Physical, mechanical and microstructural properties of alkaline and acid-activated mixtures of calcined laterite-volcanic ash based inorganic polymers: Effects of reciprocal substitution

Partial replacement of volcanic ash by bauxite and calcined oyster shell in the synthesis of volcanic ash-based geopolymers

In the context of sustainable development, earthen building materials could be a viable alternative to conventional, energy-intensive materials if the constraints to their general acceptance and widespread use are mitigated. A key challenge is the limited understanding of how intrinsic soil properties influence the performance of these materials. This study investigates the role of intrinsic iron oxides and calcium carbonate, components that are believed, yet not conclusively proven, to exert a strong influence on earthen materials by increasing strength and reducing shrinkage through aggregation and cementation mechanisms. Engineered soils based on kaolin powder, bentonite powder, and a natural clayey soil were prepared and combined with ferric oxide, iron powder, and fine limestone powder to produce mortars. Mortars with iron and iron oxides exhibited no significant improvement in compressive strength, a finding attributed to the high crystallinity and low solubility of the oxides used, as well as to the alkaline pH of the soils. In contrast, mortars containing limestone powder exhibited remarkable strength gains across all soil types, demonstrating that intrinsic CaCO3, particularly its finer and more reactive fraction, can positively impact strength development. Further analysis, including pH cation exchange capacity (CEC) and exchangeable calcium measurements, revealed that limestone powder actively interacts with the soil’s exchangeable complex, driven by its significant active calcium carbonate (ACC) content. These results underline the importance of soil chemistry in the performance of earthen building materials.

Chemico-microstructural changes in earthen building materials containing calcium carbide residue and rice husk ash

An experimental investigation on mechanical characteristics of steel-fiber-reinforced volcanic concrete

Effects of curing regimes on mechanical strength and durability of alkali-activated low reactive volcanic ashes

Bursa, the first capital of the Ottoman Empire, is one of the rare historical cities that has survived to the present day without losing its importance. As well as monumental structures such as mosques and Sultan complexes, traditional Bursa houses are also components of architectural heritage that reflect the identity of the city. The traditional building materials of these houses are wood, stone, brick and earth. Today, these materials are known as ecological building materials and their use is very important to ensure sustainability. Especially the application of traditional building techniques based on the use of these materials in restoration works is of great importance in terms of ensuring sustainability not only from an ecological point of view, but also from economic and cultural points of view. In this context, earthen building material consisting of natural raw materials and created by human hands are seen as ecological and renewable building materials. In different parts of the world, many civilizations have used earthen building materials with different usage techniques in the past. This material has not lost its importance to this day. In this study, the earthen building materials used in traditional Bursa houses are examined and their role in sustainable architecture is pointed out. For this purpose, a case study was conducted on traditional Bursa houses in three different historic neighborhoods; Hisar, Tuzpazari and Reyhan regions. Representative earthen building materials were taken from 22 traditional houses and listed with their qualities for experimental studies. Characterization tests were carried out on the samples taken from these houses. The results of the experiments have been used to develop some recommendations for the successful implementation of restorations that will help to carry out sustainable heritage conservation work in Bursa.

A review of experimental studies on Cob, Hempcrete, and bamboo components and the call for transition towards sustainable home building with 3D printing

Conventional inorganic polymers, otherwise known as geopolymers, are aluminosilicates with the desirable properties of ceramics (durability, strength) but which harden at ambient temperatures without the need for processing at high temperatures. They are commonly formed by the action of alkalis or phosphoric acid on aluminosilicate minerals such as dehydroxylated clays and consist of randomly arranged three‐dimensional assemblages of silicate and aluminate units into an X‐ray amorphous structure. The presence of charge‐balancing ions such as Na+or K+within this structure gives them useful ion‐exchange properties similar to zeolites. Analogous inorganic polymers are known in which the silicate is partially replaced by germinate units, and the aluminate units are replaced by gallate, phosphate, or borate units, giving a range of materials with a variety of properties and potential applications. The physical properties of the inorganic polymers can be manipulated by the introduction of fibers, whereas their chemistry allows the introduction of bone‐forming elements, drugs and carbon nanotubes, providing them with porosity, bioactivity, or electronic functionality. Inorganic polymers with catalytic, photocatalytic, and fluorescent functionality can also be produced. This article covers the synthesis and structure of clay‐based inorganic polymers and discusses a number of their more specialized applications. Although inorganic polymers are a subclass of alkali‐activated materials that can also be formed by a range of materials other than dehydroxylated clays (fly ash, volcanic ash, blast furnace slag), geopolymers formed from these materials are outside the scope of this article, and are not discussed here.

