Based on the backgrounds of green development trend of ultra-high-performance concrete (UHPC)and low early

strength of low-heat cement (mainly belite phase), the strength and hydration microstructure of low heat cement UHPC and

Portland cement UHPC prepared under standard curing, steam curing and autoclave curing conditions were studied. The

results showed that the compressive strength and flexural strength of UHPC were lower than ordinary Portland cement after

1 day of standard curing, but which was higher than ordinary Portland cement at 28 days age and 90 days age. After thermal

curing, the mechanical strength of low heat cement UHPC is significantly improved, exceeding the ordinary Portland cement

UHPC. UHPC paste of low-heat cement has higher C-S-H content, lower CH content and higher density of matrix, which is

especially obvious after thermal curing. When autoclaved curing for 90 days, the maximum compressive strength of low heat

cement UHPC is 197.5 MPa.

The compatibility of cement and admixture is usually tested by methods of cement slurry fluidity, cement sand

water reduction rate, concrete test. Among them, cement slurry fluidity can quickly test the compatibility of cement and

admixture, which is a good test method of compatibility with cement and admixture. A cement group with nearly 100

enterprises needs to use an admixture standard sample to control the quality of the compatibility of cement produced and

admixture by different manufacturers and regions. The reference sample of concrete admixture is a special admixture, which

requires to meet the conditions of uniform and stable, and can quickly and accurately reflect the quality of cement products.

The reference sample requires a shelf life of up to 14 months (the sample is usually prepared once a year, so it requires a

longer shelf life), which far exceeds the national standard requirement of 6 months for shelf life of concrete admixture. In

this paper, the most suitable polycarboxylic acid mother liquor varieties as the reference admixture were screened by the test,

and the shelf life of the admixture samples was effectively extended by the methods of adjusting the pH of the admixture

samples and adding fungicide.

The effects of pulverized fly ash raw ash on water requirement ratio, activity index, working performance and

strength of concrete were studied when the specific surface area of fly ash was 500~700 m2 /kg. Scanning electron microscope

and laser particle size analyzer were used to investigate the modification mechanism from the aspects of microstructure and

particle size distribution. The results showed that when the specific surface area of fly ash reaches 550~600 m2 /kg, the water

demand ratio, activity index, concrete working performance and strength of concrete all can be balanced, indicating that the

performance of high-performance fly ash grinding is the best under this condition.

The effects of monoethanol-diisopropanolamine (EDIPA) on cement properties were studied. The results showed

that EDIPA had similar promoting effects to TEA, TIPA and DEPA on cement strengthening and grinding, which significantly

improved the 28-day compressive strength of cement and the strengthening effect was better than TIPA. It is suggested that

the proportion of EDIPA in the grinding aids mixture is 0.012%~0.014%, which is relatively cost-effective to use other raw

materials to increase the early strength. The grinding performance of EDIPA is slightly better than TEA, TIPA and DEPA.

Various hazardous wastes are mixed and burned in the calciner as alternative fuels in order to achieve the harmless

utilization and promote the development of the cooperative disposal of hazardous wastes in cement kilns. In this paper, the

effect of hazardous waste fuel on the operation parameters of the cement kiln system is systematically studied, the impact

of hazardous waste fuel on the standard coal consumption and CO2 emission of clinker are analyzed, and the law of the

influence of hazardous waste fuel on clinker performance is explained. The research indicates that the hazardous waste

with a calorific value can be used as an alternative fuel to burn in the calciner, which can lower the amount of standard coal

used to produce clinker and decrease CO2 emissions. When the calorific value of alternative fuel is controlled in the range

of 7 500~8 500 (kJ/kg), the optimal feeding amount ranges from 1.6 m3 /h to 2.7 m3 /h, the maximum coal saving reaches

1.59 kg/t.cl, and the maximum CO2 emission reduction is 4.39 kg/t.cl. Increasing the unit calorific value of hazardous waste

alternative fuel and reducing its water content can save more clinker coal consumption and further reduce CO2 emission. The

process parameters of kiln system and clinker quality are unaffected by the combustion of alternative fuel when used in a

reasonable amount.