scholarly journals Early Age Compressive Strength of Waste-based-glass-powder Magnesium Silicate Binders on Initial Carbonation Curing

2020 ◽  
Author(s):  
Erick Grünhäuser Soares ◽  
João Castro-Gomes
Keyword(s):  
Grain Size ◽  
Compressive Strength ◽  
Glass Powder ◽  
Water Immersion ◽  
Magnesium Silicate ◽  
Early Age ◽  
Cement Pastes ◽  
Weight Percentage ◽  
Immersion Period ◽  
Carbonation Curing

In this preliminary study, the effect of glass powder content at early age compressive strength and its effect at strength retention coefficient during water immersion period on magnesium silicate hydroxide cement pastes on carbonation curing was investigated. A magnesium oxide-rich powder with a maximum grain size of 150 μm was used, as well as, a waste glass powder with a maximum grain size of 250 μm, which was obtained from grinded flint glass bottles. Cement pastes were produced with 0, 10, 20, 30, 40, and 50 glass powder weight percentage. The specimens were compacted into cubic moulds (e = 20 mm) under 70 MPa and, subsequently, cured on accelerate carbonation chamber for 2h at >99% CO2 concentration. The compressive strength was determined 3 days after CO2, period which the specimens were preserved on room conditions (20∘C and 60%RH), and also at 3, 7 and 14 days of water immersion period. Comparison of the results obtained for different mixing compositions, as well as, different water immersion periods are discussed in this work.

scholarly journals Preliminary Study on the Influence of Different Carbonation Curing Processes on Binders Based on Magnesium Oxide-Rich Powder Blended with Tungsten Mining Waste Mud

2020 ◽  
Author(s):  
Erick Grünhäuser Soares ◽  
João Castro-Gomes
Keyword(s):  
Compressive Strength ◽  
Magnesium Oxide ◽  
Water Immersion ◽  
Co2 Concentration ◽  
Mining Waste ◽  
Cement Pastes ◽  
Weight Percentage ◽  
Grain Sizes ◽  
Preliminary Study ◽  
Carbonation Curing

In this preliminary study, the effect of the pre-drying stage, water immersion, carbonation curing cycles, and/or drying stage on carbonation curing of magnesium oxide-rich powder (MRP) was investigated. In addition, a blend of tungsten mining waste mud (TMWM) with MRP was also evaluated. The MRP and TMWM used have maximum grain sizes of 125 μm. The cement pastes were produced with 0 and 50 of TMWM weight percentage. The specimens were compacted into cylindric moulds (∅ = 20 mm; h = 40 mm) under 30 MPa and, subsequently, submitted to five different processes of curing involving a pre-drying stage before carbonation, rapid water immersion cycles, additional drying periods, and different carbonation curing periods. The atmosphere of the pressurized carbonation curing chamber was controlled to provide  a  CO2 concentration of > 99%, the partial pressure of 1 bar and temperature of 60°C. The influence of the curing processes on the compressive strength of each mix was determined 12 hours after the carbonation curing period. This study demonstrates that the water content during the curing process plays an important role in the increase of the hardening process and on the compressive strength. Keywords: Carbonation curing, magnesium oxide, mining waste, curing processes, magnesium-based cement

Mechanical and Physical Properties of Early Carbonated High Initial Strength Portland Cement Pastes

2014 ◽  
Vol 634 ◽  
pp. 467-472
Author(s):  
Alex Neves Junior ◽  
Romildo Dias Toledo Filho ◽  
Jo Dweck ◽  
Eduardo de Moraes Rego Fairbairn
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Physical Properties ◽  
Early Age ◽  
Specific Mass ◽  
Silicate Phase ◽  
Cement Pastes ◽  
Initial Strength ◽  
Mechanical And Physical Properties ◽  
Carbonation Curing

After submitted to early age carbonation curing, mechanical and physical properties of high initial strength sulfate resistant Portland cement (HS SR PC) pastes were investigated, which were compared to those of non-carbonated reference pastes. Carbonation was performed for 1 and 24 hours, at the best conditions of CO2capturing, previously determined by the authors. Despite the compressive strength and elastic modulus of the 1h carbonated pastes were slightly higher than those of the reference pastes, their absorbed water content and porosity was slightly higher than that of the reference. In the case of 24h carbonation, its compressive strength decreases significantly because of its much higher porosity, although the new solid carbonated calcium silicate phase presents a much higher specific mass than those of the solid phases of the 1 hour and non-carbonated pastes.

