قائمة الطعام
The results show that the chemical additives with acid pH value can inhibit the hydrolysing-bridging reaction of Mg²⁺ ions in liquid phase, and delay the hydration reaction of BMSC, which is ...
h i g h l i g h t s Barite and hematite replaced serpentine by 25 and 50% of its concrete volume. Unlike barite, hematite increased the porosity of serpentine concrete (A) Barite and hematite decreased the mechanical strength of concrete A. 25% hematite revealed the highest Rth for concrete A. 50% barite showed the highest c-ray attenuation properties …
Magnesia–phosphate cement (MPC) mortars based on magnesia and ammonium dihydrogen orthophosphate (ADP) were prepared with additions of sodium triphosphate (STP), boric acid, and borax as set ...
The residual strength rate first increases and then decreases with an increasing boric acid, and reaches a maximum value of 29.7% (1wt.% boric acid is added), which is 2.3 times that of the CACC.
MOS cement is basically composed of MgO, MgSO 4 solution and appropriate retarders. The compressive strength is primarily determined by the type, relative content and microstructure of hydration products (xMg(OH) 2 ·yMgSO 4 ·zH 2 O phases), as significantly impacted by the molar ratio of MgO, MgSO 4 and H 2 O, as well as …
Except for the control mixture, boric acid (BA) was used at the ratios of 0.25-1.00% of weight of cement in mortar mixtures with Portland cement. ... The various boron additives used with concrete ...
Effect of boric acid (BA) content on the properties of magnesium phosphate cement was evaluated. Specimens were molded with different BA contents using MgO calcined at 900 and 1110 °C. Effect of the BA concentration on the properties of MPC was evaluated. It was observed an increase in the setting time and a decrease of …
In future work, the authors recommend investigating the addition of boric acid with ratios < 1% by cement mass to address more behaviors on the serpentine concrete. The authors also recommend studying the addition of nano-silica to enhance the strength of serpentine concrete containing boric acid. CRediT authorship contribution …
Except for the control mixture, boric acid (BA) was used at the ratios of 0.25-1.00% of weight of cement in mortar mixtures with …
Thus, a cationic polyvinyl alcohol (PVA) polymer, modified by glyoxal and boric acid, was discovered due to its excellence in associating with the FLA A additive for controlling the free cement-based material water amount and preventing the chelating effect of FLA A chains on the surface of the cement-based material. Glyoxal/boric acid …
method of adding citric acid to cement can obtain a ne w type of cement with a strength higher than that . ... In this study, two additives, boric acid (H 3 BO 3 ) and lithium carbonate (LI 2 CO 3 ...
The effect of clay waste (CW) containing boron on the mechanical properties of concrete was investigated. CW was added in different proportions as cement …
The additives effects on fresh concrete. As mentioned before, it has been reported that the addition of about 1% by weight of boric acid to concrete is generally considered to be adequate for shielding purpose (Kaplan, 1989). It has been noticed in this work that boric acid has a deleterious effect on the setting of cement even at lower ratios.
Abstract. Rapid-hardening magnesium oxysulfate (MOS) cements were prepared using a high-activity light-burned magnesia (HA-LBM) powder and boric acid …
Recent studies of our research group about the immobilization of natural and B-10 enriched boric acid in Portland and sulfoaluminate cement matrices as shown in figure 3, have indicated effective ...
As the BFS additive rate in boron cement increases, concrete strength values in values. This increment is considerable depending on the curing time. The strength of BA+15% BFS mortars is …
Also, boric acid which can absorb neutrons having poisonous effect in nuclear reactions is added into the cement in order to minimize environmental disaster caused by a nuclear accident.
The BAC guidebook is a key reference to WCAP-15988-NP, Rev. 1, Generic Guidance for an Effective Boric Acid Inspection Program for Pressurized Water Reactors, February 2005. WCAP-15988-NP, Rev. 1 requires that each PWR utility in the US have a Boric Acid Corrosion Control Program (BACCP) that addresses 11 specific elements.
The formation process of these complexes is mainly as follows: firstly, borax is hydrolyzed to boric acid, and then boric acid reacts to form B(OH) 4− in an alkaline solution with a pH value greater than 11, and B(OH) 4− reacts with Ca 2+ in slag to form Ca(B(OH) 4) 2. This type of complex is a product similar to a gel structure, which has ...
DOI: 10.1016/0008-8846(95)00130-5 Corpus ID: 135599673; The effect of boric acid sludges containing borogypsum on properties of cement @article{Demirba1995TheEO, title={The effect of boric acid sludges containing borogypsum on properties of cement}, author={A. Hilal Demirbaş and Selami Karslioǧlu}, journal={Cement and Concrete …
Oxysulfate Cement Containing Boric Acid Xiaoyang Chen1; Tingting Zhang2; ... be improved by the addition of small quantities of additives that promote the formation of Phase 517. The composition ...
A boric acid-citric acid gel precursor is formed in MgSO 4 solution, changing the hydration behavior of MOS cement due to electrostatic and steric stabilization. As a result, 3 Mg(OH) 2 ·MgSO 4 ·8H 2 O destabilizes to Mg(OH) 2 ·MgSO 4 ·5H 2 O and forms the phase 517 (5 Mg(OH) 2 ·MgSO 4 ·7H 2 O).
In this research, Boric Acid (BA) was used as an additive to investigate its effect on the viscosity, setting time, and bleeding of ultrafine cement (UFC), commercially known as Spinor A6, grouts, and the permeability and strength properties of the grouted …
"Can Boric Acid Corrode Concrete?" V. Bilek and Z. Kersner, eds. International Symposium on Non-Traditional Cement and Concrete, Brno University of Technology, Brno, Czech Republic. pp. 447–456. 2002.5- Jin, X., N. Jin, and Y. Tian. "Study on the Behavior and Durability of Reinforced Concrete in Boric Acid Environment."
Borax effect on the hydration of magnesium phosphate cements was studied. •. The setting was investigated with Gillmore tests, calorimetry, Raman and pH …
Boric acid is commonly used as an additive to concrete to increase its workability and setting time, and prolong its hydration (Mollamahmutoglu and Avci 2021). ...
The addition of boric acid or boric-CA precursor improves the compressive strength of MOS cement to 90 MPa at 28 days, however, both the initial and final setting times are prolonged and the early hydration temperature is reduced, as well as the compressive strength is decreased to approximately 20 MPa at 1 day [1, 30].
1. In Fig. 2 are shown samples after firing with visually recognisable important parameters- expansion of samples with 0.5% of boric acid (sample Nr. 4.5.1) is higher than with sample with 1% of boric acid (4.4.1.) and on the contrary expansion of the sample with 2.5% of boric acid additive is lower, then for a sample with 1% of boric …
et al. (2009) concluded that the effect of boric acid on concrete properties is not significant at . exposure times up to 180 days. Figure 2-6. Measured pH as a Function of Time of Boric Acid ...
Boric acid is commonly used as an additive to concrete to increase its workability and setting time, and prolong its hydration (Mollamahmutoglu and Avci 2021). B is used as retardant for magnesium ...
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