Durability of Bamboo Bio-Concretes Exposed to Natural Aging

2022 ◽  
Author(s):  
Vanessa Maria Andreola ◽  
M’hamed Yassin Rajiv da Gloria ◽  
Romildo Dias Toledo Filho
Keyword(s):  
Compressive Strength ◽  
Visual Analysis ◽  
Accelerated Aging ◽  
Natural Aging ◽  
Cementitious Materials ◽  
Volumetric Fraction ◽  
Vegetable Fibers ◽  
Cementitious Binder ◽  
Water To Cement Ratio ◽  
Hardened State

In recent years, several studies on the durability of cementitious materials combined with vegetable fibers have been developed. In order to understand the properties of these materials in different environmental conditions, they can be subjected to accelerated aging through several cycles of controlled variations of humidity-temperature, wetting-drying, freezing-thawing. However, analyzes that expose such materials to real conditions of use during their useful life are scarce. As a result, this study analyzed the physical, thermal and mechanical behavior of bamboo bio-concretes produced with different volumes of bio-aggregates, which were exposed to the natural aging of the summer in the city of Rio de Janeiro (Brazil). The cementitious binder was is composed, by mass, of cement (30%), metakaolin (30%) and fly ash (40%). The water-to-cement ratio was as 0.30. The mixtures were produced with bamboo volumetric fraction of 30%; 40% and 50%. After 3 months of natural aging during the Brazilian summer (from December to March), the property determined in the hardened state was the compressive strength. In addition, a visual analysis by photograph was also realize. The results revealed that higher the volumetric fraction, higher the decrease of compressive strength. The visual analysis showed several changes of the external aspect of the bio-concretes.

Chloride Ingress Control and Promotion of Internal Curing in Concrete Using Superabsorbent Polymer

2021 ◽  
Vol 888 ◽  
pp. 67-75
Author(s):  
Ariel Verzosa Melendres ◽  
Napoleon Solo Dela Cruz ◽  
Araceli Magsino Monsada ◽  
Rolan Pepito Vera Cruz
Keyword(s):  
Compressive Strength ◽  
Cementitious Materials ◽  
Internal Curing ◽  
Mix Design ◽  
Chloride Ingress ◽  
Superabsorbent Polymer ◽  
Cement Slurry ◽  
Chloride Permeability ◽  
Cement Ratio ◽  
Water To Cement Ratio

Chloride ingress into concrete from the surrounding environment can result in the corrosion of the embedded steel reinforcement and cause damage to the concrete. Superabsorbent polymer (SAP) with fine particle size was incorporated into the structure of concrete for controlling the chloride ingress and improving its compressive strength via promotion of internal curing. The SAP used in this study was evaluated for its absorbency property when exposed to cementitious environment such as aqueous solution of Ca (OH)2 and cement slurry. The results were compared to that in sodium chloride solution, the environment where absorbency of most of the SAP found in the market are well studied. Results showed that although SAP absorbency decreased with increasing concentration of Ca (OH)2 and cement, the results suggest that water containing cementitious materials are able to be absorbed by SAP. Chloride ingress into 28-day cured concrete specimens were determined using Rapid Chloride Penetration Test (RCPT) method employing 60V DC driving force. Concrete samples with size of 50 mm height x 100 mm diameter were prepared using a M25 mix design with 0.4 and 0.45 water to cement ratios and different percentages of SAP such as 0.05%, 0.1% and 0.15% with respect to cement mass. Results showed that concrete with 0.15% SAP gave the best result with 14% less chloride permeability than concrete with no SAP for a 0.4 water to cement ratio. Concrete samples for compressive strength tests with size of 200 mm height x 100 mm diameter were prepared using the same mix design and percentages of SAP and cured for 28 days. Results showed that the best results for compressive strength was found at 0.1% SAP at a 0.4 water to cement ratio which can be attributed to internal curing provided by SAP.

scholarly journals Effects of Bacillus subtilis biocementation on the mechanical properties of mortars

