scholarly journals A INFLUÊNCIA DO ADITIVO CRISTALIZANTE NAS PROPRIEDADES DO CONCRETO ENDURECIDO

2020 ◽  
Vol 11 (1) ◽  
pp. 14
Author(s):  
Eduardo Polesello ◽  
Marcelo Maus
Keyword(s):  
Compressive Strength ◽  
Water Absorption ◽  
Significant Influence ◽  
Capillary Absorption ◽  
Concrete Durability ◽  
High Demand ◽  
Concrete Production ◽  
Useful Life ◽  
Healing Processes

RESUMOCom a alta demanda no uso de concreto para produção de estruturas na construção civil, surge também a preocupação com sua durabilidade, ou seja, vida útil das estruturas. Para se obterem estruturas com melhores desempenhos, o uso de diferentes tecnologias e materiais tem sido aplicado, em particular, por meio da redução da permeabilidade. Diante disso, a utilização de aditivos tornou-se uma opção tecnicamente viável na produção de concreto, e, em especial, o aditivo cristalizante tem se mostrado um grande aliado na impermeabilização das estruturas, pois a permeabilidade é um dos fatores que contribui para o aparecimento de manifestações patológicas nas estruturas. O objetivo deste estudo é fornecer uma melhor compreensão da influência do aditivo cristalizante sobre o concreto, avaliando sua eficiência quanto à estanqueidade das estruturas, proporcionando assim um aumento em sua durabilidade e vida útil. Este estudo contempla a análise de um tipo de cristalizante, em três diferentes percentuais de dosagem (0,5%, 0,8% e 1,0% em relação à massa de cimento), na produção de concretos caracterizados por três relações água/cimento (a/c), definidas em 0,40, 0,50 e 0,60, submetidos a dois processos de cura, úmida e submersa. A análise, quanto ao desempenho desses concretos produzidos, aos 28 dias de idade, será pela verificação da resistência à compressão e da permeabilidade determinada por meio da absorção por capilaridade. Os resultados obtidos mostram que tanto o tipo de cura, quanto a relação a/c e a dosagem do aditivo exercem influência significativa nas propriedades do concreto. Destaca-se que a cura submersa proporcionou melhor desempenho quanto à resistência à compressão do concreto e que maiores teores de aditivo utilizados resultam em maior absorção de água por capilaridade.Palavras-chave: Concreto. Durabilidade. Aditivo cristalizante. Absorção por capilaridade. ABSTRACTDue to the high demand for concrete for the production of structures in civil construction, it is worth mentioning the concern regarding the useful life of the structures. For the structures to perform better, the use of different technologies and materials is necessary, in particular, through the reduction of permeability. This work will focus on the use of the crystallizer admixture, which has proven to be a great ally in the waterproofing of structures. The aim of this study is to provide a better understanding of the influence of the crystallizing additive on the concrete, evaluating its efficiency as regards the tightness of the structures, thus providing an increase in their durability and useful life. This study contemplates the analysis of one type of crystallizer, in three different percentages of dosage (0.5, 0.8 and 1.0% in relation to cement mass), in the production of concrete characterized by three water/cement ratios (w/c) (0.40, 0.50 and 0.60), submitted to two healing processes, wet and submerged. At 28 days of age, after the concrete production, the compressive strength and the permeability determined by capillary absorption, were analyzed. The results obtained with this experiment proved that the curing processes, w/c ratio and the crystallizer dosage have a significant influence on the properties of the concrete. It should be noted that the submerged curing provided better performance in terms of compressive strength of the concrete and that higher amounts of additives used resulted in higher water absorption by capillarity.Keywords: Concrete. Durability. Crystallizer admixture. Absorption by capillarity.

scholarly journals Properties of Concrete Prepared with Recycled Aggregates Treated by Bio-Deposition Adding Oxygen Release Compound

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2147 ◽  
Author(s):  
Yaguang Zhu ◽  
Quanquan Li ◽  
Peizhen Xu ◽  
Xiangrui Wang ◽  
Shicong Kou
Keyword(s):  
Compressive Strength ◽  
Water Absorption ◽  
High Water ◽  
Treatment Method ◽  
Recycled Aggregates ◽  
Culture Solution ◽  
Oxygen Release ◽  
Micro Cracks ◽  
Concrete Production ◽  
New Treatment

