Ehsan Mohseni

Chloride Diffusion and Acid Resistance of Concrete Containing Zeolite and Tuff as Partial Replacements of Cement and Sand

In this paper, the properties of concrete containing zeolite and tuff as partial replacements of cement and sand were studied. The compressive strength, water absorption, chloride ion diffusion and resistance to acid environments of concretes made with zeolite at proportions of 10% and 15% of binder and tuff at ratios of 5%, 10% and 15% of fine aggregate were investigated. The results showed that the compressive strength of samples with zeolite and tuff increased considerably. In general, the concrete strength increased with increasing tuff content, and the strength was further improved when cement was replaced by zeolite. According to the water absorption results, specimens with zeolite showed the lowest water absorption values. With the incorporation of tuff and zeolite, the chloride resistance of specimens was enhanced significantly. In terms of the water absorption and chloride diffusion results, the most favorable replacement of cement and sand was 10% zeolite and 15% tuff, respectively. However, the resistance to acid attack reduced due to the absorbing characteristic and calcareous nature of the tuff.

An experimental investigation into the effects of Cr2O3 and ZnO2 nanoparticles on the mechanical properties and durability of self-compacting mortar

Abstract In this paper, the effects of using Cr2O3 and ZnO2 nanoparticles on the mechanical properties and durability of self-compacting mortars are investigated. A fraction of Portland cement was replaced with 1, 2, 3, 4 or 5 wt.% of either Cr2O3 or ZnO2 nanoparticles, and 25 wt.% fly ash. The rheological properties of these mortars were determined through the mini-slump flow diameter and V-funnel flow time tests. The mechanical and durability characteristics were evaluated by compressive and flexural strength, water absorption, electrical resistivity and rapid chloride permeability tests. The microstructure of the mortars was assessed through the use of scanning electron microscopy. The inclusion of 2 wt.% Cr2O3 or 4 wt.% ZnO2 nanoparticles had the best result in compressive and flexural strength tests. Also, mixtures containing either 3 wt.% of Cr2O3 or 5 wt.% of ZnO2 nanoparticles obtained the best result in terms of durability. It can be deduced that the properties of these mixtures are significantly improved by the addition of Cr2O3 and ZnO2 nanoparticles.

Combined Effects of Metakaolin, Rice Husk Ash, and Polypropylene Fiber on the Engineering Properties and Microstructure of Mortar

AbstractThis paper reports an experimental study carried out to investigate the effects of using metakaolin (MK) and rice husk ash (RHA) as a partial replacement material for cement, and polypropyl...

Durability Characteristics of Self-Compacting Concrete Incorporating Pumice and Metakaolin

AbstractIn this study, the effects of pumice and metakaolin (MK) on the durability and microstructural properties of self-compacting concrete (SCC) are investigated. A total of 10 mixtures includin...

Effect of Nano-CuO on Engineering and Microstructure Properties of Fibre-Reinforced Mortars Incorporating Metakaolin: Experimental and Numerical Studies

In this study, the effects of nano-CuO (NC) on engineering properties of fibre-reinforced mortars incorporating metakaolin (MK) were investigated. The effects of polypropylene fibre (PP) were also examined. A total of twenty-six mixtures were prepared. The experimental results were compared with numerical results obtained by adaptive neuro-fuzzy inference system (ANFIS) and Primal Estimated sub-GrAdient Solver for SVM (Pegasos) algorithm. Scanning Electron Microscope (SEM) was also employed to investigate the microstructure of the cement matrix. The mechanical test results showed that both compressive and flexural strengths of cement mortars decreased with the increase of MK content, however the strength values increased significantly with increasing NC content in the mixture. The water absorption of samples decreased remarkably with increasing NC particles in the mixture. When PP fibres were added, the strengths of cement mortars were further enhanced accompanied with lower water absorption values. The addition of 2 wt % and 3 wt % nanoparticles in cement mortar led to a positive contribution to strength and resistance to water absorption. Mixture of PP-MK10NC3 indicated the best results for both compressive and flexural strengths at 28 and 90 days. SEM images illustrated that the morphology of cement matrix became more porous with increasing MK content, but the porosity reduced with the inclusion of NC. In addition, it is evident from the SEM images that more cement hydration products adhered onto the surface of fibres, which would improve the fibre–matrix interface. The numerical results obtained by ANFIS and Pegasos were close to the experimental results. The value of R2 obtained for each data set (validate, test and train) was higher than 0.90 and the values of mean absolute percentage error (MAPE) and the relative root mean squared error (PRMSE) were near zero. The ANFIS and Pegasos models can be used to predict the mechanical properties and water absorptions of fibre-reinforced mortars with MK and NC.

Effectiveness of different recycled materials in self-compacting mortar

Using recycled materials in concrete is a way to make the process of making concrete more economical and environmental. The use of non-renewable resources for construction is a major concern that has irreparable result for the environment. In this study, mechanical properties of self-compacting mortars containing waste materials such as recycled bricks (RB), concrete (RC), ceramics (RR) and tiles (RT) were investigated. The substitution percentage of waste material was 5, 10 and 15% replacing cement. Incorporating super plasticizer (SP) on different properties of samples was evaluated. The results of fresh mortars and also compressive strength and water absorption were assessed. The compressive strength of samples decreased slightly by using waste materials. However the percentage of decrease was between 3 and 17% that does not cause major disasters to the samples. Also water absorption results indicated an increase as waste materials were incorporated. The obtained results demonstrated that the properties of samples have only a slight difference, and that the recycled materials can successfully be utilised for making of self-compacting concrete. This innovative procedure and findings and recommendations of this research can contribute to boosting the use of recycled aggregates in the construction sector and make it a sustainable activity.

Engineering and Microstructural Properties of Fiber-Reinforced Rice Husk–Ash Based Geopolymer Concrete

AbstractThe concrete industry is a remarkable point source of carbon dioxide emission due to the disintegration of raw materials and burning of fuel during the cement manufacturing process. One eff...

Structural-functional integrated concrete with macro-encapsulated inorganic PCM

Over the last few years the application of thermal energy storage system incorporating phase change materials (PCMs) to foster productivity and efficiency of buildings energy has grown rapidly. In this study, a structural-functional integrated concrete was developed using macro-encapsulated PCM-lightweight aggregate (LWA) as partial replacement (25 and 50% by volume) of coarse aggregate in control concrete. The PCM-LWA was prepared by incorporation of an inorganic PCM into porous LWAs through vacuum impregnation. The mechanical and thermal performance of PCM-LWA concrete were studied. The test results revealed that though the compressive strength of concrete with PCM-LWA was lower than the control concrete, but ranged from 22.02 MPa to 42.88 MPa which above the minimum strength requirement for structural application. The thermal performance test indicated that macro-encapsulated PCM-LWA has underwent the phase change transition reducing the indoor temperature.