scholarly journals Evaluation of the behavior of mortars produced with fibers from the straw of carnauba: effects of the content of addition and length used

2021 ◽  
Vol 26 (2) ◽  
Author(s):  
Antunes França Eduardo ◽  
Marcilene Vieira de Nóbrega ◽  
Ruan Landolfo da Silva Ferreira
Keyword(s):  
Mechanical Properties ◽  
Mechanical Strength ◽  
Deformation Capacity ◽  
Mass Ratio ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Hardened State ◽  
The Stability ◽  
Small Deformations ◽  
Pathological Manifestation

ABSTRACT The rendering mortars must be able to absorb small deformations, in order to guarantee the stability of the masonry (performance and durability). When this premise is not met, there is a greater propensity for the appearance of cracks, one of the main and worrying pathological manifestations in mortar coverings. One of the alternatives to combat this pathological manifestation is the addition of natural/artificial fibers in order to improve the mechanical properties (mainly the traction strength) and, consequently, the deformation capacity of the mortar. In this perspective, this work analyzed the behavior in the fresh and hardened state of mortars with the addition of fibers obtained from the straw of the carnauba (Copernicia prunifera), an abundant tree in the region of the Açu valley/RN (Brazil). For this purpose, mortars were produced in a 1:3 mass ratio (binder:aggregate) with the addition of 3% and 5% fiber from the carnauba straw (CSF) in relation to the cement mass and with the water/cement ratio (w/c) fixed at 0.72 for all mixtures. The effects of using fibers with different lengths (20, 40 and 60 mm) were also investigated. The properties of mortars were evaluated in a fresh (consistency) and hardened (compression and flexural strengths) state. The results indicated that the addition of CSF results in mortar with less consistency and mechanical strength. However, in general, the best performance was obtained for additions of up to 3% and for longer fiber lengths (20 mm).

Study on Preparation of Solid Concrete Brick with Recycled Aggregate

2013 ◽  
Vol 648 ◽  
pp. 108-111
Author(s):  
Qi Jin Li ◽  
Guo Zhong Li
Keyword(s):  
Compressive Strength ◽  
Mass Fraction ◽  
Recycled Aggregate ◽  
Preparation Process ◽  
Mass Ratio ◽  
Construction Waste ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Optimal Value

The construction waste was processed into recycled aggregate to produce solid construction waste brick with grade of MU20. The preparation process of recycled aggregate and the optimal value of mass ratio of water to cement (water cement ratio) and mass ratio of recycled aggregate to cement was studied. The results shows that when the water cement ratio is 0.86 and the mass ratio of recycled aggregate to cement is 5.5 and the dosage of activator is 0.25% (mass fraction with recycled aggregate), the compressive strength of sample is 22.5MPa and can be satisfied with the requirement of MU20 solid concrete brick.

scholarly journals Mechanical Properties of Concrete with Various Water-Cement Ratio After High Temperature Exposure

2019 ◽  
Vol 2 (2) ◽  
pp. 126-136
Author(s):  
M.I Retno Susilorini ◽  
Budi Eko Afrianto ◽  
Ary Suryo Wibowo
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
High Temperature ◽  
Modulus Of Elasticity ◽  
Building Materials ◽  
Heating Process ◽  
High Temperature Exposure ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Temperature Exposure

