Research has shown that alkali-activated concrete (AAC) is comparable to ordinary Portland cement concrete (OPCC) in terms of mechanical properties and may offer ecological benefits compared to OPCC. This study evaluates the energy and emission of AAC and OPCC across different classifications of concrete compressive strength (40, 60, and 100 ​MPa). Analysis indicates that the selection of constituent materials can substantially affect the energy and emission of AAC and OPCC. Ordinary Portland cement (OPC) is the principal contributor to the energy and emission of OPCC, accounting for 80% of energy and 91% of emissions of OPCC. The activating solution, meanwhile, is the main contributor to the energy and CO2 emission of AAC. Normal strength AAC (40 ​MPa) shows 46% less energy and 73% less CO2 emission than OPCC. However, high-strength AAC (60 ​MPa), using metakaolin as a base material, experiences higher energy (8%) than OPCC yet the emission is 40% less than OPCC. A substitution of fly ash for metakaolin results in superior efficiency of AAC compared to OPCC. Two mixtures of ultra-high-strength AAC (100 ​MPa) result in contradictory findings. One mixture with a sodium hydroxide and silica fume activating solution shows 5% and 30% less energy and CO2 emission, while the other mixture with a sodium hydroxide and sodium silicate activating mixture is less efficient than OPCC.

Energy and CO2 emission assessments of alkali-activated concrete and Ordinary Portland Cement concrete: A comparative analysis of different grades of concrete

This review article proposes the identification and basic concepts of materials that might be used for the production of high-performance concrete (HPC) and ultra-high-performance concrete (UHPC). Although other reviews have addressed this topic, the present work differs by presenting relevant aspects on possible materials applied in the production of HPC and UHPC. The main innovation of this review article is to identify the perspectives for new materials that can be considered in the production of novel special concretes. After consulting different bibliographic databases, some information related to ordinary Portland cement (OPC), mineral additions, aggregates, and chemical additives used for the production of HPC and UHPC were highlighted. Relevant information on the application of synthetic and natural fibers is also highlighted in association with a cement matrix of HPC and UHPC, forming composites with properties superior to conventional concrete used in civil construction. The article also presents some relevant characteristics for the application of HPC and UHPC produced with alkali-activated cement, an alternative binder to OPC produced through the reaction between two essential components: precursors and activators. Some information about the main types of precursors, subdivided into materials rich in aluminosilicates and rich in calcium, were also highlighted. Finally, suggestions for future work related to the application of HPC and UHPC are highlighted, guiding future research on this topic.

https://www.mdpi.com/1996-1944/14/15/4304/pdf

Materials for Production of High and Ultra-High Performance Concrete: Review and Perspective of Possible Novel Materials.

Exemplification of sustainable sodium silicate waste sediments as coarse aggregates in the performance evaluation of geopolymer concrete

Synergetic effect of biomass fly ash on improvement of high-volume coal fly ash concrete properties

The use of ultra-high strength concrete (UHSC) is advantageous in construction. In fact, a combination of UHSC with regular reinforcement steel still has problems with corrosion after years in service, typically in exposed structures. This effect is more profound by climate changes (i.e., extensive heat waves or unexpected long and cold winter). This research investigates the flexural performance of concrete beams, cast with UHSC and high-performance reinforcement (HPR) steel; which is characterized by its high-strength and high-corrosion resistance. The testing matrix consisted of 8 concrete beams, cast with UHSC and high-strength concrete (HSC), in combination with ASTM A1035 Grade 830 steel and ASTM A615 Grade 420 steel. For each flexural test, along with measuring the applied loading and deflection, the variation in concrete compressive strain and steel tensile strain were monitored through a number of strain gauges. Experimental results revealed that Grade 830 can enhance the flexural capacity by 33% as compared to Grade 420 steel. On the other hand, UHSC can enhance the flexural capacity by 11% and decrease the concrete strains by up to 26% as compared to HSC.

Rahman S. Kareem

Papers

Energy and CO2 emission assessments of alkali-activated concrete and Ordinary Portland Cement concrete: A comparative analysis of different grades of concrete

Flexural behavior of concrete beams cast with high-performance materials

Structural performance of concrete bridge decks reinforced with Grade-830 steel bars

Observations of Supplementary Cementitious Materials Effects on The Performance of Concrete Foundation

Prediction of modulus of elasticity of UHPC using maximum likelihood estimation method