Strength and durability of low-impact environmental self-compacting concrete incorporating waste marble powder

This research studies the effect of waste marble powder (WMP) as substitute of Portland cement on strength and durability of self-compacting concrete (SCC) in order to produce SCC with reduced impact environmental. For this purpose, five mixtures were designed in which four mixtures contained WMP at substitution levels of 5, 10, 15, 20%, and mixture included only the Portland cement as control mix. The realized tests are compressive strength at 3, 7 and 28 days, water capillary absorption, water absorption by immersion and sulfate attack. The results show a reduction in the compressive strength with increasing WMP content. The use of WMP was found to increase both of the water capillary absorption and water absorption by immersion. SCC containing WMP subjected to magnesium sulfate attack presented a lower expansion and higher resistance to sulfate aggressions

Biocomposite Bridge

Biocomposite materials are becoming more interesting to use in infrastructural projects due to their biodegradable, renewable, recyclable and sustainable properties. With a relatively low density, it is an interesting building material regarding a bridge deck. When designing with biocomposite the following factors are important to consider: material design, fibre treatment, coating and manufacturing technique. A PLA-Bamboo biocomposite was applied to an existing design of a bridge deck made out of synthetic composite. Due to its randomly oriented fibres and its equally designed lamellae, the cross section was considered homogeneous and the stresses were calculated according to ‘Hooke’s law’. The unity checks were performed according to ‘CUR 96’ with an own devised material factor of 5,69. This factor was calculated in this study for biocomposites with untreated fibres. The calculations showed that the original material (synthetic composite) was not directly replaceable by the PLA-Bamboo biocomposite. An alternative design of the deck (deck height of 1 meter and doubled thicknesses of the skins and web plates, 40- and 10 mm) showed better results. This design complied for the unity checks for strength

Rehabilitation of existing building structure in expansive soils: A case study in Laghouat, Algeria

This work presents results obtained from a case study conducted on M’kam neighborhood (600 housing social city) in Laghouat, Algeria. The bloc (J) in this location, suffering from damages that are attributed to the expansive clayey soil interaction with sewage disposal under foundations was the subject of rehabilitation in this study.The principal causes of observed structural damages were studied through diagnostic expertise (inspection-evaluation process) of the cracks and sewage disposal system of bloc (J). The results of this diagnostic investigation show that the main damages were mainly due to swelling of soil in presence of losses from sewage disposal. Remedial actions were suggested to revise and repair all the sewage disposal system and strengthen the foundations of the building to avoid further damages

Impact of electric arc furnace slag on geopolymer composites exposed to sulphate solution

Effect of sulfate solution on the geopolymer formed from electric arc furnace slag (EAF) along with water cooled slag and cement kiln dust was studied. Activation was carried up on usage of 25% CKD as it bears high alkali content that can initiate and propagate the polymerization process. The formed geopolymer products were immersed in 5% MgSO4 solution to determine the stability up on sulfate attack. FTIR, XRD, SEM, compressive strength and water absorption were utilized to examine the resulted geopolymer product under sulfate attack. Results showed that, the compressive strength of geopolymer specimens increase with EAF slag up to 50% then decrease with further slag increase, possessing stability up 12 months and giving an increased compressive strength than the control mix that has not EAFS by 6.53%, 14.72%, 47.44% and -4.89 % after immersing ages of 3 months and 2.26, 14.26, 43.97 and 19.98 % after immersing age of 12 months for replacement by 10, 25, 50 and 75% of EAFS, respectively. Data elucidated a good stability and resistance of mix containing slag substitution by 50 % EAF and 25 % GGBFS and results in further enhancement in both mechanical and microstructural characteristics than the non-immersed samples (28days)

Effect of inclusion of crumb rubber on the unconfined compressive strength and wet-dry durability of cement stabilized clayey soil

