Alkali-silicate Reaction Research Articles

High-ferrite Portland cement with glass–ceramic aggregates: Mechanical properties, durability, and interfacial transition zone

This study aimed to improve the durability of concrete in the marine environment through the utilization of waste glass-ceramics as aggregates. The investigation focused on their effects on the mechanical strength, chloride attack resistance, and abrasion resistance of high-ferrite Portland cement mortar (HFCM). Inductively coupled plasma, X-ray diffraction, scanning electron microscopy-backscattered electronic, and microhardness techniques analyzed the impacts of glass-ceramics on the interfacial transition zone’s (ITZ) composition, structure, and strength. Results demonstrated that glass–ceramic fine aggregates possessed low alkali activity, posing no potential risk of alkali silicate reaction. The partial substitution of natural sand with glass-ceramics improved HFCM’s mechanical strength and resistance to chloride attack and abrasion. The dissolution of trace amounts of Si4+ and Al3+ from the glass-ceramics contributed to the hydration reaction and facilitated the development of a compact and robust ITZ. Overall, HFCM with glass-ceramics effectively resisted the harsh marine environment, specifically against chloride ion erosion and wave erosion.

Role carbon nanomaterials in reinforcement of concrete and cement; A new perspective in civil engineering

Nanotechnology has resulted in many advantages in different majors of science and created new approaches to them. nanotechnology has more effect on civil engineering such as utilizing nanomaterials as cement reinforcement. The improvement in quality of materials used in civil engineering such as self-cleaning, self-structural health monitoring, self-sensing, self-vibration damping, self- rehabilitation, cement reinforcement, and self-healing created a new revolutionary civil engineering. Concrete is one of the important parts of civil engineering and especially in the discussion of building and bridge retrofitting. Nanotechnology plays an important role in the concrete process such as alkali silicate reactions (ASR), hydration reactions, and fly ash reactivity. Much of the research showed that nanomaterials improved compressive and flexural strength in concrete and created the best situation for building resistant structures such as bridges, towers, and tall buildings. Due to the mechanical behavior and tensile strength of carbon nanotubes (CNTs), these compounds play a special role in improving concrete properties. Prevention of cracking is one of the positive effects of using carbon nanotubes in improving concrete properties, which has increased significant growth in the application of it in the industry. The present review paper focused on the role of nanomaterials in improving and reinforcement of concrete and the advantages of them in civil engineering.

Effect of Calcium Salts on Alkali Silicate Reaction Products by Reactive Aggregate

アルカリシリカ反応のモデル骨材として使用される水ガラスカレットを用い，プロピオン酸カルシウムがアルカリ環境下の反応性骨材の挙動に及ぼす影響について基礎的な検討を行った。また，反応性骨材として安山岩系の天然砕石を用いた場合についてもその影響を検討するとともに，カルシウム塩の影響を評価するために塩化カルシウムおよび水酸化カルシウムについても検討した。その結果，水ガラスカレットだけでなく反応性骨材においてもプロピオン酸カルシウムによるアルカリシリカ反応の膨張抑制効果が確認された。また，塩化カルシウムを添加した場合にも膨張が抑制され，Ca成分の影響により反応生成物が変質し，吸水膨張性が低減している可能性が推測された。

Full uniaxial compressive stress–strain curve of high-performance concrete with ASR inhibition measures exposed to lye solution at 38 °C for 10 years

This study focuses on the long-term stress–strain relationship of high-performance concrete (HPC) containing alkali active aggregate using Alkali-Silicate reaction (ASR) inhibition measures. The experimental study is carried out on specimens under the action of standard alkaline solution (1 mol/L) at 38 °C for 10 years. HPC with strength class C40 to C60 in the range of 0.5 % to 1.9 % equivalent alkali content using alkali-activated aggregates and large dose mineral admixture suppression measures were used in the test. The basic mechanical properties and the full uniaxial compressive stress–strain curve were measured, and the correlation between the stress–strain curve and the equivalent alkali content of long-aged HPC with potential ASR hazard was discussed. The results show that HPC has certain ASR swelling characteristics when soaked in standard alkaline solution at 38 °C for 10 years. A mathematical model of the HPC uniaxial compressive stress–strain constitutive relation considering ASR damage is established.

