Sulphuric Acid Attack Research Articles

Influence of Steel and Poly Vinyl Alcohol Fibers on the Development of High-Strength Geopolymer Concrete

The present study focuses on the mechanical performance of steel and polyvinyl alcohol fibers embedded in the geopolymer matrix. A high-strength geopolymer concrete with fly ash, slag and silica fume as precursors and sodium hydroxide and sodium silicate solutions as activators has been tested for its strength in compression and flexure. The influence of fibers on flowability, long-term shrinkage and sulphuric acid attack on the geopolymer concrete has also been studied. The dosage of fibers was maintained at 1%, 2% and 3% by volume, and fibers of length 13 mm have been used in the study. Results indicate that slag with 3% steel fibers by volume had a predominant influence on the strength development of steel fiber-reinforced geopolymer concrete, yielding a compressive strength of 107 MPa after 28 days. Blast furnace slag resulted in increasing the shrinkage of concrete due to rapid gel formation owing to the presence of calcium ions, although the fibers helped reduce the shrinkage to some extent. The strength of steel fiber geopolymer concrete was superior to PVA fiber geopolymer concrete; however, after an acid attack, the strength of steel fiber geopolymer concrete was reduced more than PVA fiber geopolymer concrete due to the enhanced corrosion resistance of PVA fibers.

Degradation effects in concrete bound ferrochrome slag under aggressive sulphuric acid and sulphate attack

Degradation effects in concrete bound ferrochrome slag under aggressive sulphuric acid and sulphate attack

Studies on Effect of Sulphuric Acid Attack on Concrete Made with Colloidal Silica as Replacement and Addition to Cement

Studies on Effect of Sulphuric Acid Attack on Concrete Made with Colloidal Silica as Replacement and Addition to Cement

Durability of organic blended lime mortar and its shear bond strength in brick masonry

Durability of historical structures is one of the most significant parameters that is appreciable and is of utmost importance. From studies conducted earlier it has been witnessed that the lime mortar used in these structures is embedded with organic additives that has enhanced the different properties of the mortar. Therefore, understanding the behaviour of these additives and their impact on the durability of the mortar is of significance use. To witness the effect of an additives on the mortar, jaggery, egg, and jute are taken as organic additives in the present study. To determine the durability properties of these organic-based lime mortar, acid attack, alkali attack, and wetting and drying tests has been performed. Further, the bond strength of these organic lime mortar in brick masonry has been examined by performing a triplet test. According to the sulphuric acid attack test, the lime mortar with jute as an additive has shown the best results with only a 5% loss in strength which is 23 % in lime mortar without any additive. In the alkali resistance test also, jute has shown exceptional behaviour with a strength loss of 1.5% which is 22% in lime mortar without additive. In the triplet test, the shear bond strength of jaggery-based mortar is 27.77% higher than the mortar without additive, hence showing the best result in the shear bond test. These results can be used in the studies conducted to repair and reconstruction of our heritage structures that need to be revived.

Evaluating resistance of ceramic waste tile self-compacting concrete to sulphuric acid attack

Ceramic waste tile aggregates produced from mixed coloured tile were utilized in self-compacting concrete (SCC). This research was aimed at assessing the performance of SCC in sulphuric acid environment by introducing ceramic waste tile (CWT) as natural fine aggregate replacement in different ratios (0%, 20%, 40%, 60%, 80% and 100%). SCC samples were exposed to a 3% sulphuric acid solution for 7, 28, 90 and 180 days. The transformation of mass, compressive strength, and micro-structure were used to assess the performance of concrete. It was discovered that CWT was sacrificial in nature when the SCC samples were subjected to an acidic environment, which helped to prevent damage to the cement hydration components that provided the strength. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) showed that the presence of CWT led to substantially less damage to the hydration products. Furthermore, the increment in replacement level after 60% has shown an increment of void ratio, leading to reduction in preliminary mechanical characteristics. It was concluded that 60% replacement level may provide the highest optimum performance in terms of compressive strength and sulphuric acid resistance. According to economic and ecological studies, SCC mixtures that comprise CWT are economical and have lower embodied energy and lesser CO2 emissions.

