Evaluation of effects of multi-varied atmospheric curing conditions on compressive strength of bacterial (bacillus subtilis) cement mortar

In order to study the influences of initial curing conditions on fly ash (FA) cement concrete durability, fly ash cement samples with 30% replacement ratio were fabricated and cured in water at 10°C, 20°C, 30°Cand 40°C for 3d, 7d, 14d and 28d respectively. Hydration degrees of fly ash at early age were measured using the selective dissolve method. Correspondingly the pore structure and morphology of FA-cement mortar and compared cement mortar were studied by using MIP and SEM methods. Then early age compressive strengths of FA-cement concrete and compared normal cement concrete were tested. Experimental results show that initial curing temperatures and ages are important factors to fly ash early age hydration degree, FA-cement system microstructure, morphology and early age compressive strength etc. High curing temperatures and longer curing time can lead higher fly ash hydration degree, and then higher compressive strength of FA-cement concrete, and make the micro-structures of fly ash-cement system denser.

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Bio-inspired self-healing cementitious mortar using Bacillus subtilis immobilized on nano-/micro-additives

Journal of Intelligent Material Systems and Structures ◽

10.1177/1045389x18806401 ◽

2018 ◽

Vol 30 (1) ◽

pp. 3-15 ◽

Cited By ~ 3

Author(s):

Rao Arsalan Khushnood ◽

Siraj ud din ◽

Nafeesa Shaheen ◽

Sajjad Ahmad ◽

Filza Zarrar

Keyword(s):

Compressive Strength ◽

Bacillus Subtilis ◽

Iron Oxide ◽

Cement Mortar ◽

Healing Process ◽

Main Concern ◽

Scanning Electron Micrographs ◽

Self Healing ◽

Micro Cracks ◽

Cracked Specimens

Bio-inspired self-healing strategies are much innovative and potentially viable for the production of healable cement mortar matrix. The present research explores the feasibility of gram-positive “Bacillus subtilis” microorganisms in the effective healing of nano-/micro-scale-induced structural and non-structural cracks. The main concern related to the survival of such microorganisms in cementitious environment has been successfully addressed by devising proficient immobilization scheme coherently. The investigated immobilizing media includes iron oxide nano-sized particles, micro-sized limestone particles, and milli-sized siliceous sand. The effect of induced B. subtilis microorganisms immobilized on nano-micro-additives was analyzed by the quantification of average compressive resistance of specimens (ASTM C109) and healing evaluation. The healing process was mechanically gauged by compressive strength regain of pre-cracked specimens after the healing period of 28 days. The pre-cracking load was affixed at 80% of ultimate compressive stress “[Formula: see text]” while the age of pre-cracking was kept variable as 3, 7, 14, and 28 days to precisely correlate healing effectiveness as the function of cracking period. The healing mechanism was further explored by examining the healed micro-crack using field emission scanning electron micrographs, energy dispersive x-ray spectrographs, and thermogravimetry. The results revealed that B. subtilis microorganisms contribute extremely well in the improvement of compressive strength and efficient healing process of pre-cracked cement mortar formulations. The iron oxide nano-sized particles were found to be the most effective immobilizer for preserving B. subtilis microbes till the generation of cracks followed by siliceous sand and limestone particles. The micro-graphical and chemical investigations endorsed the mechanical measurements by evidencing calcite precipitation in the induced nano-/micro-cracks as a result of microbial activity.

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Expansion of Cement Mortar Mixing Expansive Agent under Different Curing Conditions and Compressive Strength in Constrained Conditions

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.405-408.2534 ◽

2013 ◽

Vol 405-408 ◽

pp. 2534-2537 ◽

Cited By ~ 1

Author(s):

Yuan Yuan Wu ◽

Yuan Peng ◽

Yong Dao Liu ◽

Li Li Jia

Keyword(s):

Compressive Strength ◽

Cement Mortar ◽

Steel Tubes ◽

Curing Conditions ◽

Expansive Agent ◽

Calcium Sulphoaluminate ◽

Constrained Conditions ◽

Concrete Filled Steel Tubes ◽

Expansion Effect ◽

Closed Environment

The expansion of cement mortar mixing expansive agent under standard curing and membrane curing conditions and compressive strength in constrained conditions are studied in this paper. Results show that the early expansion effect of calcium sulphoaluminate hydrate-calcium hydroxide expansive agent is obvious, mid-to late effect of magnesia expansive agent increase clearly. Compare with standard curing, the shrinkage of the basic cement mortar increase and expansion effect of expansive agent reduce under membrane curing. The expansion effect of expansive agent B is good and persistent under membrane curing, its applicable to used in the closed environment, such as concrete filled steel tubes. The compressive strength of mortar with expansion agent is a little more than the basic mortar under the condition of limit.

