Study On The Compressive Strength Of Cement Mortar By Pre-carbonation Of In-situ Production CaCO₃ Particles

Concrete with OPC as the binder is the most widely used construction material, accounting for 70% of all building and construction materials. But the production of OPC releases a large amount of greenhouse gases. To combat global climate change, the carbon footprint of OPC-based concrete should be reduced. To this end, the amount of OPC used in concrete should be reduced since OPC is the major contributor to the carbon footprint of concrete. So, how to make use of CO2 to make it helpful to the development of building materials has become a hot topic.A new method- pre-carbonation method is proposed. In this study, gaseous CO2 is first absorbed into slurry of slaked lime which is then blended with other ingredients to produce concrete. Through the experimental study on the compressive strength of cement mortar of four aspects:the influence of water cement ratio, the amount of pre carbonation, the pre-carbonation time and the different cementitious materials, Combined with the microscopic analysis of pre-carbonation mechanism of the compressive strength of cement mortar reinforced.1) The pre-carbonation method can significantly improve the compressive strength of cement mortar. The best time for 1% of the calcium hydroxide pre-carbonation for 15min, which the second largest group of water to binder than 0.45% pre-carbonation, the 28d compressive strength increased by 25.2%, the effect is improved significantly. For the pre-carbonation 3%, its compressive strength at 10min,20min time as time increases.2) When the water cement ratio is different, the other conditions are same, the water cement ratio is 0.45, the strength of the growth is more than 0.5.3) Analysis of the mechanism of the effect of pre-carbonation on the compressive strength of cement mortar, mainly including the following aspects:physical filling effect, water role, in situ CaCO3 particle effect, active effect of CaCO3 cementitious.4) Pre-carbonation method in situ to generate CaCO3 particles, buffer alkalinity, promote cement hydration, that CSH provide point in the mortar inside the formation of a dense structure, thereby enhancing the compressive strength of mortar.5) Pre-carbonation method to generate the ACC and spherical vaterite CaCO3 can be used as cementitious material to the cement particles, reduce dilution effect caused by CaCO3 replaced cement, cement the cement capacity, reduce the concrete porosity and generate more rigid hydration products and the strength of concrete.In summary, CO2 was used as raw material to make concrete, it can reduce the energy consumption and carbon emissions, also the compressive strengths of the cement mortar is obviously improved.