Effect of magnesium sulphate and sulphuric acid attack on limestone calcined clay cement concrete

The production of cement results in significant CO2 emissions into the atmosphere, contributing to the problem of global warming. This problem can be partially solved by using ground calcined clay-limestone (GCCL) cement concrete. The paper describes an experimental study of the performance of GCCL cement concrete in a sulphate and acidic environment. The GCCL concrete is made of using mixture of clinkers: ground calcined clay: low grade of limestone: gypsum in proportion as 50:30:15:5. Weight loss, compressive strength, and microstructure of GCCL concrete were investigated and compared with Ordinary Portland Cement (OPC) concrete. The microstructures of GCCL and OPC concrete has been observed using scanning electron microscope (SEM) images. GCCL concrete shows better strength properties than concrete prepared with OPC. At 0.5 w/c ratio, 28 days, 56 days, and 90 days GCCL concrete exhibited strength loss was 3.36%, 6.16%, and 12.33 % respectively after immersion in magnesium sulphate solution while strength loss was 9.32%, 17.44%, and 19.84% respectively observed after immersion in H2SO4 solution. Similarly, weight loss of GCCL concrete exhibited higher resistance to sulphate and acid attack than as compared to OPC concrete.

Mechanical and Durability Properties of CCD-Optimised Fibre-Reinforced Self-Compacting Concrete

The accelerated advancement of industrialization, urbanization, and technology produces an enormous amount of waste materials that are channelled into the environment, contaminating the soil, water and air. This exceedingly large volume of waste in the planet’s environment has made it challenging and difficult to handle; thus, it is urgent to facilitate alternative methods of waste disposal. Moreover, the consumption of concrete raw materials increases as a consequence of a sudden increase in concrete usage. In this study, printed circuit boards (PCB), cutting waste (e-waste) (0%, 5%, 10%, 15%, 20%) and recycled concrete aggregate (construction and demolition waste) (0%, 20%, 40%, 60%, 80%, 100%) replace the fine and coarse aggregate; this is utilised in the making of self-compacting concrete (SCC). To mitigate the impact of shrinkage and micro-cracks produced during loading, synthetic fibres (polypropylene fibres) (0%, 0.25%, 0.5%, 0.75%, 1%) are incorporated into the dense matrix of concrete. Based on the experiments conducted, it is concluded that the optimum percentages of e-waste, recycled aggregate and synthetic fibres are 10%, 60% and 0.5%, respectively. It is proposed to use response surface methodology for the statistical modelling of fibre-reinforced self-compacting concrete (FRSCC) ingredients, which will diminish the number of experiments conducted during optimisation. Experimental optimisation of ingredients was carried out by determining the workability properties (slump flow, L-Box, V-Funnel and Sieve test), strength properties (compressive, split tensile, flexural at 7, 14, 28 days of curing) and durability properties against chemical exposure (sulphuric and hydrochloric acid attack, sulphate attack at 29 and 90 days of immersion). In the statistical optimisation process, the central composite design (CCD) is utilised, and it is concluded that the optimum percentages of e-waste, recycled aggregate and synthetic fibres are 9.90%, 51.35% and 0.503%, respectively, as these produce a compressive strength (CS) of 47.02 MPa at the end of the 28th day of curing, whereas FRSCC created with experimentally optimised ingredients shows a strength of 46.79 MPa with the use of 60% of recycled aggregate, 10% of e-waste and 0.5% polypropylene fibre. Hence, it is observed that the CCD-optimised ingredients were the optimum dosage of ingredients based on the compressive strength values at 28 days. It is concluded that the FRSCC specimens created with CCD-optimised parameters show better resistance against loading and chemical exposure, as these show minimum weight and strength loss when compared to FRSCC with experimentally optimised parameters.

Enhanced chemical resistance to sulphuric acid attack by reinforcing Graphene Oxide in Ordinary and Portland Pozzolana cement mortars

Concrete when exposed to aggressive environmental conditions cause significant damage to the structures which substantially reduces its durability properties. The addition of nanofillers can improve hydration properties and hence improve fresh, hardened, and durability properties. In this study, two types of cements such as Ordinary Portland Cement (OPC) and Portland Pozzolana fly ash-based cement (PPC) were reinforced with Graphene Oxide (GO) to check the chemical resistance towards 5% Sulphuric acid exposure. Initial investigations such as surface characteristics and pore size measurements were analyzed through Brunauer- Emmett- Teller (BET) analysis. The resistance to Sulphuric acid attack is assessed through the change in dimensions, mass, visual observations, un-effected depth by microscopic observations, and loss in flexural strength of acid-exposed specimens. The further obtained reaction products were characterized through Field Emission Scanning Electron Microscopy (FESEM), X-ray Diffraction Analysis (XRD), Fourier Transform Infrared-ray Spectroscopy (FTIR), and Thermogravimetric Analysis (TGA) investigations. The addition of GO improved hydration and formed dense microstructure which enhanced the resistance to acid attack by measuring the change in length, cross-section, and weight loss after the acid attack. 0.04% GO addition improved 24.5% and 1.7% flexural strength after the acid attack. The formation of flower-like crystals by the addition of GO improved better resistance to acid attack confirmed through FESEM morphology. The results obtained showed GO has the potential in improving porosity characteristics by enhancing hydration characteristics. GO helped in enhancing flexural strength and improved microstructure after 28 days of acid exposure in OPC and PPC composites. The overall results showed improved resistance characteristics to Sulphuric acid attack by reinforcing optimum GO content in enhancing hydration and microstructure in OPC and PPC composites.

