Monitoring early age strength gain of SCC with different supplementary cementitious materials using acoustic emission sensors

2019 ◽  
Vol 229 ◽  
pp. 116858 ◽  
Author(s):  
Ahmed A. Abouhussien ◽  
Assem A.A. Hassan
Keyword(s):  
Acoustic Emission ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Early Age ◽  
Strength Gain ◽  
Acoustic Emission Sensors

Effect of Various Supplementary Cementitious Materials on Early-Age Concrete Cracking

2020 ◽  
Vol 32 (4) ◽  
pp. 04020049
Author(s):  
Inamullah Khan ◽  
Tengfei Xu ◽  
Mohammad Shakhaout Hossain Khan ◽  
Arnaud Castel ◽  
Raymond Ian Gilbert
Keyword(s):  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Early Age ◽  
Concrete Cracking ◽  
Early Age Concrete

scholarly journals Feasibility Tests on Concrete with Very-High-Volume Supplementary Cementitious Materials

2014 ◽  
Vol 2014 ◽  
pp. 1-11
Author(s):  
Keun-Hyeok Yang ◽  
Yong-Su Jeon
Keyword(s):  
Compressive Strength ◽  
Weight Ratio ◽  
High Volume ◽  
Cementitious Materials ◽  
Positive Influence ◽  
Supplementary Cementitious Materials ◽  
Early Age ◽  
Freezing And Thawing ◽  
Strength And Durability ◽  
Very High

The objective of this study is to examine the compressive strength and durability of very high-volume SCM concrete. The prepared 36 concrete specimens were classified into two groups according to their designed 28-day compressive strength. For the high-volume SCM, the FA level was fixed at a weight ratio of 0.4 and the GGBS level varied between the weight ratio of 0.3 and 0.5, which resulted in 70–90% replacement of OPC. To enhance the compressive strength of very high-volume SCM concrete at an early age, the unit water content was controlled to be less than 150 kg/m3, and a specially modified polycarboxylate-based water-reducing agent was added. Test results showed that as SCM ratio (RSCM) increased, the strength gain ratio at an early age relative to the 28-day strength tended to decrease, whereas that at a long-term age increased up toRSCMof 0.8, beyond which it decreased. In addition, the beneficial effect of SCMs on the freezing-and-thawing and chloride resistances of the concrete decreased atRSCMof 0.9. Hence, it is recommended thatRSCMneeds to be restricted to less than 0.8–0.85 in order to obtain a consistent positive influence on the compressive strength and durability of SCM concrete.

scholarly journals Effects of Curing Conditions and Supplementary Cementitious Materials on Autogenous Self-Healing of Early Age Cracks in Cement Mortar

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 752
Author(s):  
Mian Luo ◽  
Kang Jing ◽  
Jingquan Bai ◽  
Ziqi Ding ◽  
Dingyi Yang ◽  
...  
Keyword(s):  
Cement Mortar ◽  
Cementitious Materials ◽  
Visual Observation ◽  
Healing Time ◽  
Supplementary Cementitious Materials ◽  
Early Age ◽  
Self Healing ◽  
Replacement Ratio ◽  
Curing Conditions ◽  
Healing Efficiency

The autogenous healing potential of cement-based materials is affected by multiple factors, such as mix composition, crack width, pre-cracking age and external environmental conditions. In this study, the effects of curing conditions and supplementary cementitious materials (SCMs) on autogenous self-healing of early age cracks in cement mortar were investigated. Three curing conditions, i.e., standard curing, wet–dry cycles and incubated in water, and two SCMs, i.e., fly ash (FA) and blast furnace slag (BFS) with various contents (cement replacement ratio at 0%, 20%, and 40%) were examined. A single early age crack (pre-cracking age of 3 days) with a width of 200~300 μm was generated in cylindrical mortar specimens. Autogenous crack self-healing efficiency of mortar specimens was evaluated by performing a visual observation and a water permeability test. Moreover, microstructure analysis (XRD, SEM and TG/DTG) was utilized to characterize the healing products. The results indicated that the presence of water was essential for the autogenous self-healing of early age cracks in cement mortar. The efficiency of self-healing cracks was highest in specimens incubated in water. However, no significant self-healing occurred in specimens exposed to standard curing. For wet–dry cycles, a longer healing time was needed to obtain good self-healing compared to samples incubated in water. SCMs type and content significantly affected the autogenous self-healing ability of early age cracks. The self-healing efficiency of early age cracks decreased with increases in FA and BFS content. BFS mortars exhibited greater recovery in relation to water penetration resistance compared to the reference and FA mortars. Almost the same regain of water tightness and a lower crack-healing ratio after healing of 28 days in FA mortars were observed compared to the reference. The major healing product in the surface cracks of specimens with and without SCMs was micron-sized calcite crystals with a typical rhombohedral morphology.

