Mechanical properties and drying shrinkage of alkali-activated seawater coral aggregate concrete

2021 ◽  
pp. 1-16
Author(s):  
Bai Zhang ◽  
Hong Zhu ◽  
Ruiming Cao
Keyword(s):  
Mechanical Properties ◽  
Drying Shrinkage ◽  
Aggregate Concrete ◽  
Alkali Activated

scholarly journals Use of Preplaced Casting Method in Lightweight Aggregate Concrete

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Qiang Du ◽  
Qiang Sun ◽  
Jing Lv ◽  
Jian Yang
Keyword(s):  
Mechanical Properties ◽  
Drying Shrinkage ◽  
Lightweight Aggregate ◽  
Lightweight Aggregate Concrete ◽  
Casting Method ◽  
Aggregate Concrete ◽  
Static Modulus ◽  
New Perspective ◽  
Flexural Tests ◽  
Static Modulus Of Elasticity

This study addresses the use of preplaced casting method in lightweight aggregate concrete (LC) to provide a new perspective to solve the aggregate segregation. In casting preplaced lightweight aggregate concrete (PLC), the lightweight aggregates are cast into formworks and then fresh grout is injected to fill voids. PLC and conventional lightweight aggregate concrete (CLC) with three different mixtures are compared to observe the degree of segregation. The properties of PLC and CLC are characterized by means of cubic and axial compression, splitting tension and flexural tests, static modulus of elasticity, and drying shrinkage measurements. Results show that the mechanical properties of PLC are improved with respect to that of CLC with the same mixture. The increase of shrinkage is approximately 13% for the CLC and 6% for PLC when w/c ratio ranges from 0.4 to 0.5 due to effect on interlocking. PLC shows an increased tendency in elastic modulus by approximately 2.5% of 0.5 w/c ratio, 2.7% of 0.45 w/c ratio, and 3.3% of 0.4 w/c ratio at the age of 28 days compared with CLC. In conclusion, PLC has significant reduction in the weight on the premise that it shows excellent mechanical properties.

scholarly journals Effects of Expansive Additives on the Shrinkage Behavior of Coal Gangue Based Alkali Activated Materials

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 816
Author(s):  
Xu Gao ◽  
Chao Liu ◽  
Zhonghe Shui ◽  
Rui Yu
Keyword(s):  
Mechanical Properties ◽  
High Performance Concrete ◽  
Early Stage ◽  
Drying Shrinkage ◽  
Coal Gangue ◽  
Reaction Process ◽  
Activated Coal ◽  
Activated Coal Gangue ◽  
Alkali Activated ◽  
Shrinkage Behavior

The suitability of applying shrinkage reducing additives in alkali activated coal gangue-slag composites is discussed in this study. The effect of sulphoaluminate cement (SAC), high performance concrete expansion agent (HCSA) and U-type expansion agent (UEA) on the reaction process, shrinkage behavior, phase composition, microstructure and mechanical properties are evaluated. The results show that the addition of SAC slightly mitigates the early stage reaction process, while HCSA and UEA can either accelerate or inhibit the reaction depending on their dosage. The addition of SAC presents an ideal balance between drying shrinkage reduction and strength increment. As for HCSA and UEA, the shrinkage and mechanical properties are sensitive to their replacement level; excessive dosage would result in remarkable strength reduction and expansion. The specific surface area and average pore size of the hardened matrix are found to be closely related with shrinkage behavior. SAC addition introduces additional hydrotalcite phases within the reaction products, while HCSA and UEA mainly result in the formation of CaCO3 and Ca(OH)2. It is concluded that applying expansive additives can be an effective approach in reducing the drying shrinkage of alkali activated coal gangue-slag mixtures, while their type and dosage must be carefully handled.

scholarly journals Mechanical Properties and Drying Shrinkage Investigation of Alkali-Activated Mortar Using Waste Glass Powder

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Jianqing Gong ◽  
Zhigang Qu
Keyword(s):  
Mechanical Properties ◽  
Construction Industry ◽  
Bp Neural Network ◽  
Glass Powder ◽  
Drying Shrinkage ◽  
Waste Glass ◽  
Waste Glass Powder ◽  
Glass Recycling ◽  
Recycled Waste ◽  
Alkali Activated

Alkali-activated mortar (AAM) is one of the products of waste glass recycling that exhibits promising potential for wide engineering applications such as the construction industry. In this study, recycled waste glass powder-based additives, namely, Silica Fume (SF) and Nano-SiO2 (NS), were investigated for their potential to enhance the mechanical properties (strength) and drying-shrinkage resistance of AAM. The results indicated that 5.0% and 1.5% were the optimum SF and NS dosages, respectively, for optimizing AAM performance in terms of the compressive strength, flexural strength, and drying-shrinkage resistance. A prediction model, based on backpropagation (BP) neural network analysis, was also satisfactorily formulated and preliminarily validated for predicting the drying shrinkage of AAM containing SF or NS.