Studies on Exciting the Activity of Waste Glass Powder by Hydrothermal Activation

2013 ◽  
Vol 871 ◽  
pp. 171-178
Author(s):  
Qing Qiu Kong ◽  
Guo Jun Ke ◽  
Dan Wang
Keyword(s):  
Compressive Strength ◽  
Hydrothermal Treatment ◽  
Glass Powder ◽  
Cement Mortar ◽  
Waste Glass ◽  
Early Age ◽  
Cement Replacement ◽  
Waste Glass Powder ◽  
Temperature And Pressure ◽  
Optimal Strength

The effect of hydrothermal activation indifferent temperature and pressure conditions on the pozzolanic activity of waste glass powder was discussed. The waste glass powder was treated at 108°C, 0.15MPa, 116°C, 0.18MPa and 121°C, 0.2MPa for 2h in an autoclave respectively after milling to 4215cm2/g. Mortar was made with untreated and hydrothermal activated waste glass power replacement of cement at 20% respectively, then tested for compressive strength at 3, 7, 14 , 28 and 90 days. Results showed that compressive strength of cement mortar had varying degrees of decline when replacing cement with untreated waste glass powder, comparing to the control one. Decline amplitude was large at early age and small at late age. Activity of waste glass powder was significantly improved after hydrothermal treatment. Compressive strength of mortar improved as temperature and pressure elevated, obtaining optimal strength at 121°C, 0.2MPa. Compressive strength of mortar with hydrothermal activated glass powder was higher than that with untreated glass powder at all age with 20% cement replacement. Compressive strength increased 5.3% ~ 13.6% at 3 d, 6.8%~9.7% at 28 d, 9.7% ~ 17.7% at 90 d. The essence of hydrothermal activation was the corrosion of water in the glass.

scholarly journals CONTINUOUS MICROSTRUCTURAL CORRELATION OF SLAG/SUPERPLASTICIZER CEMENT PASTES BY HEAT AND IMPEDANCE METHODS VIA FRACTAL ANALYSIS

Fractals ◽  
2017 ◽  
Vol 25 (04) ◽  
pp. 1740003 ◽  
Author(s):  
S. W. TANG ◽  
R. J. CAI ◽  
Z. HE ◽  
X. H. CAI ◽  
H. Y. SHAO ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fractal Analysis ◽  
Setting Time ◽  
Blended Cement ◽  
Impedance Measurement ◽  
Heat Evolution ◽  
Early Age ◽  
Contact Impedance ◽  
Cement Pastes ◽  
Early Age Hydration

This paper presents a preliminary work to evaluate the influence of slag and superplasticizer on the early-age hydration of cement pastes by an innovative non-contact impedance measurement, heat evolution method, compressive strength and setting time tests. Besides, the cumulative pore volume obtained from modulus and phase of impedance in different hydration sections is taken to continuously correlate the cumulative heat releasing of cement pastes via the fractal analysis. Retarded phenomena and mechanism of hydration in cement pastes incorporated with slag and superplasticizer are studied, respectively. It is found that the compressive strength and setting time have a good linear relation with the slag amount in blended cement pastes.

scholarly journals Effect of Using Bagasse Ash and Glass Powder on Concrete Compressive Strength

2020 ◽  
Vol 2 (2) ◽  
pp. 156-161
Author(s):  
Syafwandi Syafwandi ◽  
Latif Sulistyawan
Keyword(s):  
Grain Size ◽  
Compressive Strength ◽  
Natural Resources ◽  
Glass Powder ◽  
Silica Content ◽  
Household Waste ◽  
Strength Testing ◽  
Industrial Glass ◽  
Concrete Compressive Strength ◽  
Normal Concrete

Bagasse ash is a waste from the sugar factory industry which has silica content and grain size is relatively the same as cement. Glass powder is made from industrial glass and household waste, has a silica content and grain size is relatively same as sand. The use of both wastes as concrete substitutes is expected to reduce environmental pollution and exploitation of natural resources. This study aims to determine the effect of bagasse ash as a cement substitution and glass powder as sand substitution in a concrete mixture on the compressive strength. This study uses a mixture of bagasse ash 2.5%, 5%, and 7.5% by weight of cement, and the glass powder is 5%, 10%, and 15% by weight of sand. Compressive strength testing on days 7 and 28. The results of this study are the higher percentage of substitution materials, workability will decrease. Compressive strength testing shows that all variations have resulted under normal concrete. The highest compressive strength is obtained from variation A with a mixture of 2.5% bagasse ash + 5% glass powder that is 24.50 MPa. Variation of the mixture with bagasse ash of 2.5% has a higher compressive strength than other variations on day 28.