Concrete building safety of fire is better than other building materials such as wood, plastic, and steel,because it is incombustible and emitting no toxic fumes during high temperature exposure. However,the deterioration of concrete because of high temperature exposure will reduce the concrete strength.Mechanical properties such as compressive strength and modulus of elasticity are absolutely corruptedduring and after the heating process. This paper aims to investigate mechanical properties of concrete(especially compressive strength and modulus of elasticity) with various water-cement ratio afterconcrete suffered by high temperature exposure of 500oC.This research conducted experimental method and analytical method. The experimental methodproduced concrete specimens with specifications: (1) specimen’s dimension is 150 mm x 300 mmconcrete cylinder; (2) compressive strength design, f’c = 22.5 MPa; (3) water-cement ratio variation =0.4, 0.5, and 0.6. All specimens are cured in water for 28 days. Some specimens were heated for 1hour with high temperature of 500oC in huge furnace, and the others that become specimen-controlwere unheated. All specimens, heated and unheated, were evaluated by compressive test.Experimental data was analyzed to get compressive strength and modulus of elasticity values. Theanalytical method aims to calculate modulus of elasticity of concrete from some codes and to verifythe experimental results. The modulus elasticity of concrete is calculated by 3 expressions: (1) SNI03-2847-1992 (which is the same as ACI 318-99 section 8.5.1), (2) ACI 318-95 section 8.5.1, and (3)CEB-FIP Model Code 1990 Section 2.1.4.2.The experimental and analytical results found that: (1) The unheated specimens with water-cementratio of 0.4 have the greatest value of compressive strength, while the unheated specimens with watercementratio of 0.5 gets the greatest value of modulus of elasticity. The greatest value of compressivestrength of heated specimens provided by specimens with water-cement ratio of 0.5, while the heatedspecimens with water-cement ratio of 0.4 gets the greatest value of modulus of elasticity, (2) Allheated specimens lose their strength at high temperature of 500oC, (3) The analytical result shows thatmodulus of elasticity calculated by expression III has greater values compares to expression I and II,but there is only little difference value among those expressions, and (4)The variation of water-cementratio of 0.5 becomes the optimum value.

scholarly journals High Temperature Degradation Mechanism of Concrete with Plastering Layer

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 398
Author(s):  
Chihao Liu ◽  
Jiajian Chen
Keyword(s):  
Mechanical Properties ◽  
Mechanical Property ◽  
Thermal Decomposition ◽  
Electron Microscope ◽  
High Temperature ◽  
Thermogravimetric Analysis ◽  
Degradation Mechanism ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Scanning Electron

At present, the research on the high temperature degradation of concrete usually focuses on only the degradation of concrete itself without considering the effect of the plastering layer. It is necessary to take into account the influence of the plastering layer on the high temperature degradation of concrete. With an increase in the water/cement ratio, the explosion of concrete disappeared. Although increasing the water/cement ratio can alleviate the cracking of concrete due to lower pressure, it leads to a decrease in the mechanical properties of concrete after heating. It is proved that besides the water/cement ratio, the apparent phenomena and mechanical properties of concrete at high temperature can be affected by the plastering layer. The plastering layer can relieve the high temperature cracking of concrete, and even inhibit the high temperature explosion of concrete with 0.30 water/cement ratio. By means of an XRD test, scanning electron microscope test and thermogravimetric analysis, it is found that the plastering layer can promote the rehydration of unhydrated cement particles of 0.30 water/cement ratio concrete at high temperature and then promote the mechanical properties of concrete at 400 °C. However, the plastering layer accelerated the thermal decomposition of C-S-H gel of concrete with a water/cement ratio of 0.40 at high temperature, and finally accelerate the decline of mechanical property of concrete. To conclude, the low water/cement ratio and plastering layer can delay the deterioration of concrete at high temperature.

scholarly journals INFLUENCE OF CURING CONDITION AND WATER CEMENT RATIO ON MECHANICAL PROPERTIES OF CONCRETE IN HIGH TEMPERATURES

2016 ◽  
Vol 81 (720) ◽  
pp. 385-393 ◽  
Author(s):  
Heisuke YAMASHITA ◽  
Masatoshi TOKOYODA ◽  
Sumie SUZUKI ◽  
Masayuki SHIRAIWA ◽  
Takeo HIRASHIMA
Keyword(s):  
Mechanical Properties ◽  
High Temperatures ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Curing Condition

Effect of Water Reducer and Cellulose Ether on Sulphoaluminate Cement-Based Lightweight Thermal Insulation Board