Monitoring of Ion Mobility in the Cement Matrix to Establish Sensitivity to the ASR Caused by External Sources

The possibility of the formation of an alkali–silicate reaction (ASR) is a crucial issue for the service life of concrete. The coexistence of key parameters such as the presence of alkalis, reactive SiO2, humidity, and temperature predetermine the possibility of its formation and application. When an ASR gel forms, it results in the concreting cracking and spalling as well as in the deterioration of its overall properties. The risk of ASR depends on the concentration of alkalis and their mobility, which influence their ability to penetrate the concrete. The objective of this study was to determine the ionic mobility of not only Na+ and K+, but Ca2+ as well, from external sources (0.5 and 1.0 mol/L solutions of Na/K carbonate, nitrate, and hydroxide) to a cementitious matrix as the precursor for ASR. The concentrations of ions in both the immersion solutions (ICP) and the cementitious matrix itself (SEM-EDX) were studied as a function of time, from 0 to 120 days, for leaching, and according to temperature (25 and 40 °C). The reaction products were characterized using SEM-EDX. Different diffusion rates and behavior were observed depending on the anion type of the external alkali source. Both sodium and potassium ions in all the three environments studied, namely carbonate, hydroxide, and nitrate, penetrated into the composite and further into its structure by different mechanisms. The action of hydroxides, in particular, transformed the original hydration products into calcium-silicate-hydrate (CASH) or ASR gel, while nitrates crystallized in pores and did not cause any changes in the hydration product. The driving force was the increased temperature of the experiment as well as the increased concentration of the solution to which the test specimen was exposed.

Durability Behavior of Mortars Containing Perlite Tailings: Alkali–Silicate Reaction Viewpoint

Tailing incorporation into mortars has been the subject of much research in recent years. Despite this, most of these studies did not investigate the harmful effects resulting from the exposure of such mortars to an environment containing aggressive agents. This work investigated the effects of perlite tailing addition into mortars containing cement CP V-ARI MAX and hydrated lime. The raw materials were subjected to chemical characterization (X-ray fluorescence (XRF)) and mineralogical (X-ray diffraction (XRD)), while the samples immersed in 1 N NaOH solution were characterized by XRD, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and compression strength (CS). The results showed the harmful effects of incorporating perlite tailings into the mortar investigated. Such a degradation was proven by linear expansion and compressive strength experiments accomplished in the samples after the test of resistance to an alkali–silicate reaction.

Crystallization‐induced stabilization of foam glass aggregates for heat‐insulating concrete

AbstractResistance of the porous glass‐based aggregates to alkali‐silicate reaction (ASR) was the focus of this study. ASR was studied in mixtures of aggregates with water alkali solutions simulating alkali media of row concrete. Granular foam glass with homogeneous glass in the pore walls is ASR‐active, which leads to the leaching of glass and to the formation of hydrated Na‐silicate gel, Ca‐silicate, and aluminosilicate on the aggregate surfaces. Mitigation of ASR‐activity in granular foam glass was achieved by thermo‐induced crystallization (850‐900ºC) of micro‐ and nanoscale crystals (Na4CaSi3O9 and/or Na2Ca3Si6O16) in the pore walls with the formation of granular glass‐ceramic foams. The main characterization methods were scanning electron microscopy, x‐ray powder diffraction analysis, x‐ray fluorescence, atomic emission spectrometry, and pH analysis.

Experimental and theoretical study on elastic properties of crystalline alkali silicate hydrate

Mechanical properties of synthesized sodium silicate mineral, Na-kanemite, was investigated by synchrotron-based high-pressure x-ray diffraction experiment and first-principles calculations. Under hydrostatic pressure, the 020 interlayer peak was substantially diffused while a new 011 peak formed at 0.4 GPa due to the reduction of Pbcn symmetry. Upon unloading, the diffused interlayer peak reappeared to its original position with a less peak intensity and the newly formed peak disappeared. This temporal but reversible phase instability related to the symmetry reduction, can be induced from the vibration effect of water molecules contained in interlayer region that can more significantly affect the structural response of crystals with poor crystallinity and stacking disorder. There is a good agreement of pressure response between experimental data and calculations using GGA functional. In addition, conducted analysis on bond variation revealed that contraction of thickness and distortion of Na layer under pressure which caused partial charge redistribution. Suggested elastic properties and charge data will be used to develop reliable force-field database for further molecular dynamics simulation and diagnose macroscopic impact from alkali-silicate reaction damaged structure.

