Fiber Reinforced Alkali Activated Blended Cement Materials

1990 ◽  
Vol 211 ◽  
Author(s):  
M. R. Silsbee ◽  
D. Wolfe-Confer ◽  
D. M. Roy
Keyword(s):  
Blended Cement ◽  
Strength Development ◽  
Alkali Activation ◽  
Fiber Reinforced ◽  
Blended Cements ◽  
Alkali Activated

AbstractRecently there has been renewed interest in the use of alkali activation to increase the rate of strength development in blended cements. The objective of this study was to examine the advantages-disadvantages of using alkali activated blended cement materials with fiber reinforcing. There are advantages of the rapid set for certain applications.

scholarly journals SHRINKAGE OF VARIOUS TYPES OF PORTLAND CLINKER-BASED CEMENTS WITH RESPECT TO THEIR HYDRATION DEGREE

2020 ◽  
Vol 60 (2) ◽  
pp. 88-97 ◽  
Author(s):  
Vendula Davidová ◽  
Pavel Reiterman
Keyword(s):  
Previous History ◽  
Blended Cement ◽  
Heat Evolution ◽  
Experimental Program ◽  
Strength Development ◽  
Contact Method ◽  
Volume Changes ◽  
Hydration Degree ◽  
Suitable Material ◽  
Blended Cements

The volume changes of cement based composites are significantly exhibited in the hardening process. Initial phases of the hardening are complemented by the expansion due to the heat evolution that is subsequently alternated by the shrinkage. Both could cause a crack initiation. It is evident that ultimate volume changes of cement based composites are a complex process, because the final shrinkage is determined by the binder used, exposition and also by the previous history. The paper focuses on the evaluation of the main types of cements based on the Portland clinker by using a conventional procedure for the determination of the shrinkage on the standard cements mortars. These mortars were exposed to drying after 1 and 3 days of curing, related to the actual degree of hydration, which was estimated on the basis of compressive strength development. The hydration process was additionally monitored using thermogravimetry on the accompanying paste specimens during one year. The performed experimental program confirmed the essential sense of the curing regime especially for blended cement systems, which exhibited very low values of the hydration degree at applied curing intervals. Despite the slightly higher values of shrinkage of blended cements, the obtained results signalize the crucial effect of prolonged curing for these types of binders. The conclusion highlighted the necessity of taking into consideration the hydration degree during cement testing by using the conventional contact method. Otherwise, the simple interpretation leads to an overestimation of the less-suitable material solution.

scholarly journals Influence of Concrete Sludge Addition in the Properties of Alkali-Activated and Non-Alkali-Activated Fly Ash-Based Mortars

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Fotini Kesikidou ◽  
Stavroula Konopisi ◽  
Eleftherios K. Anastasiou
Keyword(s):  
Fly Ash ◽  
Silicon Oxide ◽  
Strength Development ◽  
Alkali Activation ◽  
Early Age ◽  
Fly Ash Concrete ◽  
High Calcium ◽  
High Calcium Fly Ash ◽  
Potential Synergy ◽  
Alkali Activated

This study investigated the use of concrete sludge, a by-product of the ready-mix concrete industry, in combination with high-calcium fly ash in binary cementless binders. Concrete sludge was used in substitution rates ranging from 0% to 60% in test fly ash-based mortars to determine potential synergy. The mortars were tested for fresh and hardened properties; workability, viscosity, strength development, open porosity, early-age shrinkage, and analytical tests were carried out. A mortar with 50% fly ash and 50% limestone filler as binders was used for comparison purposes. Furthermore, a series of mortars with fly ash and concrete sludge were alkali-activated in order to determine potential strength gain. In the activated mortars, two fractions of concrete sludge were used, under 75 μm and 200 μm, due to different silicon oxide contents, while one mortar was cured at 40°C to investigate the effect of heating on alkali activation. Results show that sludge contributes to the formation of C-S-H and strength development when used in combination with high-calcium fly ash even at high replacement rates. The alkali activation of fly ash-concrete sludge system contributed to early-age strength development and to early-age shrinkage reduction.

scholarly journals Sustainable batching water options for one-part alkali-activated slag mortar: Sea water and reverse osmosis reject water

