What are the characteristics of a good quality concrete?

GOOD QUAILTY FRESH CONCRETE  :

1 SLUP TEST UNDER LIMITS

2 TEMPRATURE OF FRESH CONCRETE UNDER LIMIT

3 GOOD WORKABILTY 

GOOD QUAILTY HARD CONCRETE 

PROPER SURFACE FINISH 

PASS ALL COMPRESSIVE STRENGTH TEST 

I not repeat that who has been already said. But It's clear that you must have good aggregates, cement, and a water of good quality. There have a lot of condition to succeed a good concrete.

The formulating must be doing by your laboratory who must determining all characteristics.

Respecting the delivery times, don't add water, use adjuvents for improve the manoeuvrability or water reduction. There are a lot of solutions for resolve the problems. 

Don't forgot to do test to durability, slump, resistance,... 

Dear Mr. NKURIKIYIMFURA ALFRED sorry for delaying in answer..

Basic philosophy of the quality of concrete is that the concrete must be economic, sound, durable, and homogenous mixing of all ingredients and delivery on time i.e.  in compliance to client requirements.

Many factors are involved to maintain the quality of concrete such as:

1.     

2.     Before Mixing we need to ensure that the either required materials are capable to produce quality concrete or not.  Capability of the materials shall be checked by applying some physical / Mechanical and chemical testes.

3.      During mixing give enough mixing time to make the concrete as homogenous as possible (mixing time should not be less than30sec for normal concrete and at least1 min if GGBS/Fly ash / MS are used.

4.     Keep Minimum water to cementations ratio (depend upon the nature of concrete i.e. either normal concrete or durable concrete)

5.     Water should be salt free.

6.     Water should be child and to maintain the temperature use flaky Ice.

7.     When u get freshly mix concrete ensure slump, temperature, bleeding, Air Content, fresh density, yield etc are under given requirements.

8.     Allow the concrete offload on site considering the temperature of concrete should not excess more than32 ˚C and ambient temperature less than42 ˚C

9.     When the concrete get set (harden) it should be less permeable, Durable etc. 

 hHope details shall comply with your needs and let me know if you are not satisfy with this reply I will reply you once again with deep details.