Heat of Hydration and Alkali- Silicate Reaction in Oil Palm Shell Structural Lightweight Concrete

In this study oil palm shells (OPS) are used as coarse and fine aggregate in making of light weight concrete. OPS are used as aggregate by many researchers but using them as both coarse and fine aggregate in concrete. Concrete with OPS as fine and coarse aggregate are examined for alkali-silicate reaction using concrete motor bar test and concrete prism test. Heat of hydration in lightweight concrete is evaluated with coffee cup calorimeter test. Water absorption test shows OPS has water absorption rate of 20–24% which is very high which helps in internal curing of concrete to takes place which may change the heat of hydration in period of time. Expansion property of mortar or coarse aggregate concrete can be found in mortar bar test and prism bar test. This test reveals the expansion of mortar bar and prism bar is within the permissible limit. Heat of hydration in conventional concrete and OPS lightweight concrete showed the 10–15% time difference in setting time of concrete, difference in heat evolved during OPS lightweight concrete heat of hydration process is 18–22% less than conventional concrete.

Study of the expansion of cement mortars manufactured with Ladle Furnace Slag LFS

Industrial by-products generated in the steel manufacturing are successfully used as raw materials in the production of construction materials. However, steel slags, due to their nature and composition, can cause undesirable side-effects in mortars and concretes. The reactive components of LFS and EAFS can affect the stability of the cement matrix. This situation may be prevented by an adequate pre-treatment of slag stabilization and a study of the possible reactions within its mineralogical components, to ensure the stability of the slag over time. In this work, an experimental process is shown to evaluate the behaviour of LFS under adverse environmental conditions when used as aggregates in the manufacture of cement mortars for masonry, such as the presence of humidity, high temperatures (80°C) and possible alkali-silica and alkali-silicate reactions. The results show an acceptable behaviour under normal environmental conditions (20°C). However, the formation crystalline acicular structures were observed under high temperatures (80°C) and in the presence of humidity, which degraded the internal structure of the mortars manufactured with LFS.

Alkali silicate reaction of cement mortar with cattle manure ash

Cattle manure ash (CMA) is an industrial waste generated by biomass power plants. Cement-based material may react with CMA via an alkali silicate reaction. The objection of this study is to confirm whether three types of biomass ash (CMAa, CMAb, CMAc) with different chemical composition will occur alkali aggregate reaction when it is added into cement mortar. To obtain three types of biomass ash, we used a muffle furnace to simulate the biomass power combustion temperature (500 °C, 650 °C, and 800 °C). These CMAs were then analyzed via X-ray diffraction (XRD) and scanning electron microscopy (SEM). The cement mortar with and without CMA was used as a comparison sample (CMA constituting volume fractions of 5%, 10%, and 15%, was used to replace the cement). The expansion length of the mortar specimen, phase of the hydration reaction product, and microstructure of the reaction product were investigated in specimens subjected to autoclaving. The results revealed that the expansion length of the autoclaved (i) control specimen was >0.1%, (ii) cement mortar with CMAa and CMAb specimen was <0.1% and cement mortar with CMAc specimen was >0.1% for CMA dosages of 5–15%. Moreover, SEM results showed that an alkali silicate reaction ring formed around the aggregate of the cement mortar with CMAc. These results indicated that the alkali silicate reaction occurred in the CMAc sample, regardless of the replacement fraction. The CMAc alkali silicate reaction was attributed to two factors, namely the amorphous silicon of CMAc was less than that of CMAa and CMAb, and CMAc was coarser than CMAa and CMAb.

