Mix Optimization for Precast Concrete Members in Building Industrialization

2014 ◽  
Vol 629-630 ◽  
pp. 382-387
Author(s):  
Jing Li ◽  
Jun Zhang ◽  
Zhao Rong Hou ◽  
Sheng Wei Wu
Keyword(s):  
Precast Concrete ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Concrete Members ◽  
Orthogonal Experiments ◽  
Mix Proportion ◽  
Early Strength ◽  
Cement Strength ◽  
Sand And Gravel ◽  
Good Workability

The traditional mix proportion for concrete used in building field could not meet the requirements for industrialization production any more, and the optimization needs developing to obtain an ideal mix proportion for precast concrete with high early strength and good workability, as well as economy. To achieve the high early strength, Low-Alkalinity Sulphoaluminate Cement was selected, accompanied by Ordinary Portland Cement. The properties of other materials, namely aggregates (medium sand and gravel) and admixtures (polycarboxylate-based superplasticizer and sodium sulfate), were determined through literature review. The parameters of materials, such as the fineness modulus, mud-content of aggregates and cement strength, were determined. Besides, the range of water-cement ratio, admixture content and the ratio of two kinds of cements etc. in a total of 13 preliminary concrete mixes are analyzed. With further analysis, the four dominant factors were chosen, that is, water-cement ratio, cement content, superplasticizer content and sand ratio, leading to a series of orthogonal experiments with 3 levels of each factor. By analysis of test result data and consideration of cost, the optimized mix for precast concrete in building industrialization was carried out, of which the compressive strength in 10 hours reached the required strength and other properties reasonable.

Study of Sleeper Concrete early Strength Based on Orthogonal Experiment

2013 ◽  
Vol 448-453 ◽  
pp. 1316-1320
Author(s):  
Hai Chao Wang ◽  
Ke Qiu ◽  
Shu Ling Gao
Keyword(s):  
Fly Ash ◽  
Design Method ◽  
Orthogonal Experiment ◽  
Orthogonal Design ◽  
Steam Curing ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Early Strength ◽  
The Difference ◽  
Railway Sleeper

Using orthogonal design method of four factors and three levels, make a mix ratio experiment on sleeper concrete of China's railway sleepers, used steam curing concrete early compressive strength (stripping strength) as evaluation index. Study on different experimental factors of water-cement ratio, sand ratio, fly ash and admixture differently influenced on the early strength of sleeper concrete and analyze the difference impact of each factor and level for the orthogonal experiment. The result shows that the admixture is the main factor for early strength of concrete, followed by fly ash, water-cement ratio and sand ratio. It can provide technical guidance for railway sleeper field and has practical value.

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.

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.

scholarly journals Degradation Mechanism of Concrete Subjected to External Sulfate Attack: Comparison of Different Curing Conditions

Materials ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3179 ◽  
Author(s):  
Gaowen Zhao ◽  
Mei Shi ◽  
Mengzhen Guo ◽  
Henghui Fan
Keyword(s):  
Degradation Mechanism ◽  
Precast Concrete ◽  
Concrete Structures ◽  
Degradation Process ◽  
Sulfate Attack ◽  
Curing Conditions ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Chemical Attack

Sulfate induced degradation of concrete brings great damage to concrete structures in saline or offshore areas. The degradation mechanism of cast-in-situ concrete still remains unclear. This paper investigates the degradation process and corresponding mechanism of cast-in-situ concrete when immersed in sulfate-rich corrosive environments. Concrete samples with different curing conditions were prepared and immersed in sulfate solutions for 12 months to simulate the corrosion of precast and cast-in-situ concrete structures, respectively. Tests regarding the changes of physical, chemical, and mechanical properties of concrete samples were conducted and recorded continuously during the immersion. Micro-structural and mineral methods were performed to analyze the changes of concrete samples after immersion. Results indicate that the corrosion process of cast-in-situ concrete is much faster than the degradation of precast concrete. Chemical attack is the main cause of degradation for both precast and cast-in-situ concrete. Concrete in the environment with higher sulfate concentration suffers more severe degradation. The water/cement ratio has a significant influence on the durability of concrete. A lower water/cement ratio results in obviously better resistance against sulfate attack for both precast and cast-in-situ concrete.