2019 ◽  
Vol 12 (1) ◽  
pp. 31-38 ◽  
Author(s):  
N. SCHWANTES-CEZARIO ◽  
M. F. PORTO ◽  
G. F. B. SANDOVAL ◽  
G. F. N. NOGUEIRA ◽  
A. F. COUTO ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Calcium Carbonate ◽  
Cementitious Materials ◽  
Mechanical Analysis ◽  
Sem Analysis ◽  
Subtilis Strain ◽  
Cement Mortars ◽  
Water To Cement Ratio ◽  
Mixing Water

Abstract This study aims to evaluate the influence of B. subtilis AP91 spores addition on the mechanical properties of mortars. B. subtilis strain AP91, isolated from rice leaves of the needle variety, which has an early cycle of production, was used at the concentration of 105 spores/mL in mortars with cement-to-sand ratio of 1:3 (by weight) and water-to-cement ratio (w/c) of 0.63. These spores were added in two different ways: in the mixing water and by immersion in a solution containing bacterial spores. Scanning Electron Microscope (SEM) analysis showed crystals with calcium peaks on the EDS, which possibly indicates the presence of bioprecipitated calcium carbonate. The results obtained in the mechanical analysis showed that the bioprecipitation of CaCO3 by B. subtilis strain AP91 was satisfactory, particularly when the spores were added in the mixing water, increasing the compressive strength up to 31%. Thus, it was concluded that the addition of B. subtilis AP91 spores in the mixing water of cement mortars induced biocementation, which increased the compressive strength. This bioprecipitation of calcium carbonate may very well have other advantageous consequences, such as the closure of pores and cracks in cementitious materials that could improve durability properties, although more research is still needed on this matter.

scholarly journals Recycled PET Sand for Cementitious Mortar

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 273
Author(s):  
Angélica Faria Campanhão ◽  
Markssuel Teixeira Marvila ◽  
Afonso R. G. de Azevedo ◽  
Tulane Rodrigues da Silva ◽  
Roman Fediuk ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mineral Resource ◽  
Sustainable Development ◽  
Compressive Strength ◽  
Quartz Sand ◽  
Mineral Resources ◽  
Cementitious Materials ◽  
Recycled Pet ◽  
Fresh State ◽  
Hardened State

Cementitious materials cause a great impact on the environment due to the calcination of clinker and the extraction of non-renewable mineral resources. In this work, the replacement of quartz sand from the river by PET sand was evaluated at levels of 10%, 20%, and 30%. Tests were performed in the fresh state through consistency, air retention, density, and incorporated air and in the hardened state for compressive strength, flexural strength, density, capillarity, and water absorption. The results show that PET sand is viable in contents of up to 10%, improving the mechanical properties of the mortar and without compromising its workability and incorporated air properties. Above that level, the loss of properties is very excessive, mainly of workability and incorporated air. The incorporated air of the 30% composition, for example, reaches 24%, an excessive value that impacts the properties of the hardened state, making it impossible to use the material at levels greater than 20%. It is concluded that the use of recycled PET sand is a possibility that contributes to sustainable development, as it reduces the extraction of quartz sand from the river, a non-renewable mineral resource.

scholarly journals Eco-efficient concrete, optimized by Alfred’s particle packing model, with partial replacement of Portland cement by stone powder

2022 ◽  
Vol 15 (2) ◽  
Author(s):  
Heloisa Fuganti Campos ◽  
André Lucas Bellon ◽  
Eduardo Reis de Lara e Silva ◽  
Maurício Villatore Junior
Keyword(s):  
Compressive Strength ◽  
Co2 Emissions ◽  
Cementitious Materials ◽  
Particle Packing ◽  
Partial Replacement ◽  
Cement Particle ◽  
Distribution Factor ◽  
Packing Model ◽  
The Matrix ◽  
Hardened State