Chemical evolution of alkali–silicate reaction (ASR) products: a Raman spectroscopic investigation

The objective of this study was to use Raman spectroscopy to study the morphology and chemical changes of alkali–silicate reaction (ASR) products over time. The reaction products induced by ASR on soda-lime glass slides in a high temperature alkaline environment (1 N NaOH at 80 °C) enriched with calcium hydroxide were studied at 0, 1, 4, 7, 14 and 28 days. The results show that the morphology of the granular-like and fan-like fascicles structure that formed at early ages was more ordered in terms of polymerization and dominated by Q3 and Q2 units. This information implies that the ASR products were probably of mainly alkali silica composition with low content of calcium in the structure. As the reaction proceeded the products depolymerized, forming a cloud-like morphology of decreased structural order which surrounded the initial product particles. It can be hypothesized that more calcium ions in the soak solution entered into the particle structure, promoting a depolymerization and possible formation of a C–S–H phase which was indicated by the dominant presence of Q1 units after 7 days of exposure. To corroborate the interpretation of Raman spectra, 28-day ASR products were verified by Fourier transform infrared.

Influence of used waste cathode ray tube glass on alkali silicate reaction and mechanical properties of mortar mixtures

Rapid transition of electronic device manufacturing industry has led towards the increase of glass waste quantities, which are still being speculated. This resulted in increasing research on the use of waste glass in many different industries. In this study, the impact of using grounded waste cathode ray tube (CRT) glass as aggregate replacement (AR) on the alkali-silica reaction (ASR), mechanical properties and structure and microscopy of mortar were examined and reported. Crushed waste CRT aggregate was used to replace 0, 25, 50, 75 and 100% of natural limestone aggregate in mortar bars. ASR expansion values of mortar with added waste glass were investigated and tested for observation period according to Ultra-accelerated mortar-bar test. The results showed that the increase of AR percentage resulted in higher susceptibility to ASR. Mechanical properties and microscopy of mortar mixtures showed the potential of using waste CRT glass, due to the small difference between tested mixtures.

Durability performance of rubberized mortar and concrete with NaOH-Solution treated rubber particles

This study experimentally investigated the durability of rubberized mortar and concrete samples with NaOH-solution treated rubber particles. The concrete samples without rubber particles were cast as control samples. The rubberized mortar or concrete samples were prepared with 15% as-received rubber and different contents of NaOH treated rubber (15%, 25%, 35% and 50% by volume of fine aggregate). The electrical resistivity, air-void measurement, and absorption tests were first conducted to evaluate the transport properties of rubberized concrete samples. The freeze-thaw durability tests on different concrete samples showed that the added rubber particles improved the freeze-thaw resistance of concrete. The effect was more significant for NaOH treated rubber particles than that of as-received rubber particles. The results of the alkali-silicate reaction (ASR) expansion test suggested that the ASR expansion was decreased in rubberized mortar compared to plain mortar. The 15% NaOH treated rubber replacement was most effective on reducing the ASR expansion among all of the rubberized mortar samples. The drying shrinkage increased with the content of rubber particles in mortar; however, the increased shrinkage in rubberized mortar appeared to be reduced when the additional rubber was treated with NaOH solution. These test results indicated that the rubberized concrete or mortar (with 15% or 25% NaOH-treated rubber replacement) samples have improved durability.

Alkali release from aggregates: contribution to ASR

The alkali–silica reaction in concrete is normally associated with alkalis from cement. However, some aggregates have alkalis in their crystalline or amorphous phases that can be released during long-term exposure to the water in concrete structures. Previous research has demonstrated that alkaline feldspars in aggregates can supply a significant amount of alkalis when exposed to alkaline solutions. Other research indicates that micas can release alkalis and promote alkali–silicate reaction. The main problem is the evaluation of the potential contribution of the alkalis released by aggregates during the service life of a concrete structure. This paper describes accelerated tests that can determine the level of alkalis released from aggregates, but finds that the results are not representative of the long-term behaviour of concrete structures. Alternative tests are being developed, but these could take much longer, and it is concluded that numerical methods may be the most practical solution.

