scholarly journals Development and Investigation of a New Low-Cement-Consumption Concrete—Preplaced Aggregate Concrete

2020 ◽  
Vol 12 (3) ◽  
pp. 1080 ◽  
Author(s):  
Jing Lv ◽  
Tianhua Zhou ◽  
Kunlun Li

Reducing consumption of cement in concrete will achieve huge benefits in decline of carbon emission, conservation of natural resources and reduction of the cost of concrete. In this paper, the low-cement-consumption concrete, preplaced aggregate concrete (PAC), is prepared and 12 types of mixtures including four water–binder ratios (W/B) and three sand–binder ratios (S/B) are designed to detect the effect of W/B and S/B on the mechanical properties and failure mechanism of PAC. Experimental and analytic results indicate that the cubic compressive strength of PAC, splitting tensile strength of PAC and elastic modulus of PAC decrease with increase in W/B and S/B. At a similar compressive strength, more than 20% increment of elastic modulus of PAC is achieved when compared with normal concrete (NC); the descent stage of stress–strain curves of PAC are steeper than that of NC and the peak strains of PAC is lower than that of NC. Guo’s model with suitable values of parameters a and b can be used to describe the stress–strain relationship of PAC. Replacing NC by PAC in concrete structures will save 15–20% cement and achieve great environmental and economic benefits.

2021 ◽  
Vol 15 (1) ◽  
pp. 45-50
Author(s):  
Bobby Asukmajaya R. ◽  
◽  
Edhi Wahjuni S. ◽  
Wisnumurti Wisnumurti ◽  
◽  
...  

Normal aggregate replacement to the onyx waste aggregate will certainly make the compressive strength and modulus of elasticity different, so it will affect the value of the compressive stress block equivalent (β1) as a result of the extent of the changing stress strain curve. In this study, trying to compare between the experimental β1 value of onyx concrete, while analytically the β1 value for normal concrete was obtained in accordance with SNI 2847 - 2019. To get the experimental β1 value from onyx concrete, it is made by looking for the compressive strength, elastic modulus and ꜫ0, for later the stress strain curve of the concrete is made to find the experimental β1 value of the onyx concrete. The results were obtained if the average β1 value of 18 specimens of onyx coarse aggregate concrete with an average compressive strength of 32.92 MPa was 0.868 while the analytical β1 value based on SNI 2847-2019 was 0.839, This shows that the B1 value for concrete with other aggregates is different, so it needs to be checked experimentally.


Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4064 ◽  
Author(s):  
Jing Lv ◽  
Tianhua Zhou ◽  
Qiang Du ◽  
Kunlun Li ◽  
Kai Sun

The recycling of waste tires in lightweight aggregate concrete (LC) would achieve huge environmental and societal benefits, but the effects of rubber particles on the partial properties of LC are not clear (e.g., the stress–strain relationship). In this paper, uniaxial compressive experiments were conducted to evaluate the stress–strain relationship of self-compacting rubber lightweight aggregate concrete (SCRLC). Rubber particles were used to replace sand by volume, and substitution percentages of 0%, 10%, 20%, 30%, 40%, and 50% were set as influence factors. Experimental results indicate that with increased rubber particles substitution percentage, the cubic compressive strength and axial compressive strength of SCRLC decreased, while the failure modes of SCRLC prism specimens gradually changed from brittle to ductile failure. As the rubber particles substitution percentage increased from 0% to 50%, the peak strain of SCRLC increased whereas peak stress, elastic modulus, and peak secant modulus of SCRLC deceased, the descending stage of stress–strain curves became softer. The rubber particles substitution percentage of 30% was the critical point at which an obvious change in the properties of SCRLC occurred. Based on the data collected from experimental studies, a predictive model for SCRLC was established and a further prediction of the SCRLC stress–strain relationship was given.


2014 ◽  
Vol 2014 ◽  
pp. 1-9
Author(s):  
Keun-Hyeok Yang ◽  
Ju-Hyun Mun ◽  
Hey-Zoo Hwang

This study examined the stress-strain behavior of 10 calcium hydroxide (Ca(OH)2)-activated Hwangtoh concrete mixes. The volumetric ratio of the coarse aggregate (Vagg) and the water-to-binder (W/B) ratio were selected as the main test variables. TwoW/Bratios (25% and 40%) were used and the value ofVaggvaried between 0% and 40.0%, and 0% and 46.5% forW/Bratios of 25% and 40%, respectively. The test results demonstrated that the slope of the ascending branch of the stress-strain curve of Ca(OH)2-activated Hwangtoh concrete was smaller, and it displayed a steeper drop in stress in the descending branch, compared with those of ordinary Portland cement (OPC) concrete with the same compressive strength. This trend was more pronounced with the increase in theW/Bratio and decrease inVagg. Based on the experimental observations, a simple and rational stress-strain model was established mathematically. Furthermore, the modulus of elasticity and strain at peak stress of the Ca(OH)2-activated Hwangtoh concrete were formulated as a function of its compressive strength andVagg. The proposed stress-strain model predicted the actual behavior accurately, whereas the previous models formulated using OPC concrete data were limited in their applicability to Ca(OH)2-activated Hwangtoh concrete.


2003 ◽  
Vol 18 (9) ◽  
pp. 2068-2078 ◽  
Author(s):  
A. DiCarlo ◽  
H. T. Y. Yang ◽  
S. Chandrasekar

A method for determining the stress–strain relationship of a material from hardness values H obtained from cone indentation tests with various apical angles is presented. The materials studied were assumed to exhibit power-law hardening. As a result, the properties of importance are the Young's modulus E, yield strength Y, and the work-hardening exponent n. Previous work [W.C. Oliver and G.M. Pharr, J. Mater. Res. 7, 1564 (1992)] showed that E can be determined from initial force–displacement data collected while unloading the indenter from the material. Consequently, the properties that need to be determined are Y and n. Dimensional analysis was used to generalize H/E so that it was a function of Y/E and n [Y-T. Cheng and C-M. Cheng, J. Appl. Phys. 84, 1284 (1999); Philos. Mag. Lett. 77, 39 (1998)]. A parametric study of Y/E and n was conducted using the finite element method to model material behavior. Regression analysis was used to correlate the H/E findings from the simulations to Y/E and n. With the a priori knowledge of E, this correlation was used to estimate Y and n.


2004 ◽  
Vol 274-276 ◽  
pp. 241-246 ◽  
Author(s):  
Bo Han ◽  
Hong Jian Liao ◽  
Wuchuan Pu ◽  
Zheng Hua Xiao

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Hongbo Zhao ◽  
Zenghui Huang ◽  
Zhengsheng Zou

Stress-strain relationship of geomaterials is important to numerical analysis in geotechnical engineering. It is difficult to be represented by conventional constitutive model accurately. Artificial neural network (ANN) has been proposed as a more effective approach to represent this complex and nonlinear relationship, but ANN itself still has some limitations that restrict the applicability of the method. In this paper, an alternative method, support vector machine (SVM), is proposed to simulate this type of complex constitutive relationship. The SVM model can overcome the limitations of ANN model while still processing the advantages over the traditional model. The application examples show that it is an effective and accurate modeling approach for stress-strain relationship representation for geomaterials.


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