Hydration and Early Age Properties of Cement Pastes Modified with Cellulose Nanofibrils

2020 ◽  
pp. 036119812094599
Author(s):  
Hosain Haddad Kolour ◽  
Warda Ashraf ◽  
Eric N. Landis
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Cement Paste ◽  
Isothermal Calorimetry ◽  
Cellulose Nanofibrils ◽  
Autogenous Shrinkage ◽  
Early Age ◽  
Hydration Reaction ◽  
Cement Pastes ◽  
Degree Of Hydration

In this work, the effects of cellulose nanofibrils (CNFs) on workability, hydration reaction, microstructure, early age shrinkage, fracture properties, flexural strength, and compressive strength of cement paste were investigated. Six batches with variable CNF concentrations with the same water-to-cement (w/c) ratio (0.35) were tested. Flow table test showed a reduction in the workability as CNF dosage increased. Isothermal calorimetry (IC) tests showed that after 3 days, degree of hydration (DOH) improved up to 8% because of the addition of CNFs. Thermogravimetric analysis (TGA) tests at 7 and 28 days showed no significant changes in DOH for all pastes. After 7 days, mixture with 0.15% CNF resulted in up to 31% improvement in compressive strength. For 0.09% CNF addition, cement paste showed 26% increase in compressive strength after 28 days. Tests revealed that adding a small quantity of CNF (0.06%) along with entraining 0.05 extra water reduces autogenous shrinkage by 49% at a cement paste with w/c = 0.30. For interpreting the results, a tunnels, reservoirs, and bridges (TR&B) model is proposed. This model suggests that, as proposed by others, CNFs can modify microstructure by providing tunnels for transporting water to unhydrated cement grain. Because of their hydrophilicity, CNFs retain water and work as reservoirs (internal curing), which explains the improvement in properties at low w/c ratios. Significant increases in fracture energy (up to 60%) and flexural strength (up to 116%) suggest that CNFs are an effective toughening mechanism, acting as bridges that increase the energy required for crack propagation.

scholarly journals Lightweight Cement Conglomerates Based on End-of-Life Tire Rubber: Effect of the Grain Size, Dosage and Addition of Perlite on the Physical and Mechanical Properties

Materials ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 225
Author(s):  
Andrea Petrella ◽  
Michele Notarnicola
Keyword(s):  
Grain Size ◽  
End Of Life ◽  
Compression Tests ◽  
Tire Rubber ◽  
Impact Compression ◽  
Weight Percentage ◽  
Deep Groove ◽  
Mechanical Strengths ◽  
The Impact ◽  
Thermal Conductivities

Lightweight cement mortars containing end-of-life tire rubber (TR) as aggregate were prepared and characterized by rheological, thermal, mechanical, microstructural, and wetting tests. The mixtures were obtained after total replacement of the conventional sand aggregate with untreated TR with different grain sizes (0–2 mm and 2–4 mm) and distributions (25%, 32%, and 40% by weight). The mortars showed lower thermal conductivities (≈90%) with respect to the sand reference due to the differences in the conductivities of the two phases associated with the low density of the aggregates and, to a minor extent, to the lack of adhesion of tire to the cement paste (evidenced by microstructural detection). In this respect, a decrease of the thermal conductivities was observed with the increase of the TR weight percentage together with a decrease of fluidity of the fresh mixture and a decrease of the mechanical strengths. The addition of expanded perlite (P, 0–1 mm grain size) to the mixture allowed us to obtain mortars with an improvement of the mechanical strengths and negligible modification of the thermal properties. Moreover, in this case, a decrease of the thermal conductivities was observed with the increase of the P/TR dosage together with a decrease of fluidity and of the mechanical strengths. TR mortars showed discrete cracks after failure without separation of the two parts of the specimens, and similar results were observed in the case of the perlite/TR samples thanks to the rubber particles bridging the crack faces. The super-elastic properties of the specimens were also observed in the impact compression tests in which the best performances of the tire and P/TR composites were evidenced by a deep groove before complete failure. Moreover, these mortars showed very low water penetration through the surface and also through the bulk of the samples thanks to the hydrophobic nature of the end-of-life aggregate, which makes these environmentally sustainable materials suitable for indoor and outdoor elements.