Recycled aggregates have high water absorption and crushing index. In order to improve the properties of recycled aggregates in concrete production, various treatments were used to modify the aggregates. In recent years, bio-deposition as a new treatment method of recycled aggregates was environmentally friendly. An improved method of bio-deposition was implemented to modify the properties of recycled mortar aggregates (RMA). O-bio-deposition is based on aerobic bacteria induced CaCO3 precipitation by respiration by varying the distance between the RMA and the bottom of the container and by adding an oxygen release compound to the culture solution that contains bacteria to promote the induction of CaCO3. First, the physical properties, including water absorption, crushing value, and apparent density, of the coarse RMA under different treatment methods were determined, and an o-bio-deposition treatment method was obtained. The fine RMA was treated and compared with the untreated RMA. Concretes were then prepared from the treated coarse RMA, and compressive strength and slump were determined. In addition, the effect of the o-bio-deposition treatment on the RMA surface and the micro-cracks of concretes were observed by scanning electron microscopy (SEM). It was found that the water absorption and crushing index of the coarse RMA treated by o-bio-deposition were reduced by 40.38 and 19.76% compared with untreated RMA, respectively. Regarding the concrete, the slump and the compressive strength (28 d) of concrete were increased by 115% and 25.3%, respectively compared with the untreated concrete.

scholarly journals Comparative Strength and Cost of Rice Husk Concrete Block

2019 ◽  
Vol 280 ◽  
pp. 04002
Author(s):  
Setya Winarno
Keyword(s):  
Compressive Strength ◽  
Water Absorption ◽  
Rice Husk ◽  
Concrete Block ◽  
Strength Analysis ◽  
Normal Concrete ◽  
Comparative Cost ◽  
Concrete Production ◽  
Sustainable Materials ◽  
The Cost

This research presents a comparative cost and strength analysis of rice husk concrete block which is aimed at reducing the cost of concrete production and emphasizing environmentally and friendly sustainable materials. Concrete block materials consist of cement, filler, and rice husk. Tests were performed to compare the strength and cost of seven cement rice husk weight ratios designated ranging from 0.67 to 2.00 with constant water cement ration of 0.4. Samples have been tested for 28-day strength. The analysis of the results has showed that the higher proportions of rice husk correspond to decreased strength dan cost polynomially. At 134% proportion of rice husk, it is optimum value for rice husk concrete block. In this point, the compressive strength satisfies the standard. Also, water absorption of 16,04% justifies the maximum standard. Overall, the cost of 134% RH concrete is Rp 511,809 per m3 which is 42.5% cheaper than normal concrete block.

scholarly journals The Influence of Discharge Time, Kind of Additive, and Kind of Aggregate on the Properties of Three-Stage Mixed Concrete

2018 ◽  
Vol 10 (11) ◽  
pp. 3862 ◽  
Author(s):  
Alena Sicakova ◽  
Karol Urban
Keyword(s):  
Compressive Strength ◽  
Water Absorption ◽  
Recycled Concrete ◽  
Recycled Aggregates ◽  
Concrete Aggregate ◽  
Discharge Time ◽  
Concrete Mixtures ◽  
Concrete Properties ◽  
Concrete Production ◽  
The Impact

Application of recycled aggregates (RA) for concrete production is limited due to their poor quality. While the environmental benefits of using the RA are well accepted, some unsolved problems prevent this type of material from wide application in structural concrete. The research and development of techniques which can minimize the adverse effect of RA on the concrete properties are highly requested. A specific mixing approach can also be helpful; here, mineral additives play a significant role for improvement of RA performance within the mixing process. However, delivery process can influence the homogeneity and uniformity of the concrete mixtures, resulting in negative effect on technical parameters. In this study, the impact of delivery time (0 min, 45 min, and 90 min) on the set of hardened concrete properties is presented while the three-stage mixing is used. Two kinds of additives—fly ash (FA) and recycled concrete powder (RCP)—were tested to coat the coarse fraction of recycled concrete aggregate (RCA) in the first step of mixing. For comparison, cement as coating material and natural aggregate instead the RCA were also used. The following parameters were tested after 28 days of setting and hardening: density, compressive strength, splitting tensile strength, water absorption capacity, and depth of penetration of water under pressure. Generally, 90 min of working with concrete mixtures left no significantly negative influence on tested characteristics. Based on ANOVA results, with prolonged discharge time, the changes in composition of the mixtures become less important for compressive strength, density, and water absorption.