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Bacillus Subtilis as Self-Healing Agent in Cement Mortar: The Effect of Curing Time and Amount of Calcium Lactate on Strength

Mehran University Research Journal of Engineering and Technology ◽

10.22581/muet1982.2104.19 ◽

2021 ◽

Vol 40 (4) ◽

pp. 889-897

Author(s):

Sohail Muhammad ◽

Humair Ahmed Siddiqui

Keyword(s):

Compressive Strength ◽

Bacillus Subtilis ◽

Calcium Carbonate ◽

Cement Mortar ◽

Calcium Lactate ◽

Self Healing ◽

Curing Time ◽

Healing Agent ◽

Cause Of Failure ◽

The Cost

Crack growth is a major cause of failure in structures that are made using cement and concrete. Healing of these cracks can increase the life span of structures. In the present study micro-organism based self-healing of structures is studied. A commonly occurring micro-organism bacterium called Bacillus Subtilis, is used in the manufacturing of cement mortar blocks as a self-healing agent for cement mortar blocks, with the use of Calcium Lactate as feed for bacteria. In the first step, colonies of Bacillus Subtilis were grown and added with calcium lactate to produce a solution. The solution was then kept for one week to observe the metabolic product of Bacillus Subtilis. It was found that the bacterial product was composed of CaCO3 and thus the bacteria is suitable to be used as self-healing agent. Self-healing cement mortar blocks were made by adding Bacteria and Calcium Lactate with usual ingredients of cement mortar, i.e. cement, sand and water. It was found that the bacteria were also effective in converting Calcium Lactate to Calcium Carbonate, when mixed in cement mortar blocks. It was observed that the pores of cement mortar blocks were filled by Calcium Carbonate and that cracks get healed by the deposition of Calcium Carbonate in the cracks. Cement mortar blocks, with and without healing agent, were made to compare the effect of curing time. The samples were tested after seven, fourteen and twenty-eight days to compare the effect of healing agent. All the samples with the healing agent showed a higher compressive strength in comparison with the samples that were made without healing agent. Different percentages of Calcium Lactate, ranging from 1-7% were also used to find the best composition for future use. It was found that the compressive strength was increasing up to 5% while above 5% the increase was marginal thus it is proposed that Calcium Lactate should be used in between 5-7 % to reduce the cost of self-healing cement in construction industry.

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Influence of Curing Conditions on Strength Characteristics of Sea Sand Mortar

INTEK Jurnal Penelitian ◽

10.31963/intek.v7i2.2720 ◽

2021 ◽

Vol 7 (2) ◽

pp. 160

Author(s):

Irka Tangke Datu ◽

Adiwijaya Ali ◽

Nur Aisyah Jalali ◽

Khairil Khairil

Keyword(s):

Compressive Strength ◽

Cement Mortar ◽

Tap Water ◽

Strength Characteristics ◽

Fine Aggregate ◽

River Sand ◽

Strength Performance ◽

Curing Conditions ◽

Water Characteristics ◽

Sea Sand

This present paper aims to investigate strength characteristics of cement mortar using natural sea sand as fine aggregate in different curing conditions. Research was carried out with making mortar mixtures by two types of cement, Portland Composite Cement (PCC) and Pozzolana Portland Cement (PPC) with tap water as mixing water. Characteristics of fine aggregate and strength of cement mortar use river sand (RS), sea sand (SS), and washed sea sand (WS) were observed. Further, specimens of cube mortar in size of 50 mm x 50 mm x 50 mm of six mortar mixture series were casted according to Indonesian Standard. At 24 hours after cube specimens were casted, cube mortar specimens were cured in three curing conditions such as tap water curing (TC), seawater curing (SC) and air curing (AC). After curing at certain period (3-day, 7-day, 14-day, and 28-day), cube mortar samples were tested in compressive strength. Results concluded that sea sand aggregate improve characteristic of mortar in compressive strength up to 28 days in all curing conditions, and there was no significant effect of type of curing water (TC and SC) on 28-day strength performance of mortar was obtained. In addition, sea sand could potentially be utilized as an aggregate in production of mortar and/or concrete.

