Enhancement of Some Mechanical Properties of White Cement Mortar by Adding Nanoparticles of Zirconium Oxide

DOI: http://dx.doi.org/10.24018/ejers.2019.4.2.1149 30  Abstract—This paper will study mortar compressive strength (fc) and flexural strength (fr) by cement replacement which is partial with the particles of Nano-Zr2O3. Zr2O3nanoparticles are used as well as using average diameter of 35 nm with four various contents by weight of cement (0.25%, 0.75%, 1.25% and 1.75%). The (fc) and (fr) tests were performed after the process of curing at the 28-days which is the standard age. The preparation of mortar of Nano-cement was done by using the ratio of cement-sand by weight which is 1:3 with the ratio of water-binder materials (w/b ratio) as 0.5. The results demonstrated that the (fc) and (fr) of the mortars of cement with Zr2O3were registered higher than cement mortar that is pure. The ultimate Nano-cement mortar strength was obtained at 1.25% of the replacement of cement. The improvement in (fc) and (fr) were 15.6 % and 18.4% in a respective way at 28 days.


I. INTRODUCTION
Concrete is regarded as construction material that are the most widely used extending throughout the world. Recently, many efforts have been exerted to enhance the concrete environmental friendliness to make it convenient as a material of a Green Building. The most successful and Foremost in this respect is the use of substitutes suitable for cement that is white [1].
Materials that are supplementary and cementitious are added to concrete as a part of the total system that is cementitious to decrease the cement total quantity to be used and most importantly to raise the concrete strength from its normal state to strength that is higher [2].
The use of nanoparticles in concrete samples were studied by many works the as mineral admixtures to enhance mechanical and physical properties [3]. Hui et al. [4] investigated the cement mortars characteristics that are mixed with nanoparticles to explore their smart and better mechanical properties. Porro et al. [5] shows the nano-silica particles use as raising the strength of compression of pastes of cement. Sobolev et al. [6] remarked that adding nanosilica generated a strength rise of 15-20%. Konsta-Gdoutos et al. [7] observed the carbon nano-fibers effect on pastes of cement (0.08% by mass of binder) and examined the strength increase.
Mohammed white Portland cement cracks by having some additive [8]. Ahmed K Al-kamal et al. observed of mechanical properties modification of mortar of cement by the addition of nanoparticles of zinc oxide [9]. Dalia Adil et al. explored the effect of modifier added on the mixture of the concrete [10] where it was discovered that the (epoxy) is a modifier that is good for mortar.
Metaxa et al. [11] made concentration process of an ultracentrifugation more advanced for producing suspensions that are highly concentrated of nanotubes of carbon.
The pozzolanic reaction rate is proportional to the surface area amount that is available for reaction. Thus, it is reasonable to mix nanoparticles of Zr2O3 of a purity that is high (99.9%) and a value of Blaine fineness which is high (68 m 2 /g) so as to improve the cement mortars properties [12].
In this study an attempt has been done to demonstrate that by having new materials, there is a possibility to gain performance concrete that is high (HPC) or strength concrete that is high (HSC) with slight rise in cost. Due to its ability to decrease the structural fundamentals area which is cross-sectional, HPC and HSC are greatly used in multistory buildings and constructions.

II. MATERIALS AND MIXTURE
A. Materials 1) Nano-Zr2O3 particles Nano-Zr2O3 with particle of average size of 35 nm gained from NANOSHEL US company, was used as it was received.

2) Cement
The cement that is used in this work is the type known as

3) Aggregate
White cement is available locally in Iraq, with diameter of sand that is less than 4.75 mm; it is used in this study which has (S.G.) specific gravity is of (2.61), but the (F.M.) fineness modulus of (2.57) and (SO3%) sulfate content is an of (0.08%) from weight of sand, which is done based on Iraqi standard specification limit No. 45 / 1984.

B. Mixture:
The preparation of mixtures with the replacement of cement by weight of 0.25%, 0.75%, 1.25% and 1.75% was done. The sand to cement ration for all mixture groups was recorded to be at (3:1), and the ration of water to binder materials ratio was recorded at (0.5). The mixtures proportions are shown in Table III.

A. Procedure of Work
Mixtures Preparation was conducted in method that similar to ASTM C 305-14 [13].

C. Specimens of (fr):
This test was conducted based on ASTM C 293-14 [15]. The prism specimens (160 × 40 × 40) mm were tested at the period of 28 days.

A. fc
The results of (fc) of the whole mixtures are illustrated in Table IV. Comparing the results of specimens for 28 days reflects that the rise in (fc) with particles of nano-Zr2O3 reach around 1.25% and then it witnesses a decline.

B. fr
The results of (fr) are illustrated in Table V. The specimens (fr) rises with particles of nano-Zr2O3 to reach around 1.25% and then it witnesses a decline.