Study on Synthesis and Application of Superplasticizer from Chitosan

2012 ◽  
Vol 430-432 ◽  
pp. 1207-1210
Author(s):  
Sheng Hua Lv ◽  
Jian Ping Duan ◽  
Rui Jun Gao ◽  
Qiang Cao
Keyword(s):  
Mechanical Properties ◽  
Sulfuric Acid ◽  
Cement Paste ◽  
Cement Ratio ◽  
Water To Cement Ratio

Sulfonated chitosan (SCS) was prepared from chitosan and sulfuric acid via sulfation reaction. SCS was used as superplasticizer in cement. The test showed that the maximum fluidity of the cement paste was 232 mm with dosage of 0.75 wt % at water to cement ratio (w/c) of 0.29. Meanwhile, lesser loss of fluidity and slump over 60 mins were observed comparing to naphthalene sulfonated formaldehyde condensates (NSF). A well-distribution of cement particles can be seen from the image of SEM in the sample of mortar prepared by SCS. The water reduce ratio of SCS reach 19.2 %. The applied results showed that SCS could slightly improve the mechanical properties of mortar. The paste fluidity, mechanical properties and slump loss of the cement paste incorporated SCS indicated that it can be used as superplasticizer in concrete.

scholarly journals CO2 Curing Efficiency for Cement Paste and Mortars Produced by a Low Water-to-Cement Ratio

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3883
Author(s):  
Seong Ho Han ◽  
Yubin Jun ◽  
Tae Yong Shin ◽  
Jae Hong Kim
Keyword(s):  
Cement Paste ◽  
Pressure Vessel ◽  
Gas Pressure ◽  
Strength Development ◽  
Co2 Uptake ◽  
Cement Pastes ◽  
Co2 Gas ◽  
Cement Ratio ◽  
Mix Proportion ◽  
Water To Cement Ratio

Curing by CO2 is a way to utilize CO2 to reduce greenhouse gas emissions. Placing early-age cement paste in a CO2 chamber or pressure vessel accelerates its strength development. Cement carbonation is attributed to the quickened strength development, and CO2 uptake can be quantitatively evaluated by measuring CO2 gas pressure loss in the pressure vessel. A decrease in CO2 gas pressure is observed with all cement pastes and mortar samples regardless of the mix proportion and the casting method; one method involves compacting a low water-to-cement ratio mix, and the other method comprises a normal mix consolidated in a mold. The efficiency of the CO2 curing is superior when a 20% concentration of CO2 gas is supplied at a relative humidity of 75%. CO2 uptake in specimens with the same CO2 curing condition is different for each specimen size. As the specimen scale is larger, the depth of carbonation is smaller. Incorporating colloidal silica enhances the carbonation as well as the hydration of cement, which results in contributing to the increase in the 28-day strength.

Effects of Fly Ash Addition on Compressive Strength and Flexural Strength of Foamed Cement Composites

2013 ◽  
Vol 795 ◽  
pp. 664-668 ◽  
Author(s):  
Roshasmawi Abdul Wahab ◽  
Mohd Noor Mazlee ◽  
Shamsul Baharin Jamaludin ◽  
Khairul Nizar Ismail
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Fly Ash ◽  
Flexural Strength ◽  
Cement Composites ◽  
Volume Percent ◽  
Foaming Agent ◽  
Cement Ratio ◽  
Water To Cement Ratio

In this study, the mixing of polystyrene (PS) beads and fly ash as a sand replacement material in foamed cement composites (FCC) has been investigated. Specifically, the mechanical properties such as compressive strength and flexural strength were measured. Different proportions of fly ash were added in cement composites to replace the sand proportion at 3 wt. %, 6 wt. %, 9 wt. % and 12 wt. % respectively. The water to cement ratio was fixed at 0.65 meanwhile ratios of PS beads used was 0.25 volume percent of samples as a foaming agent. All samples at different mixed were cured at 7 and 28 days respectively. Based on the results of compressive strength, it was found that the compressive strength was increased with the increasing addition of fly ash. Meanwhile, flexural strength was decreased with the increasing addition of fly ash up to 9 wt. %. The foamed cement composites with 12 wt. % of fly ash produced the highest strength of compressive strength meanwhile 3 wt. % of fly ash produced the highest strength of flexural strength.

Quantitative Characterization of Effective Porosity in Cement-Based Composite Materials

2010 ◽  
Vol 163-167 ◽  
pp. 3174-3179
Author(s):  
Guo Wen Sun ◽  
Jin Yang Jiang ◽  
Yun Sheng Zhang ◽  
Cai Hui Wang
Keyword(s):  
Composite Materials ◽  
Cement Paste ◽  
Pore Diameter ◽  
Effective Porosity ◽  
Hardened Cement ◽  
Hardened Cement Paste ◽  
Pore Characteristics ◽  
Cement Ratio ◽  
Water To Cement Ratio ◽  
Second Peak

The method of the second intrusion mercury in MIP was used to investigate the pore characteristics of hardened cement paste with w/c ratio 0.23, 0.35 and 0.53, respectively, in order to research the quantitative relationship between transport properties and pore characteristics in cement-based composite materials. The results show the second intrusion mercury could well determine the effective pore structure parameters, and effective porosity accounts for 25% to 50% of total porosity in cement paste. At the same time, the existence of the first and second peak in pore size distribution curves is confirmed by MIP, such as, the first peak in hardened cement paste with water to cement ratio 0.53 is very distinct, however, with the decrease of water to cement ratio, the first peak gradually disappears. The pore diameter corresponding to the first and second peak is critical pore diameter of capillary pore and gel pore, respectively.