scholarly journals Evaluation of Cassava Effluent as Organic Admixture in Concrete Production for Farm Structures

2020 ◽  
pp. 271-282
Author(s):  
Ovie Isaac AKPOKODJE ◽  
Goodnews Goodman AGBI ◽  
Hilary UGURU
Keyword(s):  
Compressive Strength ◽  
Water Absorption ◽  
Fresh Water ◽  
Absorption Rate ◽  
International Standards ◽  
Partial Replacement ◽  
Strength Development ◽  
Water Absorption Rate ◽  
Concrete Production ◽  
Farm Structures

This paper evaluated the influence of cassava effluent on the compressive strength of concrete for farm structures. Three sets of concrete cubes were produced with a concrete mix ratio of 1:2:4 (C 15) and a water to cement ratio (w c-1) of 0.5. The 1st set was produced with 100% fresh water (tap water). The 2nd set was produced with 75% partial replacement of the fresh water with fresh cassava effluent, while the 3rd set was produced with 75% partial replacement of the fresh water with old cassava effluent. The density, water absorption rate and compressive strength of the concrete cubes was tested in accordance with ASTM International standards, at the end of 7, 14, 21, 28 and 56 curing days. The results revealed that, the cassava effluent slightly increased the cubes density; but reduced their water absorption rate. The study further showed that, concrete produced with fresh cassava effluent, developed the highest compressive strength (29.57 MPa) at the end of the 56th curing day. In contrast, concrete produced with old cassava effluent developed the lowest compressive strength (24.43 MPa) at day 56, which was lower than the compressive strength of 27.18 MPa developed by the concrete produced with fresh water (also at day 56). In addition, the cassava effluent retarded the initial rate of strength development, as such, increasing its prospect as an organic concrete admixture. This study will be helpful in mitigating the harmful effects of cassava effluent in the environment, since it can be utilized in concrete production.

Influence of Morphology of Cathode-Ray Tube Glass as Coarse Aggregates on Compressive Strength and Water Absorption of Concrete

2018 ◽  
Vol 280 ◽  
pp. 399-409
Author(s):  
Nurul Noraziemah Mohd Pauzi ◽  
Maslina Jamil ◽  
Roszilah Hamid ◽  
Muhammad Fauzi Mohd Zain
Keyword(s):  
Compressive Strength ◽  
Water Absorption ◽  
Coarse Aggregate ◽  
Capillary Water ◽  
Capillary Water Absorption ◽  
Coarse Aggregates ◽  
Concrete Properties ◽  
Concrete Production ◽  
Cathode Ray Tube ◽  
Texture Size

The study on the substitution for natural coarse aggregates using waste CRT funnel glass in spherically shapes is still limited. In this paper, the waste CRT glass has been processed to form a spherical CRT glass (GS) and crushed CRT glass (GC), which were used as a coarse aggregate in concrete production. Results indicated that the inclusion of GS and GC has lower the compressive strength and decreased the rate of capillary water absorption of concrete. It was demonstrated that the morphology properties of GS and GC (shape, surface texture, size, grading) is significantly affected the concrete properties.

scholarly journals The use of glass waste cullet in the concrete production as an important factor in the circular economy

2021 ◽  
Vol 900 (1) ◽  
pp. 012013
Author(s):  
J Junak ◽  
N Junakova
Keyword(s):  
Compressive Strength ◽  
Water Absorption ◽  
Circular Economy ◽  
Negative Impact ◽  
Glass Cullet ◽  
Total Water ◽  
Glass Waste ◽  
Concrete Production ◽  
Aggregate Fractions ◽  
Real Density

Abstract The paper focuses on the use of glass waste as a substitute for aggregates (0/4, 4/8 and 8/16 mm) in the production of concrete in order to reduce the negative impact of existing waste on the environment. For the study, 5 mixtures were designed with gradual replacement of individual natural aggregate fractions in the concrete mixture by glass cullet. Real density, total water absorption and compressive strength were monitored on cubes with an edge of 100 mm for a period of 14 days to 3 years. The achieved compressive strength of samples with glass as a filler at the level of 50 MPa gives a good precondition for the real use of such concrete in practice. In addition, when combined it with lower real density and total water absorption.