PLoS ONE ◽  
2020 ◽  
Vol 15 (11) ◽  
pp. e0242462
Author(s):  
Tero Luukkonen ◽  
Juho Yliniemi ◽  
Paivo Kinnunen ◽  
Mirja Illikainen
Keyword(s):  
Reverse Osmosis ◽  
Sea Water ◽  
Strength Development ◽  
Alkali Activation ◽  
Similar Amount ◽  
Alkali Activated Slag ◽  
Reject Water ◽  
Concrete Production ◽  
Activated Slag ◽  
Alkali Activated

Concrete production is globally a major water consumer, and in general, drinking-quality water is mixed in the binder. In the present study, simulated sea water and reverse osmosis reject water were used as batching water for one-part (dry-mix) alkali-activated blast furnace slag mortar. Alkali-activated materials are low-CO2 alternative binders gaining world-wide acceptance in construction. However, their production requires approximately similar amount of water as regular Portland cement concrete. The results of the present study revealed that the use of saline water did not hinder strength development, increased setting time, and did not affect workability. The salts incorporated in the binder decreased the total porosity of mortar, but they did not form separate phases detectable with X-ray diffraction or scanning electron microscopy. Leaching tests for monolithic materials revealed only minimal leaching. Furthermore, results for crushed mortars (by a standard two-stage leaching test) were within the limits of non-hazardous waste. Thus, the results indicated that high-salinity waters can be used safely in one-part alkali-activated slag to prepare high-strength mortars. Moreover, alkali-activation technology could be used as a novel stabilization/solidification method for reverse osmosis reject waters, which frequently pose disposal problems.

scholarly journals Physicochemical Properties of Hydrated Portland Cement Blended with Rice Husk Ash

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Joseph Mwiti Marangu ◽  
Cyprian Muturia M’thiruaine ◽  
Mark Bediako
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Rice Husk ◽  
Elevated Temperatures ◽  
Rice Husk Ash ◽  
Blended Cement ◽  
Strength Development ◽  
Carbonation Depth ◽  
Blended Cements ◽  
Carbonation Resistance

In the presence of significant quantities of carbon dioxide (CO2) and elevated temperatures in the atmosphere due to climate change, cement-based materials are susceptible to carbonation. Blended cements are more prone to carbonation attack than Portland cement. There is a need to evaluate the carbonation resistance of blended cements in a carbonation-prone environment. This paper presents experimental findings obtained from an evaluation of carbonation resistance tests on Rice Husk Ash- (RHA-) blended cement. The blended cement was made by intergrinding of Portland Cement (PC) and RHA to make the test cement (PC-RHA). The RHA dosage in the PC-RHA was varied from 0 to 30% by mass of PC. Pozzolanicity, standard consistency, and setting time tests were conducted on PC-RHA. Mortar prisms measuring 160 mm × 40 mm x 40 mm were separately cast at a water/cement ratio ( w / c ) of 0.50 and 0.60 and cured in water for 2, 7, 14, 28, and 90 days. Compressive strength tests were conducted on the mortar prisms at each of the testing ages. The prepared mortars were also subjected to accelerated carbonation tests in two Relative Humidity (RH) curing regimes, one maintained at an RH greater than 90% and the other between 50–60%. Carbonation resistance of the mixtures was evaluated in terms of the changes in carbonation depth using a phenolphthalein test at the age of 7, 14, 28, and 56 days of curing in a continuous flow of CO2. Compressive strength measurements were also taken during each of the carbonation testing ages. For comparison, similar tests were conducted using commercial PC. The results showed that PC-RHA was pozzolanic while PC was nonpozzolanic. Higher water demand and longer setting times were observed in PC-RHA than in PC. Moreover, there was increased strength development in water-cured samples with increased curing duration. Carbonation results indicated that there was a marked increase in carbonation depth with increased dosage of RHA in PC-RHA binders, increased duration of exposure to CO2, and decreased RH (RH between 50–60%). PC-RHA binders exhibited lower carbonation resistance than PC. In conclusion, for mortars at any w / c ratio, carbonation resistance decreased with increase in RHA dosage and increased w / c ratio.

scholarly journals The effects of seawater and nanosilica on the performance of blended cements and composites