2014 ◽  
Vol 541-542 ◽  
pp. 273-276
Author(s):  
Xiao Nan Dong ◽  
Xi Chen ◽  
Ling Chao Lu ◽  
Shuai Yang
Keyword(s):  
Mechanical Strength ◽  
Thermal Insulation ◽  
Influential Factor ◽  
Cellulose Ether ◽  
Dry Density ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Sulphoaluminate Cement ◽  
Effect Of Water ◽  
Good Workability

The effects of two admixtures content i.e. water reducer, cellulose ether and water-cement ratio on mechanical strength and dry density of cement-based lightweight thermal insulation board are studied. The result indicates that the water-cement ratio is the important influential factor, which is easier to get good workability. And based on the mechanical strength and dry density, the best range of water reducer content and cellulose ether content are 0.3%-0.6% and 0.4%-0.6% respectively.

Laboratory Experimental Research on Mix Ratio Test of Cement Soil

2013 ◽  
Vol 438-439 ◽  
pp. 197-201
Author(s):  
Xian Hua Yao ◽  
Peng Li ◽  
Jun Feng Guan
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Unconfined Compressive Strength ◽  
Cement Content ◽  
Ratio Test ◽  
Curing Time ◽  
Curing Conditions ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Cement Soil

Based on the generalization and analysis of laboratory experimental results on mix ratio, the effects of various factors such as cement content, water-cement ratio, curing time, curing conditions and types of cement on the mechanical properties of unconfined compressive strength of cement soil are presented. Results show that the unconfined compressive strength of cement soil increases with the growing curing time, and it is greatly affected by the cement content, water-cement ratio, cement types and curing time, while the effect of curing conditions is weak with a cement content of more than 10%. Moreover, the stress-strain of the cement soil responds with the cement content and curing time, increasing curing time and cement content makes the cement soil to be harder and brittle, and leads to a larger Young's modulus.

scholarly journals Influence of Expansive Agent on the Dimensional Stability and Mechanical Properties of Gypsum Plaster

2019 ◽  
Vol 8 (4) ◽  
pp. 928-931
Keyword(s):  
Mechanical Properties ◽  
Water Absorption ◽  
Dimensional Stability ◽  
Early Hydration ◽  
Expansive Agent ◽  
Gypsum Plaster ◽  
Hardened State ◽  
Dimensional Variation ◽  
The Stability

Nowadays the use of gypsum plaster has gained momentum due to their economic and eco-friendly nature. The objective of this work was to study the influence of expansive agent such as CaO and MgO on the properties of the gypsum plaster. The effect of expansive agent on the physical, mechanical, water absorption and porosity were analyzed. The dimensional stability of the plaster with various percentages of Cao and MgO were also evaluated. From the results obtained it was confirmed that the addition of expansive agent increased the stability of the gypsum plaster to dimensional variation both during early hydration periods and also at hardened state without affecting the strength of the plaster.

scholarly journals Optimization of the Physical and Mechanical Properties of Grouting Material for Non-Soil-Squeezing PHC Pipe Pile

Crystals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 10
Author(s):  
Zhenkun Hou ◽  
Mengxiong Tang ◽  
Shihua Liang ◽  
Yi Zhu
Keyword(s):  
Mechanical Properties ◽  
Physical And Mechanical Properties ◽  
Reducing Agent ◽  
Curing Time ◽  
Shrinkage Ratio ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Cement Mixture ◽  
Early Strength ◽  
Late Stages

