[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

Mix design and mechanical properties of geopolymer and alkali activated concrete: Review of the state-of-the-art and the development of a new unified approach

Augmenting agility in production flow through ANP

Geopolymer concrete is an inorganic concrete that uses industrial or agro by-product ashes as the main binder instead of ordinary Portland cement; this leads to the geopolymer concrete being an eco-efficient and environmentally friendly construction material. A variety of ashes used as the binder in geopolymer concrete such as fly ash, ground granulated blast furnace slag, rice husk ash, metakaolin ash, and Palm oil fuel ash, fly ash was commonly consumed to prepare geopolymer concrete composites. The most important mechanical property for all types of concrete composites, including geopolymer concrete, is the compressive strength. However, in the structural design and construction field, the compressive strength of the concrete at 28 days is essential. Therefore, achieving an authoritative model for predicting the compressive strength of geopolymer concrete is necessary regarding saving time, energy, and cost-effectiveness. It gives guidance regarding scheduling the construction process and removal of formworks. In this study, Linear (LR), Non-Linear (NLR), and Multi-logistic (MLR) regression models were used to develop the predictive models for estimating the compressive strength of fly ash-based geopolymer concrete (FA-GPC). In this regard, a comprehensive dataset consists of 510 samples were collected in several academic research studies and analyzed to develop the models. In the modeling process, for the first time, twelve effective variable parameters on the compressive strength of the FA-GPC, including SiO2/Al2O3 (Si/Al) of fly ash binder, alkaline liquid to binder ratio (l/b), fly ash (FA) content, fine aggregate (F) content, coarse aggregate (C) content, sodium hydroxide (SH)content, sodium silicate (SS) content, (SS/SH), molarity (M), curing temperature (T), curing duration inside ovens (CD) and specimen ages (A) were considered as the modeling input parameters. Various statistical assessments such as Root Mean Squared Error (RMSE), Mean Absolute Error (MAE), Scatter Index (SI), OBJ value, and the Coefficient of determination (R2) were used to evaluate the efficiency of the developed models. The results indicated that the NLR model performed better for predicting the compressive strength of FA-GPC mixtures compared to the other models. Moreover, the sensitivity analysis demonstrated that the curing temperature, alkaline liquid to binder ratio, and sodium silicate content are the most affecting parameter for estimating the compressive strength of the FA-GPC.

/pdf/systematic-multiscale-models-to-predict-the-compressive-ijsvpxd157.pdf

Systematic multiscale models to predict the compressive strength of fly ash-based geopolymer concrete at various mixture proportions and curing regimes.

Study on the mechanical properties of the nanoconcrete using nano-TiO2 and nanoclay

Utilisation of fly ash and Ground Granulated Blast Slag as an alternative material in concrete reduces the use of OPC in concrete. Evolution of geopolymer concrete cured at ambient temperature broadens its suitability and applicability to concrete based structures. This paper presents the mix proportions and outcome of an experimental study on the density and compressive strength of geopolymer concrete. Fly ash was used as a base material which was made to react with sodium hydroxide and sodium silicate solution to act as a binder for fine and coarse aggregate. Ground Granulated Blast Slag was replaced in different proportions to fly ash to enhance various properties of concrete. The concrete was subjected to curing at ambient temperature. Based on the study carried out, replacement of GGBS in fly ash up to 50% produced better mechanical properties.

Mechanical Behaviour of Geopolymer Concrete under Ambient Curing

This paper presents the experimental investigation to evaluate the flexural performance of newly developed hybrid Engineered Cementitious Composite (ECC) layer at tension zone around the main reinforcement of beam. Four different ECC mixes are used in the beam to evaluate the flexural performance, hybrid ECC based on the low modulus poly vinyl alcohol (PVA) and high modulus steel short random fibre reinforcement. The aim of hybridation is to improve the flexural, energy absorption and ductility performance of reinforced concrete beams. In addition to the compressive strength, young’s modulus, uniaxial tensile strength and bond strength of ECC mixes are determined. ECC with PVA fibre with 2.0% volume fraction mix is kept as reference mix, hybridation is made with PVA (1.35%) and steel (0.65%), PVA (1.00%) and steel (1.00%) and finally with PVA (0.65%) and steel (1.35%). This hybridization has a remarkable achievement in mechanical properties and in the flexural behavior in ECC layered RC beam. From the results, it has been observed that mono fiber ECC reinforced with PVA of 2.0% and hybrid fiber ECC reinforced with 1.35 % of PVA fiber and 0.65% of steel fiber has reasonable flexural characteristics than the conventional beam.