Influence of Sulphuric Acid on the Compressive Strength of Ternary Blended Geopolymer Mortar

The deteriorating effect of acid media on cement based constructions has become a worrying problem all over the world. These media generally occur as solutions in various branches of the industry, acid rains and mists, and acid ground-waters. A very popular form of acid attack on concrete that is usually referred to as biogenic sulphuric acid attack also occurs in both industrial and urban sewer systems. The emergence of new cementitious materials, like geopolymer cements, during the past decades necessitates detailed experimental work and research activities to investigate their durability in aggressive acid environments. The study therefore explored the development of alkali-activated CPA-SHA-MK ternary blended geopolymer mortar (GPM) using sodium silicate (Na2Si3) and sodium hydroxide (NAOH) solutions with 9M constant concentration as alkaline activators under both the aggressive and ambient-temperature curing media. The mass ratio of sodium silicate to sodium hydroxide (NS: NH) and as well as the binder to fine aggregate were fixed at 2.5 and 0.8 respectively. The durability of the ternary blended geopolymer mortar was examined through acid resistance test using 50 mm cubes after 28, 56 and 90 days of curing. The results revealed that the setting time prolonged as the replacement levels of RHA-MK increased at a decrease in the replacement levels of CPA. The results also showed that both the PCM and GPM samples studied suffered mass and strength losses in the acid solution and the loss increases at an increase in the hydration periods. The strength losses were observed to be higher in PCM mix (12.19 N/mm2 at 90 days) as compared to the GPMs (6.67 N/mm2 at 90 days) while the mix incorporated 50% CPA, 33% MK and 17% RHA (C50M33R17) was observed to be better compared to other mixes in durability behaviour. The study therefore recommends C50M33R17 mix proportion for good durability performance.

Effective Microorganism Solution and High Volume of Fly Ash Blended Sustainable Bio-Concrete.

Currently, the production of sustainable concrete with high strength, durability, and fewer environmental problems has become a priority of concrete industries worldwide. Based on this fact, the effective microorganism (EM) solution was included in the concrete mixtures to modify the engineering properties. Concrete specimens prepared with 50% fly ash (FA) as an ordinary Portland cement (OPC) replacement were considered as the control sample. The influence of EM solution inclusion (at various contents of 0, 5, 10, 15, 20, and 25% weight) in the cement matrix as water replacement was examined to determine the optimum ratio that can enhance the early and late strength of the proposed bio-concrete. The compressive strength, porosity, carbonation depth, resistance to sulphuric acid attack, and the environmental benefits of the prepared bio-concrete were evaluated. The results showed that the mechanical properties and durability performance of the bio-concrete were improved due to the addition of EM and FA. Furthermore, the inclusion of 10% EM could increase the compressive strength of the bio-concrete at 3 (early) and 28 days by 42.5% and 14.6%, respectively. The durability performance revealed a similar trend wherein the addition of 50% FA and 10% EM into the bio-concrete could improve its resistance against acid attack by 35.1% compared to the control specimen. The concrete mix designed with 10% EM was discerned to be optimum, with approximately 49.3% lower carbon dioxide emission compared to traditional cement.