In the present study, the effect of inclusion of waste crumb rubber and cement on the unconfined compressive strength and wet-dry durability of clayey soil has been investigated. Crumb rubber and cement were added to clayey soil at ranges of 2.5%-10% and 3%-6% respectively. The results of the investigation revealed that the incorporation of crumb rubber influenced the unconfined compressive strength, axial strain at failure, energy absorption capacity and wet-dry durability of the cement-stabilized clay. The study reveals that as the content of crumb rubber in the cement-stabilized clayey soil increases the unconfined compressive strength decreases but prosperously changes the behavior of the cement-stabilized clay from brittle to ductile. The axial strain corresponding to peak axial stress and energy absorption capacity of the specimens can be increased by limiting the content of crumb rubber up to 5%. The weight loss of the cement-stabilized clay mixed with crumb rubber increases as the content of crumb rubber increases. With the prolongation of the curing period, the weight loss of cement-stabilized clay mixed with crumb rubber decreases. Further, the weight loss of 90 days cured specimens of clayey soil incorporated with 6% cement and crumb rubber up to 5% meets the recommendation of the material to be used in construction of road pavements as a base, sub-base, and shoulder. Most importantly, the utilization/disposal of this hazardous waste material reduces its impact on environment and health

Effect of content and fineness of slag as high volume cement replacement on strength and durability of ultra-high performance mortar

Replacement of cement by slag in ultra-high performance concrete (UHPC) makes it a green material for building and construction application. However, slag hydrates slower which delay strength gain in UHPC which can be addressed by using slag of high fineness. In this study, cement is replaced by slag at 20% and 60% by weight. Slag of three different fineness is used: 400±4 m2/kg, 556±5 m2/kg and 750± 5 m2/kg at constant water-binder ratio of 0.25 for all mixes. Compressive and flexural strength were measured for mechanical performance while water penetration test and chloride migration test were conducted to enumerate durability.Results show that early and late compressive strength and flexural strength are improved significantly by incorporation of slag with fineness 556 ± 5 m2/kg compared to reference and slag of 400 m2/kg fineness. However, at similar fineness 20% slag incorporation is found to produce higher early strength compared to 60% slag although 90 day strength for both replacement percentages are similar. On durability aspects it is found that slag with fineness of 556 m2/kg and 750 m2/kg demonstrates significantly lower penetration depth and very high resistance to chloride migration at 28 day and 90 day age irrespective of slag replacement percentage. The study suggests that slag of high fineness (about 556 m2/kg based on the study) and 20-60% cement replacement can significantly accelerate hydration and improve long term durability of UHPC mortar

The effect of coal bottom ash (CBA) on mechanical and durability characteristics of concrete

The present paper would contribute to the efforts being made in the field of concrete technology towards development of concretes possessing good strength and durability properties along with economic and ecological advantage. In the present study it was found that with increase in amount of coal bottom ash, standard consistency, initial and final setting time increase at the same time workability of concrete decreases. Early age strength is less for bottom ash concrete compare to control mix, but as the age increases they show good improvement in strength due to pozzalanic reaction. Optimum dosage is observed to be 10% Grinded Bottom Ash (GBA) which shows about 14 % more strength compared to control mix at 56 days. Also 20% replacement by GBA gives results comparable to control concrete. GBA concrete shows more resistance to acid attack compared to Original Bottom Ash (OBA). Mix M7 with 30 % replacement by GBA shows highest resistance to acid attack. With the increase in amount of bottom ash water absorption capacity of concrete increases, also as the age increases for all the mix water absorption capacity decreases. It was also found that at optimum dosage i.e at 10% replacement of cement with GBA it is also economical and also less amount of CO2 is emitted that mean it is also environmental friendly compared to control mix

Durability of concrete using marble mining waste

The aim of the study was to study behavior of concrete containing marble mining waste under aggressive environment. Waste from marble mining and processing industries was used in concrete as coarse aggregate in combination with conventional coarse aggregate. The particle packing density approach was followed to design the concrete mix and 75% conventional coarse aggregate was replaced by aggregate obtained by crushing waste from marble mining waste. The water-cement ratio was fixed 0.45 for all the mixes. Properties of concrete under aggressive environment such as chloride ion penetration, resistance to sulphates were evaluated. The test results revealed that, resistance to chloride ion penetration and sulphate attack increased as compared to control concrete. Overall the results supported by microstructure analysis indicate that there is no significant adverse effect on the use of marble waste as a coarse aggregate on the durability properties of concrete. The results of fire study reveal that, concrete with marble waste performs better than control concrete up to a temperature of 800 ºC