Abstract The partial replacement of clinker by complementary cementitious materials can significantly contribute to the reduction of carbon emissions in the production of concrete. Another alternative to reduce these emissions is to increase the efficiency of the concrete, achieving higher compressive strength with lower consumption of cement. Particle packing models are efficient tools to optimize the composition of the matrix and contribute to the production of more eco-efficient concretes. In this context, the objective of the present study is evaluating the production of concretes with partial replacement of cement by stone powder, optimized by Alfred’s particle packing model, seeking to reduce cement consumption and CO2 emissions per MPa of compressive strength. The replacement content of cement by stone powder was 20% by mass (equivalent to 22.4% by volume). Concretes were produced with different distribution factor (q) - 0.37; 0.21; 0.45 - to verify the influence of fines on the flow between particles and on the efficiency of the produced concrete. The analyses were carried out in terms of properties in the fresh state, hardened state, and sustainability parameters (cement consumptions and CO2 emissions). The application of the proposed method resulted in a higher compressive strength than the expected for the water/cement ratio used (0.5). The most efficient concrete reached the compressive strength of 68 MPa with 240 kg/m3 of cement, which represents 3.5 kg of cement/m3/MPa and 3.1 kg of CO2/m3/MPa, a value below the references found in the literature for conventional concretes. Therefore, the proposed method allows to produce more eco-efficient concrete, contributing to the use of waste and reducing CO2 emissions.

Investigation on a New Hydraulic Cementitious Binder Made from Phosphogypsum

2013 ◽  
Vol 864-867 ◽  
pp. 1923-1928
Author(s):  
Yue Xu ◽  
Jian Xi Li ◽  
Li Li Kan
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Active Carbon ◽  
High Strength ◽  
Tricalcium Silicate ◽  
Dicalcium Silicate ◽  
Cementitious Material ◽  
Saturation Ratio ◽  
Tricalcium Aluminate ◽  
Cementitious Binder

A new kind of high strength cementitious material is made from phosphogypsum (PG), active carbon and fly-ash. Through the orthogonal research, it was showed that the calcination temperature, retention time, dosage of active carbon and fly ash on the compressive strength of cementitious binder are the most important. The result also showed that, in the conditions of temperature 1200°C, time retention 30 min, dosage of active carbon 10%, dosage of fly ash 5%, the compressive strength of the cementitious material for 3d and 28d could reach to 46.35MPa and 92.70MPa, the content of sulfur trioxide was 11.60% accordingly. A lot of active mineral materials, such as dicalcium silicate, tricalcium silicate, tricalcium aluminate were formed in the calcination. The C-S-H gel, calcium hydroxide and ettringite were found in 3d and 28d hydrates. It is found that the lime saturation ratio and silica modulus need to be control between 0.40~0.65 and 4~8 in order to produce high strength cementitious material.

scholarly journals Waste-Based One-Part Alkali Activated Materials

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2911
Author(s):  
Margarida Gonçalves ◽  
Inês Silveirinha Vilarinho ◽  
Marinélia Capela ◽  
Ana Caetano ◽  
Rui Miguel Novais ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Microstructural Analysis ◽  
Construction Materials ◽  
Sodium Metasilicate ◽  
High Compressive Strength ◽  
Hardened State ◽  
First Time ◽  
Furnace Slag ◽  
Alkali Activated

Ordinary Portland Cement is the most widely used binder in the construction sector; however, a very high carbon footprint is associated with its production process. Consequently, more sustainable alternative construction materials are being investigated, namely, one-part alkali activated materials (AAMs). In this work, waste-based one-part AAMs binders were developed using only a blast furnace slag, as the solid precursor, and sodium metasilicate, as the solid activator. For the first time, mortars in which the commercial sand was replaced by two exhausted sands from biomass boilers (CA and CT) were developed. Firstly, the characterization of the slag and sands (aggregates) was performed. After, the AAMs fresh and hardened state properties were evaluated, being the characterization complemented by FTIR and microstructural analysis. The binder and the mortars prepared with commercial sand presented high compressive strength values after 28 days of curing-56 MPa and 79 MPa, respectively. The mortars developed with exhausted sands exhibit outstanding compressive strength values, 86 and 70 MPa for CT and CA, respectively, and the other material’s properties were not affected. Consequently, this work proved that high compressive strength waste-based one-part AAMs mortars can be produced and that it is feasible to use another waste as aggregate in the mortar’s formulations: the exhausted sands from biomass boilers.

