If concrete is crack free,deleterious substances can be avoided entering the body of the material,that may corrode the rebar or encourage freeze/thaw damage.This paper examines a self healing system of cementitious ma...If concrete is crack free,deleterious substances can be avoided entering the body of the material,that may corrode the rebar or encourage freeze/thaw damage.This paper examines a self healing system of cementitious materials.Microbial induced calcite precipitation was used to heal cracks in concrete with calcite using bacillus bacteria in alkaline conditions to generate a calcite filling material.Self healing of cracked prisms was determined using a water flow and absorption test and the results were expressed to record the healing as a percentage.The findings of the tests showed that a significant degree of self healing had taken place after 56 days after inducing a crack to the concrete prisms and the water flow test was appropriate to determine the degree of self healing taking place.Limitations of this process are such that the process requires a biological laboratory to create the spore impregnated aggregate.Once the aggregate is prepared,the batching process is essentially the same as any normal concrete.A practical use of this system could be developed using cover panels of self healing material to act as permanent formwork,thus placing the healing ingredients where they are needed at a minimum cost.The system has huge potential for the creation of a self repairing sustainable infrastructure.展开更多
This self repair system is based upon harmless ground borne bacteria as the self-healing agent.The bacteria are activated after the concrete is cracked and the bacterial spores are exposed to moisture and air.The bact...This self repair system is based upon harmless ground borne bacteria as the self-healing agent.The bacteria are activated after the concrete is cracked and the bacterial spores are exposed to moisture and air.The bacterial reproduction process creates a calcite by-product which fills the cracks in the concrete.By sealing the cracks in concrete,an effective barrier to air or liquid borne deleterious materials are formed and as a consequence of this,enhanced durability is achieved in the structure,result-ing in lower life cycle costs.The concrete/mortar prisms were cracked and tested for water flow.They were then left for 56 days to heal and were subject to a test for water tightness.Healing was observed and a reduced water flow(74%and 32%healed)measured with the healed samples when compared to the specimens that were cracked and subjected to a water flow test without any healing agent.The number of samples were limited and a larger scale test is recommended for further work;however,this is a proof of concept of the process of healing and testing.展开更多
文摘If concrete is crack free,deleterious substances can be avoided entering the body of the material,that may corrode the rebar or encourage freeze/thaw damage.This paper examines a self healing system of cementitious materials.Microbial induced calcite precipitation was used to heal cracks in concrete with calcite using bacillus bacteria in alkaline conditions to generate a calcite filling material.Self healing of cracked prisms was determined using a water flow and absorption test and the results were expressed to record the healing as a percentage.The findings of the tests showed that a significant degree of self healing had taken place after 56 days after inducing a crack to the concrete prisms and the water flow test was appropriate to determine the degree of self healing taking place.Limitations of this process are such that the process requires a biological laboratory to create the spore impregnated aggregate.Once the aggregate is prepared,the batching process is essentially the same as any normal concrete.A practical use of this system could be developed using cover panels of self healing material to act as permanent formwork,thus placing the healing ingredients where they are needed at a minimum cost.The system has huge potential for the creation of a self repairing sustainable infrastructure.
文摘This self repair system is based upon harmless ground borne bacteria as the self-healing agent.The bacteria are activated after the concrete is cracked and the bacterial spores are exposed to moisture and air.The bacterial reproduction process creates a calcite by-product which fills the cracks in the concrete.By sealing the cracks in concrete,an effective barrier to air or liquid borne deleterious materials are formed and as a consequence of this,enhanced durability is achieved in the structure,result-ing in lower life cycle costs.The concrete/mortar prisms were cracked and tested for water flow.They were then left for 56 days to heal and were subject to a test for water tightness.Healing was observed and a reduced water flow(74%and 32%healed)measured with the healed samples when compared to the specimens that were cracked and subjected to a water flow test without any healing agent.The number of samples were limited and a larger scale test is recommended for further work;however,this is a proof of concept of the process of healing and testing.