Fresh and hardened properties of self-compacting concrete with different mineral additions and fibers

In this work, several reinforced self-compacting concretes were prepared by using three types of fibers made of steel, polypropylene and glass, and three different types of mineral additions (marble powder, metakaolin and limestone powder). The water to cement ratio was kept constant at 0.34 and fibers were used in combination, keeping the total fiber content constant at 60 kg/m3. Slump flow diameter, L-Box, stability and air content were performed to assess the fresh properties of the concrete. Compressive strength, flexural strength, splitting tensile strength and ultrasonic pulse velocity of the concrete were determined for the hardened properties.Noteworthy performances were generally obtained, particularly in hardened properties for the self-compacting concretes prepared with steel fibers in association with polypropylene fiber and marble powder as mineral addition

Effect of limestone powder as a partial replacement of crushed quarry sand on properties of self-compacting repair mortars

Self-compacting repair mortars (SCRM) are particularly desired for the rehabilitation and repair of reinforced concrete structures. The properties of SCRM can be improved by using chemical, mineral, polymer and fiber additives. In limestone quarries, considerable quantities of limestone fine powder are obtained during the process of crushing rock. These fine powders are being collected and their utilization is a big problem from the aspects of disposal, environmental pollution and health hazards. The introduction of limestone powder as cement and sand replacement present interesting possibilities to reduce the cement cost production, CO2 emission and the conservation of natural resources. The effects of limestone powder content in crushed sand on the properties of SCRM are not studied. An experimental study was undertaken to find out the effect of limestone powder content on fresh and hardened properties of SCRM. SCRM mixtures were prepared using crushed sand partially replaced with limestone powder at varying percentages up to 30%. Results indicate that the limestone powder as sand replacement significantly improves the fresh and hardened properties of SCRM with a content ranging from 10 to 15%. The use of limestone powder in repair mortar and concrete application would offer technical, economical and environmental advantages for concrete producers.Self-compacting repair mortars (SCRM) are particularly desired for the rehabilitation and repair of reinforced concrete structures. The properties of SCRM can be improved by using chemical, mineral, polymer and fiber additives. In limestone quarries, considerable quantities of limestone fine powder are obtained during the process of crushing rock. These fine powders are being collected and their utilization is a big problem from the aspects of disposal, environmental pollution and health hazards. The introduction of limestone powder as cement and sand replacement present interesting possibilities to reduce the cement cost production, CO2 emission and the conservation of natural resources. The effects of limestone powder content in crushed sand on the properties of SCRM are not studied. An experimental study was undertaken to find out the effect of limestone powder content on fresh and hardened properties of SCRM. SCRM mixtures were prepared using crushed sand partially replaced with limestone powder at varying percentages up to 30%. Results indicate that the limestone powder as sand replacement significantly improves the fresh and hardened properties of SCRM with a content ranging from 10 to 15%. The use of limestone powder in repair mortar and concrete application would offer technical, economical and environmental advantages for concrete producers.Self-compacting repair mortars (SCRM) are particularly desired for the rehabilitation and repair of reinforced concrete structures. The properties of SCRM can be improved by using chemical, mineral, polymer and fiber additives. In limestone quarries, considerable quantities of limestone fine powder are obtained during the process of crushing rock. These fine powders are being collected and their utilization is a big problem from the aspects of disposal, environmental pollution and health hazards. The introduction of limestone powder as cement and sand replacement present interesting possibilities to reduce the cement cost production, CO2 emission and the conservation of natural resources. The effects of limestone powder content in crushed sand on the properties of SCRM are not studied. An experimental study was undertaken to find out the effect of limestone powder content on fresh and hardened properties of SCRM. SCRM mixtures were prepared using crushed sand partially replaced with limestone powder at varying percentages up to 30%. Results indicate that the limestone powder as sand replacement significantly improves the fresh and hardened properties of SCRM with a content ranging from 10 to 15%. The use of limestone powder in repair mortar and concrete application would offer technical, economical and environmental advantages for concrete producers