Nanotechnology: The Emerging Field of Civil Engineering Particularly in Developing Countries

Nanotechnology has taken the world of science by a storm and construction industry is no exception. The most important aspect of construction industry that can be influenced by nanotechnology is cement and concrete. Recent research on application of carbon nanotubes (CNT), both single-walled and multi-walled, shows significant increase in mechanical properties of concrete. Other properties of concrete e.g. durability, permeability, cement hydration etc. can be conveniently influenced with the help of Alkali-Silicate Reaction (ASR) studies, nanoScale Silica Fume, integration of nanoParticles in cement-synthesis and a lot other methods. And as a matter of fact, the future of cement based construction industry seems to be shaped by nanotechnology as even developing countries like Bangladesh are coming forward now-a-days to harness the potential of this rapid growing field.

Self-healing of cracks in cement paste affected by additional Ca2+ ions in the healing agent

Cracks in reinforced concrete provide preferential access for aggressive substances into the concrete. Therefore, the corrosion of reinforcement bars is accelerated. Besides, carbonation, sulfate attack, and alkali–silicate reaction take place deep inside the concrete. Fortunately, from previous experiments, it was found that cracks in concrete can be healed with water and Ca is a main chemical element of the reaction products of self-healing. However, the ion concentrations in water can be various depending on the sources of water. There is still a lack of information on the effect of ion concentrations on self-healing. In this article, the effect of Ca2+ ions on self-healing was investigated experimentally. Ca(OH)2 was added into water as a healing agent. Self-healing behavior of cracks with saturated Ca(OH)2 solution was explored and compared with that with distilled water. In order to gain deeper insight into the mechanism, the reaction products of self-healing were characterized by energy-dispersive spectroscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. In addition, the filling fraction of cracks as a function of time was determined by means of backscattered electron image analysis. The efficiency of self-healing induced by saturated Ca(OH)2 solution was evaluated and compared with that with distilled water.

Fresh and Hardened Properties of Concrete Incorporating Recycled Glass as 100% Sand Replacement

AbstractThis paper investigates the use of glass cullet as a 100% sand replacement in Portland cement concrete (glasscrete) systems. Specifically, this paper evaluates the fresh and hardened properties of these systems in comparison with conventional natural sand concretes on the basis of similar 28-day design compressive strength, or the same w/cm. The results show that glasscrete mixtures need a lower w/cm to match the 28-day compressive strength of conventional concrete. In addition, glasscrete mixtures have greater elastic modulus, less drying shrinkage, less water sorptivity, and greater resistance against chloride ion penetration. Empirical curves are developed to provide material engineers and suppliers with necessary design specifications on the proper w/cm to implement when proportioning glasscrete mixtures. This study concludes that glasscrete mixtures are producible with adequate consistency and mechanical and durability performance, as long as the alkali-silicate reaction is properly controlle...

The Inhibition Studying of Single-Doped Mineral Admixture for Concrete Alkali Silicate Reaction

The research uses Mortar bar rapid method. The experiment of single-doped mineral admixture such as fly, slag and silica fume has been done on the base of the theory of mineral admixture suppressing concrete alkali silica reaction (ASR).The effect of each mineral admixture on suppressing concrete ASR has been analysis ed. It shows that the inhibition for suppressing concrete ASR was the most beneficial when the addition of fly is 50% and the more the dosage is, the better the inhibition is. The silica fume is more beneficial for suppressing concrete ASR relatively and it also needs less addition. The effect of slag is the poorest and it also needs more addition.

The Inhibition Studying of Many-Doped Mineral Admixture for Concrete Alkali Silicate Reaction

In the theoretical basic of only mixing the pulverized fuel ash, the slag or the silicon ash experiments, carrying on concrete alkali-aggregate reaction experiment separately that double-doped the pulverized fuel ash and the silicon ash, double-doped the pulverized fuel ash and the slag, double-doped the slag and the silicon ash, three-mixed the pulverized fuel ash, the slag and the silicon ash. The result indicated the effect of mixing pulverized fuel ash and the silicon ash is better than the mixing silicon ash and slag or pulverized fuel ash and slag. Besides three-mixed the pulverized fuel ash, the slag and the silicon ash can effectively suppress the reaction of concrete alkali-silica acid response（ASR）