/pdf/flexural-performance-of-hybrid-engineered-cementitious-241dzvzx39.pdf

Flexural Performance of Hybrid Engineered Cementitious Composite Layered Reinforced Concrete Beams

Abstract This study focuses to develop a new hybrid Engineered Cementitious Composite (ECC) and assesses the performance of a new hybrid ECC based on the steel short random fiber reinforcement. This hybrid ECC aims to improve the tensile strength of cementitious material and enhance better flexural performance in an RC beam. In this study, four different mixes have been investigated. ECC with Poly Vinyl Alcohol (PVA) fiber and PolyPropylene (PP) fiber of 2.0% volume fraction are the two Mono fiber mixes; ECC mix with PVA fiber of 0.65% volume fraction hybridized with steel fiber of 1.35% volume fraction, PP fiber of 0.65% volume fraction hybridized with steel of 1.35% volume fraction are the two additional different hybrid mixes. The material properties of mono fiber ECC with 2.0 % of PVA is kept as the reference mix in this study. The hybridization with fibers has a notable achievement on the uniaxial tensile strength, compressive strength, Young’s modulus, and flexural behavior in ECC layered RC beams. From the results, it has been observed that the mix with PVA fiber of 0.65% volume fraction hybrid with steel fiber of 1.35% volume fraction exhibit improvements in tensile strength, flexural strength, and energy absorption. The PP fiber of 0.65% volume fraction hybridized with steel of 1.35% volume fraction mix has reasonable flexural performance and notable achievement in displacement ductility over the reference mix.

/pdf/flexural-performance-of-engineered-cementitious-3p00ar1lot.pdf

Flexural performance of engineered cementitious compositelayered reinforced concrete beams

Typically, Concrete mixture is firm in Compression yet sickly in Tension and shear Reason for this examination is to discover the conduct of cement built up with half-breed full-scale strands By adding Luffa strands in rates like 05%, 1%, 15%& 2% to the solid, the mechanical properties are researched The ideal level of Luffa fiber was discovered to be 1% Marble has been generally utilized in structures since old occasions The current examination is pointed toward using waste marble dust (WMD) in development industry itself as fine total in solid, supplanting characteristic sand and furthermore by adding the ideal level of Luffa fiber The substitution is done halfway and completely in the different extents like 0%, 20%, 40%, 60% and 80% and its impact on properties of cement were examined The ideal level of the solid by adding 1% of Luffa fiber and the extents was discovered to be 20%

An Experimental Investigation of Marble Dust in Luffa Fibre Reinforced Concrete

The latest thesis deals with the issues of natural fiber in order to observe the strength properties and even a reduction in the replication of the shrinkage crack problemsin concrete. The organic fibers such as coir, palm, kenaf, jute, sisal, banana, pine, sugarcane and bamboo etc. Various researchers are studied as building materials that can be found in cement paste, mortar, concrete. It was observed that the results of few fiber are most promising and given below. The present work focuses to improve the ductility and strength properties of concrete on bringing out. The same proportions of different fibers cannot be changed by all the normal concrete. This research may include the characteristics, behaviors and consistency of the fibers between themselves. Finally, the study focuses solely on similarities and variations between all kind of natural fibers. The goal of this analysis is to provide an analysis of the factors influencing the overall performance and reliability. The proportions for comparisons and conclusion were studied.

A.R. Krishnaraja

Papers

Mechanical Behaviour of Geopolymer Concrete under Ambient Curing

Flexural Performance of Hybrid Engineered Cementitious Composite Layered Reinforced Concrete Beams

Flexural performance of engineered cementitious compositelayered reinforced concrete beams

An Experimental Investigation of Marble Dust in Luffa Fibre Reinforced Concrete

Natural Fibers in Concrete – A Review