Correlation of Strength, Rubber Content, and Water-Cement Ratio in Roller Compacted Rubberized Concrete

2011 ◽  
Vol 243-249 ◽  
pp. 1179-1185
Author(s):  
Jing Fu Kang ◽  
Chun Xia Yan
Keyword(s):  
Compressive Strength ◽  
Test Results ◽  
Rubberized Concrete ◽  
Rubber Content ◽  
Normal Concrete ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Strength Based ◽  
Strength Formula ◽  
Cement Strength

This research investigated the influences of rubber content and water-cement ratio on the compressive strength of roller compacted rubberized concrete (RCR). The mix design of RCR was made by replacing same volume of sand with rubber chips based on the control concrete mix. Four rubber contents (50 kg/m3, 80 kg/m3, 100 kg/m3 and 120 kg/m3) and six water-cement ratios (0.30, 0.35, 0.40, 0.45, 0.50 and 0.55) were used. The specimen cubes were tested in compression at 28d with the load continuously and automatically measured until failure. Test results show that RCR exhibits low compressive strength but a ductile and plastic failure mode, the more the rubber used, the more the compressive strength reduced and the larger toughness obtained. Same as normal concrete, the compressive strength of RCR is also directly related to the water-cement ratio，the smaller the water-cement ratio, the higher the compressive strength. Based on the experimental results, a strength formula was developed to estimate the strength of RCR as a function of the cement strength, water-cement ratio and the rubber content.

Survey on Factors Affecting Impermeability of Waterproof Concrete

2011 ◽  
Vol 250-253 ◽  
pp. 1320-1323
Author(s):  
Yi Jin Li ◽  
Yun Li Gong ◽  
Jian Yin
Keyword(s):  
Fly Ash ◽  
Ash Content ◽  
Raw Material ◽  
Factors Affecting ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Mix Proportion

This paper describes the influence of raw material, water-cement ratio, sand ratio, cement-sand ratio and fly ash content on impermeability of waterproof concrete. The value ranges of several important mix parameters are summarized, that provides the reference to select the parameters of mix proportion of waterproof concrete for subway.

Study of RPC Mechanical Properties and Anti-Freeze-Thaw Resistance

2010 ◽  
Vol 168-170 ◽  
pp. 1742-1748
Author(s):  
Yan Zhong Ju ◽  
Feng Wang ◽  
De Hong Wang
Keyword(s):  
Mechanical Properties ◽  
Silica Fume ◽  
Steel Fiber ◽  
Fiber Content ◽  
Reactive Powder Concrete ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Freeze Thaw ◽  
Early Strength ◽  
Reactive Powder

To study the mechanical properties of RPC performance and freeze-thaw resistance，through the experimental study discussed the water-cement ratio, silica fume cement ratio, steel fiber content, curing system and other factors on the mechanical properties of reactive powder concrete and anti-freezing properties. Research indicates that many factors in the RPC, the water cement ratio is the most important factor, followed by the silica fume cement ratio, finally the steel fiber content, and curing system for the growth of its early strength also have a greater role.

scholarly journals Pipe pressure of mining wet shot crete flowing in pipes

2021 ◽  
Vol 303 ◽  
pp. 01035
Author(s):  
Lianjun Chen ◽  
Xuekai Jiang ◽  
Guoming Liu ◽  
Xiangfei Cui
Keyword(s):  
Pressure Drop ◽  
Flow Rate ◽  
Solid Phase ◽  
Pressure Change ◽  
Rheological Parameters ◽  
Computational Formula ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Mix Proportion ◽  
Phase Pressure

In order to explore the pressure change law of mining wet shotcrete in pipes, the rheological model was built based on rheology principle, and the computational formula of rheological parameters of wet shotcrete was deduced with the linear regression. 100 m full-scale pipeline platform of wet shotcrete was designed and built to study the relationship of pressure and other factors including flow rate, water cement ratio, mix proportion, and pipe bends. Results show: pipe pressure increases with the increase in flow rate and declines with the increase in water-cement ratio, the pressure may fluctuate with a high water cement ratio which can cause cement overhydration and bleeding separation. It will be more beneficial to transport materials if the continuous grading and straight pipe were considered. According to the tests of mix proportion 1:1.5:2.25, the pressure drop is 0.032 MPa·m−1 and the bend pressure drop is 1.3 times higher than in the straight line. We also conclude that solid phase pressure is bigger than liquid phase pressure and they both decline along the pipe based on FLUENT simulation. Finally, the formula of on-way resistance used in mine production was deduced.

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