Development of low absorption and high-resistant sodium acetate concrete for severe environmental conditions

This research presents new insight on the performance of concrete when integrated with sodium acetateand cured under extremely harsh environmental conditions: freezing temperature of 25°C and hottemperature of 60°C. Mechanical properties, water absorption, microstructural analysis and interactionmechanism of concrete and sodium acetate were evaluated by conducting the compressive strength test,Initial Surface Absorption Test (ISAT), Scanning Electron Microscope (SEM) analysis and Fourier-transform Infrared Spectroscopy (FTIR) analysis. Despite the harsh curing conditions, results showedan enhancement of 64% in compressive strength when 4% (based on the weight of cement) sodium acet-ate is incorporated within concrete with w/c ratio of 0.32 and cured under temperature of 60°C. Also,water absorption was observed to decrease by more than 79% when 2% sodium acetate is added to con-crete with w/c ratio of 0.32. SEM and FTIR analyses revealed the formation, high distribution and strongbonding of sodium acetate crystals within the concrete’s micropores

Advanced Freeze-Thaw Assessment of Internally Integrated Concrete with Sodium Acetate

A new line of research is presented in this study where sodium acetate is used as a protective material for concrete. A newly developed freeze-thaw method that depends on the alteration of temperature and humidity is introduced in this research to investigate the efficacy of integrating sodium acetate with concrete with different water to cement ratios (w/c). Results from the introduced freeze-thaw method were compared with the outcomes of a standard freeze-thaw testing method. The distressed concrete was tested for water absorption and compressive strength after finishing six months of freeze-thaw testing. Results demonstrated the effectiveness of sodium acetate in protecting concret

A novel approach of introducing crystalline protection material and curing agent in fresh concrete for enhancing hydrophobicity

A new line of research to enhance the performance of concrete under adverse (harsh) and normal (air cured) curing conditions is presented. A crystallising hydrophobic admixture and curing agents were added to fresh concrete to improve its resistance against severe environmental conditions. A two-stage approach was pursued by adding the crystallising admixture to fresh concrete followed by curing agents, in a wax and liquid forms, in a separate application process, followed by exposing concrete to normal and adverse curing conditions. Results obtained suggests that protecting concrete with the crystallising admixture followed by applying wax based curing agent improves concrete strength and its resistance to water ingress than concrete cured with the liquid curing agent. When following the crystallising-wax treating system under adverse curing conditions, a more conserved strength was noticed compared to that produced by the crystallising-liquid system. Using the liquid curing agent in concrete with high water to cement ratio (w/c) has increased the cracks in the internal structure, while water permeability has decreased, either under normal curing conditions or adverse conditions. Following this protection-curing system in industry would resolve the problem of applying protection on wet surfaces and increase concrete’s resistance to deterioration. A microscopic study of the crystallising material was attained with a Scanning Electron Microscope (SEM) to check crystal growth with time

Microstructural, Mechanical and Physical Assessment of Portland Cement Concrete Pavement Modified by Sodium Acetate under Various Curing Conditions

Portland Cement Concrete (PCC) pavement was studied with incorporation of an environmentally friendly eco-additive, sodium acetate (C2H3NaO2). This additive was added to PCC pavement in three different percentages of 2%, 4% and 6% of binder weight. For a comprehensive elucidation of the eco-additive incorporation on the performance of PCC pavement, casted samples were cured in three different environments, namely: water, outdoors and pond water. Water absorption tests, flexural and compressive strength tests after 7 and 28 days of curing were conducted and results compared with the control samples without any addition of sodium acetate. Results demonstrated a significant improvement in the impermeability, compressive strength and flexural strength of PCC pavement when sodium acetate concrete is cured in a water bath and outdoors. However, no/little improvement in the impermeability, compressive strength and flexural strength was observed in sodium acetate samples that were cured in pond water. Microstructural analysis of treated samples by using scanning electron microscopy (SEM) illustrated the strengthening effect that sodium acetate provides to the pore structure of concrete pavement

Performance of magnetite-based stone mastic asphalt (SMA) as a superior surface course material

A new line of research is reported in this study where magnetite is used as a partial replacement of traditional aggregates in stone mastic asphalt (SMA) mixtures. The objective is to enhance the functional and mechanical properties of SMA while taking advantage of better thermal properties of magnetite to promote self-healing characteristics of the asphalt surface. Granite and gritstone based SMA mixtures were modified with 50% magnetite coarse aggregate and their mechanical, functional, and long-term performance against ageing and water sensitivity were investigated. In terms of stiffness, an increase of 45% and 32% was achieved in magnetite with granite and magnetite with gritstone mixes, respectively. Both dry and wet friction and macrotexture of magnetite-based mixtures were found either comparable or better than conventional mixtures. Furthermore, compared to control mixtures, the magnetite-based mixtures retained more stiffness after three moisture conditioning cycles. The stiffness increase after long-term ageing was marginally higher in modified mixtures than the control ones. Finally, magnetite worked on improving thermal conductivity, which is a beneficial property to promote better interface bonding between two asphalt layers

Investigation of the interfacial bonding between flax/wool twine and various cementitious matrices in mortar composites

This study investigates the interfacial bonding of natural fibre reinforced (NFR) cementitious composites by exploring the incorporation of 20–30 mm strands of uncoated and resin coated flax/wool twine into various cementitious matrices. Cementitious matrices consisting of pulverised fly-ash (FA), ground granulated blast furnace slag (GGBS) and ordinary Portland cement (OPC) in various ratios were tested with the addition of flax/wool twine (1% volume ratio). The mechanical properties of these samples were assessed at 7 and 28 days. The results showed a reduction in the flexural and compressive strength of uncoated NFR samples compared to unreinforced (UNR) counterparts due to weak interfacial bonding between the uncoated fibres and the cementitious paste, therefore, formation of voids. Epoxy (EP) and polyurethane (PU) resin were then used to coat the flax/wool twine prior to their inclusion in various cementitious pastes. The results revealed improvements in both flexural and compressive strengths exhibited at 7 and 28 days compared to UNR and uncoated NFR samples. The greatest improvement of flexural strength, 61% compared to UNR, was achieved by the mix consisting of 50% OPC and 50% FA matrix with EP resin coated flax/wool twine at 28 days. While PU coated samples exhibited an increase of 31% in flexural strength at 28 days for the same cementitious mix ratio. The morphology of the resin coated NFR samples showed an intimate interfacial bond to surrounding cementitious paste, which explains the increased mechanical performance