2020 ◽  
Vol 10 (12) ◽  
pp. 5009-5026 ◽  
Author(s):  
Pawel Sikora ◽  
Didier Lootens ◽  
Maxime Liard ◽  
Dietmar Stephan
Keyword(s):  
Transport Properties ◽  
Reaction Rate ◽  
Mechanical Performance ◽  
Setting Time ◽  
Blended Cement ◽  
Heat Of Hydration ◽  
Strength Development ◽  
Cement Pastes ◽  
Blended Cements ◽  
Setting Times

AbstractThis study investigates the effects of seawater and nanosilica (3% by weight of cement), on the fresh and hardened properties of cement pastes and mortars produced with two types of low heat cements: Portland pozzolana cement (CEM II) and blast furnace cement (CEM III). The heat of hydration, initial and final setting times, rheological properties, strength development, sorptivity and water accessible porosity of the cement pastes and mortars were determined. The data reveal that cement type has a significant effect on the reaction rate of cement with seawater and nanosilica (NS). Specimens produced with slag-blended cement exhibited a higher cement reaction rate and the composite produced exhibited better mechanical performance, as a result of the additional reaction of alumina rich phases in slag, with seawater. Replacement of freshwater with seawater contributes mostly to a significant improvement of early strength. However, in the case of slag-blended cement, 28 day strength also improved. The incorporation of NS results in additional acceleration of hydration processes, as well as to a decrease in cement setting time. In contrast, the addition of NS results in a noticeable increment in the yield-stress of pastes, with this effect being pronounced when NS is mixed along with seawater. Moreover, the use of seawater and NS has a beneficial effect on microstructure refinement, thus improving the transport properties of cement mortars. Overall, the study has showed that both seawater and NS can be successfully used to accelerate the hydration process of low heat blended cements and to improve the mechanical and transport properties of cement-based composites.

New Rapid Setting Alkali Activated Cement Compositions

1989 ◽  
Vol 179 ◽  
Author(s):  
D. M. Roy ◽  
M. R. Silsbee ◽  
D. Wolfe-Confer
Keyword(s):  
Mechanical Property ◽  
Alkali Activation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Blended Cements ◽  
Setting Times ◽  
Rapid Setting ◽  
Alkali Activated ◽  
Alkali Activated Cement

AbstractThe advantage of utilizing blended cements for many applications has been well documented. However, the use of these materials has been limited by the longer setting times associated with the use of these materials. This report discusses the development of formulations employing alkali activation to shorten the setting times. The results of characterization of these materials using calorimetry, microscopic, x-ray diffraction, and mechanical property techniques are discussed.

A Binder from Alkali Activation of FCC Waste: Use in Roof Tiles Fabrication

2015 ◽  
Vol 668 ◽  
pp. 411-418 ◽  
Author(s):  
María Antonia Mas ◽  
Mauro M. Tashima ◽  
J. Payá ◽  
M.V. Borrachero ◽  
Lourdes Soriano ◽  
...  
Keyword(s):  
Catalytic Cracking ◽  
Blast Furnace Slag ◽  
Impact Resistance ◽  
Fluid Catalytic Cracking ◽  
Strength Development ◽  
Alkali Activation ◽  
Construction Sector ◽  
Alumino Silicate ◽  
Furnace Slag ◽  
Alkali Activated

Nowadays, scientific community is looking for alternatives to reduce the problem of CO2emissions, making more sustainable binders and reusing wastes from other industries.In this line, the technology of geopolymers was born, in which, binders based on alkali-activation can be produced entirely or almost entirely from waste materials. In alkali-activation a source of aluminosilicate is dissolved by a highly alkaline solution previous to precipitation reactions that form a gel binder.The use of alumino-silicate minerals such as metakaolin, blast furnace slag and fly ash to produce alkali-activated cements has been extensively studied and it’s increasing the interest in investigating the suitability of using other materials. Different wastes containing silica and alumina, such as hydrated-carbonated cement, glass, fluid catalytic cracking catalyst residues (FCC) have been activated.The aim of this study is to verify if the use of geopolymers is compatible with the manufacturing technology of typical building elements, in this case roof tiles.Mechanical properties of mortars and roof tiles using as source of aluminosilicates FCC have been studied, with different mixtures and variating the proportions of NaOH and waterglass.Compressive strength development was evaluated in mortars cured at 20oC for 7 and 28 days and flexural strength, impermeability and impact resistance were evaluated in roof tiles. The results obtained demonstrated the feasibility on the use of geopolymers in the design of new products with less CO2emissions and then the contribution to the sustainability in the construction sector.

