords: Oryza, residue, cinder, pozolanicity.

Research Progress on the Hydration of Portland Cement with Calcined Clay and Limestone

2021 ◽  
Vol 1036 ◽  
pp. 240-246
Author(s):  
Jin Tang ◽  
Su Hua Ma ◽  
Wei Feng Li ◽  
Hui Yang ◽  
Xiao Dong Shen
Keyword(s):  
Mechanical Properties ◽  
Portland Cement ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Research Progress ◽  
Hydration Reaction ◽  
Hydration Products ◽  
Early Hydration ◽  
Calcined Clay ◽  
Dense Microstructure

The use of calcined clay and limestone as supplementary cementitious materials, can have a certain influence on the hydration of Portland cement. This paper reviewed the influence of limestone and calcined clay and the mixture of limestone and calcined clay on the hydration of cement. Both limestone and calcined clay accelerate the hydration reaction in the early hydration age and enhance the properties of cement. Limestone reacts with C3A to form carboaluminate, which indirectly stabilized the presence of ettringite, while calcined clay consumed portlandite to form C-(A)-S-H gel, additional hydration products promote the densification of pore structure and increase the mechanical properties. The synergistic effect of calcined clay and limestone stabilize the existence of ettringite and stimulate the further formation of carboaluminate, as well as the C-(A)-S-H gel, contributed to a dense microstructure.

scholarly journals Bloques de Tierra Comprimida (BTC) estabilizados con cal y cemento. Evaluación de su impacto ambiental y su resistencia a compresión

2020 ◽  
Vol 10 (2) ◽  
pp. 70-81
Author(s):  
Santiago Pedro Cabrera ◽  
Yolanda Guadalupe Aranda-Jiménez ◽  
Edgardo Jonathan Suárez-Domínguez ◽  
Rodolfo Rotondaro
Keyword(s):  
Compressive Strength ◽  
Environmental Impact ◽  
Portland Cement ◽  
Life Cycle Analysis ◽  
Negative Impact ◽  
Santa Fe ◽  
Compressed Earth Blocks ◽  
Earth Blocks ◽  
Negative Environmental Impact ◽  
The City

This work presents the evaluation of the environmental impact and compressive strength of Compressed Earth Blocks (CEB) stabilized with hydrated aerial lime and Portland cement. For this, 12 series of blocks stabilized with different proportions of lime and cement were manufactured and the Life Cycle Analysis (LCA) methodology was used. After conducting these assays and simulations, it could be concluded that, using earth and sand typical of the city of Santa Fe (Argentina), stabilized with certain percentages of Portland cement between 5 and 10% in weight, CEB can be produced with sufficient levels of strength for them to be used in load-bearing walls, in this way minimizing the negative environmental impact associated with their manufacturing. It is also concluded that the stabilization with aerial lime does not increase the CEB’s compressive strength and, on the contrary, significantly increases their negative impact on the environment.

scholarly journals Influences of shrinkage reducing admixture on the mechanical properties, drying shrinkage, water absorption and porosity of Portland cement mortar

2021 ◽  
Vol 15 (3) ◽  
pp. 55-67
Author(s):  
Nguyen Van Chinh
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Portland Cement ◽  
Water Absorption ◽  
Drying Shrinkage ◽  
Effective Porosity ◽  
Minor Effect ◽  
Wide Range ◽  
Shrinkage Reducing Admixture ◽  
A Minor

Drying shrinkage is the main cause of early age cracking of concrete and mortar. A wide range of research has been conducted to reduce the drying shrinkage, including using fibres or chemical admixtures. This paper investigated the effect of shrinkage reducing admixture on the flexural strength, compressive strength, drying shrinkage, water absorption and porosity of mortar. The mix compositions were ordinary Portland cement (OPC) : sand : liquid = 1: 1: 0.38 in which liquid consisted of water and shrinkage reducing admixture (SRA). SRA was used at the proportions of 2%, 4%, and 7% by weight of cement. The test results show that SRA reduces the flexural and compressive strengths of mortar. The reduction in flexural strength and compressive strength at 28 days is 14% and 25%, respectively at 7% SRA dosage. In addition, SRA significantly reduces the drying shrinkage and water absorption of mortar. At 7% SRA dosage, the drying shrinkage at 53 days is reduced by 60% while the water absorption rate at 24 hours is reduced by 54%. However, SRA has a minor effect on the pore size distribution, effective porosity, and cumulative intrusion volume of mortar.

scholarly journals Chloride Ingress in Chemically Activated Calcined Clay-Based Cement