Durability Aspects of Geo-Polymer Mortar Using Single Alkaline Activator Solution

The present study mainly focuses on durability aspects of combination of fly Ash and GGBS based geo-polymer mortar were investigated by immersing the mortar cubes in sea water and against 5% sulphuric acid attack. To carry out the experimentation a single alkaline activator solution of sodium silicate (Na2SiO3) was used to produce geo-polymer mortar specimens. In this, varied parameters are mix proportion of fly ash and GGBS and binder (fly ash + GGBS) to fine aggregate selected as 1:1 and 1:3. Similarly alkaline to binder ratio are 0.45and 0.60 respectively. Casted specimens of size 100mmx100mmx100mm and tested for 7 days and 28 days and cured under ambient temperature. In this experimentation varied mix proportions are (100 % FA-0 % GGBS, 75 % FA-25 % GGBS, 50 % FA-50% GGBS, 25 % FA-75 % GGBS, and 0% FA-100 % GGBS). The mixes with higher GGBS content shows greater mass loss and strength degradation when the cubes were immersed in sulphuric acid solution. The obtained results shows that the immersed specimens in sea water shows very less mass loss and strength loss when compared with specimens immersed in sulphuric acid solution.

Fly ash geopolymer concrete durability to sulphate, acid and peat attack

The durability of concrete has a profound impact on the service life of structural elements. Indonesia has extensive peat soils, which provide a highly aggressive environment for concrete structures. Geopolymer concrete has demonstrated good durability when exposed to acid /sulphate conditions similar to those encountered in peat soils. This paper investigates the performance of geopolymer concretes produced using Indonesian type F fly ash under sulphate and acid chemical attack. Geopolymer concrete specimens have been exposed for 12-months in a range of solutions: 5% sodium sulphate, 5% magnesium sulphate, 1% and 3% sulphuric acid, and simulated peat solution. The mechanical and durability properties of specimens together with a control concrete have been monitored for compressive strength, change in mass, water absorption and volume of permeable voids, ultra pulse velocity, air and water permeability, pH profile, and microstructural analysis (XRD, SEM/EDS). The control immersed in water achieved 56.93 MPa at 12-months of age. Magnesium sulphate exposure had a significant deterioration impact on the compressive strength of geopolymer concrete, demonstrating an 11% reduction in strength, while those exposed to sodium sulphate had an 8.9% increase in strength. Specimens exposed to peat solution displayed a slightly increased strength and those in acid conditions a 1.2% and 4.5% decrease in 1% acid and 3% acid, respectively. In general, the geopolymer concrete displayed a high level of resistance against sodium sulphate, 1% sulphuric acid and simulated peat attack.

Self-compacting concrete between workability performance and engineering properties using natural stone wastes

The current work aims at studying the chemical and mineralogical composition in addition to the physical properties of natural stone wastes as cement replacement and their effect on the fresh and hardened properties of self-compacting concretes (SCC). In the present study, two types of natural stone wastes were used: carbonaceous stone wastes (C) and siliceous stone wastes (S). The chemical, mineralogical, and physical characterization of the different wastes were performed using X-ray fluorescence (XRF), X-ray diffraction (XRD), water pycnometer, and Specific surface area.Nine SCC mixes coded (Ref., C10, 20, 30, 40% - S10, 20, 30, 40%) were formulated by incorporating four proportions of each type of the stone wastes other than the reference mix. The initial and final setting times, fresh density, air content, flowing - ability by slump flow, filling ability by T500 and V-funnel time, passing ability by L-box, U-box, and block assessment by J-ring were measured for the fresh mixes. For the hardened mixes, the water absorption, density, voids, compressive, flexure, and splitting tensile strengths were tested, in addition to their resistances against water penetration and chloride ion penetration, as well as sulfuric acid attack.The results revealed a slight to noticeable enhancement in the workability performance of SCCs with increasing stone wastes proportions. Using up to 40% stone wastes led to an increase in the flow- and passing-abilities by not less than (1.45%, 4.88%), while decreasing in the filling times by not less than (7.14%, 30%) as compared to the reference mix with a slight sign of bleeding and lacking an evidence of segregation or blocking.Using up to 10% stone wastes has an insignificant drop in the water absorption and density, compressive, flexure, and splitting tensile strengths values by not more than (1.64%, 0.42%, 3.65%, 3.88%, 10.51%), respectively at late age. A better resistance toward the sulphuric acid attack, in terms of strength and mass loss, was noticed for all replacement levels by not less than (17%, 13%), respectively at maximum exposure time, as compared to the reference mix.