scholarly journals Fibers, Geopolymers, Nano and Alkali-Activated Materials for Deep Soil Mix Binders

2020 ◽  
Vol 6 (4) ◽  
pp. 830-847
Author(s):  
John Kok Hee Wong ◽  
Sien Ti Kok ◽  
Soon Yee Wong
Keyword(s):  
Portland Cement ◽  
Ground Improvement ◽  
Strength Development ◽  
Alkali Activation ◽  
Deep Soil ◽  
Recent Developments ◽  
Improved Performance ◽  
Soil Mix ◽  
Performance Research ◽  
Alkali Activated

Ordinary Portland Cement (OPC) and Lime (CaO) have traditionally been used as binder materials for Deep Soil Mix (DSM) ground improvement. Research has been conducted into possible alternatives such as pozzolans to reduce reliance on either cement or lime. However, pozzolans still undergo similar calcium-based reactions in the strengthening process. In this review, further alternative binder materials for soil strength development are explored. These recent developments include fiber reinforcement materials, alkali activation methods, nanomaterials and geopolymers, which can potentially achieve equal or improved performance. Research to date has shown that alkali-activated materials and geopolymers can be equivalent or superior alternatives to pozzolanic supplemented cement binders. The case is made for GP cements which potentially produces 80% less CO2 than conventional portland cement during manufacture. One-part AAM and GP cements are a promising substitute for portland cement in DSM. A combined approach which incorporates both Ca and alkali activated/geopolymer types of materials and hence reactions is proposed.

scholarly journals Alkali-activated laterite binders: Influence of silica modulus on setting time, Rheological behaviour and strength development

2021 ◽  
pp. 100175
Author(s):  
Cyriaque Rodrigue Kaze ◽  
Adeyemi Adesina ◽  
Gisèle Laure Lecomte-Nana ◽  
Thamer Alomayri ◽  
Elie Kamseu ◽  
...  
Keyword(s):  
Setting Time ◽  
Rheological Behaviour ◽  
Strength Development ◽  
Alkali Activated

scholarly journals Mechanical and durability assessment of cement-based and alkali-activated coating mortars in an aggressive marine environment

2021 ◽  
Vol 3 (6) ◽  
Author(s):  
Salar Lashkari ◽  
Farzad Yazdipanah ◽  
Mahyar Shahri ◽  
Prabir Sarker
Keyword(s):  
Silica Fume ◽  
Marine Environment ◽  
Strength Test ◽  
High Rate ◽  
Chloride Diffusion ◽  
Strength Development ◽  
Diffusion Resistance ◽  
Capillary Absorption ◽  
Durability Analysis ◽  
Alkali Activated

AbstractCoatings are used as practical solutions against the intrusion of corrosive ions into concrete structures, particularly, in the harsh marine environment. In the present study, the effectiveness of using cement-based and geopolymer-based coatings produced using by-product materials has been evaluated. Silica fume and GGBFS at their optimum dosages were incorporated into mortar mixtures as a cement replacement, and mixtures of NaOH or KOH and sodium silicate solutions were used in the alkali-activated mortars. Shrinkage test, RCMT, and capillary absorption test as common experiments for durability analysis, as well as tests related to the mechanical and bonding properties including compressive strength test, pull-off test, and shear bonding strength test were carried out on the specimens. According to the results, both geopolymer and cement-based mortars improved the compressive and bonding strengths, and chloride diffusion resistance of coatings compared to the OPC mortar. Silica fume was found to be more effective in the strength development of mortars at young ages, while GGBFS was more responsible for acting as a filler and producing further gel in the older ages. The major drawback with geopolymer mortars is the high rate of water absorption and shrinkage coefficient in the early hours, which shows the importance of curing of these mortars at young ages. Overall, the mix design produced with 30% GGBFS and 7.5% silica fume showed the highest durability and mechanical properties and proved to be more compatible with the harsh environment of the Persian Gulf.

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