Mechanical Properties Of Ecological Engineered Cementitious Composite (ECO-ECC) With Recycled Brick Powder Under Low Temperature

Engineering cementitious composite(ECC),which was called ultrahigh-toughness cementitious composite(UHTCC),a new type of cementitious material that is suitable for durability repair of deteriorated concrete structures and also is a type of fiber-reinforced cement-based material developed in recent 20 years.Due to its excellent compression performance and bending toughness,ECC has used in civil engineering.Moreover,ECC has excellent durability and long-term performance due to the PVA fiber and quartz sand used in preparation of ECC.In recent years,due to the acceleration of increasing of construction waste and renovation in the city and rural area,the amount of waste sintered bricks have been produced.We have seen that nowadays,the construction waste and renovation waste are directly transported to suburbs or country side.The construction waste and renovation waste need large of landing fill.During the transportation,it generates dust which cause seriously to the environment.In this paper,the purpose of this experiment is to study the reuse of resources and reduction of using natural resources,reduction costs for civil engineering in China and around the world.In this experiment,the use of recycled brick powder to replace quartz sand with a particle size between 75 μm to 200 μm for preparing ECO-ECC and cured under low temperature.The compressive test,flexural test and bending test have been conducted according GB/T17671-1999(inspection method of cement mortar strength)was carried out two type of concretes: the first one is the ECC which use the natural materials and PVA fiber.The second is the ECO-ECC material was contained PVA fiber and the recycle material with four difference type by mass combination at 25%,50%,75% and 100% of recycled brick powder(RBP)and used PVA fiber equal 1.75% by mass.The specimen was cured under low temperature until the test date(7days)after demold,and using low temperature are 0℃,-10℃,-20℃,and-30℃.PVA played in the important role for increasing strength to the specimen.The main purpose of the research contents and conclusions in this paper are follow as below:(1)The recycled brick powder is used to replace quartz sand,the 7 days compressive strength and flexural strength of the ecological engineered cementitious composite(ECOECC)gradually decrease with the decrease of temperature;at the same of this condition,the compressive strength and flexural strength also decrease with the increase of recycled brick powder amount.The better temperature that should be cured is 0℃ and the recycled brick should be use is 25%.(2)The cracking deflection and cracking strength of ECO-ECC under four-point bending load are decreased with the decrease of temperature(decrease from 0℃,-10℃,-20℃ and-30℃);when the recycled brick powder amount increase(increase from 25% to50%),the cracking strength is decrease but the cracking deflection is decreased;when the RBP amount increase(increase from 50% to 100%),the cracking strength is decreased.(3)The ultimate bending strength and ultimate deflection of ECO-ECC is decrease with the decrease of temperature;the ultimate bending strength and ultimate deflection increase when the recycled brick powder increase to 50%,but it decreased when the recycled brick powder amount increase to 100%;the higher value is better when the specimen cured under 0℃ and the recycled brick powder amount is 50%.