The effect of water to cement ratio and age on the mechanical properties of cement mortar and concrete made of micro‐nano bubbles without adding any admixtures

2019 ◽  
Author(s):  
Mohammad Sheikh Hassani ◽  
Ali Torki ◽  
Gholamreza Asadollahfardi ◽  
Seyed F. Saghravani ◽  
Jalil Shafaei
2010 ◽  
Vol 168-170 ◽  
pp. 190-194 ◽  
Author(s):  
Zhen Jun Wang ◽  
Rui Wang ◽  
Yu Bin Cheng

In this paper, styrene-butadiene polymer emulsion SD622S was adopted to modify cement mortar; mechanical properties of cement mortars were studied and microstructures was analyzed by means of Scanning Electron Microscope (SEM) and Specific Surface Area & Pore Distribution Analyzer. The results show that in contrast to ordinary cement mortar, if water to cement ratio (W/C) is constant, compressive strength of modified cement mortar can decrease, while flexural strength and toughness, ratio of compressive strength to flexural strength, increase with the increase of polymer to cement ratio in mass (P/C) at 7 and 28 curing days. With the increase of P/C, net structure made from polymer and cement hydration products is developed and pore whose size is smaller than 200Å begins to increase, which indicates pore diameters in modified cement mortar change to be finer. So microstructures of modified cement mortar become denser and display higher toughness.


Crystals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 240
Author(s):  
Jianlan Chen ◽  
Jiandong Wang ◽  
Rui He ◽  
Huaizhu Shu ◽  
Chuanqing Fu

This study investigated the effective chloride diffusion coefficient of cement mortar with different water-to-cement ratio (w/c) under electrical accelerated migration measurement. The cumulative chloride concentration in anode cell solution and the cumulative chloride concentration drop in the cathode cell solution was measured by RCT measurement and the results were further used to calculate the chloride diffusion coefficient by Nordtest Build 355 method and Truc method. The influence of w/c on cement mortar’s chloride coefficient was investigated and the chloride diffusion coefficient under different determination methods were compared with other researchers’ work, a good consistency between this work’s results and literatures’ results was obtained. The results indicated that the increased w/c of cement mortar samples will have a higher chloride diffusion coefficient. The cumulative chloride concentration drop in the cathode cell solution will have deviation in early stage measurement (before 60 h) which will result in overestimation of the effective chloride diffusion coefficient.


2020 ◽  
Vol 15 (4) ◽  
pp. 185-197
Author(s):  
Daniel Hatungimana ◽  
Şemsi Yazici ◽  
Şevket Orhan ◽  
Ali Mardani-Aghabaglou

ABSTRACT Portland cement is extensively used as a binder in concrete production. However, with Portland cement production, 5% of the natural resources used in this production are consumed, constituting 5–7% of the total CO2 emission. In order to mitigate the environmental problems associated with cement production, styrene-butadiene rubber latex was used as cement replacement up to 20%. In this study, compressive strength, flexural strength, unit weight, water absorption, open porosity, water sorptivity and the chloride ion permeability of Portland cement mortar mixtures modified by styrene-butadiene rubber (SBR) polymeric latex were investigated. For this purpose, the sand/cement ratio and the water/cement ratio were kept constant as 3/1 and 0.5, respectively. In addition to the control mixture containing no polymer, 1, 2, 3, 5, 10 and 20 wt.% of cement was replaced with SBR. In this way, seven mortar mixtures were prepared. Mixed curing (wet cure and dry cure) method was applied to the mortar specimens. Results showed that up to a 5% replacement level, it is possible to improve the mechanical properties of cement mortars with SBR latex addition. However, at a 10% and 20% replacement level, SBR had a significant detrimental effect on the mechanical properties of polymer modified mortars. However, the transport properties decreased with the incorporation rate of SBR latex and the detrimental effect of SBR replacement was more pronounced in 20% SBR mortar mixtures.


2019 ◽  
Vol 9 (1) ◽  
pp. 468-480 ◽  
Author(s):  
Warzer Qadir ◽  
Kawan Ghafor ◽  
Ahmed Mohammed

AbstractIn this study, the effect of lime content (L %) on the plastic properties such as water-cement ratio (w/c), setting times, flowability, compressive, flexural and bond strengths of cement mortar were investigated. Based on the information in the literature the amount of lime varied between 0 to 45% (by weight of cement). The experimental results were compared with the data collected from different research studies and quantified using two different models. The plastic and hardened properties of the cement mortar modified with different percentage of lime were conducted according to the ASTM and BS standards. Based on the literature data the water to cement ratio (w/c) ranged between 0.3-0.74 percent, the w/c of 0.5 was selected in this study. The compressive and flexural strengths of cement mortar modified with lime up to 28 days of curing were ranged between 3 MPa to 65 MPa and 2 MPa to 12 MPa respectively. The compressive, flexural and bond strengths of the cement mortar decreased with increasing lime content. Vipulanandan correlation model was used to correlate the relationship between lime with consistency, setting times, flowability and compressive strength of cement mortar. Compressive and flexural strengths of cement mortar modified with lime were quantified very well as a function of w/c, lime content and curing time using nonlinear relationship.


2013 ◽  
Vol 795 ◽  
pp. 664-668 ◽  
Author(s):  
Roshasmawi Abdul Wahab ◽  
Mohd Noor Mazlee ◽  
Shamsul Baharin Jamaludin ◽  
Khairul Nizar Ismail

In this study, the mixing of polystyrene (PS) beads and fly ash as a sand replacement material in foamed cement composites (FCC) has been investigated. Specifically, the mechanical properties such as compressive strength and flexural strength were measured. Different proportions of fly ash were added in cement composites to replace the sand proportion at 3 wt. %, 6 wt. %, 9 wt. % and 12 wt. % respectively. The water to cement ratio was fixed at 0.65 meanwhile ratios of PS beads used was 0.25 volume percent of samples as a foaming agent. All samples at different mixed were cured at 7 and 28 days respectively. Based on the results of compressive strength, it was found that the compressive strength was increased with the increasing addition of fly ash. Meanwhile, flexural strength was decreased with the increasing addition of fly ash up to 9 wt. %. The foamed cement composites with 12 wt. % of fly ash produced the highest strength of compressive strength meanwhile 3 wt. % of fly ash produced the highest strength of flexural strength.


2011 ◽  
Vol 225-226 ◽  
pp. 457-460
Author(s):  
Wei Li

Aimed for current situation that most scholars concerned with mechanics, deformation, flow performance of modified cement mortar, the paper selected carboxyl styrene-butadiene latex as the modified material, researched on cement mortar’ water reducing effect, wear resistance, corrosion resistance-mechanical properties, drying shrinkage before modifing and after modifing. Compared cement fine mortar’s properties with cement mechine-made mortar’s properties before and after modification. Research results showed that the addition of carboxyl SB latex, the overall performance of cement mortar is greatly improved, and with the increase of polymer cement ratio, this improvement trend is more obvious, those changes especially are suitable for extra-fine cement mortar. The results clarify the properties variation law of cement mortar before and after modification, this provides scientific guidance for polymer latex modified cement mortar mix design.


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