The physical and mechanical properties of grouting materials greatly affect the friction resistance and the bearing performance of a non-soil-squeezing PHC pipe pile. Orthogonal tests for four factors at five levels were carried out to optimize the proportion of the water–cement mixture by using Portland cement as a raw material and a water-reducing agent, expansion agent and early-strength agent as additives. The following conclusions were obtained: (1) Both the water–cement ratio and the dosage of water-reducing agent are positively correlated with the fluidity of the water–cement mixture and have the greatest influence on the fluidity, followed by the expansion agent and early-strength agent. The saturation point of the water-reducing agent is 1.5%. (2) The strength of the grouting body decreases linearly with the increase of the water–cement ratio, and the dosage of the water-reducing agent has no obvious effect on the strength. As the dosage of expansion agent increases, the strength of the grouting body decreases rapidly. The expansion agent mainly plays a key role in the middle and late stages of the hardening process of the slurry. Early-strength agents have a greater impact on the early strength, but less on the later strength. When the slurry is solidified for 3 h, the early-strength agent has the greatest impact on the strength with an optimal dosage of 5%. (3) The volume of the grouting body has an inverse relationship with the water–cement ratio, and the optimal amount of expansion agent is 12%. The incorporation of an expansion agent makes the volume increase of the grouting body exceed the volume shrinkage ratio caused by the hardening of the grouting body with a curing time of more than 3 days, ensuring a slight increase in the volume of the grouting body. After 3 days, even though the effect of the expansion agent is gradually weakened, it can still ensure that the volume of the grouting body does not shrink. With the increase of the amount of water-reducing agent, the volume of the grouting body gradually decreases. When the amount of water-reducing agent exceeds 1.5%, the volume of the grouting body no longer decreases. (4) The early-strength agent has almost no effect on the volume of the grouting body. When the curing time is 3 h, the water–cement ratio has the greatest influence on the volume of the grouting body, followed by the water-reducing agent, and, finally, the expansion agent. After 3 h, the water–cement ratio still has the greatest influence, and the influence of the expansion agent gradually exceeds that of the water-reducing agent. The water-reducing agent mainly affects the volume of the grouting body in the water separation stage, and the expansion agent mainly plays a role in the middle and late stages of the slurry solidification. After optimized ratio analysis, the fluidity of the water–cement mixture can be improved, the volume shrinkage ratio rate can be lowered and the early strength can be increased.

The Effect of Redistribution of the Mixing Water of the Concrete Lining on its Quality

2016 ◽  
Vol 843 ◽  
pp. 103-110
Author(s):  
Yuri Kulikov
Keyword(s):  
Mechanical Properties ◽  
Physical And Mechanical Properties ◽  
External Pressure ◽  
Concrete Lining ◽  
Residual Water ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Axial Forces ◽  
Roof Part ◽  
Mixing Water

In the heart of the processes of formation of physical and mechanical properties of secondary lining of underground structures is the residual water-cement ratio, which indicates the extraction of the mixing water of the concrete mixture under the action of external pressure forces. This article examines the nature of the redistribution of the mixing water in the concrete lining of the tunnels. Under the influence of radial and axial forces from laid concrete mix there is an increase in water-cement ratio in the direction from the sole to the vault head of the tunnel. This leads to deterioration of physical and mechanical properties of the lining in the roof part of the tunnel. When calculating the strength and water resistance of the secondary concrete tunnel lining the characteristics of the concrete type by strength and waterproof, adjusted by the weakest part of the lining – its roof part – should be taken into account. The analysis of influence on the technology of erection of the lining is given.

Experimental Study of Mechanical Properties of Concrete after Freeze-Thaw Exposures

2014 ◽  
Vol 912-914 ◽  
pp. 131-135
Author(s):  
Xiang Ping Fu ◽  
Xiao Xue Liu ◽  
Yi Ze Sun ◽  
Pei Huang ◽  
Yu Chen Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Experimental Study ◽  
Compressive Strength ◽  
Elasticity Modulus ◽  
Concrete Specimen ◽  
Concrete Compressive Strength ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Freeze Thaw ◽  
Cold Area

The experiment studies how the freeze-thaw cycles influence concrete compressive strength and elasticity modulus with different water-cement ratio under the air-entraining agent and zero of that value respectively. It can be found that modulus of elasticity and compressive strength of the concrete specimen reduced significantly when there is air-entraining agent; the durability of freeze-thaw resistance, however, makes great improvement; as the cement increases, both of them improves effectively. Through the comparison of concrete compressive strength and elastic modulus with different water-cement ratio and air-entraining agent, the optimal water-cement ratio and air-entraining agent were determined. The results of experiment can be used in concrete engineering design in severe cold area.

Sign in / Sign up

Export Citation Format

Share Document