Mechanical properties and durability for concrete using waste heat resistance glass (Pyrex Type) as coarse aggregate

this study aims to investigate some mechanical properties along with durability against several sever environmental conditions of concrete using waste heat resistant glass (Pyrex glass) as a replacement of coarse aggregate with several replacement ratios. Study shows higher mechanical properties improvements by using this type of aggregate, compressive, tensile and flexural strengths were improved by 20%, 54% and 230% respectively by 75% replacement. Moreover, modulus of elasticity was also investigated, it was found that it is also increased from 2.3234 GPa for reference mixes to 2.8452 GPa for mixes with 75% aggregate replacement. The study also includes durability investigations against several severe environmentally conditions which are: acid attack and fire exposure, study shows significant improvement in resistance of Pyrex aggregate concrete against both sulphuric acid attack and fire exposure comparing with normal concrete.

Behaviour of Fly ash and Metakaolin Based Composite Fiber (Glass and Polypropylene) Reinforced High Performance Concrete under Acid Attack

Improvements in concrete properties have been achieved by researchers with the invention of High-Performance-Concrete (HPC), which can now be improvised by using a combination of mineral admixtures. HPC is usually more brittle which can be made ductile by modifying its composition by adding fibers in the design mix, which led to the development of fiber-reinforced concrete. High-Performance-Concrete made with glass fibers and polypropylene fibers is regarded as Composite Fibre (Glass and polypropylene) Reinforced High Performance Concrete (CFRHPC). The development of cost-effective state-of-the-art procedures for producing, evaluating, and designing with CFRHPC will enhance the performance for each performance characteristic and can be reliably achieved in the field. This investigation evaluates the effect of cement being partially replaced by combined fly ash and metakaolin with glass fibers and polypropylene fibers as an addition to produce high-performance concrete with composite fiber for resistance to hydrochloric acid, magnesium sulphate, and sulphuric acid attack for 30, 60, and 90 days. The water to binder ratios (W/B) of 0.275, 0.300, 0.325, and 0.350 and an aggregate to binder ratio (A/B) of 1.75 were adopted. Fly ash and metakaolin were replaced in the range from 0% to 15% each, glass fibers were added in volume percentages from 0% to 1%, and polypropylene fibers were kept constant at 0.25%. The combined effect of fly ash and metakaolin at 5% each as replacement of cement and the addition of composite fiber dosage of glass fiber=1% and polypropylene fibers=0.25% for W/B of 0.275 was found to be the optimum combination to obtain maximum acid attack resistance, which was also justified by SEM, EDX, and XRD analysis done in this investigation. CFRHPC production minimizes enormous cement production and safeguards the environment from pollution and concrete from environmental pollution throughout its service life.

Unusual Perforations in Phlogopite Crystals from Caldara di Manziana (Italy) Caused by Sulphuric Acid Generated by Microbial Oxidation of H2S Emanations

Phlogopite flakes strewn on the soil of Caldara di Manziana (Italy) display multiple minute perforations. The site is a caldera linked to recent volcanism (90 ka to 0.8 Ma) with present emanations of CO2 (~150 t d−1) and H2S (~2.55 t d−1). Stereomicroscopy and SEM–EDX observation of the phlogopite crystals shows holes and depressions <200 µm to 2 mm across. They are circular, pseudo-hexagonal, or irregular. Within the depressions, there are deposits of phlogopite alteration products consistent with a sulphuric acid attack, showing loss of Mg and K. Some are thin and homogeneous; others are thick, irregular, and chemically heterogeneous, including plates, flakes, tubes of Fe-beidellite or Fe-bearing halloysite, silica, Fe oxides, and gypsum. Areas of phlogopite surface are also altered. Sulphuric acid is produced from the H2S gas by the mediation of sulphur-oxidizing bacteria. Pseudo-hexagonal perforations are interpreted to result from slow acid attack with dissolution controlled by phlogopite crystal symmetry. Some depressions developed surrounding films of pseudo-hexagonal shape, interpreted as jarosite crystallizing radially outwards from the depressions. This style of acid attack is possibly promoted by local high humidity and precipitation that generate long-lived water droplets and films on mineral surfaces where sulphuric acid is active for prolonged times.