EFFECT OF RECYCLED CONCRETE AGGREGATE QUALITY ON PROPERTIES OF CONCRETE

2020 ◽  
Vol 15 (2) ◽  
pp. 57-69
Author(s):  
Daniel Hatungimana ◽  
Şemsi Yazıcı ◽  
Ali Mardani-Aghabaglou
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Water Absorption ◽  
Recycled Concrete ◽  
Recycled Aggregates ◽  
Concrete Aggregate ◽  
Hardened Concrete ◽  
Recycled Concrete Aggregate ◽  
Waste Concrete ◽  
Concrete Production

ABSTRACT The possibility of the use of recycled aggregates from the construction industry in green concrete production is of increasing importance to reduce the negative environmental impact associated with construction and demolition wastes. The objective of this study is to investigate the effect of recycled concrete aggregate (RCA) quality on the properties of hardened concrete properties such as compressive strength, splitting tensile strength, density, water absorption capacity and porosity accessible to water. The RCA used in this study was obtained from the crushing of waste concrete with two different compressive strengths (LRCA obtained from the crushing of waste concrete having compressive strengths below 30 MPa and HRCA obtained from the crushing of waste concrete having compressive strengths above 30 MPa). The natural coarse limestone aggregate was 100% replaced with coarse LRCA and HRCA. As a result of the study, the use of 100% HRCA and %100 LRCA instead of limestone coarse aggregate in the concrete adversely affected its mechanical and physical properties. In addition, HRCA showed better performance in terms of compressive strength, tensile strength, water absorption and porosity compared to the use of LRCA. Furthermore, the percentage of adhered mortar on the surface of LRCA and HRCA was analyzed using a computerized micro tomography device, and it was found that the percentages of attached mortar and aggregates are 61% and 35.5% for LRCA, whilst the attached mortar and aggregate contents for HRCA are 45.9% and 53.7%, respectively.

3-Aminopropyl-Triethoxysilane Functionalized Graphene Oxide for Silane-Based Consolidation Treatments to Increase Mortar Performances

2021 ◽  
Vol 21 (4) ◽  
pp. 2351-2359
Author(s):  
C. Cadar ◽  
C. I. Fort ◽  
A. Mihis ◽  
Zs. Kedves ◽  
K. Magyari ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Graphene Oxide ◽  
Water Absorption ◽  
Untreated Control ◽  
Mechanical Tests ◽  
Capillary Absorption ◽  
Capillary Water ◽  
Functionalized Graphene Oxide ◽  
Capillary Water Absorption ◽  
Control Samples

The influence of chemically converted GO (graphene oxide) functionalized with APTES (3-aminopropyl-triethoxysilane) and unfunctionalized GO, dispersed in ethanolic solution of TEOS (tetraethyl orthosilicate), on the performances of the mortar samples, such as capillary water absorption and compressive strength was evaluated. The effect of the GO based nanomaterials (GO and GO functionalized with APTES) on the mortar microstructure was investigated by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscopy (SEM). The multifunctionality of the mortar brushed with GO based nanomaterials consolidation suspension was proved by the results (i) of the mechanical tests which show an improvement of the compressive strength and (ii) the capillary water absorption results which indicate the decreasing of the water penetration speed. For the mortar samples brushed with GO consolidation suspension, an increase value for the compressive strength of approximately twice compared to the untreated control samples and a decreased value for the capillary absorption water coefficient with one order of magnitude in comparison with the untreated control samples were obtained.

scholarly journals Experimental Investigation on Effect of Partial Replacement of Cement with Bamboo Leaf Ash on Concrete Property

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Gashaw Abebaw ◽  
Bahiru Bewket ◽  
Shumet Getahun
Keyword(s):  
Compressive Strength ◽  
Water Absorption ◽  
Construction Industry ◽  
Concrete Strength ◽  
Setting Time ◽  
Sulfate Attack ◽  
Partial Replacement ◽  
Concrete Production ◽  
Bamboo Leaf Ash ◽  
Price Escalation