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Bacillus Subtilis as Self-Healing Agent in Cement Mortar: Combined and the Separate Effect of Bacteria and Calcium Lactate on Self-Healing Behavior in Cement Mortar

Mehran University Research Journal of Engineering and Technology ◽

10.22581/muet1982.2102.16 ◽

2021 ◽

Vol 40 (2) ◽

pp. 426-434

Author(s):

Sohail Muhammad ◽

Humair Ahmed Siddiqui ◽

Muhammad Ishaque Abro ◽

Adil Usmani ◽

Muhammad Amjad Anwar Malik

Keyword(s):

Compressive Strength ◽

Bacillus Subtilis ◽

Cement Mortar ◽

Surface Characteristics ◽

Calcium Lactate ◽

Sand Sample ◽

Self Healing ◽

Cement Sample ◽

Remarkable Change ◽

Surface Appearance

Cement mortar, which is one of the most useful materials for construction applications, can deteriorate its performance by developing cracks. In order to cope with this issue, the materials’ scientist came forward with a unique biogeochemical phenomenon in which cement mortar can selfheal its crack autonomously using calcium carbonate precipitating bacteria and their feed. In this research, it was intended to study the separate and combined effect of Bacillus Subtilis (bacteria) and Calcium Lactate (feed) on the properties of conventional mortar. Cement mortars were made using conventional method and cast in the form of cylinders. Four types of samples were taken. Sample-N contains only cement and sand, Sample-B was made by addition of bacteria Bacillus Subtilis with sand and cement, Sample-C contains Calcium Lactate which is usually used as feed for Bacteria while the last sample ‘BC’ have both Bacteria as well as Calcium Lactate. The samples were observed up to 44 days for their surface characteristics and compressive strength. The Sample-N and B did not show any remarkable change in their surface appearance with respect to curing time. Sample-C and BC did show the precipitation of CaCO3 but the Sample-C precipitation was stopped soon while for Sample-BC, the precipitation was continued for a longer time. The Sample-BC showed the highest compressive strength (approximately 17.57 MPa), followed by Sample-N (approximately 13.32 MPa), Sample-B (approximately 11.04 MPa) while Sample-C displayed lowest strength (approximately 2.75 MPa). This gives an idea that Calcium Lactate which acts as feed for bacteria has the negative effect on the strength if not consumed and converted into CaCO3.

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Incorporation of Iraqi Rocks in the Production of Eco-Friendly Cement Mortar

Engineering and Technology Journal ◽

10.30684/etj.v38i10a.1479 ◽

2020 ◽

Vol 38 (10A) ◽

pp. 1522-1530

Author(s):

Rawnaq S. Mahdi ◽

Aseel B. AL-Zubidi ◽

Hassan N. Hashim

Keyword(s):

Mechanical Properties ◽

Thermal Conductivity ◽

Compressive Strength ◽

Water Absorption ◽

Structural Properties ◽

Mechanical Milling ◽

Cement Mortar ◽

Cement Mortars

This work reports on the incorporation of Flint and Kaolin rocks powders in the cement mortar in an attempt to improve its mechanical properties and produce an eco-friendly mortar. Flint and Kaolin powders are prepared by dry mechanical milling. The two powders are added separately to the mortars substituting cement partially. The two powders are found to improve the mechanical properties of the mortars. Hardness and compressive strength are found to increase with the increase of powders constituents in the cement mortars. In addition, the two powders affect water absorption and thermal conductivity of the mortar specimens which are desirable for construction applications. Kaolin is found to have a greater effect on the mechanical properties, water absorption, and thermal conductivity of the mortars than Flint. This behavior is discussed and analyzed based on the compositional and structural properties of the rocks powders.