scholarly journals Effect of Calcium Nitrate on the Properties of Portland–Limestone Cement-Based Concrete Cured at Low Temperature

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1611
Author(s):  
Gintautas Skripkiūnas ◽  
Asta Kičaitė ◽  
Harald Justnes ◽  
Ina Pundienė
Keyword(s):  
Compressive Strength ◽  
Cement Paste ◽  
Setting Time ◽  
Calcium Nitrate ◽  
Curing Temperature ◽  
Hardened Concrete ◽  
Cement Pastes ◽  
Initial Setting Time ◽  
Initial Setting ◽  
Early Strength

The effect of calcium nitrate (CN) dosages from 0 to 3% (of cement mass) on the properties of fresh cement paste rheology and hardening processes and on the strength of hardened concrete with two types of limestone-blended composite cements (CEM II A-LL 42.5 R and 42.5 N) at different initial (two-day) curing temperatures (−10 °C to +20 °C) is presented. The rheology results showed that a CN dosage up to 1.5% works as a plasticizing admixture, while higher amounts demonstrate the effect of increasing viscosity. At higher CN content, the viscosity growth in normal early strength (N type) cement pastes is much slower than in high early strength (R type) cement pastes. For both cement-type pastes, shortening the initial and final setting times is more effective when using 3% at +5 °C and 0 °C. At these temperatures, the use of 3% CN reduces the initial setting time for high early strength paste by 7.4 and 5.4 times and for normal early strength cement paste by 3.5 and 3.4 times when compared to a CN-free cement paste. The most efficient use of CN is achieved at −5 °C for compressive strength enlargement; a 1% CN dosage ensures the compressive strength of samples at a −5 °C initial curing temperature, with high early strength cement exceeding 3.5 MPa but being less than the required 3.5 MPa in samples with normal early strength cement.

scholarly journals Effect of Waste Glass on the Properties and Microstructure of Magnesium Potassium Phosphate Cement

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2073
Author(s):  
Qiubai Deng ◽  
Zhenyu Lai ◽  
Rui Xiao ◽  
Jie Wu ◽  
Mengliang Liu ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Glass Powder ◽  
Setting Time ◽  
Potassium Phosphate ◽  
Heat Of Hydration ◽  
Waste Glass ◽  
Hydration Heat ◽  
Magnesium Potassium Phosphate Cement ◽  
The Matrix ◽  
Powder Content

Waste glass is a bulk solid waste, and its utilization is of great consequence for environmental protection; the application of waste glass to magnesium phosphate cement can also play a prominent role in its recycling. The purpose of this study is to evaluate the effect of glass powder (GP) on the mechanical and working properties of magnesium potassium phosphate cement (MKPC). Moreover, a 40mm × 40mm × 40mm mold was used in this experiment, the workability, setting time, strength, hydration heat release, porosity, and microstructure of the specimens were evaluated. The results indicated that the addition of glass powder prolonged the setting time of MKPC, reduced the workability of the matrix, and effectively lowered the hydration heat of the MKPC. Compared to an M/P ratio (MgO/KH2PO4 mass ratio) of 1:1, the workability of the MKPC with M/P ratios of 2:1 and 3:1 was reduced by 1% and 2.1%, respectively, and the peak hydration temperatures were reduced by 0.5% and 14.6%, respectively. The compressive strength of MKPC increased with an increase in the glass powder content at the M/P ratio of 1:1, and the addition of glass powder reduced the porosity of the matrix, effectively increased the yield of struvite-K, and affected the morphology of the hydration products. With an increase in the M/P ratio, the struvite-K content decreased, many tiny pores were more prevalent on the surface of the matrix, and the bonding integrity between the MKPC was weakened, thereby reducing the compressive strength of the matrix. At less than 40 wt.% glass powder content, the performance of MKPC improved at an M/P ratio of 1:1. In general, the addition of glass powders improved the mechanical properties of MKPC and reduced the heat of hydration.

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