Improved performance of concrete incorporated with natural zeolite powder as supplementary cementitious material

Blended cement containing natural zeolite powder exhibits improved performance & resistance to concrete against aggressive environmental attacks. Concrete structures when exposed to aggressive environments possess several negative impacts due to migration of chloride & sulphate ions, carbonation, acid attack, etc. Due to these, exposures the concrete structure lose their strength gradually, which results in the decreased life span. At present, research work focused on the influence of lower w/b ratios on higher replacement levels of zeolite on the performance of concrete in mechanical & durability aspects. And this study also attempts to generate quantitative data & understand the relationship between lower water-binder ratios 0.30 & 0.40 and higher replacement levels 30%, 40% of zeolite & compressive strength. Mechanical aspects such as compressive strength, split tensile strength, flexural strength tests. Durability aspects like chloride attack through Rapid chloride penetration test (RCPT), Sulphuric acid attack. Magnesium sulphate attack, tests were carried out. Altogether, in the practical point of view test results revealed that concrete incorporating natural zeolite powder gets substantial compressive strength beyond the 28-day period, i.e., strength increases gradually with respect to time. Improvement is noticed at a low water-binder ratio. Increases resistance against chloride, sulphate attacks.

Compressive Strength and Durability Properties of M35 Grade Concrete by Replacing Sand Partially with Vermiculite and Granite Powder and Coarse Aggregate by Re-Cycled Aggregate

The Construction Industry is one of the industries contributing highest GDP in Indian economy. The material that is most chosen in construction Industry is concrete. Concrete is a material made with Cement, Fine aggregate in the form of sand, Coarse aggregate in the form of gravel and water. With increasing scarcity of sand, construction works are coming to jolt and thereby increasing the need for choosing an alternative material. Vermiculite is a material which after exfoliation can be used as a filler material replacing sand partially without affecting strength much. One more material Granite (by product which is a waste is causing lot of environmental Issues), produced from granite industry, is available in India in several million tons. Coarse aggregate generally used is a crushed aggregate obtained from rocks like granite, basalt and soon. Recycled aggregate is an aggregate which is obtained after demolishing of an existing building, which is a waste causing economical in balance and which if put into use can not only decrease the construction cost but also make this waste into a better use. In the present study, for a M35 grade of concrete, Vermiculite (0, 5%, 10% and 15% of weight of sand) and granite powder (fixed at 10% of weight of sand used) is used to replace sand partially and in the place of normal coarse aggregate, recycled aggregate is used which is 20 mm passing and 12 mm retained After preparation of Mix-Design(1:1.83:2.69 with w/c ratio of 0.38) the concrete cubes are casted to test for compressive strength after curing for 28 days, 56 days and 90 days. Forsec brand super plasticizer is used to take care of workability requirements. Durability test in the form of resistance to attack of sulphuric acid was conducted along with compressive strength. The test results were promising at 10% replacement levels of Vermiculite.

Piezoresistivity deterioration of smart graphene nanoplate/cement-based sensors subjected to sulphuric acid attack

Smart cement-based sensors with self-sensing capacity have been explored for structural health monitoring (SHM) with the intrinsic piezoresistive performance. However, few studies had studied the piezoresistivity degradation of cement-based sensors after exposure to the aggressive environments, especially under sulphate acid attacks. In this study, graphene nanoplate (GNP)/cementitious composites were immersed in sulphuric acid solutions (concentrations of 0, 1%, 2%, and 3%) for 90 and 180 days. Then surface appearance, weight loss, mechanical properties, piezoresistivity and microstructure were investigated and compared before and after sulphuric acid immersion. The results show that after acid immersion, the surface deterioration and mass loss were increased, and the compressive strength was significantly decreased. As for the intact GNP/cementitious composite, the piezoresistivity exhibited excellent linearity and repeatability, demonstrating the great potential to act as intelligent cement-based sensors for SHM. After 90 and 180 days of acid immersion, the piezoresistivity was sensitive to the initial low load initially but then turned less sensitive to the later high load. The highly corroded GNP/cementitious composites exhibited porous microstructures associated with the low compressive strength. The fractional changes to resistivity (FCR) under the low load could be attributed to the compressed pores and voids filled with erosion products that would form conductive passages. In contrast, with the increase of applied load, the intact cement matrix became much denser, which in turn constrained the further development of conductive passages in the GNP/cementitious composites.

Sulphuric Acid Resistance of Slag Geopolymer Concrete Modified with Fly Ash and Silica Fume

This work is an experimental study on sulphuric acid resistance of geopolymer concrete. The main variables considered throughout the research program were fly ash content from 0.0 to 40% and silica fume content as replacement of quenched slag in addition to sodium hydroxide molarity and added water content. These variables were studied through 18 mixes. Compressive strength loss, weight loss, absorption, SEM, and X-ray diffraction analysis tests were used to evaluate acid resistance. From the test results, the use of slag geopolymer concrete showed the best sulphuric acid attack resistance compared with those containing fly ash and silica fume.