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Mechanical Behavior of Brick Masonry in an Acidic Atmospheric Environment

Materials ◽

10.3390/ma12172694 ◽

2019 ◽

Vol 12 (17) ◽

pp. 2694 ◽

Cited By ~ 2

Author(s):

Shansuo Zheng ◽

Lihua Niu ◽

Pei Pei ◽

Jinqi Dong

Keyword(s):

Mechanical Properties ◽

Compressive Strength ◽

Fly Ash ◽

Acid Rain ◽

Cement Mortar ◽

Brick Masonry ◽

Atmospheric Environment ◽

Peak Strain ◽

Lime Mortar ◽

Attenuation Model

In order to evaluate the deterioration regularity for the mechanical properties of brick masonry due to acid rain corrosion, a series of mechanical property tests for mortars, bricks, shear prisms, and compressive prisms after acid rain corrosion were conducted. The apparent morphology and the compressive strength of the masonry materials (cement mortar, cement-lime mortar, cement-fly ash mortar, and brick), the shear behavior of the masonry, and the compression behavior of the masonry were analyzed. The resistance of acid rain corrosion for the cement-lime mortar prisms was the worst, and the incorporation of fly ash into the cement mortar did not improve the acid rain corrosion resistance. The effect of the acid rain corrosion damage on the mechanical properties for the brick was significant. With an increasing number of acid rain corrosion cycles, the compressive strength of the mortar prisms, and the shear and compressive strengths of the brick masonry first increased and then decreased. The peak stress first increased and then decreased whereas the peak strain gradually increased. The slope of the stress-strain curve for the compression prisms gradually decreased. Furthermore, a mathematical degradation model for the compressive strength of the masonry material (cement mortar, cement-lime mortar, cement-fly ash mortar, and brick), as well as the shear strength attenuation model and the compressive strength attenuation model of brick masonry after acid rain corrosion were proposed.

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Preparation of Electric- and Magnetic-Activated Water and Its Influence on the Workability and Mechanical Properties of Cement Mortar

Sustainability ◽

10.3390/su13084546 ◽

2021 ◽

Vol 13 (8) ◽

pp. 4546

Author(s):

Kaiyue Zhao ◽

Peng Zhang ◽

Bing Wang ◽

Yupeng Tian ◽

Shanbin Xue ◽

...

Keyword(s):

Magnetic Field ◽

Mechanical Properties ◽

Compressive Strength ◽

Flexural Strength ◽

Cement Paste ◽

Cement Mortar ◽

Environmental Issues ◽

Chemical Admixtures ◽

Untreated Water ◽

Alternating Voltage

Cement-based materials prepared with activated water induced by a magnetic field or electric field represent a possible solution to environmental issues caused by the worldwide utilization of chemical admixtures. In this contribution, electric- and magnetic-activated water have been produced. The workability and mechanical properties of cement mortar prepared with this activated water have been investigated. The results indicate that the pH and absorbance (Abs) values of the water varied as the electric and magnetic field changed, and their values increased significantly, exhibiting improved activity compared with that of the untreated water. In addition, activated water still retains activity within 30 min of the resting time. The fluidity of the cement paste prepared with electric-activated water was significantly larger than that of the untreated paste. However, the level of improvement differed with the worst performance resulting from cement paste prepared with alternating voltage activated water. In terms of mechanical properties, both compressive strength and flexural strength obtained its maximum values at 280 mT with two processing cycles. The compressive strength increased 26% as the curing time increased from 7 days to 28 days and flexural strength increased by 31%. In addition, through the introduction of magnetic-activated water into cement mortar, the mechanical strength can be maintained without losing its workability when the amount of cement is reduced.

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Assessment of the influence of fine aggregates on Portland cement mortar compressive strength

Results in Materials ◽

10.1016/j.rinma.2021.100182 ◽

2021 ◽

pp. 100182

Author(s):

Alberto Muciño ◽

Lauro Bucio ◽

Eligio Orozco ◽

Sofía Vargas ◽

Nora A. Pérez

Keyword(s):

Compressive Strength ◽

Portland Cement ◽

Cement Mortar ◽

Fine Aggregates

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