Drying Shrinkage Performance of Ambient Cured Blended Alkali-Activated Concrete

2019 ◽  
Vol 394 ◽  
pp. 109-114
Author(s):  
Fatima Yousuf ◽  
M. Talha Junaid ◽  
Salah Altoubat
Keyword(s):  
Mechanical Properties ◽  
Resource Use ◽  
Drying Shrinkage ◽  
External Loading ◽  
Early Age ◽  
Physical And Chemical ◽  
Curing Regimes ◽  
Alkali Activated Concrete ◽  
Alkali Activated ◽  
Significant Attention

The environmental burden due to the production and use of Ordinary Portland Cement(OPC) has become significant in terms of resource use and atmospheric emissions. Alkali-activatedbinders have gained significant attention in recent years as a possible alternative to OPC. Concreteundergoes physical and chemical changes through its lifetime. These changes affect propertiesresulting in either increase or decrease of performance and serviceability. Concrete contracts due tothese changes leading to shrinkage. Shrinkage induces tensile stresses within the members, whichleads to a tendency of cracking, resulting in compromised durability. Shrinkage behavior analysis ofAlkali-Activated Concrete (AAC), without any external loading, is crucial to assess as there is limiteddata available. To further test for shrinkage under restraint conditions, mix development of AAC isnecessary. Mechanical properties and drying shrinkage potential of AAC are evaluated and comparedwith OPC concrete. Basic properties assessed to understand the performance of AAC are compressivestrength, splitting tensile strength and free drying shrinkage. Drying shrinkage test is performed as perASTM C157 for 90 days. Furthermore, the effect of different curing regimes (dry curing, three daysmoist curing, and seven days moist curing) on the mechanical properties and shrinkage is evaluated.The results show that drying shrinkage of AAC exhibit similar behavior to that of OPC concrete whilehaving better early-age strength under moist curing regimes.

scholarly journals Effects of the alkaline solution/binder ratio and curing condition on the mechanical properties of alkali-activated fly ash mortars

2017 ◽  
Vol 24 (5) ◽  
pp. 773-782
Author(s):  
Maochieh Chi
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Fly Ash ◽  
Alkaline Solution ◽  
Drying Shrinkage ◽  
Strength Development ◽  
Initial Surface ◽  
Binder Ratio ◽  
Curing Condition ◽  
Alkali Activated

AbstractThe study investigates the effects of the alkaline solution/binder ratio and the curing condition on the mechanical properties of alkali-activated fly ash (AAFA) mortars. Class F fly ash was used as the raw material, and sodium hydroxide and liquid sodium silicate were used for the preparation of alkaline activators. Three alkaline solution-to-binder ratios (0.35, 0.5, and 0.65) and four different initial curing conditions (curing in air at ambient temperature for 24 h, 30°C for 24 h, 65°C for 12 h, and 85°C for 6 h) were considered. Test results show that AAFA mortars with alkaline solution-to-binder ratio of 0.35 had higher compressive strength, lower drying shrinkage, lower water absorption, and lower initial surface absorption rate than the other mortars. Furthermore, the curing condition influenced the compressive strength development and drying shrinkage of AAFA mortars at early ages. AAFA mortars cured at 65°C for 12 h appeared to have superior mechanical properties. XRD demonstrates that the hydration products of AAFA mortars are mainly amorphous alkaline aluminosilicate gel, which attributed to the compressive strength. Consequently, the alkaline solution-to-binder ratio significantly affects more the mechanical properties than the curing condition based on the presented results.

Mechanical Properties of Alkali Activated Fly Ash Geopolymer Stabilized Expansive Clay

2019 ◽  
Vol 23 (9) ◽  
pp. 3875-3888 ◽  
Author(s):  
Anant Lal Murmu ◽  
Anamika Jain ◽  
Anjan Patel
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Expansive Clay ◽  
Alkali Activated

scholarly journals Experimental Study on the Mechanical Properties and Compression Size Effect of Recycled Aggregate Concrete

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2323
Author(s):  
Yubing Du ◽  
Zhiqing Zhao ◽  
Qiang Xiao ◽  
Feiting Shi ◽  
Jianming Yang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Size Effect ◽  
Compressive Stress ◽  
Failure Modes ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Aggregate Concrete ◽  
Substitution Ratio ◽  
The Impact

To explore the basic mechanical properties and size effects of recycled aggregate concrete (RAC) with different substitution ratios of coarse recycled concrete aggregates (CRCAs) to replace natural coarse aggregates (NCA), the failure modes and mechanical parameters of RAC under different loading conditions including compression, splitting tensile resistance and direct shear were compared and analyzed. The conclusions drawn are as follows: the failure mechanisms of concrete with different substitution ratios of CRCAs are similar; with the increase in substitution ratio, the peak compressive stress and peak tensile stress of RAC decrease gradually, the splitting limit displacement decreases, and the splitting tensile modulus slightly increases; with the increase in the concrete cube’s side length, the peak compressive stress of RAC declines gradually, but the integrity after compression is gradually improved; and the increase in the substitution ratio of the recycled aggregate reduces the impact of the size effect on the peak compressive stress of RAC. Furthermore, an influence equation of the coupling effect of the substitution ratio and size effect on the peak compressive stress of RAC was quantitatively established. The research results are of great significance for the engineering application of RAC and the strength selection of RAC structure design.

Sign in / Sign up

Export Citation Format

Share Document