Ethiopia’s construction industry is aggressively expanding than ever before. Cement is the most essential and expensive material in this regard. Cement takes 10%–15% by volume of concrete. Nowadays, the construction industry is challenged by the scarcity of cement and price escalation of the cement market. However, scholars try to replace cement with pozzolanic material. Besides this, they investigated that bamboo leaf ash possesses pozzolanic properties. Ethiopia has about 850,000 hectares of lowland bamboo, so it is good to utilize bamboo leaf ash as a replacement material for cement. In this study, the capability of lowland Ethiopian bamboo leaf ash as a partial substitute for cement in C-25 concrete production with 0%, 5%, 10%, 15%, and 20% replacement of OPC by BLA with 0.49 percent water-to-cement ratio was investigated. This study examines the chemical properties of BLA, physical properties of cement paste, workability, compressive strength, water absorption, density, and sulfate attack of concrete. The chemical composition of bamboo leaf ash was examined, the summation of SiO2, AlO3, and FeO3 is 76.35%, and the ash was classified class N pozzolan. The normal consistency percentage of water increases as the BLA replacement amount increases, and both initial and final setting time ranges increase as the BLA replacement amount increases. The compressive strength of concrete for 5% and 10% BLA achieves the target mean strength (33.5 MPa) on the 28th day, and on the 56th day, 5% and 10% replacements increase the concrete strength by 1.84% and 0.12%, respectively. The water absorption and sulfate attack have significant improvement of the BLA-blended concrete on 5% and 10% BLA content. According to the findings, bamboo leaf ash potentially substitutes cement up to 10%. The outcome of the study will balance the cement price escalation and increase housing affordability without compromise in quality.

scholarly journals Possibility of Using Cotton Knitted Fabric Waste in Concrete

2021 ◽  
Vol 1203 (2) ◽  
pp. 022074
Author(s):  
Bruno Bartulović ◽  
Sandra Juradin ◽  
Dujmo Žižić ◽  
Silvija Mrakovčić
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Water Absorption ◽  
Construction Industry ◽  
Lower Percentage ◽  
Knitted Fabric ◽  
Percentage Increase ◽  
Concrete Production ◽  
Concrete Mix ◽  
Cotton Knitted Fabric

Abstract The use of waste and recycled materials in the construction industry, especially in concrete production, is becoming increasingly popular. The production of cotton underwear generates a certain amount of knitted fabric waste. This study was conducted to investigate the possibility of using cotton knitted fabric waste (CKFW) in concrete and to explore its potential application in the construction industry. The aim of the study is not only to reduce the waste but also to add positive properties to the concrete. A total of 4 mixes were prepared for testing purposes. CKFW were cut into small pieces of size about 6-8 cm x 2 cm. The addition of CKFW was a substitute for aggregates and replaced 0, 2.5, 5 and 10% of the total volume of aggregates in the concrete mix to make the concrete lighter. All mixes have the same amount of cement, water and superplasticizer. The knitted waste was saturated in water before mixing with other concrete components. The properties of the fresh mix were determined by slump method. The dynamic modulus of elasticity, flexural strength and compressive strength were tested on 28 days old concrete specimens. The σ-δ diagram is also presented. It was found that specimens with CKFW have better flexural strength and higher ductility but lower compressive strength than the reference concrete mix. The mix with the highest percentage of CKFW reduced the compressive strength by 28%, while the specimens with lower percentage of CKFW increased the flexural strength by 20% compared to the reference mix. The capillary water absorption capacity of concrete is closely related to its durability. The water absorption by capillarity was measured after 2, 4, 8, 15, 30, 45, 60 min, and 4 and 24 h. The increase in the amount of water absorbed was found to be higher than that of the reference mix. It was related to the percentage increase in the knitted waste and the values obtained ranged from 3.3 to 5.6% of the mass of the dry sample. The largest reduction in concrete density was 3.8% compared to the reference mix. Based on the obtained results, recommendations for further tests are given.

Sign in / Sign up

Export Citation Format

Share Document