Bentonite Clay Modified Concrete

Replacing cement with pozzolanic materials to some extent in construction is found to be one of the sustainable approaches in the construction industry. Pozzolanic materials of industrial origin like fly ash and Ground Granulated Blast furnace Slag will have to be replaced with natural pozzolanic materials once the world moves towards renewable energy sources. Bentonite is one such pozzolanic clay material that is rich in SiO2 content. A little research was made to assess the performance of bentonite modified concrete. Based on those, an improvement in the fresh, hardened, durability properties was reported. This chapter presents the current scenario on the development of bentonite modified concrete. It also reviews the literature about the physical & chemical properties of bentonite, bentonite blended cement mortar, bentonite modified cement concrete, and reinforced concrete. The history and development of Bentonite modified concrete were also briefly presented in this chapter

A Comprehensive Review on Sustainable Natural Fiber in Cementitious Composites: The Date Palm Fiber Case

The use of natural fibers in cementitious composites continue gaining acceptability and applicability due to the shortcomings and disadvantages of synthetic fiber; this is because natural fibers have advantages of sustainability, eco-friendliness, and economy. Biodegradable natural fibers, being low density and lightweight, with typical values of strength-to-weight ratio, aspect ratio, elastic modulus, and strength, may be competitive for substituting synthetic fibers such as glass and carbon. Indeed, natural fibers are mostly non-irritating for the skin and typically pose no troubles or issues for breathing, which is not the case with many synthetic fibers. Date palm fiber (DPF) is a natural fiber obtained as waste material from a date palm tree. In many countries, with large date production, DPF is easily available as a process by-product, with a low processing cost. Being sustainable and environmentally friendly, DPF is continuously gaining acceptability as fiber material in different composites such as concrete, mortar, gypsum composites, clay composites, and bricks. Based on the most available literature reviewed, DPF reinforced composites have been found to be a good insulation material, with higher thermal properties, thereby reducing energy consumption which consequently saves the running and maintenance cost of the building. DPF reinforced composites were reported to have higher energy absorption capacity, ductility, and bending resistance, leading to delaying crack propagation and preventing catastrophic failures of structures such as beams and slabs. Additionally, due to its lower density, DPF reinforced composites have the advantage for usage in areas prone to seismic effects, and when used for buildings, the overall weight of the building is expected to reduce hence reduction in foundation cost. The major setback of using DPF in composites is the reduction in the compressive strength of the composites and the durability performance of the composites. Therefore, for effective usage of DPF in composites to derive the maximum benefits, there is a need to devise a method of mitigating its negative effects on the compressive strength and durability performance of the Composites; this is a future study that needs to be explored for better performance of DPF in cementitious and other materials composites

Properties of nano-silica modified pervious concrete

The aim of this study is to evaluate the effects of inclusion nano-silica (also known as nano-SiO2) on the properties of pervious concrete containing fly ash (FA) as a partial replacement to cement. It has been found, for cementitious paste, that incorporating NS leads to reduce the cumulative pore volume by 13.4%. While the compressive strength of NS modified pervious concrete has been improved without adversely affecting its void ratio and permeability. The workability has been adversely affected by the inclusion of NS, which can be enhanced by incorporating the fly ash and superplasticizer. The porosity of cementitious paste has increased as the FA content is increased. These results are in good agreement with SEM results. For the pervious concrete voids ratio, permeability and infiltration rate were decreased against the increase of paste to the aggregate ratio Response surface methodology (RSM) has also been used to develop a model for navigating the design space of NS modified pervious concrete. Models revealed 95% significance of confidence level with difference less than 0.2 between Pred R-Squared value of 0.9515 and Adj R-Squared. The general expression has been developed for all the responses with the different coefficients using the RSM. Keywords: Fly ash, Final setting time, Infiltration rate, Pervious concrete, Nano-silic

Effect of superplasticizer in geopolymer and alkali-activated cement mortar/concrete: A review