scholarly journals The Effect of Bacteria on Early Age Strength of CEM I and CEM II Cementitious Composites

2022 ◽  
Vol 14 (2) ◽  
pp. 773
Author(s):  
Tsz Ying Hui ◽  
Lorena Skevi ◽  
Bianca Reeksting ◽  
Susanne Gebhard ◽  
Kevin Paine
Keyword(s):  
Flexural Strength ◽  
Surface Morphology ◽  
Cementitious Materials ◽  
Strength Reduction ◽  
Cement Matrix ◽  
Early Age ◽  
Bacterial Cells ◽  
Strength Gain ◽  
Strength Tests ◽  
Lower Carbon

Despite being associated with lower carbon emissions, CEM II cementitious materials exhibit reduced early age strength compared to that of CEM I. Several studies have demonstrated early age strength improvements by incorporating bacterial cells in concrete. In this study, live vegetative bacteria and dead bacteria killed in two different ways were used to explore whether changes in strength are related to the bacteria’s viability or their surface morphology. Compressive and flexural strength tests were performed at mortars with and without bacteria for both CEM I and CEM II cement. Their microstructure, porosity and mineralogy were also examined. No net strength gain was recorded for either CEM I or CEM II bacterial mortars compared to non-bacterial controls, although changes in the porosity were reported. It is proposed that two phenomena, one causing strength-reduction and one causing strength-gain, took place in the bacterial specimens, simultaneously. It is suggested that each phenomenon is dependent on the alkalinity of the cement matrix, which differs between CEM I and CEM II mortars at early age. Nevertheless, in neither case could it be recommended that the addition of bacteria is an effective way of increasing the early age strength of mortars.

scholarly journals Portland blended cements: demolition ceramic waste management

2017 ◽  
Vol 67 (325) ◽  
pp. 114 ◽  
Author(s):  
M. A. Trezza ◽  
S. Zito ◽  
A. Tironi ◽  
E. F. Irassar ◽  
V. F. Rahhal
Keyword(s):  
Compressive Strength ◽  
Cementitious Materials ◽  
Pozzolanic Activity ◽  
Supplementary Cementitious Materials ◽  
Early Age ◽  
Blended Cements ◽  
Ceramic Waste ◽  
Materials Used ◽  
Potential Use

Demolition ceramic wastes (DCWs) were investigated in order to determine their potential use as supplementary cementitious materials in Portland Blended Cements (PBCs). For this purpose, three ceramic wastes were investigated. After characterization of the materials used, the effect of ceramic waste replacement (8, 24 and 40% by mass) was analyzed. Pozzolanic activity, hydration progress, workability and compressive strength were determined at 2, 7 and 28 days. The results showed that the ground wastes behave as filler at an early age, but as hydration progresses, the pozzolanic activity of ceramic waste contributes to the strength requirement.

Acoustic Emission Sensors using Silicon Mechanical Resonators

2015 ◽  
Vol 135 (12) ◽  
pp. 484-489
Author(s):  
Kengo Takata ◽  
Takashi Sasaki ◽  
Mitsutomo Nishizawa ◽  
Hiroshi Saito ◽  
Shinsuke Yamazaki ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Mechanical Resonators ◽  
Acoustic Emission Sensors
Sign in / Sign up

Export Citation Format

Share Document