Cement being the binder in concrete production, is an extensive industrial commodity, the production of which leads to the emission of a vast amount of carbon dioxide which causes greenhouse gas emission and global warming. There is need for alternative materials that are environmentally friendly, economical and accessible. The research investigates the strength properties of concrete produced with volcanic ash and metakaolin as a partial cement replacement. Cement was partially replaced at 5%, 10%, 15%, 20%, 25% and 30%. Volcanic-metakaolin Fresh and hardened strength tests on mortar and concrete were carried out by adding 0–30% pozzolana, in which the water-to-binder ratio was 0.5 kept the same for all replacement levels. Density, compressive strength, flexural strength, and water absorption tests were carried out. Incorporation of volcanic ash and metakaolin reduces total voids in concretes. The result showed that VA-MTK has a pozzolanic effect on concrete properties by considering the strength activity index, higher compressive strength, higher flexural and splitting strength comparable to the control concrete 10% pozzolanic content. The maximum compressive strength at 28 days was the 10% VA/MTK as partial cement replacement, which achieved 28.5N/mm2 compared to the control, which achieved 28.2N/mm2. The flexural strengths at 10% achieved 5.22N/mm2, while the control concrete achieved 5.11 N/mm2. Considering the environmental and strength performance, a 15% cement replacement with metakaolin was convincing. Thus, the research shows that the use of VA/MTK as a partial replacement for cement in concrete, at a lower volume of replacement, will enhance the reduction of cement...

The effect of gamma radiation on the mechanical and microstructural properties of Fe-rich inorganic polymers

Kelut volcano had erupted in February 2014. The eruption has produced various materials i.e. ash, sands, etc. Volcanic ash contains various elements such as Si, Al, Ca, Fe, Na and P. It is potential to be used as raw material for cement-based products. This study investigates the utilization of Kelut’s volcanic ash as the raw material of cement-brick. The Kelut’s volcanic ash was analyzed to determine the contents of iron (Fe), aluminum (Al), and silica (Si). The volcanic ash was screened to obtain 100 mesh size of ash. The volcanic ash of 100 mesh size was mixed with cement, sand, and water with ratio of 1 kg cement, 2 kg volcanic ash, and 15 kg sand (1 :2 :15). The mixture of volcanic ash, sand and cement was poured and pressed in the concrete brick mold. The concrete brick was then aerated in a room for hardening process. The experiment was repeated for another ratio of raw material (cement: volcanic ash: sand = 2:1:15) and the age of the concrete brick (46, 61, 75 and 89 days). Concrete bricks were analyzed to determine the quality and the mechanical characteristics. The results has shown that Kelut’s volcanic ash has a composition of aluminum (Al) 4.707%, silica (SiO2) 23.4%, and iron (Fe) 3.85%, that is like the composition of the cement materials. The concrete bricks which are made of cement, Kelut’s volcanic ash, and sand with the ratio of 2:1:15 has a maximum compression strength of 18.85 MPa at the age of 89 days. The addition of Kelut’s volcanic ash has improved the strength of concrete brick. However, too much volcanic ash will lead to increasing compression strength.

Effective mechanical reinforcement of inorganic polymers using glass fibre waste

Augmented electronic metal-support interaction of single-atomic NiNC supported PtRu nanoalloys and their boosted activity and durability for hydrogen evolution and oxygen reduction reactions in both alkaline and acidic media.

The concrete need curing for cement hydration that is a chemical reaction in each step require water supply throughout the time period. The traditional concrete cured by external method that prevents the concrete surface dry so that keeping the concrete mixture wet and warm. The internal curing was adopted in normal and high strength concrete such as reactive powder concrete. In present paper, experimental approach is to study the mechanical properties of reactive powder concrete cured internally with thermostone material. The materials that adopted to evaluate and find out the influences of the internal curing on the mechanical properties of reactive powder concrete is focused with different curing methods such as in water, air and combined water and air. Thermostone aggregate are used as partial sand replacement by volume with different percentages to explore the percentage that effects of the concrete mechanical properties. Test results showed that the best partial replacement by thermostone is 5% gave enhancement and increase in compressive strength and flexural resistance strength (modulus of rupture) and concrete density. Highest increasing of compressive strength is 10.07in case of 5% partial replacement at 90 days. In case of cured the specimens up to 90 days, the increase in modulus of rupture is 4.53%

The task of turning agricultural waste into practical construction and building materials has been placed before civil engineers. Coffee husk is produced in vast amounts due to the global commerce of coffee beans, which are incinerated into ash when used as fuel, producing coffee husk ash (CHA). Even though many researchers have worked on the utilization of CHA in concrete, they have been used as partial cement replacement but not as a replacement of aggregates. The experimental study of the performance of concrete on fine aggregate replaced partially with CHA is represented in this paper. The fine aggregate is replaced by 0%, 2%, 4%, 6%, and 8% by weight of CHA. The performance of the partially replaced fine aggregate with CHA is reviewed by considering the compressive strength and workability of fresh concrete and the splitting tensile strength, flexural strength, durability under acid and alkaline media, thermal conductivity, and rapid chloride permeability test of hardened concrete. The results indicate that the partial replacement of fine aggregate with 4% of CHA (CHA04) in concrete provides a positive impact to all the selected performance parameters. The compressive strength, flexural strength, and splitting tensile of the CHA04 mix were 43.4 MPa, 3.7 MPa, and 2.44 MPa, respectively, which were 28.4%, 19.35%, and 1.66%, respectively, greater than normal concrete mix (CHA00). Even the study of acid and alkaline attack on the CHA04 mix showed lesser strength reduction as compared to other mixes. The RCPT showed less chloride permeability, and the thermal conductivity is higher for CHA04, indicating lesser voids compared to other mixes. With the help of this investigation, it can be said that fine aggregate replacement with 4% CHA has the best strength and durability properties compared to regular concrete.