Proportion Design of Concrete with Gravel-Crushed Proto-Machine-Made Sand

2011 ◽  
Vol 295-297 ◽  
pp. 436-439
Author(s):  
Chang Yong Li ◽  
Qiu Yan Sun ◽  
Feng Lan Li
Keyword(s):  
Mechanical Properties ◽  
Water Content ◽  
Fresh Concrete ◽  
Hardened Concrete ◽  
Cement Ratio ◽  
Water To Cement Ratio

Experiments were conducted to study the workability of fresh concrete and basic mechanical properties of hardened concrete with gravel-crushed proto-machine-made sand. Effects of water to cement ratio and content of stone powder were mainly considered. Based on the test and before, the values of practical parameters in formula are obtained for calculating mixed strength of concrete, and the beneficial range of water to cement ratio is proposed. Meanwhile, the reasonable water content, sand ratio and content of stone powder are also suggested.

Study on Mechanical Properties and Water Permeability of Recycled Aggregate Porous Concrete

2011 ◽  
Vol 366 ◽  
pp. 36-39 ◽  
Author(s):  
Chang Yong Li ◽  
Pin Nie ◽  
Feng Lan Li
Keyword(s):  
Mechanical Properties ◽  
Water Permeability ◽  
Orthogonal Test ◽  
Test Method ◽  
Recycled Aggregate ◽  
Cement Ratio ◽  
Porous Concrete ◽  
Test Parameters ◽  
Water To Cement Ratio ◽  
Orthogonal Test Method

Experiments were conducted to study the mechanical properties and water permeability of recycled aggregate porous concrete. The orthogonal test was designed considering four parameters including water to cement ratio, cement content, grain series of recycled aggregate and aggregate to cement ratio, each parameter was set at three levels. Performances of porous concrete were measured such as cubic compressive strength, flexural strength, continuous porosity and water penetration coefficient. Test results are analyzed on the basis of orthogonal test method, the optimum proportions corresponding to every test parameters are given out. The ranges of every test parameters are also proposed. It provides a reference for constructing porous concrete roads by recycled aggregate made of old concrete from dismantled buildings.

Basic Mechanical Properties of Concrete with Machine-Made Sand and Recycled Coarse Aggregate

2013 ◽  
Vol 357-360 ◽  
pp. 1102-1105 ◽  
Author(s):  
Shun Bo Zhao ◽  
Qi Guo ◽  
Guang Xin Li ◽  
Yan Feng Su
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
Coarse Aggregate ◽  
Cement Ratio ◽  
Recycled Coarse Aggregate ◽  
Water To Cement Ratio ◽  
Current Specification ◽  
Current Design ◽  
Axial Compressive Strength

Experimental study was carried out on the concrete mixed with machine-made sand and recycled coarse aggregate (MSRAC), three strength grades of concrete were designed by changing the water to cement ratio as 0.36, 0.45 and 0.55, while the sand ratio varied in a range of 32%~38%, 32%~42% and 38%~44% successively. The workability and the mechanical properties such as compressive and splitting tensile strengths and elastic modulus of MSRAC were tested. The results show that although the mechanical properties of MSRAC were influenced by sand ratio, they were still controlled by the water to cement ratio. The ratio of axial compressive strength to cubic compressive strength and the elastic modulus of MSRAC basically satisfy the specifications of the current design code for concrete structures. It should be noticed that the tensile strength of MSRAC is lower than current specification, and tends to reduce with the increase of water to cement ratio.

Effect of Heat-Treatment on Microstructure and Mechanical Properties of Magnesium Phosphate Cement

2016 ◽  
Vol 680 ◽  
pp. 447-450
Author(s):  
Xin Tao ◽  
Jia Chen Liu ◽  
Ming Chao Wang
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Compressive Strength ◽  
Magnesium Phosphate ◽  
Cement Ratio ◽  
Heat Treated ◽  
Water To Cement Ratio ◽  
Heating Up ◽  
Physical And Chemical ◽  
Made In

Magnesium phosphate cement with M/P of 6, borax content of 4.8 wt% and water-to-cement ratio of 0.12, were made in this study. Heat-treatment was conducted from 200 °C to 1200 °C, and the physical and chemical evolution in the process of heating up was investigated via TG/DSC, XRD and SEM. Besides, the compressive strength, density and porosity of the heat-treated specimen were measured and the influence of treating temperature was discussed. The results show that magnesium phosphate cement possesses good chemical stability at 1200 °C and the strength has reduced only by 32.2% compared with none-treating specimens.

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