Accelerated Aging of Deacidified and Untreated Book Paper in 1967 Compared with 52 Years of Natural Aging

2020 ◽  
Vol 41 (3) ◽  
pp. 131-152
Author(s):  
Tali H. Horst ◽  
Richard D. Smith ◽  
Antje Potthast ◽  
Martin A. Hubbe
Keyword(s):  
Room Temperature ◽  
Accelerated Aging ◽  
Natural Aging ◽  
Scanning Electron Micrographs ◽  
Surface Ph ◽  
Room Temperature Storage ◽  
Folding Endurance ◽  
Endurance Tests ◽  
Breaking Length ◽  
Temperature Storage

AbstractThree copies of a book that had been optionally deacidified using two different procedures in 1967, and then subjected to accelerated aging, were tested again after 52 years of natural aging. Matched copies of the book Cooking the Greek Way, which had been printed in Czechoslovakia on acidic paper, were evaluated. Nonaqueous treatment of two of the copies with magnesium methoxide dissolved in chlorofluorocarbon solvent had been found in 1967 to have decreased the susceptibility to embrittlement, as evidenced by the results of the accelerated aging, followed by folding endurance tests. Retesting of the same books in 2019, after 52 years of room temperature storage, showed that the deacidification treatments had achieved the following benefits in comparison to the untreated book: (a) higher brightness; (b) higher folding endurance; (c) tensile breaking length higher in the cross-direction of the paper; (d) substantial alkaline reserve content, (e) an alkaline surface pH in the range 7.1–7.4, and (f) higher molecular mass of the cellulose. Remarkably, some of the folding endurance results matched those of unaged samples evaluated in 1967. Scanning electron micrographs showed no differences between the treated and untreated books.

scholarly journals Effects of carbon nanotubes on expanded glass and silica aerogel based lightweight concrete

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Suman Kumar Adhikary ◽  
Žymantas Rudžionis ◽  
Simona Tučkutė ◽  
Deepankar Kumar Ashish
Keyword(s):  
Carbon Nanotubes ◽  
Compressive Strength ◽  
Silica Aerogel ◽  
Lightweight Concrete ◽  
Lightweight Aggregate ◽  
Cementitious Materials ◽  
Lightweight Aggregate Concrete ◽  
Multi Wall Carbon Nanotubes ◽  
Sem Image ◽  
Study Results

AbstractThis study is aimed to investigate the effect of carbon nanotubes on the properties of lightweight aggregate concrete containing expanded glass and silica aerogel. Combinations of expanded glass (55%) and hydrophobic silica aerogel particles (45%) were used as lightweight aggregates. Carbon nanotubes were sonicated in the water with polycarboxylate superplasticizer by ultrasonication energy for 3 min. Study results show that incorporating multi-wall carbon nanotubes significantly influences the compressive strength and microstructural performance of aerogel based lightweight concrete. The addition of carbon nanotubes gained almost 41% improvement in compressive strength. SEM image of lightweight concrete shows a homogeneous dispersal of carbon nanotubes within the concrete structure. SEM image of the composite shows presence of C–S–H gel surrounding the carbon nanotubes, which confirms the cites of nanotubes for the higher growth of C–S–H gel. Besides, agglomeration of carbon nanotubes and the presence of ettringites was observed in the transition zone between the silica aerogel and cementitious materials. Additionally, flowability, water absorption, microscopy, X-ray powder diffraction, and semi-adiabatic calorimetry results were analyzed in this study.

The Utilization of Vegetable Fibers in Cementitious Materials

2020 ◽  
pp. 649-662
Author(s):  
Oussama Benaimeche ◽  
Nadhir Toubal Seghir ◽  
Łukasz Sadowski ◽  
Mekki Mellas
Keyword(s):  
Cementitious Materials ◽  
Vegetable Fibers
Sign in / Sign up

Export Citation Format

Share Document