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Joseph Mwiti Marangu ◽  
Joseph Karanja Thiong’o ◽  
Jackson Muthengia Wachira
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Strength Development ◽  
Chloride Ingress ◽  
Calcined Clay ◽  
Apparent Diffusion Coefficients ◽  
Apparent Diffusion ◽  
Lower Porosity ◽  
Lower Chloride

Chloride-laden environments pose serious durability concerns in cement based materials. This paper presents the findings of chloride ingress in chemically activated calcined Clay-Ordinary Portland Cement blended mortars. Results are also presented for compressive strength development and porosity tests. Sampled clays were incinerated at a temperature of 800°C for 4 hours. The resultant calcined clay was blended with Ordinary Portland Cement (OPC) at replacement level of 35% by mass of OPC to make test cement labeled PCC35. Mortar prisms measuring 40 mm × 40 mm × 160 mm were cast using PCC35 with 0.5 M Na2SO4 solution as a chemical activator instead of water. Compressive strength was determined at 28th day of curing. As a control, OPC, Portland Pozzolana Cement (PPC), and PCC35 were similarly investigated without use of activator. After the 28th day of curing, mortar specimens were subjected to accelerated chloride ingress, porosity, compressive strength tests, and chloride profiling. Subsequently, apparent diffusion coefficients (Dapp) were estimated from solutions to Fick’s second law of diffusion. Compressive strength increased after exposure to the chloride rich media in all cement categories. Chemically activated PCC35 exhibited higher compressive strength compared to nonactivated PCC35. However, chemically activated PCC35 had the least gain in compressive strength, lower porosity, and lower chloride ingress in terms of Dapp, compared to OPC, PPC, and nonactivated PCC35.

Alkali-Activated EAF Reducing Slag as Binder for Concrete

2013 ◽  
Vol 723 ◽  
pp. 580-587
Author(s):  
Wen Huan Zhong ◽  
Tung Hsuan Lu ◽  
Wei Hsing Huang
Keyword(s):  
Portland Cement ◽  
Drying Shrinkage ◽  
Portland Cement Concrete ◽  
Steel Making ◽  
Chemical Content ◽  
Alkaline Activator ◽  
Furnace Slag ◽  
Alkali Activated ◽  
Better Than

Electric arc furnace (EAF) reducing slag is the by-product of EAF steel-making. Currently, reducing slag is considered a waste material by the industry in Taiwan. Since the chemical content of reducing slag is similar to blast furnace slag (BFS), it is expected that reducing slag exhibits a similar pozzolanic effect as the BFS. This study used alkaline activator consisting of sodium silicate and sodium hydroxide to improve the activity of reductive slag so as to replace Portland cement as binder in concrete. Some BFS was used to blend with the reducing slag to enhance the binding quality of alkali-activated mixes. The results show that a blend of 50% BFS and 50% reducing slag can be activated successively with alkali. Also, the sulfate resistance of concrete made with alkali-activated EAF reducing slag is found to be better than that of concrete made with portland cement, while the drying shrinkage of alkali-activated EAF reducing slag concrete is greater than that of portland cement concrete.

scholarly journals Synthesis of Pectiniform Polyurethane-Modified Polycarboxylate and Its Preliminary Application in Ultrahigh-Performance Concrete

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Shuncheng Xiang ◽  
Yingli Gao
Keyword(s):  
Silica Fume ◽  
Negative Impact ◽  
Raw Materials ◽  
Synthesis Method ◽  
Autogenous Shrinkage ◽  
Drying Shrinkage ◽  
Isophorone Diisocyanate ◽  
Initiation System ◽  
Dry Shrinkage ◽  
Preliminary Application

In this paper, modified polyurethane prepolymer was synthesized by the segmental synthesis method using isophorone diisocyanate (IPDI), hydroxyl-terminated silicone, and polyether glycol dimethylolpropionic acid as raw materials. After that, pectiniform polycarboxylate, of which side chains were in roughly the same polymerization degree and main chains were in different lengths, was synthesized at normal temperature in the complex initiation system of H2O2, APS, sodium bisulfite, and Vc. Then, compared with commercial Sika polycarboxylate, their applications in ultrahigh-performance concrete (HUPC), including flowability, strength, drying shrinkage, and autogenous shrinkage, were investigated. The results showed that, due to the molecular structure of polyorganosiloxane, the synthesized polycarboxylate could be better dispersed. Dosage of silica fume could effectively improve the compressive strength of UHPC, while slag had a certain negative impact on its strength. Incorporation of slag and silica fume could effectively reduce the dry shrinkage of UHPC.

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