The cement and construction industry creates around 10% of the global carbon footprint. Geopolymer and alkali-activated concrete provide a sustainable solution to conventional concrete. Due to its disadvantages, the practical usage of geopolymer and alkali-activated concrete is limited. Workability is one of the issues faced in developing geopolymer and alkali-activated concretes. Plenty of research was conducted to provide a solution to enhance the ability to use different superplasticizers (SPs). The present article extensively reviews the effects of SPs on geopolymer and alkali-activated concretes. The research articles published in the last 5 years in high-quality journals are considered for the chemical composition of the different SPs and analyses of their exact impact on geopolymer and alkali-activated cement mortar and concrete. Later, the impact of SPs on the normal consistency and setting times of cement mortar, workability, compressive strength, flexural strength, split tensile strength, microstructure, and water absorption of geopolymer and alkali-activated concrete was determined. SPs improve the geopolymer and alkali-activated concretes upon their use in desired dosages; more dosage leads to negative effects. Therefore, selecting the optimal superplasticizer is essential since it impacts the performance of the geopolymer and alkali-activated concrete

Optimization of Graphene Oxide Incorporated in Fly Ash-Based Self-Compacting Concrete

Self-compacting concrete (SCC) was developed to overcome the challenges of concrete placement in dense or congested reinforcement structure, where the concrete can flow under its own weight to fill the densely reinforced structure. However, production of SCC mostly involves the use of high cement to achieve the desired strength. Therefore, to reduce the needed amount of cement, pozzolanic materials such as fly ash can be used to partially replace cement. However, fly ash has been reported to decrease the strengths of concrete especially at early ages. In this study, a self-compacting concrete (SCC) was developed with fly ash as a basic replacement material considering the efficiency of fly ash and incorporating graphene oxide (GO) as a cement additive to counteract the negative effect of fly ash. Response surface methodology (RSM) was utilized for designing the experiments, investigating the effects of fly ash and GO on SCC properties, and developing mathematical models for predicting mechanical properties of SCC. The ranges of fly ash and graphene oxide were 16.67 to 35% and zero to 0.05%, respectively. Statistical analysis was performed by using Design Expert software (version 11.0, Stat Ease Inc., Minneapolis, MS, USA). The results showed that fly ash had a positive effect while GO had a negative effect on the workability of SCC. The incorporation of fly ash alone decreased the compressive strength (CS), splitting tensile strength (STS) and flexural strength (FS), and additionally, increased the porosity of SCC. The addition of GO to fly ash-based SCC reduced its porosity and enhanced its mechanical strengths which was more pronounced at early ages. The developed models for predicting the mechanical strengths of fly ash-based SCC containing GO have a very high degree of correlation. Therefore, the models can predicts the strengths of SCC using fly ash and GO as the variables with a high level of accuracy. The findings show that based on the EFNARC guidelines, up to 35% of fly ash can be used to replace cement in SCC to achieve a mix with satisfactory flowability and deformability propertie

Optimization of Graphene Oxide Incorporated in Fly Ash-Based Self-Compacting Concrete

Self-compacting concrete (SCC) was developed to overcome the challenges of concrete placement in dense or congested reinforcement structure, where the concrete can flow under its own weight to fill the densely reinforced structure. However, production of SCC mostly involves the use of high cement to achieve the desired strength. Therefore, to reduce the needed amount of cement, pozzolanic materials such as fly ash can be used to partially replace cement. However, fly ash has been reported to decrease the strengths of concrete especially at early ages. In this study, a self-compacting concrete (SCC) was developed with fly ash as a basic replacement material considering the efficiency of fly ash and incorporating graphene oxide (GO) as a cement additive to counteract the negative effect of fly ash. Response surface methodology (RSM) was utilized for designing the experiments, investigating the effects of fly ash and GO on SCC properties, and developing mathematical models for predicting mechanical properties of SCC. The ranges of fly ash and graphene oxide were 16.67 to 35% and zero to 0.05%, respectively. Statistical analysis was performed by using Design Expert software (version 11.0, Stat Ease Inc., Minneapolis, MS, USA). The results showed that fly ash had a positive effect while GO had a negative effect on the workability of SCC. The incorporation of fly ash alone decreased the compressive strength (CS), splitting tensile strength (STS) and flexural strength (FS), and additionally, increased the porosity of SCC. The addition of GO to fly ash-based SCC reduced its porosity and enhanced its mechanical strengths which was more pronounced at early ages. The developed models for predicting the mechanical strengths of fly ash-based SCC containing GO have a very high degree of correlation. Therefore, the models can predicts the strengths of SCC using fly ash and GO as the variables with a high level of accuracy. The findings show that based on the EFNARC guidelines, up to 35% of fly ash can be used to replace cement in SCC to achieve a mix with satisfactory flowability and deformability propertie